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Discussion Starter #1
I have some questions. My current state is, I just finished (after 5 years) restoring/highly modifying my 87 300zx. Restored as in all new interior carpet seats, new paint, etc.... get tired just thinking about all of it. Modified, well that would take a day to type it all out. Here is the thing I am a big on being unique, so rather than going turbo, I decided to super charge my Z (Vortec S trim ) Yea, no kit for our cars, had to fab it all. I upgraded the fuel system with Jim Wolf's 450hp control system upgrade to ensure I would always have plenty of fuel. The engine is build to handle what ever (knock on wood), I had the crank magna-fluxed used 90+ model TT, eagle "H" beam rods, 90+ model TTJE forged pistons( ceramic coated on tops and Teflon Molly coating on skirts), and for course all balanced. So I would hope that the bottom end is pretty strong. I also did some head work cams ( 270 dur. / .445"lift) , Isky 906AM valve spring (outer) and Nissan 2000 roadster inner springs. The blower makes 13psi right at the rev limiter, aprox. 7000 rpm, makes about a pound or two around 2000 rpm. This all sounds good, and don't get me wrong the car pulls really good, great torque....But it just not all I'm looking for. I put it on the dyno last Friday, and to my disappointment it only made 247 hp at the rear wheels. I having been thing about going turbo, I fell sure with the way the motor is build I should be able to make 400hp easy with a turbo and I/C. But I just hate to scrap all the time and fabrication I have in the S/C set up, plus it so different, and I love the look on peoples' face when I open the hood. I'm going to order a wideband to see exactly what my AFRs are doing because on the dyno they had the tail pipe sensor in the exhaust and it was reading like 14.5:1 ( I know I know take a breath thats super dangerously lean) until I got to about 4000-4500 rpm the they almost instantely went to around 13:1 to 12.5:1 close to what they should be. One thing is I do still have the cat in the car so that supposingly will make the tail pipe tester read a half a point to a full point leaner. Thats another thing thats got to be done, out with the cat and bigger exhaust. I have 2 1/4" ID exhaust now (it was a NA car before I started) and man its really pushing the exhaust out, sounds a lot like a turbo car the way it thrusting the exhaust out. I do have headers on the car though. Anyway right now I can't decide wither I should go turbo, or still work on tuning the S/C system. Most folks think that with some bigger exhaust and proper fuel tuning I should be able to get 300-325 RWHP. If I were to go turbo what turbo would you recommend? A T3/T4? what size ARs? I have a Holset HX40W, if you are familiar with Holset, do you think thats too big? What so you all think I should do?
Thanks,
Brain
 

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Get us some pics, like I asked on Z31.com. Also, make sure you are getting the flow you need from that SC. Does the Charger move the kind of Air Volume you want? Remove the exhaust before the Cat, and see if it makes a difference. I dont think you are going to add 100+ HP with an Exhaust change, and tuning. (unless youre tune is WAY off). How is the pipeing run? You have too many varibles to consider for anybody to give you advise on youre set-up. With all the work you have into it, I wouldf continue with this SC idea, until it is a success.
 

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Discussion Starter #6
If you all only knew how tight it was fitting in the SC.... The is NO room for a turbo too. I will make some close ups of it all and post them soon. what you see here is before I finished the installation, added BOV and wrikle coated all the plumbing.
 

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There is ALLWAYS a Way. The turbo could be mounted remotely like mine, Somewhere it would fit. I was told that all my **** wouldnt fit too. Well I made it fit.



You can to. Fabulous job on the Charger!!!

Also, Why dont you have an Intercooler now? Im sure those charge temps are pretty hot @ 13 psi. Intercool it, and change the maps, and you may increase youre power quite a bit.



Post Edited (Oct 18, 1:50pm)
 

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Discussion Starter #8
How did all this work out for you? what kind of numbers does it make? Very impresive. I have a holset HX40W I was thinking of putting on, I noticed you had a big turbo with T4 flange, How does it spool? What boost do you run?
Thanks,
Brian
 

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I am still in tuning, but the highest I have had it is 11 PSI, and it spools by 3800-4000 rpms. I am maxing injectors, they are 340 cc. I need larger injectors!
But if I am Maxxing 340cc @11 psi then I basiclly have a 340hp car right now . I figure with 500 cc injectors, I can run up to 20 psi, and hopefully hit 480+RWHP that is right at the end of the efficiancy range on this compressor. The turbo is a Straight T-4 .84 Turbine with an "O"trim wheel. And the compressor side is a TO4E- 50 trim. The car has No power from 2000-3000 rpms. I run 3.90 gears so that actually helps the drivability.

