Should I Change Turbo

[=premo=]

I've been building an RB30det for some time now and I'm ver close to finishing it, just waiting for the head to be ported.

Specs:

RB26 head

H beam rods

Aries pistons (suited to RB30/26)

Standard cams

crank collar

GTR oil pump

800cc injectors

etc

Its for drift use and for a while it may be registered and used legaly on the street.

I have a killa trust T04z turbo kit for it with all the lines, manifold, wastegate, front pipe, twin pod intake kit, etc. The T04z will make massive power on this engine and I like the idea of massive power however I'm not going to use the car for drags so its not very practical. The lag may be an issue for drift and I want this engine to be tuned safe so I wont be revving it very high which means the power band is going to be very small with the T04z. Problem is I want this engine finished and everything is already paid off and ready to put together. I dont have any more cash to just go and get another turbo setup.

A better turbo setup for me would be a GT35/40.

Should I try to change turbo setups or just make do with what I've got?

[Al]

For a drift orientated street car i would definitely go the GT35R with a 0.82a/r ext. housing or maybe slightly bigger.

I have a fully built rb30det (25 head) with a gt30r and a 0.82a/r ext. housing and it's absolutely awesome. Full boost by 2800rpm and doesn't drop at all till redline. So far it is still in run-in tune (274rwkw@15psi), so i'm not too sure how the turbo will go with 20psi, more timing, cam gear adjustments and an extra 1000rpm: time will tell, but am hoping for about 310rwkw.

[=premo=]

Would it be easy enough to cut the T4 flange off my manifold and attach a T3 flange?

Would the braided lines for the T04z fit a GT35?

Thanks,

Daniel

[dano4127]

Swap you my 35/40 .5 or .7 front 1.06 rear

In all honesty 35 with the .82 or 1.06 will still make a bunch of power and be a lot more responsive and have a larger powerband for drifting it

[=premo=]

Wouldnt the 1.06 housing still be fair laggy?

If your serious about the swap, PM me details (weather you wanna swap full kit or just turbo and if its a vband clamp or flange housing?)

thanks

[=premo=]

Just found the specs for the T04z, might not be as bad as I originaly thought. Garrett t04z (0.84 rear, 0.70 front)

[dano4127]

honestly dont know mate def wouldnt be as lagy as the big boy

But mine is not tuned yet

I know a couple of 25's kicking around with the .82 rears and I wouldnt call them laggy

1.06 on a 3L is supposed to be similar response to a .82 on a 2.5L

Couldn't really swap manifolds anyway cause i have 25 head

[=premo=]

Think I'm going to stay with the T04z seeing the housing sizes are almost the same as the GT35. Really wish I knew more about the differences between turbo's.

[dano4127]

Forgive me if I am wrong but I was under the impression that the housing sizes are much larger than the GT35

If i am correct AR stands for air ratio so a GT3582R's 0.7AR Compressor cover could be a completely different size to a T04Z 0.7AR Compressor Cover

[=premo=]

Can anyone confirm this for me?

[dano4127]

A/R describes a geometric characteristic of all compressor and turbine housings. It is defined as the inlet cross-sectional area divided by the radius from the turbo centerline to the centroid of that area.

* Compressor A/R - Compressor performance is largely insensitive to changes in A/R, but generally larger A/R housings are used to optimize the performance for low boost applications, and smaller housings are used for high boost applications. Usually there are not A/R options available for compressor housings.

* Turbine A/R - Turbine performance is greatly affected by changing the A/R of the housing. Turbine A/R is used to adjust the flow capacity of the turbine. Using a smaller A/R will increase the exhaust gas velocity into the turbine wheel, causing the wheel to spin faster at lower engine RPMs giving a quicker boost rise. This will also tend to increase exhaust backpressure and reduce the max power at high RPM. Conversely, using a larger A/R will lower exhaust gas velocity, and delay boost rise, but the lower backpressure will give better high RPM power. When deciding between A/R options, be realistic with the intended vehicle use and use the A/R to bias the performance toward the desired powerband.

[paulR32gtr]

area/radius ratio - so a 16 cyl truck turbo can have a .42 exhaust housing as can a little Garret GT17

[=premo=]

So the A/R can stay the same even if the turbo size gets bigger. So I'm back to square one, I've been told that a GT35 1.06 starts boosting around 3800rpm on an RB30 and from a dyno graph the T04z with .84 looked like it was boosting around 4000rpm on a 2.6

So a T04z with .84 housing should be about the same as a GT35 with 1.06 housing however I'm getting told by other's that a GT35 with .82 would be only slightly more responsive than my T04z .84 and that my T04z will make more power easier.

Fk it, I'll stay with the T04z, I've never drifted with a powerful car before so I'm not going to be able to tell the difference and if it turns out to be too hard then I'll change it later on. Although if its harder and I can learn to control it then when I do get a more suited turbo I should be even better at drifting... I hope...

[paulR32gtr]

Think of a housing as essentially a cone that is wrapped around the exhaust wheel.

For an exhaust housing think of the A as the area of inlet where ex. gases are flowing in to the housing. Then think of the R as the distance from the center of the wheel to the center of the inlet or "cone" where A is measured.

The housing is a measure of controlling the velocity of the exhaust gases - smaller housing = quicker spool but less flow / more chance of back pressure buildup forcing exhaust gasses back into the cylinders, larger housing = slower spool but more flow.

I guess the idea with response is to have an exhaust housing small enough to keep as close to the line of reversion without it occurring. Makes your head hurt thinking about it...

Here is a crude diagram I found - not completely accurate but close.