I take no credit for this. I also hope it is not a repost but it is a very lengthy read none the less and informative to anyone I thought. The post was from a website here...compliments of member Broke_as_****
Destroying the world in your Z32: Tuning tips
*DISCLAIMER*: The various evil in this post about things you can do to your car may have certain side effects:
-Destroy any claim to being street legal
-Increased wear on/destruction of: tires/gas/clutches/pistons/transmissions/various other parts not to mention tearing the leather off the seat when your ass cheeks clench shut like a vice because you down shifted from 5th to 3rd on the freeway in a 500+rwhp Twin turbo.
-Dying in a firey crash to be covered by all of 30 seconds of local news coverage at two in the morning because you have the driving skills of a blind retarded carrot.
Bottom line: Be smart and realistic. Know your limits in all things. Mechanically (don't take your engine apart to swap pistons if you can't even open a juice box), financially (don't try to drop $1900 on inconel manifolds if you work at McDonalds for minimum wage) and most importantly, don't overdrive your skill level. Go to the track and take some learning courses. Get into cart and club racing. Learning to drive a car fast and hard safely is 200% above and beyond knowing how to make the car go around a corner. Don't forget that when you are upgrading a car, if you are paying for it yourself, you are essentially pissing money down the drain. Most people can only get about half or even a third the upgrade money out of the car when then go to sell it (IE, $15,000 car with $15,000 worth of go-fast parts for sale for $20,000) And given that you decide to proceed with said money wasting proceedures, make sure you have a defined goal in mind and plan out how to get to that goal before you make any purchases. Yeah it might be cool to say you have huge, high tech 700BB turbos in your car but if you don't plan on doing an engine build you probably won't be able to take full advantage of them and it's a waste of money. Easiest way to go about it is to set a power goal or 1/4 mile time or whatever, study up on the cheapest, easiest, safest way to get there. Also, if you plan to do any of the work below yourself, get a factory service manual. They can be expensive, up to $150 if you have to buy from a dealership, but it will pay for itself eveytime you don't have to spend five hours in the middle of the night staring at something trying to figure out where it goes, how it works and whats wrong with it.
Path to Power: Handin' out the beat downs in a Z32 Twin Turbo
Going past stock and getting to 3rd Base: A Stage 3 TT is generally considered an intake, cat-back and ECU upgrade, giving you an extra 100hp or so at around 11-14psi of boost. This translates into 300-330rwhp depending on the individual car and other factors. Just about anyone with simple tools and half a brain can do these upgrades. I’ll go more in depth in this section just because this is as far as most people will go. I'll list NA potential gains here too since all these apply to the non-turbo as well. Be thankful because the VG motor, especially the TT, responds very well to upgrades and loves to make power.
First off, the cheap stuff:
Single Cone Intake: Pretty obvious, increases the rate at which your engine can inhale life giving oxygen. Many people make them, some of the better ones are the Jim Wolf popcharger, K&N popcharger, HKS and so on. This will run you about $100-$150 dollars for a good, washable, reuseable piece. All it requires to install is removing the nose panel, unbolting the stock air box and putting in the higher flowing unit.
Estimated Power Gain-NA: 5-10hp TT: 10-20hp
Cat-back exhaust: Well known every where cars are found. Increases exhaust flow, keeps the emissions required catalytic converters in place. These systems range in price, flow, and style but unless you are flowin big power, the power differences between any two given systems is usually small. Borla, HKS, LaBree and Jim Wolf all make great units. However if you get 8” wide polished cans that stick halfway out from under your bumper and look like shiny logs jammed up the ass of your Z32, I’ll be forced to beat you with them. Prices are anywhere from $500 to $1000. Installing will mean jacking up the car, unbolting the stock system from the cats and juggling the new pieces into place.
Estimated Power Gain-NA: 10hp TT: 20hp
ECU: Remapped computer. This is not so much a power upgrade as it is a safety issue, making it safer for your engine to run hard at higher boost. They do this by modifying timing retard, air/fuel ratio and a few other things. There is pretty much two places to get this if you are looking for a bolt in: Jim Wolf and the AshSpec. Each has been hailed, Jim Wolf's has been around longer. Each has a full line of chips that you can snap in once you start upgrading other things. AshSpec runs $250 with a $250 (where applicable) refundable core charge (money you get back when you send them your old part) and the Jim Wolf goes about $550+$500ish core charge. Now before you say, "Well **** that, I'm buying the AshSpec" remember that different people do different things to the ECU. I'm not trying to insult or support any given product here, what I am saying is that you need to do you're own research to make a decision that will work for you. At the time of this writing the AshSpec is only available for 90-92 NAs and 90-94 TTs. The Jim Wolf ECU is available for all years. And also remember there is a variety of other places that sell performance chips and whole ECUs so look around but beware of bad merchandise. There is some sellers that just take a stock chip and reprogram it to run rich or disable the intake air temp sensors or even do nothing more than remove the stock rev limiter and then try to sell them as "performance tuned".
-The stock computer is located under a wood panel on the passenger side, pull back the carpet from under the dash to see it. All you have to do is unbolt the old ECU from its bracket and the wiring harness connector end. Put the new one in its place and put all the bolts back where you found them.
-For the TT owners, you’ll get a set of boost jets with the ECU that partially block the air flow to the waste gates, letting you run more boost, usually about 12-14psi. These are small, round pieces of metal with a hole in the center that install in the wastegate hose that attaches to the "out" side of the intercooler piping. An aftermarket boost gauge is required at this point so you can keep an eye out for boost spikes and other turbo damaging problems. The balance tube on the top of the intake plenum to the rear has a hose off the left end that feeds the stock boost sensor. This will be disconnected and the connecting end for the new gauge installed. There is a hole in the firewall between the clutch and brake pedals that you can route the hose through up to what will most likely be a pillar mount gauge.
Estimated Power Gain-NA: 10hp TT: 60hp (~12-14psi)
At this point you'll probably be putting out in excess of 300rwhp and should be able to run consistent mid 12s in the 1/4 even without a dedicated drag setup. You probably have around $1500-$2000 invested in upgrades right now.
Going farther: Now we get into things that require more serious disassembly to install, a decent wrench with enough tools and some Z32 experience will be fine, automotive gimps add extra for labor costs.
Underdrive pulley: This is slightly more work, you have to pull the entire front of your motor apart. If you can do this with a timing belt change, do that. This will add another 10-20hp or so to your TT, mostly in the top end, because this pulley is smaller, which reduces the speed at which all the other pulleys run thus cutting the load on the engine. It will also be lighter, taking less power to turn then the heavy stock pulley. This upgrade runs $200 for the crank pulley or $400 for the whole set, both of which should include the different belt packages you’ll need to run these smaller pulleys.
