Chris White

You can run a dead stock motor up to 7k rpm and it will not ‘let go’….however – anything much over 6k and the valve guides start wearing quickly. If you use 6400 the increase in wear is acceptable unless you hold it at 6400 for a long time (I have seen drivers (students) hold 6400 rpm down most of the Glen back straight, a good 10 seconds – in fact my student this last week end (Audi s4) did not like shifting so he held 7200 for most of the straight!).

If you are running up the rpms on occasion there it is not an issue – but you will need a valve/guide job sooner!

Chris White

toddk911

Ok cool.

But what about fuel cut/rev limit? I thought even with aftermarket chips and such they still have rev limiter and fuel cut very close to redline?

I know I hit it in 1st gear sometimes. Never gone that deep in other gears to check.

Chris White

Different chips have different limits!

toddk911

Here Tedesco:

toddk911

Now, what do you really look for in a compressor map in regards to what it will do on your car?

toddk911

But the Super 75 is obviously bigger then a stock turbo but not as most seem to describe it.

Like comparing a canalope size to grapefruit size. At least in my opinion.

Porschefile

Todk911, I take it you got that compressor chart from ATP Turbo? Hehe, I'm not sure why but they listed the compressor wheel as 68mm on the chart, which isn't correct, though the flow chart itself looks to be the correct one. Here's the official Garrett link Gt35r It has a 61.4mm inducer and 82mm exducer on the compressor side. Now if you check out Precision's Website The PT-67 is listed as having a 2.620" inducer (66.55mm) and 3.310" exducer (84mm). Also, the gt35r is only a 56 trim, as opposed to the 63 trim of the T67. If you want to get an idea of how large a T67 is, check out this Link That's a webpage of Mk4 Supra dynos. There are people making in excess of 700rwhp! That is, of course, on full T4 T67's. The Super75 we are discussing still has a k26 hotside, so it does not quite have the flow capacity as the larger T4 series housings and turbines do. To be honest, the gt35r is still a pretty large turbo, and plenty of people have made over 600rwhp on 4cyl's with them. A gt30r (gt3076r to be exact) might be a better choice, and is still rated at ~525hp with the larger exhaust housings. Edman951 was reporting 1bar by ~3100rpm with one of these (.63 exhaust), although I think you'd have to run ~20+psi to push 400rwhp. At that point, whether or not you could run pump gas would be a matter of tuning it really well. I know the GT series are controversial due to the custom work, however ATP has them with the KKK replica housings which would save some of the trouble.

Wes, are you looking to make 400rwhp at 1bar? Are you choosing 1bar simply to keep it on pump gas? If that's the case, you can run more boost then this and still run pump gas. With a good standalone and maybe water injection or some other mods, 20psi for example, on pump is not out of the question. This would allow you to run a much smaller and more responsive turbo.

WesM951

No, not at 1bar. 19-20psi is what I plan on running. Any suggestions?

tedesco

I completly agree to "Porschefiles" statements. GT30R looks the perfect match for the 2.5L engine. The stock rew limit is just slightly past the max efficiency area of the compressor until quite high boost levels. But as I mentined, I already run the super 75 on a 2.5l and the lag that comes with that is known to me. If you increase displacement or the rew limit the GT30R get a bit small. There is a very long thread in this forum and you can find it by searching for "GT30R or GT35R". It also includs dyno charts.
So the step to go for the GT35R was well thought especially with one 2.8l engine and a bit different 3L which is still in work.

tedesco

Here is the link. Project done by Markus951. Dont know if it works like this...

https://rennlist.com/forums/showthre...ighlight=gt30r

toddk911

Actually I just googled "gt35r"

But on the LR site they say the comp is 67mm... ?

Also, they say it is a Garret "hybrid" which I assume means all internals are exaclty the same and the only changes are so it will work/fit with the 951.

Can anyone tell me what to look for or what is the compressor map showing?

I see some effeciecny % and flows, but what does that mean in terms of the car's performance to said turbo?

toddk911

"Edman951 was reporting 1bar by ~3100rpm with one of these (.63 exhaust)"

So what is the exhaust of the 75? And how did he get 1 bar so soon?

tedesco

Here you can find basic explanations about turbos:

http://www.turbobygarrett.com/turbob...o_tech101.html
http://www.turbobygarrett.com/turbob...o_tech102.html
http://www.turbobygarrett.com/turbob...o_tech103.html

Porschefile

That wasn't a Super75. It was a Gt3076r with a .63ar exhaust. The smaller exhaust side helped it spool so quickly, though it is still a responsive turbo for a 2.5l to begin with. With a .63ar it's going to cut down the power potential.

I believe the Super75 uses either a /8 or /10.

If you look at the Super75 description, it has the exact same specs as a T67 compressor wheel so it has to be one of those. They don't mention much on the exhaust side, so it could still be using a KKK turbine for all we know.

Wes, I vote for either a 57 trim or 60 trim.

333pg333

This is a fascinating read. I don't understand a lot of it but am learning everyday. Why could we not coalate all this material or info and keep it in a sort of separate area so that members can access it and put in their desired outcome and intended use and then be provided with a mode of action. EG If I wanted a car for road but also track use that largely consisted of short sprint events I could cross reference this 'organic'* table and have a list of options. These options could involve costs, vendors, octane, even altitude I guess. I may have $3500 to spend and this program or table could direct me in the best way possible. Alternatively you could just put in your desired rwhp and it comes up with the many ways to achieve this. So Wes wants 400rwhp on pump gas. Punch this in and out comes eg Vendor 'x' kit + dyno work = $3000. Or Vendor 'y' cam, head, and standalone = $5000. Is it possible to do something like this or would it require too much involvement/time from the controllers/editors to be justifiable? This would be like a condensed version of this forum. As much as this forum is a great thing who wouldn't like to be able to punch in the questions and receive direct answers? Maybe it's just a simple table/chart with various dyno results which you cross reference: costs=y, method=x, outcome is linear.
*organic is used to suggest that this is updated over time and peoples experiences.
Maybe I'm dreaming... :