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Discussion Starter · #1 ·
Well, not that long.
I've been trying to make some time to write down some things on the Turbo ZXT's but of course I can use a little help to complete it.
I would LOVE to see some of you write more in any of the topics and if you disagree in something I wrote just tell me, I may change it if it makes sense.

here is a copy of what I have so far...
any volunteers?
I am not finished, I will write more, I think, a lot more but oppinions from other fellas are very important, cause knowledge resides in all of us. I am very positive we all can learn from each others experiences and mistakes.

this is it:
*************
This applies to a '81.5-'83 zxT engine with stock injectors and ECCS as starting point and that the goal is to take most of the L6 engine. Some stuff I have used already some other I've read and some other heard from friends experiences.

CHECK YOU ENGINE
Check the condition of your engine with the proper compression test and leakdown checks.

ENGINE BLOCK
Personally I don't trust the non-metal head gaskets for 10+ psi of boost. Replace with HKS 1 mm or 2mm if you think the lower compression ratio/higher boost combo is good for your case. The 2mm head gasket can lower your compression ratio by nearly 0.5 point.

CRANKSHAFT, CONNECTING RODS & PISTONS
The factory crankshaft-rods-pistons combo are able to produce at least high 12's and maybe lower times at the 1/4 mile, but at those hp levels (350+) they will be as reliable as your fuel and ignition timing is.

Keep in mind that stock turbo pistons although have the same dish volume as the '79-'80 ZX's have different ring landings configuration (turbo pistons have two, 1mm rings while the n/a piston has one 1mm and the other 0.5mm ring)and from factory came with chromemoly rings (stronger against heat and some detonation) and that is also the reason rings for turbo pistons are so **** expensive compared to those for the n/a. I am not sure if the thickness of the top is different in them. Bottomline, the "only" culprit in using a '79-'80 n/a block is the 2nd ring thickness, the chromemoly rings, maybe the piston top thickness and the head bolts which can be easily replaced while changing the gasket.

HEAD
About heads, The head in the '82-'83 ZXT had square exhaust ports and is supposed to be one of the best flowing heads in the L6 Family, as good as the one that came in the 240Z (E31?) with the same square exhaust ports. The head chamber volume should be one of the main concerns when determining the desired compression ratio for the engine, the ZXT head had a volume of 53.6cc's compared to 42.5 on the popular E31 which will provide for at least 1 point increase in compression ratio. If going forged, plan for a moderate C.R. increase (say 8.5:1 to 9.0:1), it will give you better turbo response.

FUEL
Fuel requirements for the Turbo L6 will NEVER be the same as a n/a L6. As most of you should have heard already, "An engine is an air pump, the more air with the corresponding fuel you can pass trough it the more power you will have". There is a ratio established in the auto industry of 14.7 to 1. It is a mass ratio, not a volume ratio. Some people prefer the "perfect ratio, some leaner (supposedly for more power but risky ) and some richer (some loss of power but conservative and safe)
The factory fuel injectors in the Turbo ZX are capable of 259 cc/min vs. the 180 cc/min of the n/a ZX. The turbo units are supposed to be good up to 300 hp (at 100% duty cycle) with a rising rate pressure regulator. I think the most versatile unit out there is the Bell FMU in which you can adjust the rate of fuel pressure increase vs. the boost increase, almost all others are 1 psi of fuel to 1 psi of boost.
The Stock fuel pump is another limitation, it will provide for around 300 hp but nothing more. The MSD 43GPH unit is a good buy for around $125 and capable flowing fuel for 500hp.
Next, the fuel lines, increase their size. Factory hoses are 5/16" diameter, but changing them and leaving the stock fuel rail wont do much so leave it there until you are able to get a custom fuel rail.
Get a fuel pressure gauge, to monitor pressures. The ones that go inside the car are more expensive due to the isolator, but you can get a regular unit and at least monitor idle fuel pressure.

INTERCOOLING
For you to be able to get any serious power from your Turbo Z get an intercooler. The function of the intercooler is to reduce the temperature of the air that will enter the combustion chamber after it is pressurized by the turbo. Bigger intercooler means better cooling but more lag get it for a happy medium.
Intercoolers from starions/conquests are very popular for the ZX, it is good enough for the factory turbo.
I think Bell Engineering "makes" an intercooler for around $500 (I am not sure) which size is near to the biggest you can fit in the front of the Z, 24"x14"x3". If you plan for the future, get this one or a similar unit from the beginning.

INTERCOOLER PIPING
All my setups have been cutting trough the side of the intake hose at the radiator support. Even the HKS unit for the ZX was done that way. You can have a muffler shop bend you pipes but the bents are not of equal diameter and thus, hurt performance. If you plan to stay with a T3 or at the most a regular T4 you can get the pipes of 2" diam., but if you plan to go BIG, like the T series Turbochargers, get'em 2.5" diam. Remember your i/c tanks should have that diam. Too.
Try to get you pipes mandrel bent. If no mandrel bending machines are available at your area, you can consider fabricating your own pipes from mandrel bent U's that are not difficult to get.
A good piping setup should consist of 2 pipes from the turbo to the I/C and 2 from the I/C to the intake manifold

TURBOCHARGERS
At last, the fun part. The unit that came on the ZXT's were a humble T25 best known as a T3 which is a very low profile turbocharger, good maybe for 250hp. There are lots of options for turbocharging the L6, one of the most popular is the hybrid, an original T3 turbine with a TO4 compressor housing and wheel. This gives you better performance (up to 375-400hp) but limits you on the turbine side flow capability. The other options are full TO4's or T series turbochargers from Turbonetics.

WASTEGATES

CLUTCHES


DIFFERENTIALS, DRIVESHAFTS & AXLES

ENGINE MANAGEMENT AND/OR IGNITION UPGRADES
 

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<b>RE: Incomplete FAQ for turbo nuts (extremely lo

Thank you very much. I'm new to this turbo game but have a lot of automotive knowledge and fell into a stock turbo setup that I will install in my 240 with enhancements. You've already answered questions that I had and verified things that I had figured out and given me the confidence to go on with the project. Thanks again
 

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RE: Incomplete FAQ for turbo nuts (extremely lo

Hello,
Where did you get your information on the flow of the 2 engines, and the injectors? Is there a specific book you bought that gave you some of that information? I only have a few manuals, and have never been able to locate that type of information, please advise.

Thanks
Scott Milella
 

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<b>RE: Incomplete FAQ for turbo nuts (extremely lo

Very good Carlos I like the recomendation of the Bell I/C it is the best and cheapest . I will do some writing to add to your stuff . Injector duty cycle and raising fuel pressure, flow vs pressure 2 different things . EGT readings and A/F meters,diagnosing plugs for preignition. The staged upgrades for the ZXT ie stock, increased boost, intercooled, intercooled hybrid turbo, tec II ..... One thing I would like to see stated is that it is not worth turboing a non turbo motor . I am probably going to get shot for saying this, first of all it is possible but only for someone who has owned and played with a turbo car and understands the principles of turbocharging . Second most people who understand these principles will tell you that a junk yard ZXT motor will get it done with more HP, reliablity, and way cheaper than a non turbo motor could ever be done . I am sure I will think of more later . You build it Carlos and they will come .
 
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