-Note about UD pulleys: The stock pulley is equipped with a harmonic damper that basically absorbs the vibrations from the crank. A UD pulley is not going to have this. However, this has never been a problem with the VG as they are much more naturally balanced then say an inline 4 cylinder or other V6s. This is mostly due to their straight through firing order that loads the next cylinder as the one before it is unloaded. Many UD pulley equipped VGs have 50,000+ miles on them with no problems.
Down pipes: These replace the stock pre-cats that are located directly behind the turbos, putting a nice open pipe in there really helps to spool your turbos faster, sometimes up to 500 rpm faster, producing a noticeable 10hp gain. However, installing these is a major pain in the ass if you don't drop the transmission, if you can’t do that yourself, then you better add some money in for labor costs. These will run you about $500. Another option is gutting the pre-cats, kind of a ghetto downpipe. This involves removing the pre-cats and basically pounding out the catalytic bricks inside. Frankly I'm not into this type of stuff but there is plenty of info on how to do it. Try www.twinturbo.net
for more info.
Testpipes: Removing the last of the turbo-back stock exhaust. This fits between the downpipes and the cat back. These will add a little more power than the down pipes but at the cost of your emissions required catalytic converters. You can get pre-made, ready to order test pipes with high-flow cats already welded in if the car still needs to pass smog, but naturally, with the cats still on there the gains will be slightly smaller and the pipes more expensive. Figure these to be $400-500 and a 15hp gain without cats, $500-600 and a 10hp gain with. You can usually get custom made testpipes from a local shop cheaper than shipping a pre-made set but this is application specific so check around for pricing on both options.
Clutch: At this point the stock clutch will start slipping under heavier boost loads, so we upgrade to stronger bits. A clutch kit for this level will run around $350-500 dollars and will be much stiffer then the stock one.
Flywheel: While you have your transmission out for the clutch and the down pipes you might as well add a lightened flywheel to help the engine rev freer and the turbos spool quicker as a result. Since the flywheel acts as an energy storage device (the large mass of the flywheel helps keep the motor spinning to make it easier to drive) and takes power to turn, a lightened flywheel will pull less power from the engine to turn it. A stock unit is 25lbs or so and most aftermarket units are in the 12-15 lbs range so you can see how big a difference this can make. This will run about $400-500.
At this level you have a car generally known as a "Stage 5+" Z, basically all the easy bolt-on mods you can do. Your VG is probably putting down upwards of 375-400rwhp now and 11 second 1/4 miles are well with in reach given some sticky tires and slick driving. Upgrading has sucked approximately $3000-$4000 out of your pocket by now. This isn't really a bad place to stop. The small stock turbos and the mods you have done should give you little to no turbo lag, you have plenty of power, you haven't spent A LOT of money on upgrades and daily drivability is still pretty good.
Going beyond kid stuff: We are now getting to the limit of the stock fuel injectors and unaided pump gas. At point this you start getting into engine pulling, disassembly and possibly rebuilding. Prepare for big boost at the cost of a lot of money. Professional machining is required for some of this work, and unless you are a good mechanic with a small shop worth of tools at your disposal, you’ll have to find a real shop to do a lot of this. Also, by this point, you are looking at having your engine/car in pieces for extended periods of time. You can install a set of test pipes over an afternoon in your driveway but it will take you a while to rebuild the heads. If you are going to pull the upper plenum or do an engine pull make sure you have: Another car to get around in, a place to work and have stuff spread out in a manner where it's not going to get damaged or lost.
Have money too. Lots of it.
Fuel injectors: The stock 370cc units aren’t going to go beyond 15psi or so and thus we upgrade. Nismo units are generally considered to be the best, and with an item this critical you want nothing less. The Nismo units come in 555cc (90-94), 615cc (95-96) and 740cc (95-96) units, for this level, 555ccs or 615ccs will probably be all you’ll need. Either of these sets will run about $900. So why not get the larger 740ccs just for the **** of it? If you are running injectors that are oversized for your power level it can actually decrease power and increase risk of detonation and engine damage as larger injectors are less accurate. If you need the 740ccs for your 90-94 engine, you're looking at swapping the fuel injector wiring harness connectors with 95-96 model connectors and replacing or machining the lower intake plenum to match the newer style injector and fuel rail. There may additional changes needed, I haven't really looked into this aspect much so search around if this applies to you. To go beyond the range of the 740ccs, and we're talkin really big power here, Power Enterprises makes a 850cc injector set that will handle anything short of an utter max power quest.
-There has been issues with the earlier model (90-94) fuel injector style failing. This doesn't mean a 90-94 injector is a time bomb waiting to **** up your engine but if it is something you are concerned about then simply update to the newer style.
ECU upgrade: To run those larger injectors you’ll need to swap out the chip on your aftermarket ECU. This is fairly easy and cheap as upgrades go. $100 or so depending on where you source the chip and many times you can find the chip you need included with the next upgrade.
Dual intake: You'll want to split the intake pipes so you have one feeding each turbo once you get past 375rwhp or so. You can do it before this point but its not going to add too much extra power. The Jim Wolf unit is widely used and the newer DOOLZ intake piping by Ashspec is becoming popular as well. To run this upgrade you’ll need to upgrade the ECU, which is easily done while you’re upgrading the fuel injectors. This upgrade ranges from $300 to $600 depending on what is included in the specific kit.
Intercoolers: The stock intercoolers should be switched for higher flowing units around this time (if not before now) to feed the increasingly hungry turbos. It will drop intake air temp a good deal, making it safer to run higher boost and create an easier passage through the intake system. This will run around $1000 and usually only requires the removal of the front bumper. Some aftermarket intercoolers will need new duct work to force the air through them. And while many would look at the few large front mount kits that are offered for the Z32, an upgraded pair of sidemounts that use the stock positioning will work best up til about 700hp. Beyond that they are starting to become bottlenecks air flow wise.
Gauges and controllers: Once you start getting up in power it becomes more and more vital that you know what is going on in the engine and have more control over it. A basic boost controller and gauge will suffice for now but looking into more advanced units that can give you data on and control air-fuel ratios, engine timing and other engine vitals is a good idea and will be required futher down the line, not to mention being vital to getting the most out of your car with custom tuned injection maps and such.
