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Old 12-30-2010, 06:58 PM   #7
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Member#: 74110
Join Date: Nov 2004
Location: PERRIN Performance

Back on the dyno again finally. I was pretty excited to see what kind of power this GTX3582R was going to make. I installed it with the .63AR housing as this has been becoming the more popular choice lately. My initial impressions on the street were that it's a little laggier, but still pretty snappy. Also I found that on the street it "felt" like it made more power. So when I put it on the dyno my plans were to do it a little different and start with GTX3582R w/.63 first then go to the GT3582R w/.63. Then do the same boost levels, AFR levels, timing and same 7000 redline.

To recap, car has the exact same parts as before, all our normal parts, plus our Meth injection kit, Cosworth ECU, and stock TGV housings. Goal is to run 1.2bar, 1.5bar, 1.7bar, and 1.9bar all at .79-ish lambda.

First run at 1.2 bar was exactly the same power, exactly the same everything except laggier. At these boost levels it was consistently 400RPM laggier. Here is a graph of some runs. This shows the 1.5bar levels of the GTX3076R and the GTX3582R. you can see that on a typical run its 500RPM slower, but when quick runs are done the split is more like 350RPM.

Moving on to 1.5 bar then 1.7 bar I found the exact same thing! Only difference was i added a bit more fuel (no power change). I was really wondering when this larger more efficient compressor wheel was going to start coming into play. I felt cheated a bit so I started tuning the 1.7 bar range. I added some timing, leaned it out, and basically the changes were not worth anything, maybe 5WHP. I put the changes back and hoped that 1.9 bar would show some real gains.

So one last ditch effort, I ran it at at 1.9 bar and guess what! NOTHING!! It made the exact same power as the GTX3076R in all instances and since it was laggier, it made less peak TQ.

You can see here the raw data runs and how they were making the same power. At these boost levels i also did some tuning and found that timing was much more on the edge. Adding a degree or half neted in a large change to engine noise. Still no knock, but again, the 5HP wasn't really worth it to make it that much on the edge. I did see evidence that the compressor was more efficient as i was needing to add more fuel, but not tons.

Here is a nother few runs, showing the GTX3076R at 1.5bar of boost and the GTX3582R at 1.5bar of boost. Its easy to see what turbo is going to be the next popular turbo from this.

The question is why? I am sure there is a bit of power to be gained with the TGV's being deleted (Proving this soon as well), and potentially there is some power to be gained with bigger cams, but realistically it's the turbine housing. In the past with GT turbos, we never really found the flow limit of the turbine housings. In this case we did. Now looking at the Turbine housing flow charts we can see why we hit this limit.

You can see how a 30R.82 flows about 23lbs/min under those conditions and as the turbine pressure raises it hit a wall. Basically adding more exhaust pressure will not do anything for the ultimate flow of the engine. On the 35R turbine map the .63AR housing hits a similar wall at 23lbs/min. This is why at the same boost levels as the 30R the engine wasn't flowing more air making more HP. But if we step up to the .82 there is an instant 5lbw/min of air flow gained from the turbine wheel. 5lbs/min is 50 engine HP worth of airflow so this should net close to 50 more Wheel HP. But of course at the expense of lag. In past tests .82 GT3582R would spool around 4500 RPM and with the GTX i think it will be the same.

In the past we would say that when pushed the GT30R w/.63 made about, 400WHP, then .82 added 50WHP to that number, then a GT35R w/.63 added another 50 ish and then the .82 added even more. But with the case of the GTX3076R it really does fit a broader range of HP without sacrificing spool. The GTX3076R w/.82 AR now covers 2 turbos In the end your choice of turbos are going to be GTX3076R w/.63, or GTX3076r w/.82, or GTX3582r w/82.

From this I can 100% conclude that the GTX3582R with a .63 housing is NOT the turbo to buy. A much better choice is the GTX3076R with .82 housing. Its cheaper and spools quicker. From this I can also conclude that a GT3582R with .63 housing is also not a good choice as the GTX3076R is better, but it does cost a bit more. The only thing left on the table is GTX3582R with .82 ar exhaust housing test. If there was one on the shelf i might have stolen it for this test, but i think its going to have to wait a week. Sorry!

If people are still wondering are the GTX turbos worse in any way performance wise. I am pretty confident in saying not at all. The only issue they have is they cost more. But overall when looking at a complete turbo kit or a complete car build, its not that much overall.

Originally Posted by jkelz25 View Post
any results on that gtx35 yett??
I know, i know, i have completely neglected this thread last week. Sorry, i was setting up the web pages and things for the turbo kits. We also added a new Tuner Turbo kit, which is everything minus turbo and wastegate. We get about 2 calls a week about this asking if we can sell a kit like this so we are!

A few pages back i said this 35R .82ar exhaust housing flows about 50more HP than the .63ar housing so i should be seeing about 50HP with just bolting this on. It wasn't too far off from that at higher RPMS!

Here is a comparison of the GTX3076R w/.63 vs .82 and the GTX3582R w/.63 vs .82. On the street the GTX3582R w/.82 is very laggy off boost. Its a huge difference!

Onto the fun stuff. Here is the GTX3582R w/.82 housing at different boost levels. It does make more power than the GTX3076R but not tons and tons more. I think that if i had reved the engine 8K we would see the GTX3582R start to show its worth. At 30psi, the 2.5L is needing about 70lbs-min of air and going up to 8000 adds 10lbs-min more. That is where the GTX3076 falls off and the GTX3582R would really show some gains.

The question is, "Is it worth going to the .82 over the .63 GTX3582r?" I would say for sure, if you are wanting more power and are going to rev the engine high. Here is a graph showing the .63 runs versus the .82 runs. Like all other runs, i did no tuning to increase power, just to bring the AFRs back in check. What i found was i needed more fuel at the higher RPM's which is expected with a more efficient turbo. What i notice on the road is the car is laggy, then BAM, power, and once on boost, its a very linear feel all the way to redline. There is no drop in power and it really makes me want to rev the car higher and higher, but i am not....

My personal choice after all is said and done... GTX3076R with .82ar. Check out the difference. And what you can't see on the graphs is the off boost power. Personally if i was limiting my redline to 7000 RPM, then i would loose 30WHP to get the better response and fun factor of the smaller turbo.

Here is another comparison of some turbos. I couldn't overlay the GTX3582R w/.82 without doing some free hand drawing. But check out at 4000RPM and where the TQ is on all these as well as the above graphs. Keep in mind these are not all GTX turbos, but what i am showing is the response and TQ from the GT or GTX 3076R and the GT or GTX3582R with different housings.

At 3500RPM........

-3076R w/.63 hits 340ft-lbs of TQ

-3076R w/.82 hits 280ft-lbs of TQ

-3582R w/.63 hits 240ft-lbs of TQ

-3582R w/.82 hits 220ft-lbs of TQ

AT 4000RPM......

-3076R w/.63 hits 420ft-lbs of TQ

-3076R w/.82 hits 420ft-lbs of TQ

-3582R w/.63 hits 320ft-lbs of TQ

-3582R w/.82 hits 270ft-lbs of TQ

Originally Posted by jkelz25 View Post
(sorry for the double post)

Are rotated kits for the gtx series avaible yet? if so where?
They sure are we have been shipping them the last couple weeks! (Except for a few delays from the eastcoast weather)

Originally Posted by Phatron View Post
i got $100 that says it wasnt a gtx3071 cause clark hates them (gt3071) and would most likely never tell anyone to put one on a 2.5L
Sorry Garret, but what a waste those things are!
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Last edited by PERRINJeff; 10-22-2013 at 02:47 PM. Reason: New info!
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