You need to consider some kind of Upper intake plenum. That thing is ROBBING you of power on rpms over 4500. Trust me Mine made a HUGE difference. Plus... youre heads are all built, you are bottlenecking it before the heads. You will get a much larger benifit from the head work if you scrap that factory Stuffer.

Also, with the motor you have discribed, I wouldnt even consider a t3-t4. you should be able to rev 7000 rpms with the top part of the motor the way you have discribed, I would go with a Med. to Larg frame turbo, to utilize the motor work and to get REAL HP!



Post Edited (Oct 18, 3:31pm)
 

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that cat can be choking your horsepower to death, with a supercharger like that you should be boosing way sooner. maybe a smaller pulley. those 5.0 stang guys get alot of ponies from those setups so something just needs to be tuned, after your done getting it figured out put a 100 hp of NOS and you should be doing some low #'s
 

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I respect what you have done to your Z its very clean and looks like some serious time and effort has been put into it. But If you want to make serious Horsepower you will need to go turbo. the Holset Turbo you have is HUGE if you really want to make big numbers and dont mind waiting for that monster to spool id stick with it. You already have what sounds like a pretty solid motor with alot of potential. Throw a Turbo on there start turning up the boost! yea and do something with that upper plenum the stockers really are no good at all.
 

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It seems to me that 13psi at 7000rpm is a bit of a waste of the substancial time and effort put in so far.
Having to rev that high raises questions about waterpump cavitation and hydraulic lifter pump-up, just for starters.
I'd be interested to see an exhaust manifold pressure measurement at full noise.
An intake charge temp reading could be enlightening as well. What is the supercharger efficiency at your peak revs?
 

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I like it.

Side note: I LOVE huge power, mine comes on like a time machine, but sometimes the low rpm, we are moving right now kinda feeling has alot of merit. His low rpm spooling ability on that Supercharger, will be interesting. Once that car is Dialed in, an I/C fitted on it, and the PUNY exhaust is upgraded( by the way, I have owned Many Thuderbird S/C, the the exhaust is a very large restriction, uncap it and the majic happens.) It will be quite a fun car. Keep going on it. His Supercharger, by the way is perfectly capable of providing that engine with enough air for 380hp At least.

The biggest over-all benifit of a turbo over a S/C is the fact a turbo uses it Turbine to collect wasted energy (exhaust) to produce power, as a (belt-driven)S/C requires about 20% of the engines power to produce the power. So youre Charger has to make up for driveline losses first. Its like kicking you in the balls before the race
 

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Discussion Starter #20
I think I have decided to keep the SC on the car for now. I going to fab up some 3” exhaust ( fabbing looks cheaper than buying ), get a wideband, an AFC and do some tuning. Then I will see what kind of numbers I’m making. If I can get it up to 300-325rwhp with just the motor I’ll be happy. Then top that with ~75 shot of nitrous, and she should be running pretty good. Its hard to part with the SC,,, everybody has turbos on Zs, but I haven’t seen too many with supercharges, and I am big on being unique. Besides, there’s nothing like listening to the whine of a SC under the hood of your Z… I’ll be keep you all posted, and I put up some pictures of what it all looks like now when I get the SC out back on, had it out looking at turbo possibilities.

Oh yea, When I said it make 13psi boost at 7000rpm, some of you though that was high rev for boost, but you have to remember a SC is driven directly by the engine, so I am always making 1.5-2 psi boost even at 1500-2000rpm.

Thanks to all who support keeping the SC system. All you turbo people, I know where you are coming from, big power could be easy with a turbo, I know, I know. I had my 73 240Z turbo charged, and man what a beast it was. 60mph 3rd gear roll on the boost and started spinning the back tires, that was the day I said ****! Enough said…. I love turbos too,, When I get to redoing my other 240Z, I’m thing RB26DETT,, Ha ha ha, now that’s going to be a sick car, but until the its only a bunch of talk, so…..

Any suggestions on which way I should go? Stand alone ECU, or tuning the JWT ecu with an AFC???
 
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