Oil coolers and radiator: You'll want to install a higher capacity oil cooler and radiator at this point to shed some of the extra heat your engine is going to be putting out. A radiator will run you around $400. If you are going to be putting a huge capacity electric fan on, you'll probably want to look into boosting the alternator to make up for not only the increased demand from everything else due to higher power output but also the huge draw on your electrical system that a large fan will cause. Nismo sells the European spec oil cooler, which was about 3 times larger, Stillen has a nice oil cooler for around $200 but if you don't mind making a few connectors you can get a more generic model and fit it to your system for less.
Water/Alcohol injection: Basically all it is is a little nozzle that shoots water into your intake. Yep, water in the engine. Sounds bad does it not? But the amount of water is limited, a very light mist being shot into the hot dry air flowing through the intake. Its purpose is to cool the air being fed into the engine and help reduce uncontrolled detonation of the fuel in the cylinder (the power of the exploding gas in the confined area is incredible, if all the working bits inside aren't at the right place when the gas lights off serious damage can be done, to the point of literally blowing an engine to pieces). With the risk of detonation lowered, you can run more boost. Not a huge amount more but enough to see substancial power increases. And its just a good idea to be as safe as you can when you are talking about adding a lot of power to an engine. Alcohol-Water injection is basically the same as straight water injection except with the added cooling power alcohol brings. I'm not going to go into it in too much detail here because it basically needs to be tailored to your car for the best effect. If you are going to get a custom ECU chip then it would be best to add any type of water/alcohol injection system you are going to run and tune the car with the system active.
-Most systems are designed to come on only after a certain amount of boost has been reached. More advanced systems are paired with a custom ECU and take into account: throttle position, fuel/air ratio, intake and fuel temps, and a few other factors that can be programed in. This is one of those things you just have to tune relentlessly for the greatest effect. But even just a simple system set up to inject X amount at Y boost and only uses a simple progression of X+1 amount at Y+1 boost will do wonders for performance. This can be done at any time during upgrading, even just going from stock to make it safer to run hard on stock injectors and pump gas. However this usually does not come into play until boost levels start getting higher with upgraded turbos.
The following items will require an engine pull. Only ye experienced VG wrenches tread here. If you are having a performance shop do the work be warned: labor costs on a pull can be huge, sometimes equaling the cost of parts. If you are doing the work yourself, be warned you are now getting into taking things apart that: A. Don't like being taken apart B. Will cost you serious money to fix or replace and C. Could cause serious damage to the car and you if you get it put together wrong.
Greg Dupree Inconel exhaust manifolds: Repeat after me: Greg Dupree, thou art a Z God. He runs SpecialtyZ and has a knack for coming up with trick parts for the Z32. Stainless steel manifolds have been found to crack and fail in a Z32 so Mr. Dupree decided to go up the metallurgical food chain and made some tubular manifolds from the incredibly strong, light, and heat resistant metal, Inconel. These have been shown to make another 40hp and upwards of 50lbs of torque compared even to ported stock manifolds at just about every part of the powerband. They are simply a must have item for a high power Z32 TT. The downside, you guessed it, they aren’t cheap. $1875 dollars to be exact. That’s a premium indeed but the performance they offer just can’t be matched by anything else. Also to help take the weight off the manifolds, you need to install in or buy pre-made test pipes with flex joints in them. When buying the flex pipe equipped test pipes with the manifolds, SpecialtyZ offers a 1 year warranty on the manifolds, something fairly unheard of for performance parts like this and speaks volumes about their strength.
-If you don’t want to drop the cash on these, you can get ported stock manifolds for about $400 and they will help reduce lag and increase top end power as well as fatten your power band but not in anyway as dramatic as the inconels. Basically if you are dropping huge money on an engine build, cams and turbos etc and so on it makes sense to get the inconels too. To me anyway.
-Side note: There is other people making manifolds, Pentaroof for example. However, many of these will only mount certain types of turbos or are made from metals of lesser durablity. If anyone knows of a set that can rival the Greg Dupree manifolds, please PM with some info. I merely listed the Specialty Z set as it has been my experience that they are generally considered to be the best in the market.
Turbos: Yeah, that’s right, we’re talking badass SOBs now. Debates over which turbos best suit which application are fierce and loyalty to an specific turbo can be border line fanatic. A person can go crazy trying to find the correct turbo for their car (especially if they don't have a clear picture of what they want from the car) and having raving, drooling brand loyalists confusing things doesn’t help. This is going to be a big investment in cash and is one of the primary factors in the feel of the car. Do a lot of research on this before choosing and remember that each car is different so a turbo set that makes 500rwhp on one car may make 540 on another or only 470 on a third car. Alot of that variation has to do with the supporting upgrades done to the car (exhaust manifolds, cams, etc). A good general rule of thumb with turbo selection is to have a power goal in mind and find the smallest turbo that will still support that much power so you'll suffer the least amount of lag and gain the greatest amount of response.
The stock turbos: Factory spec T25s. They're small. They spool so fast they'll make boost with nothing but a good hooker attached to one end. But as a smaller turbo, they're only going to flow so much air. They're pretty good up to about 16-17 psi, so if thats all you plan to run, by all means, keep the little buggers and save your money. However, if you want more than 350-400rwhp-ish then you'll have to upgrade. Chances are that if you are reading this, "turbo upgrade" is the first thing that crosses your mind whenever you're not thinking about boobs, as rare as that might be for some people. Anyway, you can find a decent low mile set of stock turbos fairly cheap, $500ish for a pair, usually from someone doing a turbo upgrade, or rebuilt ones for a bit more. However, rebuilt turbos tend not to have a great track record. Brand new in the box OEM Nissan T25s retail for about $1500 for a set.
As for upgrading, the generally accepted turbos for this range are:
-Jim Wolf Sport 500: Not a huge upgrade over stock but it will produce about 75-100 more rwhp then the stock T25s with almost no increase in lag. As the smallest of the common turbo upgrades, they spool like a crazy mofo. These can get you upwards of 450rwhp or better and run about $1500-$2000.
-Jim Wolf 530BB: BB stands for ball bearing, meaning these things will spool harder than plain bearing turbos. SpecialtyZ has gotten 520rwhp with these and from what I’ve been told, that was without performance cams, a lot of ECU tuning or portwork on the cylinder heads, so more may be obtainable, perhaps even into the 550rwhp range. $2900ish
-HKS GT2530: These have a cult following. And rightly so, they spool hard and have netted in the range of 500-550rwhp with some well tuned cars getting upwards of 580rwhp. Also a ball bearing unit, they have more lag than the 530BBs but have been proven to make more power. These run about $3800-$4200 and come with varying amounts of gaskets, tubing and related hardware depending on the source of the turbos.
