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Dynoed my car

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Old 03-22-2015, 01:46 PM
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gruhsy
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Have you measured cross-over pipe back pressure at all? Just curious if you did what you are getting.

My T4 0.68 on my super 75 is very close to 1:1 at 18psi boost the other day I was at 20 psi back pressure.

Temp was only 3 degrees Celsius
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Old 03-22-2015, 07:14 PM
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KSira
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Originally Posted by gruhsy
Have you measured cross-over pipe back pressure at all? Just curious if you did what you are getting.

My T4 0.68 on my super 75 is very close to 1:1 at 18psi boost the other day I was at 20 psi back pressure.

Temp was only 3 degrees Celsius
No. That's part of the reason why we did not push any further. My tuner said that often when the head flowed very good like the 16v head does. A small housing will make a big impact because so much exhaust will revert back in to the cylinders. He were pretty confident that a .81 would really open up the motor
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Old 03-23-2015, 12:07 AM
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You really think a T4 .68. hotside is too small? I'm not convinced. There are many supras running far more power by far on a .58, which is what I run and I'm making a bit more power.
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Old 03-23-2015, 01:07 AM
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i would measure the cross-over pressure before making any changes. it would be good to get the data. I think it would be lower than expected.
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Old 03-23-2015, 01:15 AM
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Originally Posted by gruhsy
at 18psi boost the other day I was at 20 psi back pressure.
At what RPM was that?
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Old 03-23-2015, 02:05 AM
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Originally Posted by blown 944
You really think a T4 .68. hotside is too small? I'm not convinced. There are many supras running far more power by far on a .58, which is what I run and I'm making a bit more power.
I know, but the intake temp increased by 10deg c from 1.1 to 1.2 bar and there where almost no power gains. And with no back pressure measurement that's why we did not push any more. This tuner have tuned hundreds of cars. Also supras with .68 that makes 700whp.

I'll deliver the car to the new owner today so my time as a 944 owner is over. ☺
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Old 03-23-2015, 05:47 AM
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Godspeed!
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Old 03-23-2015, 09:42 AM
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Full boost around 3800-4000 and held to 6700. crossover did not exceed 20 while boost held at 18. I did this about a dozen times in 3 gear.

Originally Posted by TurboTommy
At what RPM was that?
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Old 03-23-2015, 10:20 AM
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Originally Posted by gruhsy
Full boost around 3800-4000 and held to 6700. crossover did not exceed 20 while boost held at 18. I did this about a dozen times in 3 gear.
16V or 8V?
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Old 03-23-2015, 10:25 AM
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Originally Posted by Thom
For what it's worth both the S2 and 968 feature dips in their officially-published factory torque curves. In the case of the S2 I would think it may be caused by a "restricted" tune, as the long runner intake should provide great ram effect between 2.5k and 3.5k rpm, where the dip occurs.

Do you mean you have some kind of overboost protection that may have kicked in at the moment of the dip?
I got the same dip when I was tuning the Variocam set point on my old 16v turbo engine so on the 968 charts the intake doesn't seem to be part of the reason for the dip.
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Old 03-23-2015, 10:45 AM
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8V LR level 3 head

Originally Posted by KSira
16V or 8V?
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Old 03-23-2015, 11:14 AM
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Is level 3 based on 951 or 2.7 head?
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Old 03-23-2015, 12:59 PM
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951 head. Also remember I am running 5 inch exhaust and dump to atmosphere wastegate. Plus a larger cam

Originally Posted by Voith
Is level 3 based on 951 or 2.7 head?
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Old 03-23-2015, 04:36 PM
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Originally Posted by gruhsy
Full boost around 3800-4000 and held to 6700. crossover did not exceed 20 while boost held at 18. I did this about a dozen times in 3 gear.
That's surprising; usually the turbine inlet pressure will go up at least a little bit with increasing RPM.
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Old 03-23-2015, 05:41 PM
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I do get a slight spike about 2-3 psi higher which I am positive is the wastegate opening then settles to say 20psi if the contoller is set to 18.
Last year I was seeing 17 and 20. May have been the cooler temps not certain if that could be why. Some of the experts on here might know
The dump to atmosphere really helps I am sure.

Originally Posted by TurboTommy
That's surprising; usually the turbine inlet pressure will go up at least a little bit with increasing RPM.
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