What turbo for 9:1 compression, GTX28/30?

[Synack]

Originally Posted by woode

Timing. Pump gas with that high of CR and that much boost needs more timing to be pulled to keep knock away, which results in more heat. A lower CR could surely run less boost and more timing and make similar numbers more safely even.

There are so many different approaches to tuning and engine building.. everything is a compromise.

Honestly this is good to know, and falls right in line with what @Manji was saying. I thought I was screwed after we made the power we did at 20psi with this compression. I'm almost certain my tuners went super conservative on the tune. We're also running meth so honestly this car is probably extremely bulletproof as it sits right now.

[Synack]

Originally Posted by King Tut

$32.5k. My M3 is sold, and it is time to build another turbo 4 cylinder.

Wish I could help! Sounds like a fun project. My buddy here in Atlanta is mostly just working on his friend's cars now and he finished his Supra so there isn't anyone to help or tweak builds with here.

[cdrazic93]

Indeed, but the lower the CR the less hp per PSI youll get from a 28, as opposed to a stock CR.

So, will the increased timing that is safely done on a 9:1 motor counteract the less hp per PSI?

[Synack]

Originally Posted by cdrazic93

Indeed, but the lower the CR the less hp per PSI youll get from a 28, as opposed to a stock CR.

So, will the increased timing that is safely done on a 9:1 motor counteract the less hp per PSI?

It's my understanding that you can increase as much timing as you need for it to keep making power until it starts to ping/spark knock. Then back off a little bit. Then compensate your tune and boost to make your power goal. (If it's possible with your setup)

I've also done some research and found that someone running 350whp at 13psi (I'm guessing) on a 12.5:1 compression will have more heat than someone running 350whp at 20psi on 9:1 compression.

[ptuning]

Originally Posted by Synack

It's my understanding that you can increase as much timing as you need for it to keep making power until it starts to ping/spark knock. Then back off a little bit. Then compensate your tune and boost to make your power goal. (If it's possible with your setup)

You will actually want to tune it for MBT (minimum best timing) on the dyno. With your lowered compression ratio and especially at low boost levels, you will likely be going well over MBT under most load/rpms ranges if you try to tune off of the ECU's knock feedback. The only reason tuners (not all) are able to sort of eTune the timing on this car is because, even at lower boost levels on the stock compression, you'll likely be dancing on the edge of knock feedback at most load points before you even reach MBT.

When ETuning, it's best to start off with a known working map that you've developed on the dyno over an extended period of time. This ensures that the ignition and cam timing that you start off with will be close to where it needs to be.

- Toan

[Synack]

Originally Posted by ptuning

You will actually want to tune it for MBT (minimum best timing) on the dyno. With your lowered compression ratio and especially at low boost levels, you will likely be going well over MBT under most load/rpms ranges if you try to tune off of the ECU's knock feedback. The only reason tuners (not all) are able to sort of eTune the timing on this car is because, even at lower boost levels on the stock compression, you'll likely be dancing on the edge of knock feedback at most load points before you even reach MBT.

When ETuning, it's best to start off with a known working map that you've developed on the dyno over an extended period of time. This ensures that the ignition and cam timing that you start off with will be close to where it needs to be.

- Toan

Thanks! But I don't plan on e-tuning. I plan on possibly getting the original tune from D3 and have them send it over to Top Speed here in Atlanta and get dyno tuned the proper way.

[ptuning]

Originally Posted by Synack

Thanks! But I don't plan on e-tuning. I plan on possibly getting the original tune from D3 and have them send it over to Top Speed here in Atlanta and get dyno tuned the proper way.

Agreed, dyno tuning is the only right way to do it in your particular case.

- Toan

[Synack]

Originally Posted by ptuning

Agreed, dyno tuning is the only right way to do it in your particular case.

- Toan

It's extremely convenient having them less than 5 miles from here.

[Dipstik-sportech]

On my 9.5:1 block on a gt2871 with american 89 I made 373whp but pulled it back to 360 to be safe @16psi

[Synack]

Originally Posted by Dipstik-sportech

On my 9.5:1 block on a gt2871 with american 89 I made 373whp but pulled it back to 360 to be safe @16psi

That's good to hear. Hopefully I can reach 400.

[Manji]

Originally Posted by Synack

That's good to hear. Hopefully I can reach 400.

Motivation for you.


GTX2867R on a stock displacement SR20, 9.0:1. It is on e30, but only gaining 40-50hp from that over pump fuel.

Competes in D1NZ against cars with twice the power and 100x the sponsorship revenue (literally 100x)

How? Because its uber responsive.

Also guy is a great driver.