-PE 1420: One of the less widely used turbos, the 1420s are ball bearing units and a good balance of power and lag, netting upwards of 550rwhp. These are priced $2400-$2900 depending on the kit and supplier.
-Jim Wolf Sport 600: An older turbo on the market, they are still highly potent. The right tuning can get you upwards of 550rwhp. Pricing is usually around $2500 but as they are plain bearing turbos and are larger then 530s or GT2530s they’ll have more lag.
-GReddy TD05-16G: One of the largest turbos for this range, they can make upwards of 600 rwhp and come with a set of stainless steel exhaust manifolds for quicker spool up as well as the various gaskets and tubes you’ll need. Kits run around $4200-$4500.
There are many other turbos out there for the Z32, I've only listed some of the more main stream ones. If you can do a bit of fab work on brackets and oil/coolant lines then you can get just about any turbo you want and mount it up to your car.
Cams and valve springs: Since you are going to have the engine out for the turbos then you’ll probably take the time to get another 40rwhp with a set of performance cams and the required performance valve springs. There are a few different cams on the market and their prices are roughly the same, about $1000 for the performance cams plus about $350 for performance valve springs. Jim Wolf does offer a mild set of cams for about $600 that can use the stock springs, making the install almost bolt in compared to swapping springs. Obviously these aren't going to make as much of a power difference as the bigger cams but its much easier. However, given a higher mileage engine, it is a sound idea to replace the springs, be it performance or stock, as they get worn over time. If you are getting the stiffer springs or just replacing the stocks, it will most likely require a professional install. This is because they are pressed together as a package of spring, valve, oil seal and a few other things all stuffed down into a little hole under the lash adjusters. It takes some specialty equipment and training to pull it all apart and put it back together right. By comparison, replacing the just the cams is really simple, just pop the valve covers off and there they are.
-You can do cams before getting all the way to engine pulls and turbo upgrades but it will make less of a difference at lower levels. At stock, a set of cams may give you a mere 10-15 hp boost. However at higher levels, they can add 30-40rwhp through out most of the power band, improve upper rpm range performance dramatically, quicken spool up and improve throttle response. There is many advantages but usually not unless you are doing the whole engine.
-Another thing about cams, they will change how the engine responds dramatically. Cams determine where the power starts, how hard the engine revs through a certain range and last but not least how the car drives at low speeds. Performance cams are setup to deliever power in the mid or upper rpm ranges while most stock cams are setup for good idle and low end power. Cams designed for max power may cause slight hesitation and loss of power in the low end. Side note on cams: as you are radically changing the duration of the intake and exhaust, you may push your car over the limit as far as emissions tests are concerned.
Forged Pistons: Even though they are cast pieces, the stock pistons can take a **** of a beating so this is not an absolute if you are going for the 400-500rwhp range and in fact I wouldn't bother with it if you're not going for more that 500rwhp (assuming your engine is in atleast fairly good shape). There are Z owners running 25+psi of boost and 600+rwhp on the stock bottom end. It's all about tuning the engine correctly to avoid piston killing detonation. Sheer power output is not going to destroy a motor. But its always good to make everything stronger. The stock cast pistons are not going to hold up against detonation at higher power levels. The sooner an engine build is done, the less you'll worry later on after you have the car together, afraid to push your new turbos hard because you don't want to fracture a piston if you start getting engine knock. If you are going to run more than 500rwhp with any amount of frequency and are doing an engine rebuild anyway then you’ll probably want to install some forged pistons. The stock cast pieces are coming up on the edge of reliability at this point and there is no sense blowing a motor when you can get a full set of forged pistons for $600 or less.
-This will almost certainly require professional installation unless you happen to be a professional with a machine shop in your garage so better add some money for that, how much will vary depending the shop and the condition your engine is in. At this point your engine is in pieces so make sure you have a place for everything if the whole thing isn’t in a shop somewhere.
-Get whatever pistons you go with heat coated and balanced while they are out. Costs around $200 to get the six set coated with a ceramic (anti-heat) top and moly (anti-friction) side coat. That can save an engine, especially one that runs as hot as the VG. A set of good, low mile stock pistons that have been heat coated and balanced will be good for all but the highest power applications given proper tuning. Overkill is good when building an engine but there is no point in droping alot of cash on forged pistons if your power levels don't really need it.
Connecting rods: The stock Z32 rods are some of the strongest stock rods ever put into a production engine and are good til 600rwhp or better so this is also not a "must have" upgrade. You can get a good set of forged rods (Eagle H beams for example) for about $600 with the pieces needed to put it all together which should include a trick ass set of ARP rod bolts. If you are going to use the stock rods (and have them reconditioned to proper length) then you can pick up the ARP rod bolt set for $60.
A word about built engines: People tend to refer to a engine with all forged and balanced internals as "bullet proof". Stupid can destroy anything. While a built engine is going to be able to take more abuse, nothing is fool proof. A well tuned stock engine will be safe to 500rwhp or better. A fully built engine tuned by Jack Mehoff is a grenade at stock boost levels.
Going big or going home: When doing an engine build you have alot of options as to how far to go and how much money to spend. A typical rebuild with just a set of forged pistons will run at least $2000-$3000 for the long block depending on the shop you go to and any stock pieces that need to be replaced. Obviously somethings (like gaskets, main seal, cam seals etc etc) are all going to need to be replaced but sometimes given a low mile engine and moderate power goals you can reuse the stock lifters, waterpump and things like that. However, given higher power goals and longer parts lists you can spend upwards of $4000-$5000 on the short block easily and have upwards of $7500 in the complete long block. Add all the other pieces of the engine in and you can have $10,000 invested in the engine very quickly even without an expensive pair of turbos on it.
Other engine parts and work: To put in the pistons you’ll need to straighten the cylinders and clean the walls up, which needs to be done at a machine shop. That costs money. Also while its out you should replace the main and rod bearings and have the stock crank checked. That’s more money. And when you go to put it together you’ll want a new head gasket set (stock head gaskets are more than enough for anything under 700+hp) and some good ARP main and head bolts. Yup, that’s more money. Call around to local shops for prices on labor.
-While you are taking everything apart, getting your intake plenums honed internally (polished to increase airflow) and a set of ported heads can boost the power. A boxed up ready to ship set of intake plenums can be found at www.stillen.com
, however you must trade your original plenum to them or double the cost with a core charge. The head porting is usually best done at a local shop that knows what its doing, this can be expensive so check around for rates. However I will point out that the stock 300ZX heads flow pretty **** good for stock bits and there isn't too much in the way of actually widening the ports that can be done. Mostly head work for a VG30 means polishing up the interior to flow easier. Its not really a must do item but it does help increase air flow through the engine and since the engine is apart and you are spending all this money anyway...whats another bit of cash right?
