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MHI will have more back pressure at 5000+ rpm.
If we look at the perfect situation, 2 psi is 6.8% more pressure (2 psi ÷ 29.4 psia). That comes out to about 25hp. If we can keep compressed temp and engine/driveline efficiency the same, then we can expect a max of 25 hp more. But we know air temps will increase some with higher pressure (even with FP Red BB), especially with MHI version. I am surprised that you lost power with 2psi extra boost. Makes me wonder how much I'm losing from using a HFC over a test pipe. Lol
VD has dynojet and Mustang dyno correction factors. Tscomptuned uses VD exclusively for his remote tunes with great results and accuracy. With the right road and very accurate profile settings it’s definitely a useful tool.
MHI will have more back pressure at 5000+ rpm.
If we look at the perfect situation, 2 psi is 6.8% more pressure (2 psi ÷ 29.4 psia). That comes out to about 25hp. If we can keep compressed temp and engine/driveline efficiency the same, then we can expect a max of 25 hp more. But we know air temps will increase some with higher pressure (even with FP Red BB), especially with MHI version. I am surprised that you lost power with 2psi extra boost. Makes me wonder how much I'm losing from using a HFC over a test pipe. Lol
Soon I will have answers!! Lol
I think if the HFC is well constructed then gains would be minimal. However I think it also depends on your setup. If you’re running 30lbs on a Fp Black vs 25psi on a stock turbo you’d probably experience more bottlenecking on the Black than the stocker
WGDCs are 73% up to 80% at redline.
Heres a good VD chart with those settings
Yeah if you are at that much of a wastegate duty cycle then you are definitely hitting a back pressure issue. Usually start seeing back pressure issues around 55 to 60% wastegate duty cycle. She needs something to help her breathe a little better.
Yeah if you are at that much of a wastegate duty cycle then you are definitely hitting a back pressure issue. Usually start seeing back pressure issues around 55 to 60% wastegate duty cycle. She needs something to help her breathe a little better.
That would depend entirely on the turbocharger and WGA being used.
You have/had an FP Red correct? What WGA are you running and what are your WGDC around 7000rpm? If you don’t want to share the exact #, are my settings reasonable considering good preload on a 22psi actuator?
I know on my s257 sx-e at 62% wastegate duty cycle I started to run into back pressure issues. It is a t3 .82ar w/ a 46mm wastegate. Turbo isn't much bigger than an fp red if you look at them side by side.
I know on my s257 sx-e at 62% wastegate duty cycle I started to run into back pressure issues. It is a t3 .82ar w/ a 46mm wastegate. Turbo isn't much bigger than an fp red if you look at them side by side.
What was the cause of your backpressure issues? Exhaust diameter/setup? Did you ever get it fixed?
What was the cause of your backpressure issues? Exhaust diameter/setup? Did you ever get it fixed?
Exhaust diameter. Need to go with a bigger turbo back exhaust. I'm at a 3" now. Need to go with a 3.5 or 4" to fix the issue. I kind of fixed the issue. Took the s257 off and put my 6466 on. 90 lbs/min turbo is gonna move air better than 65 lbs/min turbo and make more power with less boost. Haha. Other than that I am gonna run into the same issue with the exhaust on the 6466 as well. But since I had to rebuild my exedy triple disc clutch I haven't even worried about fixing the back pressure issue.
You have/had an FP Red correct? What WGA are you running and what are your WGDC around 7000rpm? If you don’t want to share the exact #, are my settings reasonable considering good preload on a 22psi actuator?
I have FP's 25lb WGA. Wastegate pressure (0 WGDC) was 20-21 PSI. With (IIRC) 68% WGDC out the top, it held 28-28.5psi at 8k.
Originally Posted by cficare68
I know on my s257 sx-e at 62% wastegate duty cycle I started to run into back pressure issues. It is a t3 .82ar w/ a 46mm wastegate. Turbo isn't much bigger than an fp red if you look at them side by side.
Not even close to comparable. You have a turbine housing the actually flows well, a different exhaust manifold, and an external gate. The MHI hot side is TINY. And the spring pressure in your gate matters too.
Alright everyone so as a quick summary, my exhaust is not the problem. Virtual dyno runs are mostly similar. If it was the exhaust being a bottle neck I would have expected better gains across the board, especially considering there is a 2-2.5psi difference between the exhaust dump run (purple) and previous mild tune by myself (green). I find it especially odd that at the top end the car just seems like its getting hot air and falls on its face with more boost. Granted, the temps when I did the exhaust dump pull were very hot, but i still see no reason why it shouldn't be holding better. The car has a 3.5 inch FMIC from Perrin and it is a little banged up but not in terrible shape by any means...
Aug 2, 2018, 09:42 AM
