MaDMaX024

Planning for boost obviously and i've been rattling different turbos around in my head for a while now so i figured why not ask?
first:
i want 1psi by 2200rpm in 3rd gear, 6psi by 3200rpm in 3rd gear and full boost by 4000rpm in 3rd gear. i would like to hit at least 2psi in first gear but that might be a pipe dream as first gear is useless above 50% throttle now . by full boost i mean 12psi (or more if i can safely run it). my car has a good bit of N/A power now so i can drive normally and not make boost without having any issues. if i can pick out a turbo that spools faster, makes the same power and holds boost till redline (or more, i want to tach out at 7000rpm) i'll do it but so far i've got my sights set on a T4/GT40 .70a/r compressor and the .6x a/r turbine from cheapturbos.com. i was considering a T3 60-1 but decided the exhaust would be too small, plus its more expensive than the t4/gt40 which flows more air according to cheapturbos.com, also considered a T4/T04R but decided it would make boost alot later than i'd like.

my goal is 400hp on 12psi and about the same torque, but if i can make that power on less boost thats even better.
assuming i have good engine management (narrowed down to emanage or zemulator but might pick up the emanage for now with the profec E01, just need to find a way to increase the rev limit to 7100) i'll run 14+psi if its reasonably safe(i have no reservations about blowing my transmission to bits either as i'll be strengthing a spare before i boost, i'm only concerned with the motor). my motor has 4700 miles on it as of right now, rebuilt to stock specs with nissan rings/bearings, all new gaskets/seals, rebuilt VTCs, finally runs perfect after chasing down several tiny problems.
my turbo feed setup is going to be almost identical to the Z31 and julio's turbo VE.
wastegate will likely be a tial 38mm, not sure on a recirc valve setup yet.

what am i forgetting??
am i way off base with this turbo choice?
the car wont be boosted for several months but i'm going to start making the manifolds and charge pipes in the next few weeks, have the turbo by christmas time and tie up all odds and ends by the end of march to finish the install by the end of may.

Nealoc187

iTrader: (23)

Have you tried plugging all this into some compressor maps?

MaDMaX024

from what i know about reading compressor maps, the T4/GT40 will support 400hp on 12psi..i'm not sure how to figure out where it should spool though.

Boosted Maxima

QUOTE"i want 1psi by 2200rpm in 3rd gear, 6psi by 3200rpm in 3rd gear and full boost by 4000rpm in 3rd gear. i would like to hit at least 2psi in first gear but that might be a pipe dream as first gear is useless above 50% throttle now . by full boost i mean 12psi (or more if i can safely run it). "

Can't quite pick numbers for different gears and RPM ranges. Not like entering numbers on a lotto ticket

It could proably be done but it'd take a series of solinoids and stuff to do it and would not help power at all.

The exhaust A/R housing size directly effects the spool up time (amongst other things) and the point where the turbo reaches it's effecency range
-VS- RPM. Stock GN housings are .67 which seems to work fine on my car.
While under low throttle (normal driving) I can hear it working but i'm building 3lbs of boost or less can still feel it picking up the motor. When under full throttle I make 8lbs of boost around 2-2500rpm and it ramps up quickly to 8lbs and does not drop off at the upper rpm limits 5000 or so. I can tell the stock programing of my ecu does not have enough fuel so I generaly short shift my car now and it still makes good power. I would definaly NOT SUGGEST much over 5500rpm for these engines. Absolutly no need for twisting them that hard. Same thing for Buick GN engines 55-6000MAX rpm.
Last summer a Camaro I setup with the Buick Gn engine never passed 5800rpm and ran 10.98@124mph on 19lbs of boost,Pump gas Through the mufflers on DOT tire with a 1.48 60' time.

Sounds cool to say your shifting at 7000rpm till your picking up connecting rod peices. Let your honda buddys brag about reaching 1000000rpms cause their engines have to spin the parts that hard to make the lawnmower blade rotate
~Scott

MaDMaX024

im not really picking solid numbers, but full boost by 4000rpm is good with me...if its earlier thats great, i figured i'd mention 3rd gear as first is like i already said, a waste of tires now and i'm still n/a. the other thing about the boost is, i dont want it to be like my saab where it makes an estimated 3psi until 3000rpm, then all of a sudden the second it passes 3k its at 24+, i know that has to do with wastegate control but it still did it bypassing the APC solenoid (advanced performance control..its a boost/timing ECU that works EXCELLENT from what i've seen except for the spooling thing). the VE loves the revs, and internally its the same as the VG30DE with a few exceptions that do not affect its strength so i'm far from worried about reving to 7000rpm.
what is the GN turbo comparable to?
i havent gotten a turbo yet..i just want 400hp on 12psi with maximum area under the curve.

yes, i'm a turbo sizing retard :mamaru:

mtcookson

iTrader: (2)

in the higher gears there is more load on the engine when you open the throttle. higher load equates to more fuel being used. i'd bet you would hit full boost well before 4,000 rpm in a higher gear like 3rd due to the load. (unless you have something ridiculous like a T66 or something)

subs1000w

dont you have the VG30DE 10.5:1 pistons in your new motor. that should help spool the turbo even faster

MaDMaX024

yep, that was on the tip of my brain. i had a definite brain fart..i'll be amazed if it makes boost in first gear at all..

MaDMaX024

yep! thats why i think its easily possible with the right turbo to do 400hp on 12psi.

KLoWnPR109

iTrader: (9)

How do pistons have anything to do with the turbo spooling?

nismology

iTrader: (8)

They're talking about the compression ratio. With the pistons that he put it that raise the compression ratio, the turbo will start spooling sooner in the rev-range.