-On that note, if you want to tweak your plenums a bit without dropping alot of cash something you can do is bolt the upper and lower plenums together before engine assembly. Using a long neck dremel, file or whatever else you have to, start shaving away the metal that hangs out where the plenums don't exacly match up. Once they are matched up, take some sanding/buffing wheels on your dremel or just some sandpaper and smooth out what you can reach of the plenums. After doing this be sure to clean the metal shavings and dust out of the plenums thoroughly. You can do the same thing by bolting up the lower plenum to the heads but if you do remember that it's very important to keep the by products of the process contained to be cleaned out. Overall, it's not going to make a big difference, but if you are strapped for cash and want to give your Z as much of a boost as you can, it's something to consider.
-Your stock fuel pump flows enough for about 600hp at the stock 12 volts. An aftermarket fuel pump will flow more at the same 12 volts or you can get an amp kit that will raise the power to your stock pump to 16 volts, still well with in the safety margin of the pump so you really don't have to worry about it unless its has big mileage numbers on it. A boosted 16 volt stock pump is good for about 750hp. Also note that the stock pump is a two speed piece, meaning it operates on low voltage then kicks into high gear when making boost. An aftermarket pump usually runs full voltage the entire time, giving some pumps an annoying high pitched whine at low speeds.
-If you are going to be doing a rebuild anyway spend the money on new PVC tubes, complete gasket set and all that happy crap. No sense putting new pistons in an 150,000 mile engine because everything else will still have 150,000 miles on it. A bit of money and time spent while the engine is out can save hours and hours of work later. Especially if you are doing a swap or replacement with a JDM motor, as they tend not to be in great shape.
-Getting good replacement motors is getting harder and harder as the years roll on. Most will either have high miles or will have sat somewhere for years. Now depending on what you plan to do with the car you can make the choice to rebuild the replacement motor while it is out or just drop it in. If you just plan on cruising, its not a problem to drop in a motor that already has 80,000 miles on it. Getting the motor to replace the blown one in your "one 1/4 mile too many" weekend toy? Probably want to rebuild that one. And speaking of which, if you have high miles and a good block (IE no pistons have exited the block involuntarily) then it is usually cheaper and easier to get the engine rebuilt rather than replaced. A overbore on the cylinders, block cleaning, head rebuild and all that other work that will bring a motor up to virtually show room new condition shouldn't cost more than $1500-$2000, the cost of a clip or used replacement motor. Another major plus of this is now you have a motor with no miles that you can be sure is good AND you can drop in some forged pistons and whatnot while you are rebuilding and have a solid bottom end to play with. AND by going the rebuild route you keep the available pool of engines larger for us all, doesn't that make you feel all warm and socially responsible inside?
Your new engine and you: You've saved and waited and built and ordered and slaved away and you finally have it. You're engine is the shizznit. Titanium rods, big cams, heat coated everything, flowed heads, oversized valves...and zero miles. And that presents a problem/opportunity. Any good engine builder will tell you that the key to power and reliablity is ring seal. Don't break your engine in properly and you'll suffer low compression for the rest of the engine's life span. It's not going to blow up on you but it won't be putting out what it could have and the motor isn't going to last as long.
So then, that being said, how do we ease our slick new power plant into the world? Well thats where the war starts. Some people will give you exact mileages and proceedures to follow, others will tell you outright that if it's going to run hard it's going to run hard and not to worry about it. Frankly there is too much conflicting information out there and I'm not going to cover it all and start some unholy battle of the tuners. Suffice to say, follow some general guidelines and you should be alright:
-Figure a good break in window is 1000 miles, excessive by some standards in fact
-Don't rev the engine hard, keep it under 4000 rpm
-Don't go wide open throttle on it during that first 1000
-Don't let the engine idle or remain at one rpm for long periods of time
-Get a couple hundred miles on it and change the oil. Don't be too disturbed by the amount of metal you may find in the filter
-Change the oil again at 1000 miles or whenever you think it's ready
-Pay very close attention to any knocking, squeeking, groaning, scraping and any other noises not meant to come from an engine. Getting to a problem quickly will usually save the motor in the long run
Leader 4.10 rear dif gears: Richmond Gears produces a 4.10 ratio ring gear and pinon set designed by Leader Gears. These will reduce your final drive ratio and improve acceleration more than just about any other upgrade. The set runs around $700.
Non-turbo rear differential: The stock Twin Turbo rear end houses 3.692 gears and the stock NA is 4.083. This does require swapping out the rear subframe for an NA model and robbing the speed sensor off a NA transmission. The reduction will improve acceleration at the cost of top end speed. Run the math and it shows you'll lose around 20mph in the top end. But thats still around 170 mph so it's not a big concern. But just as food for thought, with upgraded valve springs you'll be able to get another 500 rpm out of the engine safely. FYI: Stock TT rear end + 7500rpm = 200mph. Just sayin.
Tuning: Nowadays, as it has been for quite a while, we list our upgrades as part numbers in somebodies catalog and brag about them in hopes of gaining some reflected glory from some big name tuner company. "Dude, I got a Blitz BOV, a GReddy Turbo and stick in my brain. The stick alone adds mad horsepower yo!" I blame Cardomain.com. Anyway, while it is true that an engine and car as a whole are made up of component parts and we have to individually upgrade these parts, it takes more than throwing together a bunch of sticker clad expensive hop up parts to get the most out of your car. On some level many people think of it as "If I add X turbo to Y engine with Z, T and R upgrades, I'll get D hp, its just simple math." The manufacturers listed power gains are a decent indication of what your getting into but after the first round of simple bolt on parts, all bets are off. Thus we need to hone the brain of our cars (fuel injection maps, ignition advance/retard, air fuel ratios and etc) to get all these pieces from various companies working together properly, especially once you start getting into turbo upgrades, upgraded manifolds and all that happy crap. Meaning: strapping your car to a dyno, cracking open the ECU and hooking it up to a computer to find the optimum settings. An off the shelf ECU upgrade is performance tuned compared to a stock piece but each individual car will be unique even among the same model and that aftermarket ECU has to work in all of them. So isn't going to be the ideal setup for yours. You may be getting lean spots and hesitation because of intake and exhaust upgrades. BOVs can cause rich off throttle conditions. Boost controllers and AFCs alter whats being fed into the engine in dramatic and some times harmful ways. A custom tuned chip can for the most part eliminate all that and get power from what were dead spots in the power band. If you are going far enough to upgrade the turbos, I would strongly recommend dropping some money to get a custom tuning done. And speaking of which...
