Stock boost+aftermarket exhaust

[krystalized_jdm]

Alright, so I have a 93 Gts-t. Recently got a new jdm tuned ecu that removes all the governor ********. Now I'm after an exhaust system, but wondering what approx boost is best for a stock rb20det. I hear they can run 15 psi, but from what I know sometimes its hot air, and not much of a hp gain. So my question is, What psi should I be running? Also, what size of exhaust piping would you guys recommend? I'm not super technical, still learning. But from what I hear, too big of piping wont have enough pressure for it to spool properly (or somethin like that, forgive me if im wrong xD) and too small of piping causes some turbo lag. This is all me having my heads in the cloud, I have no experience with this. Any help would be greatly appreciated! Thanks

-Stephen

[TheyKilledKenny]

If you want engine longevity then go for lower boost 8-10psi, for power run 12-16psi. Id run atleast 2.5" pipe back, I have 3" and its great. I heard that turbo vehicles dont really need much back pressure.

[Tony-R32]

use the search function, lots of info on this! pretty much the general consensus is don't run your stock turbo on an rb20 over 15 psi which is pretty much 1 bar (your stock pressure is 10 psi). keeping it at 14-15 psi high for a long period of time will run ur turbo into the ground. As for exhaust, 2.5" is acceptable, but 3" would probably better as it restricts less air!

[RHDskyline]

i run 3 inches all the way back from the turbo elbow. no cat, no muffler, no nothing but pipe. i love it.

but not everywhere can have that

[Skym]

Max safely on stock R32 GTS-T ECU with stock ECU tune = 12psi (Apexi podfilter, 3" front pipe, 3" catback exhaust, BOV), stock turbo for around 250hp at engine. Can run a bigger turbo to 12psi on stock ECU tune (same mods) with safe A/F (Air/Fuel) ratio at peak hp, but runs lean at lower rpm's. Increase in hp comes from increase in boost level that leans out rich factory A/F ratio.

Stock exhaust goes like this -

Stock turbo > 2.25" dumppipe > 2.5" frontpipe > Catylitc convertor or Cat elimination pipe > 2.5" Catback exhaust

3" exhaust on RB20DET is big enough for stock turbo. Factory exhaust is around 2.25" for dumppipe and 2.5" for rest of exhaust (around 7-8psi at factory).

Add FMIC (Front Mount InterCooler) and boost level can rise to 13.5psi and get an extra 23hp due to more air reaching engine and cooler intake temps. That's if engine doesn't lean out too much due to faulty fuelpump, etc, so probably would need a upgraded fuelpump, ECU tune to trim the fuelmap. Engine should produce around 270hp.

There's up to around 30hp with a ECU tune using Nistune to make stock ECU retuneable (depends on octane of gas your running). So around 300hp.

Also clutch needs to be upgraded to handle extra hp.

Can run up to 1bar = 14.5psi with supporting mods (ECU, fuelsystem, clutch, FMIC, engine oilcooler, boost controller, etc) for around 330hp at engine. But it depends on how good intercooler is, so can sustain that boost level, as intake temps can rise and need to pull ignition timing to prevent engine knocking (unstable combustion).

This R32GTS-T has around 330hp (14.5psi) at engine with stock RB20DET engine, stock RB20DET turbo and can pass boosted up stock GTR's in Targa. Here's it catching up to and passing a R32GTR in Targa -

http://www.youtube.com/watch?v=fgD5j52ltFA

Owner of above R32 GTS-T used to own a N1 R34GTR -

http://www.youtube.com/watch?v=ai1u2TldTkY

But says that R32 GTS-T is quicker in Targa.

Same R32 GTS-T on racetrack -

http://www.youtube.com/watch?v=f74NM5236zw

http://www.youtube.com/watch?v=M9L49eCE7RU

[BrianV8]

on turbo cars the turbo is the back pressure, once you leave the turbo faster you can get rid of exhaust the better

[krystalized_jdm]

skym, love every bit of that. That helps ALOT. Going to get a boost controller and fmic and set it to that. I'll see how it runs. Also, were can i get nistune? I've never heard of that before o.0

[Nismo_line]

i got a hks turbo back exhaust, hks intake and was running 12 psi now that i am gonna be throwing on a fmic if i raise it to 13 psi it should be fine ?

[Skym]

Sorry, forgot to mention ECU retune with upgraded fuelpump, as engine runs rich at higher rpm's, etc, so fuelmap needs to be trimmed, etc.

With FMIC, boost controller, I would suggest you have at least a upgraded fuelpump, ECU retune minimum. Best to have FMIC, ECU retune, 550cc Deatchwerks injectors, 255lph Nismo fuelpump (comes with all the gaskets, etc that you normally would have to buy separately from Nissan with other aftermarket fuelpumps), Z32 MAF with plug / tail (plug needs to be wired into factory loom).

[Nismo_line]

already got walbro 255 would a mines ecu be good?

[Skym]

Best to use Nistune, as every engine is different and using another ECU tune from another engine is usually not a good idea, even when using the same mods.

This explains what Nistune is and what can be done with Nistune tuning software, etc -

http://www.youtube.com/watch?v=WjQJxWSEgHE

On R32 it doesn't use USB (only older stock ECU's like R31, Z31, etc), it uses factory consult plug that's located under dash on drivers side of car. Pull the clipped in access panel off under dash (to access fuses) and you'll see a grey plug next to fuses. That's the consult plug.

[RB30DET]

For your RB20det

* Set boost with a bleed-valve boost controller to 12psi
* RB26DET GTR injectors (2nd hand-get them sonic-cleaned and flow matched)
* Warbro or Tomei in tank pump
* Front mount intercooler
* Split-dump pipe
* Front pipe
* Hi-flow cat
* 3-inch all the way to the back with high flow muffler
* ECU remapped

My mate has this same setup except running a old school T4 turbo, he built it on the cheap in his R31 and it puts out 320 rwhp