.48 a/r or .63 a/r in t3/t04e?

[elpiar]

If I'm aiming for 350-400 whp, which one should I go with?

will .48 a/r turbine housing help me with spool? how much?

Also, how is the spool of AMS GT32 compared with the usual t3/t04e with .63 a/r hot side?

[Chezedik]

You should go with the .63 A/R. BTW, what is the .62 A/R?

[elpiar]

You should go with the .63 A/R. BTW, what is the .62 A/R?

I meant .63 a/r, sorry it's 2am

post corrected.

so you think .48 a/r will choke the flow a lot?

[KATwo40]

Yep. Also, you'll be hittin' the surge line pretty hard with a .48 A/R.

[WDRacing]

I think the .48 will be ok for 400ish. But not any more then that. But 400 is plenty is a 240. The spool will be almost instant and the compressor puts out plenty of volume.

WD

[elpiar]

I think the .48 will be ok for 400ish. But not any more then that. But 400 is plenty is a 240. The spool will be almost instant and the compressor puts out plenty of volume.

WD

So you're saying the .48 will give me better spool? how much earlier rpm would I get? 500?

[WDRacing]

500-700 I'd say easy.

[elpiar]

Will I be better off with t3/t04e 50 trim, .48 a/r? or with AMS GT32 (I think they only offer it in .63 a/r)?

[WDRacing]

Depends on what you're paying for either turbo. I'd go with a .63 AR because a little lag isn't a big deal at all in real world driving. Especially on a car that is running more then a few psi.

But thats my personal opinion, I don't do anything small.

[hannibal]

I'd go with a 0.63 for 400whp. I was originally planning for a 350whp setup, and I thought 0.48 was too small for that goal.

[WDRacing]

I know Greg (AZHitwoman) runs a .48 on his T3/TO4E and is probably real close to 400whp. Spool is right now fast and first gear is utterly useless. So...

But I agree with the .63, its simply a more efficient setup.

[C-Kwik]

You should also note what stage/trim exhaust wheel you'll be using as well. A .63 A/R on a Stage 1 is going to respond and flow differently than a stage 3 wheel.

Personally, for 400 HP, I'd be looking at something on the bigger side. If HP is your goal, a bigger turbine overall will yield the best efficiencies up high where you need it. I'd be most inclined to use a T4 turbine myself, but one of the larger T3 turbines should still be a good match for 400 HP.

[turbo2nr]

sorrie to thread jack but what is the t04b good for .67/.58? i think its a v-trim? over 350whp?

[Chezedik]

T04b never came in a .58 unless you maybe have a straight T4. Also, I believe that the V-Trim is a .60A/R too. I have the V-Trim and mine is a .60, but since it is trim, they may have offered that trim in a different A/R.

The T04b can handle 350hp in the 15-18psi range. Maybe a little lower with a straight T4, but in the ball park. Tuning will be an issue also.

[DRFT(kinda)]

To add my 2 cents, I have a .48 A/R on my T3/T04E. The motor isn't broken in yet, but with the intercooler disconnected, it pushing about 0 VAC at idle. It pretty much is "instaboost" on a KA. Like others had said, its close to the surge limit. I'm starting to get into compressor maps for turbos and for the .48 A/R and the 2.4 liter motor, at 10 PSI you are using 80% of the turbo. That in turn means that it spools very very quick and after about 15~18 PSI you will see no gain in horsepower because the motor will start "out-running" the turbo. If your goal is 400whp, then I would suggest going with the bigger A/R because you will get higher horsepower. But you also have to concider what you are building the car for, if its to drift with, a quick spooling turbo is better, but if its a drag car, then lag wouldn't hurt you because it will allow you to get better traction of the start before the turbo "kicks in".

[turbo2nr]

yes its a straight t4, so what do you mean by tuning may be an issue?

[Chezedik]

How did you determine that you are using 80% of the turbo, I hope you are not talking about the 78% in the center of the T04e's map.

2nr, what I meant was that you will get better power with a more avant garde tune, but the T04e is still a more efficient turbo. We have just happened to get turbos that are a little more affordable. You will be happy with the T04b, but you can give up on instant boost. I would guess around 240-250 in the 8psi range, obvious increases with boost increase.

EDIT: Also, where are you sampling boost from for your gauge, because at idle, with no throttle you should be making 17". An engine will not run with 0 vac at idle.

[elpiar]

Does anyone has the compressor map for AMS GT32?

I haven't got into choosing the turbine wheel stage. I'm familiar with the a/r and trim for compressor wheel (I plan to use 50 trim t04e btw). Can anyone tell me how the turbine wheel stages affect flow and spool and physically what difference are we seeing on the geometry of the turbine wheel?

[Chezedik]

No, and no one will. The problem is the kind of machinery it takes to create that map. You can use the Garrett GT32 as a judge, but no one knows what they do besides put a larger turbine on it. Which may or may not have any affect on flow. I have also heard they use a GT35 wheel in the GT32 housing.

Turbine wheel will only affect exhaust flow, which is very secondary to compressor flow in terms of power created at boost. It really only tells you when you will make boost. Also, the later you make boost, the more power you will make, all other things being equal. So a turbine wheel with an A/R of .48 will always have a ratio of .48 from small to big on the wheel. But a different stage will be a physically larger wheel, where a stage one wheel is in the 1" range, a stage 5 is closer to 3". This will affect spool but allow more top end horsepower due to the increase in exhaust flow, but will cause a higher boost threshold (higher spool).