The Zemulator: So there is a guy named Ash who is badass to the point of making ninjas look lame. He has his own line of sport tuned Z32 ECUs, intake kits, brakes etc and so on. Dude has earned your worship as a Z owner. Anyway, the Zemulator goes in place of the ECU chip in your performance tuned ECU. Just plug it in and it will run the car with the program already in it. Now, hop your happy ass on a dyno and proceed with a base run. Plug the cable off the Zemulator chip into a computer loaded with the Zemulator program that comes with the chip and proceed to tune to your hearts content. Fuel maps, ignition timing, injector size, intake type, just about anything and everything can be tweaked as needed. Ever hear someone with a complete stand alone engine management system raving about how badass they are? This is a bolt-on stand alone system made just for the Z32. No, it doesn't get much better than that. A good tune job has seen gains of 50+rwhp or more. This obviously requires someone who knows what they are doing. That being said, at a price of $600 for chip and program, this is something that everyone who is dropping the money for a turbo upgrade should look into.
-More tuning stuff to be included
Running with the Big Dogs: After you start getting past 600rwhp you start getting into the limits of a lot more stock systems. Fuel pump, transmission, ignition and a few other things you really don’t want to have go out on you. This is the realm of enough power to alter the fabric of the universe. Once you get to this point, you’re reaching the limits of off the shelf parts and you have to start more custom work as far as system set ups. Nitrous spool kits come in here to help reduce the lag of the huge turbos needed to produce this kind of power.
Fuel system: The stock fuel pump is good for 600hp or so, provided it's in good condition. After this point you can get an aftermarket high flow unit or just add a 16 volt amp kit to the stock pump. If you are going to go with the amp kit, I would suggest getting a new stock pump.
-The stock fuel rails will flow enough for just about anything. The only real reason to upgrade them is because the larger and larger fuel injectors you'll need will at some point no longer fit into the stock rails. Power Enterprises 850cc kit for example comes with it's own set of rails. If you need anything beyond the 850cc kit (900hp territory) then you'll probably have to get a set of huge ass injectors and fabricate (you'll be doing alot of that) custom fuel rails to fit.
Engine: A performance engine build is going to be required for these power levels. And there is going to be more work done at this level then there was at the previous.
-Forged pistons, perhaps of lower compression (for example: 8.0:1 rather than stock 8.5:1), and forged rods are definately going to be found here.
-Upgraded valve springs and a big cam set are almost certainly on the list if for no other reason then to help spool the large turbos now required. It would also be wise to look into solid lifters and upgrading the valves and valve guides to stronger material (titanium, inconel, sodium filled etc) if you are trying to push huge power or get 8000 rpm out of your engine or something like that. A 8000 rpm VG is certainly doable, usually just a matter of money. And wouldn't that be badass?
-There is alot of little details that can prove beneficial when building a high performance engine. For example, honing up and polishing the coolant and oil passages. Nitrating the cam lobe surfaces. Putting in a dry sump oil system.
Intake: Larger intercoolers, like a very large front mount, will come into play. Water/alcohol injection is strongly recommended at this point. There are oversized throttle bodies on the market for the VG. However given the length of the intake piping, you'll have to upgrade the whole system from filter to throttle body to see any substancial gains. That will mean custom making all your intake piping, not the most expensive thing in the world but it will usually have to be done a professional shop.
Electrical: Your stock ignition system could use a boost after 600 some horsepower. Any number of the aftermarket ignition amps will work for this task. The stock Twin turbo 90 amp alternator will put out enough juice for these amounts of power when combined with an amp. If you are going to putting in a huge capacity electric fan, run huge boost and have a stero system with more bass than a nuclear weapon then you might want to look into installing a larger alternator.
Turbochargers: You are now getting into some really massive turbos. Not massive in the context of the ginormous shells a single turbo Supra might run but very massive considering you only have 1.5 liters pushing it. All of these turbos require substancial engine building and supporting upgrades to perform at their best. A nitrous spool kit would definately come in handy here.
Jim Wolf Sport 650: Big as you can fit with no substancial fitment work to the car or the turbo. It's rated at the namesake 650hp at the flywheel but history has taught us something about Jim Wolfs turbos, a well sorted car with a good tune job can usually match their flywheel ratings at the wheels. $3300
Jim Wolf 700BB: A newer turbo on the market, this is a revised and updated version of the venerable GT28RS, aka the "Disco Potato", that kicked so much ass back in the day. These turbos put some serious power to the ground, upwards of 700rwhp given the appropriate supporting upgrades. They run around $3600.
PE 1820: A big ass turbo from Power Enterprises. ~$3500
Suckin’ air: The Z32 NA
Actual upgrades for the NA are limited, without forced induction you’re pretty much stuck with whatever cheap external upgrades you can do before you are looking at a complete engine rebuild for more power and probably a really big nitrous tank. As listed in the basic upgrade section at the top, an intake, cat-back and ECU are all going to be on your list. The underdrive pulley, flywheel upgrade and a set of test pipes will help here as well. Now what? Well you NA guys can say that you have atleast one mod the turbo guys can't have:
Tubular Headers: An exhaust manifold minus the turbo mount, otherwise refered to as "header" or "headers" in this case. A set of stainless steel or coated steel headers can really free up your NA engine, to the point of making another 20hp. These can be installed while the engine is in the car. This can run you upwards of $600. That being said, you will see much smaller gains from these if you already have a full aftermarket exhaust. If you have a set of test pipes and a good cat back, your upgrade money is probably best spent on something else.
If you've done the headers, test pipes, and cat-back, your NA is probably going to be loud as a mother****er. Check your local noise ordances.
Okay so thats done, what else? Well you're running out of bolt on parts so you'll have to start getting more creative.
Nitrous: Obviously an option, the stock bottom end can withstand upwards of a 100hp shot of the cold juice. Only real problem here is that even "bolt on" kits usually require a certain amount of modification or even fabrication of fitment parts. This should probably be left to a shop if you aren't equipped and skilled enough for the task. Also, nitrous is illegal in some places, in extreme cases they'll impound your car if you have an armed system (read: bottle valve open and ready to go). And of course, when the bottle is empty its probably time to head home. As a side note: to run large shots of nitrous you will almost always need large bottles. Large bottles lose pressure quickly, reducing the effectiveness of your system as you continue to use it. Its not uncommon for large bottles to become ineffective after even just a few hard hits.
