Turbo Choice

[sweetr33]

Hey i recently had a GT35/40 turbo on my rb25 but it had a .63 ex housing when i bought it, well that was abit responsive and not ideal for the power range im after, so it is now sold.......... my issue now is im not sure whether to buy another GT35/40 turbo with a larger ex housing OR use a T04Z with similar size ex housings.....anyone no which would be a better choice???? Power output im chasing is 450hp at wheels, lag could be an issue, so thats why im asking for any opinnions.... cheers guys.. 35/40 or T04Z????? oh n i forgot to mention, its a t3 flange at the moment but am changing that to t4 at present so both turbo choices will be used in conjunction with a T4 flange

[T04GTR]

t04z. much funner with a beesdick more lag

[2rismo]

Power output im chasing is 450hp at wheels, lag could be an issue

The above = GT35 with 0.82 rear housing. Suggesting the T04Z is a bit silly.

[sweetr33]

i dont see the sillyness but thanks for your input anyway

[R31Nismoid]

I'll help you see the silly.

T04z - upto 450rwkw.

So if you only want 330rwkw, then its not smart to go a big huffer like the t04z.

The GT35 is far better suited to that range and will be more responsive and feel a truck load better for only 330rwkw.

[Devils_Advocate21]

gt3540 82 rear on a top mount manifold well designed ie: 6boost, external gate, and 19psi roughly? As sugested much much better than the T04z.

1+ the T04Z prefers 24psi and upwards of boost where as the 3540 will spool earlier and less boost to make better power? as far as i can gather

[dangerous_daveo]

What he forgot to mention is the engine is about 2.7L... If that changes which turbo to go for or not I dont know. But its handy to have some specs on the engine.

[R31Nismoid]

Nah not really.

Turbo choice remains the same generally for a given power aim

[N I B]

The Turbo you sold can easy do what you wanted if everything is setup and tuned right.

[sweetr33]

ah i see, thanks nismoid, much clearer, now comes the choice of .8 ex housing or 1.0

and whether t3 flange is restricting it enough to go to t4?

[ish]

with different engine litre size the rear A/R needs to be considered to establish when it spools up and when peak power will be made at what rpm.

Edited July 9, 2007 by ish

[R31Nismoid]

ah i see, thanks nismoid, much clearer, now comes the choice of .8 ex housing or 1.0

and whether t3 flange is restricting it enough to go to t4?

The .82 will do the job just fine dude.

[SimonR32]

What he forgot to mention is the engine is about 2.7L... If that changes which turbo to go for or not I dont know. But its handy to have some specs on the engine.

how does rb26 crank and rods = 2.7L?!?

i would definately go the gt3540r, supports your aimed power output with better response and also suits your engine build better, t04z is too big and i would imagine you would start breaking internals

[sweetr33]

na its 2.6 not 2.7...cheers nismoid, your a legend.. the .63 ex housing on my previous 35/40 would start to make boost at 2800rpm, im looking for one that comes on song about 4000rpm.. give or take. but ideally if the target hp (450hp) is reached then i'm happy either way... next is the fact the manifold has a t3 flange, with previous turbo (.63 ex housing) the housing and manifold and top of dump pipe would glow red at cruise on dyno, not even giving it a power run, was thinking maybe the t3 flange is abit restrictive so enlarging to t4 flange might have to be the go this time round also.????????????

[SimonR32]

all turbo housings glow red like that...

just get it ceramic coated

Edited July 10, 2007 by Cerbera

[sweetr33]

um not on cruise they dont, when i told the tuner he stopped n let car idle till things stopped glowing, wasn't even boosting it, my mates hi mount turbo sr20 that was there with me only glowed once they did some full power runs

[2rismo]

um not on cruise they dont, when i told the tuner he stopped n let car idle till things stopped glowing, wasn't even boosting it, my mates hi mount turbo sr20 that was there with me only glowed once they did some full power runs

Yes they do champ. At cruise the AFR's are considerably leaner and as such, make for much hotter exhaust gasses. Your manifold is more likely to glow like that at part throttle and cruising than under medium to full load.

Fact.

[sweetr33]

ok, my bad, its just that i thought of it this way........ with power comes heat, for example lets say we have a car that makes 400hp flat out, and to keep it simple maths we'll say it uses 100hp at cruise which is only a 1/4 of its potential hence internal combustion temps not being that hot so i didnt think the manifold would glow however at full noise your using 400hp its now making 4 times the power and your internal combustion temps have gone through the roof hence exhaust metals changing colour. this is the way i thought it was, regardless of mixtures being lean or rich, at the end of the day if your cruising you wouldnt think the internal temps would get hi enough to glow manifold unless there was a build up of....back pressure due to t3 flange or .63 ex housing?? now i may be wrong but i dont remember seeing cars exhaust glowing on cruise unless there was a restriction....???????? make any sense?