The geometry is the trim, and as far as it is concerned on a turbine, it doesn't change much. This is because the shape is optimal pretty much regardless as it is, as a driving wheel. It changes in the Compressor more for a number of reasons.

[elpiar]

No, and no one will. The problem is the kind of machinery it takes to create that map. You can use the Garrett GT32 as a judge, but no one knows what they do besides put a larger turbine on it. Which may or may not have any affect on flow. I have also heard they use a GT35 wheel in the GT32 housing.

Turbine wheel will only affect exhaust flow, which is very secondary to compressor flow in terms of power created at boost. It really only tells you when you will make boost. Also, the later you make boost, the more power you will make, all other things being equal. So a turbine wheel with an A/R of .48 will always have a ratio of .48 from small to big on the wheel. But a different stage will be a physically larger wheel, where a stage one wheel is in the 1" range, a stage 5 is closer to 3". This will affect spool but allow more top end horsepower due to the increase in exhaust flow, but will cause a higher boost threshold (higher spool).

The geometry is the trim, and as far as it is concerned on a turbine, it doesn't change much. This is because the shape is optimal pretty much regardless as it is, as a driving wheel. It changes in the Compressor more for a number of reasons.

Thanks for the technical insight!

So let me summarize what I understand from what you wrote:

Turbine housing A/R affect spool. The earlier spool means higher end power is sacrificed. Turbine wheel does the same thing by changing the wheel trim (inducer/exducer ratio) instead of the housing geometry.

Compressor wheel trim affects the flow rate a lot and therefore determines the power limitation of the turbo, but does not affect spool that much.

Any correction or other opinion?

[GEO]

I run the same turbo as greg, .48 a/r with a 57 trim on a stage 5 wheel. I love it, instant boost and all.

[hannibal]

^ You pretty much nailed it.

So a turbine wheel with an A/R of .48 will always have a ratio of .48 from small to big on the wheel. But a different stage will be a physically larger wheel, where a stage one wheel is in the 1" range, a stage 5 is closer to 3". This will affect spool but allow more top end horsepower due to the increase in exhaust flow, but will cause a higher boost threshold (higher spool).

What youre describing as A/R is actually trim. Stg 3 is 76 trim and stg 1 is 69 trim. Trim is based on the size of the small end of the wheel (exducer) and the big end (major/inducer). The stg 3 is less restrictive at higher flow rates due to this ratio. It also happens to have a large major than the stg 1.

The A/R (area/radius) describes the housing. The A/R indicates maximum exhaust flow. A higher A/R can flow more air than a smaller one and allow for more horsepower.

Both affect boost threshold (when the turbo begins building boost). A smaller A/R housing and/or a lower wheel trim will make boost faster.

[NateDogg]

If you want <350whp, you might be able to make that by maxing out the turbo at around 20-24psi, depending on your tuning ability and medium.

In my opinion you will want the .63 a/r for >350whp. It can make up to about 450whp at 25psi.

The difference in spool will only be noticeable at less than 3500rpm, and who races at that rpm anyway??? Unless you want the feeling of a V8

[elpiar]

^ You pretty much nailed it.

What youre describing as A/R is actually trim. Stg 3 is 76 trim and stg 1 is 69 trim. Trim is based on the size of the small end of the wheel (exducer) and the big end (major/inducer). The stg 3 is less restrictive at higher flow rates due to this ratio. It also happens to have a large major than the stg 1.

The A/R (area/radius) describes the housing. The A/R indicates maximum exhaust flow. A higher A/R can flow more air than a smaller one and allow for more horsepower.

Both affect boost threshold (when the turbo begins building boost). A smaller A/R housing and/or a lower wheel trim will make boost faster.

So in addition to the .63 a/r, are you suggesting I should get a stage 3 wheel for the turbine wheel?

[WDRacing]

Small is for p******...I have the .63 with the stg 3 wheel...DO IT. The 240 community is filled with lame *** wimps who want boost from 2000 on. Or else they call it "laggy". This group of people has succeeded in ruining the knowledge base as far as what represents a good turbo. Ask Porsche or Corky Bell what they think about that. The terms "heat pump" "poor efficiency" will be heard quite often in circles where people actually know what they're talking about.

Atleast you've crossed the hump and got away from the T3 super60 or T2 size turbo's. The smaller T3/TO4 is still a good turbo since the compressor is very efficient, its just a matter of how much power you actually want. This is largely controlled by the exhaust housing AR size.

This thread has been very informative and has great posts in it. Even Mr Ultra Gay himself...thats Cheze...had some good points.

To best answer your own question, simply find an end goal for WHP and base the decision on that.

WD

[elpiar]

Yes, I was all for quick spool when I boosted my integra GSR a year ago. Mostly due to the high rev motors in hondas. It was fun, but I figured if I want true instant boost I better go with superchargers (and I did).

To answer your question, my goal is about 350whp for low boost and 400whp for high boost.

I think I decide to go with t04e 50 trim .63 a/r stage 3 wheel or the AMS GT32, depending on the price.

[KATwo40]

I have the hookup on T3/T04E's.

[hannibal]

^ O Rly?

0.63 A/R with stg 3 wheel sounds perfect to me. Great for 300 to 400+whp IMO. FYI, orion made 300whp at 12psi. I think you'll made 350whp around 15-16psi. Cory (nissanfanatic) is making 420whp at 20psi with this turbo and a damn good Enthalpy ECU.

[KATwo40]

^ O Rly?

Yep. Less than $400 with a 1yr warranty. Garrett internals, aftermarket housings.

[elpiar]

AMS claim that with the GT series wheel they have, it has better flow and spool. Do you think it's worth $650? (not ball bearing)