-With nitrous comes the need for more fuel. Easy enough, simply grab an set of stock Twin Turbo fuel injectors and you're in business, given you have the appropriate ECU to run them. Luckily enough, if you are getting into the nitrous stage of upgrading, you should have already invested in an aftermarket ECU, of which there are many already setup to run nitrous.
Okay we got our boost for off line or the dash to the finish, what can we do now. Well, not much. At this point you're really starting to look at having to rebuild and the engine to run bore/stroker kits with larger, higher compression pistons and of course you can add ever increasing amounts of nitrous to the plan. That costs alot of money. And really, you're not going to get much for that money. A tricked out NA engine built to the hilt will probably make some where in the area of 300rwhp, maybe some more. Of course you can add another 200 with nitrous but thats temporary. And you are passing out of anything in the range that could be called "streetable". This is where you are going to have to be creative.
A word about boost: It is possible to run boost on the stock NA 10.5:1 compression ratio. Not alot of course and you have to be very careful about how you go about this and expect to have problems along the way. If you are going to do this I very strongly recommend that do an engine build with forged pistons, and yes, people make forged 10.5:1 pistons. Race grade gas is pretty much a must have to go this route. You'll be limited to about 8 psi or so even with all precautions taken. Thats not alot of boost in the context of the 30+psi the higher power twin turbos push but fortunately it doesn't take much to give you alot more power. And since you are using smaller turbos to make a small amount of boost with higher compression pistons, turbo lag shouldn't be any kind of a problem. Or there is other options. And here is where we depart from the main stream. Put a screwcharger on your Z32 NA. This is along the lines of the Vortech systems for the S2000 and the 350Z. They both have high compression pistons and only run 6 psi or so but as you can see from the results they've posted, it can increase power like little else can. Even just 5 psi of boost can make another 75hp. And since superchargers in general prefer lower boost levels whereas turbos prefer higher boost, its in general a better idea to go this route. In my mind, the GReddy and Jim Wolf turbo kits for the 350Z are a complete waste of turbos. Really, using TD05s or 530BBs to make a mere 6psi boost is like using a nuclear weapon to clear out a ground hog tunnel. Anyway, to go this seldom walked path expect to do alot of fabricating and tuning on your own or shelling out big dough to have someone do it for you.
Thinking outside the box and getting really off the the ****in wall
There is any number of things you can do if you don't want to stay with the stock pieces. Exotic engine swaps (anyone got a spare 427?), switching fuels to nitromethane and anything else you can come up with. Frankly, I want to see a Z32 with a helicopter turbine under the hood. Rev right past 50,000 rpms so you can probably have a direct shaft 1:1 drive ratio with a staged clutch pack like top fuel dragsters, it makes killer torque right off the line and all across the power band (which in this case is everywhere) and since its just spinning rather then the jolting up and down of piston engines, these things run uber-smooth.
The VH45DE engine swap: This has been done by a few people and there is apparently even a kit in the works. The engine is the aluminum block 4.5 liter V8 out of an Infiniti Q45. 100lbs lighter than a VG30DETT, DOHC, 32 titanium vavles, forged crank/rods/pistons and some other heavy duty hardware. Makes 340hp even with the Q45s luxury biased tuning. A good intake and exhaust setup should make about 400hp. Add to that some turbos, about 10psi of boost (with the needed anti-detonation precautions) and some other performance upgrades and you should be sitting in the mid 400rwhp range or better pretty easy. To go much further than that boost wise you'll have to take the engine apart and lower the compression ratio with some different pistons. This has been done more than once and each time it is badass.
It is not a kit, not yet anyway. Thus you're looking at fabricating engine mounts, exhaust pieces, wiring bits, doing some custom ECU work and probably some other stuff too. Also, as you may have noted, its the VH45DE, not the VH45DETT. You want those turbos (or a supercharger as the case may be) then you are looking at a custom setup there as well. This is not a project for beginners. Also, as the Q45 was never thought of as a performance car, there is no ready made performance cams, exhaust manifolds or anything else waiting to be ordered, not that I have seen anyway. Pretty much to go this route you are on your own so if you have money, skills, balls and a torch: have at it.
Going fast bulimic style
Everyone knows that if you drop weight your car will go faster. This is especially true with cars that have little to no power (*cough*CIVIC*cough*), which tends not to be a problem with a Twin Turbo Z. But even your 600rwhp Z32 will benefit from a lessening of the mass. As far as sports cars of the era go, the Z32 was not a light weight but it wasn't that heavy either. Ranging from 3300 to 3500 lbs depending on Twin Turbo or NA and various trim levels, its not bad but there is room for improvement. And there is much to remove if you don't mind trashing alot of really nice interior trim. Remember, the Z32 wasn't really designed as a hardcore race car.
Ditching the cowhide: A Z32 equipped with leather seats smells reallllllllllllly good inside. Unfortunately those sweet ass REAL leather seats (none of this fake leather crap) aren't light. I've never weighed them but I believe I read a stock leather seat with full power (lots of heavy electric motors) weighs in slightly north of 50lbs. So figure if your replacing driver and passenger seats with 10lbs racing seats then you stand to drop upwards of 60lbs or better.
Taking the knife to her: Given the nice interior of a Z32, you could probably drop a few hundred pounds with a full interior ruinage. I've never weighed the exact results because I've never seen one thats been shelled. But a 3100lbs 500rwhp Twin Turbo sounds pretty nice.
Just as FYI: The Z32 is not some overweight beauty queen. The cars designers made every effort to lighten it even while keeping interior standards up and production costs down. For example aluminum was used extensively (hood, engine mounts, front and rear bumpers and all intake castings are aluminum).
Its all about the corners baby
Now if all we wanted was power that would make us pretty **** pathetic wouldn't it? The Z32 is probably one of the best handling cars under $50,000 ever built. It lives for the turns. And there is plenty you can do to take it to the next level.
Tires: The most basic and easiest upgrade of the handling system, its also the most effective. The way tires work is the rubber gets crushed down into the pavement, filling the tiny holes and gaps in the surface of the road. So the softer the rubber is, the more it will mold into the road and the more traction you will get. Z rated tires are pretty much a must have for any sports car and thankfully Zs had them stock. But I doubt your car still has the factory tires, and if it does, you have bigger problems. The downside to Z rated rubber is that it does wear faster and the tread designs used for maximum grip usually don't lend themselves to anything but dry pavement too well. Pricing and quality varies wildly here so you're own your own to do some research in this area. Some names to check out are Toyo, Bridgestone, and Goodyear plus many other quality manufacturers.
