gonna try out a little rear mount boost

Old 11-01-2011, 10:32 AM
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Default gonna try out a little rear mount boost

hello everyone, im new to the work of aftermaket performance turbos..
altho i used to have a 1987 saab turbo.. does that count
i just bought a car as a project and i am going to try to boost it slightly.

its a 1994 nissan 300zx naturally aspirated.

before anyone says it - let me just clarify that yes i know nissan made a twin turbo version of this car, and yes i should just drop in the TT version of the same engine. but honestly i dont want to.

i want to try something different. i am hoping that i can get some valid feedback from people on here because all i ever got from the nissan forums was - "Just do the TT swap"

i have seen some of the NA 300zx cars running slight boost on stock internals - like 4 to 8 psi and wow, what a difference in HP. and because the NA engine runs at such a high compression there is little to no lag time and better MPG.
i know it will never be capable of 500WHP and im ok with that

dont get me wrong, if i could have found a TT in good shape for a reasonable amount of money i would have picked it up, but alas they are hard to find - if they are in good shape they are closer to 10k than 5k and if they are affordable they always need "slight repairs"..

anyway , i am off subject SO let me break down some of my plans.

first of all i just want to let everyone know that i have a spare complete engine in the garage with 36k miles for when the one i have is totally gone. depending on the success of this project it may or may not remain stock.

now on to the interesting bits..

firstly, i want to do a rear/ remote mount single turbo and run about 4 to 6 psi of boost.
i saw a video of a guy doing this on the same car i have and he added almost 100hp to rear wheels. and claimed it was his daily driver.

so with this setup i and going to probably do a couple things a particular way.


i want to keep my turbo oil seperate from my engine oil. i am looking at trying a trunk mount oil tank collector with 2 small oil coolers mounted to the outside of the trunk - not sure where yet but basically 1 before the turbo and one after so that the temp of the oil is cooler going back into the tank.
i do have a couple questions about this set up tho because i havent seen it before.
first - should i put my scavenger pump before or after the turbo, and should i use check valves and pressure regulators to slow the oil down or can i just pump it through the turbo at whatever speed the pump works at? or maybe its to keep boost pressure out of the oil tank?


the 300zx has a dual log/ dual throttle body intake that has basically 2 -2 inch intakes
i want to build my own upper plenum with a single throttle body - i am probably gonna do this with carbon fiber, but it will probably be sheet metal to start because it may take a few tries to get something i like functionwise

i did the math to figure out that one 80mm throttle body will allow about the same air throughput as 2 56mm throttle bodies. there are tons of these all over ebay for cheap that can be fitted with the nissan TPS so it shouldnt be an issue.

but thats a 3.5 inch intake - kinda hard to build up boost in an intake that big in a rear mount set up - seems like thats why most rear mounts run 2 or 2.5 inch piping up to the intake right?

keep in mind i want to run a small amount of boost since the stock pistons wont handle over 8 psi for long

so should i run a 2.5 intake up to the intake and then expand out to a 3.5 to fit the throttle body? or maybe run a smaller throttle body? this may be answered by my next question..

MAF placement..?
i have seen 2 different set ups for the MAF. one is on the intake side of the turbo so it meters raw air coming into the turbo, the other is right in front of the intake after the turbo.

both seemed to work, but it seems like the maf would work better on the raw intake side because it works by temperature, i would be afraid the air after the turbo would be heated enough that it would affect the MAF's ability to correctly set up air/ fuel mixture.

i guess i should note that the setup i saw that had the MAF metering raw air used a stock ECU.

next question is overall turbo size

i am not wanting to create a ton of boost, and i want it to spool up quickly. the one set up i saw that made 320 hp had a smallish turbo on it, about the size you would put on a 4 cylinder or something. seems like because it was smaller , it spooled up pretty fast and didnt have any real lag time. the power came on pretty strong around 2000 to 2500 rpm.
the thing is -- i dont really know turbo numbers and how it translates to size.

basically the 94 300zx is a good car. reliable, decent mpgs. but in the NA form it lacks alot of horse power to the wheels.
222hp at the crank and about 180 at the wheels.
no i am freeing up som hp with a lighter flywheel, underdrive pulleys, Electric fan and lighter one piece drive shaft but dont expect a dramatic improvement.
it already has an intake kit and to be honest, it doesnt do much

but 250 275 to the rear wheels should be very achievable with a rear mount turbo. i have priced everything out either in kits or seperately and it still way under a grand closer to 500. but since this is my first time i expect an additional amount of money to be broken free from my secret account the ole lady doesnt know about.

just for reference..
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Old 11-01-2011, 10:38 AM
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Old 11-01-2011, 01:39 PM
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