Urethane bushings: Like just about every other car ever made, the Z32 came with gel filled rubber bushings, ie the parts that connect suspension pieces. This makes for a nice, smooth ride but the softer the bushings the more movement you get in the suspension system which translates into more body roll and less traction over all. Especially given a older car like the Z32 when normal wear and tear over the years has cracked and split the OEM bushings. This is where urethane comes in. Its essentially hard plastic, though with a little bit of play in it. Without any soft bushings squishing around, the suspension and steering will feel and react much firmer, because it is. This helps you get more from your tires and makes hard steering more predictable. The downside to urethane bushings is that the car will ride much stiffer, you'll feel just about every bump on the road. Nismo makes a pretty cheap set from hard rubber, which has just a little more play to it then urethane and you don't get quite as much of a rough ride but its not as stiff, go for your preference. The Hyper-Flex master kit comes with just about every bushing on the car and runs a mere $150. This alone increases handling like a crazy mofo.
Sway bars: Also known as stablizer bars, these are sort of like strut braces in that they help connect the two sides together but unlike strut braces, sway bars are meant to bend under heavy cornering. Stiffer sway bars will transfer more of the load to the opposite tire to help even the force and get better traction. The only real problem here is if you go way too stiff, the car will be harder to turn, it will want to "push" to the outside. However, just about all aftermarket units are adjustable so you can change the cars setup as needed. These usually run about $250 for front and rear sway bars with bushings.
Strut braces: Generally this aren't a requirement on a Z32 because the chassis was pretty stiff from the factory. However as you replace other pieces with upgraded parts, more and more stress is put on the frame and it will begin to flex more because the suspension that was supposed to be flexing has gotten alot stiffer. Strut braces help to more directly connect the left and right sides of the suspension system. Uber-high quality major brand name strut braces are expensive, Nismos are about $450 for front and back. Frankly: thats rape. Yeah, they look nice and shiny but ****, I can make my own brace out of some 1/4" plate and a bit of metal tube. Of course not everyone can weld so there is a solution. Ebay. Thats right, for this one time I endorse Ebay as a source for car parts. I mean really, all a strut brace is is a piece of metal wedged between two other pieces of metal. Its not rocket science, it doesn't have to be precision ground. You can find strut braces there for less than ten bucks. Nismo wanted $115 just for the front brace on my 240SX. I got the front and rear for $65 and thats including shipping. If you don't want to go through ebay, just take a few website names off an ebay search and go through those sites. A brace should bolt right up (you may have to do some drilling/filing if you go the cheap route, but its probably worth it) the only issue with the 300ZX is you have to cut part of the trim pieces that sit over the tops of the rear strut towers, which is not difficult and when done right doesn't look too bad.
Misc other braces: There is alot more in the way of bolt on braces for just about every car out there. Ladder bars, fender braces, lateral braces, just about everything. With the Z32 these do not really come into play until later but a stiffer chassis can always be appreciated and these upgrades aren't that expensive. If you are handy with a drill and a torch you can make you're own easily enough but for most people, bolt ons will be the way to go.
Springs: Eibach makes a nice set of lowering springs for the Z32. These will drop your car about an inch (.8" to be exact) and make for a stiffer ride with all that comes with that. It's a fairly good drop all things concerned. You don't sit too low and have to lift your car over speed bumps, it helps pull what little body roll the car has out even though it won't ruin stock suspension geometry. However since you are now lower and thus off from the stock camber specs, you'll want to invest in the ready to order camber correction kit from 300 Degree. Between the two expect to spend around $300.
Upgraded shocks: KYB has come out with a set of adjustable shocks for the 300ZX. Four way adjustability upfront and eight way in back, they start out stiffer than stock shocks and allow for greater control over your suspension. The only downsides to this setup is their controls are on the shock meaning you'll be doing so time on your hands and knees to adjust them and naturally you lose out on the in-cockpit electronically controlled stock pieces. $350 for the four corner set.
The next set of parts is for the more track inclined out there, if you have already done the suspension pieces above then chances are your car handles so good the only place you will be able to test the next series of upgrades is at the track. Now before you go changing alot of the settings on your suspension make sure you know what you are doing because an ill set up suspension can be dangerous to drive on much less to drive fast on.
Coilovers: The stock set of shocks and springs is more than adequate and the stock shocks with the Eibach springs and urethane bushings will pretty much out handle everything this side of a go cart. But at some point in your skid pad endevours you'll want more control over the suspension, which is where a fully adjustable set of coil overs comes in. These can run $1000-$1500 easily so this is not for everyone.
Adjustable control arms: Allows you to adjust the camber (vertical inward/outward tilt of the tires) which is handy for the race track or cars that have extreme lowering or aftermarket rim offset. Set of rears runs $250-350 with fronts going for $300-450 a set.
If you got it moving and around the corner, chances are you are going to want to slow it down eventually. The stock Z32 brakes are above average factory pieces. Posting 111 foot 60-0 distances, the 4 piston mono-block calipers provide a hard bite but they have room for improvement as the Z is not a tiny car. And as a heavier ride, quick heating brake pads and rotors and the resulting brake fade are a problem if you are driving hard for extended periods of time. To address this we go to the following.
Slotted or Crossed drilled rotors: The basic idea here is to increase the total surface area of the brake rotor to bleed more heat off the metal and to direct that hot gas coming off the pads and rotors outward away from the brakes. This reduces the temperature of the brakes and prevents the loss of hard braking power that occurs when pads and rotors overheat. Cross drilled rotors have somehow developed a chip on their shoulder, rumors that they'll crack easily under heavy use. Pure BS. If you have a really crappy set of cross drilled rotors and drive hard alot then maybe after 20,000 miles you'll start seeing some wear and tear beyond anything you'll see normally. Think of it this way, Porsches, Ferraris and other high end sports cars to mention just about every race car put on a starting field has some sort of cross drilled or slotted rotor. Slotted rotors serve the same purpose except they use the slots in the surface to channel heat away from the pads and contact surface of the rotor.
Now that we aren't overheating the brakes, we'll still want to stop quicker. There is three general ways to increase braking power. 1. Increase friction, 2. Increase leverage, 3. Increase pressure on the rotor.
Upgraded pads: These address the first item on the list. A set of metalic or semi-metalic pads will increase the friction of the pads on the rotor. They will also usually run cooler due to superior materials and heat dissipation. This upgrade is usually done at the same time as the slotted/crossed drilled rotor upgrade. WARNING: Some "race only" pads have little to no stopping power until they are hot.
Larger rotors: To increase the leverage when it comes to a circle, you simply go farther out, ie. wider. So we increase the size of our brake rotors so the pads are farther out in relation to the center of the wheel and we get more leverage. Larger rotors usually have larger contact surfaces (the area that the pads grip