Turbo s50 whats the issue

[fastboy]

Good Day Gents

I went to the dyno a couple days ago. Built S50 9.0 CR GT35R on a 666 manifold 63 back housing with a M50 cams (long story on that on) 3inch cold side and 2 1/4 hot side for the intercooler MS3 as the managment. 15psi on 90 octane pump gas. What is causing the the top end to fall off so badly?



Thanks in advaince

[vollosso]

I’m going to take a wag. Upload a picture where we can read the afr and I can do better.

1. Tuning
2. Back-pressure


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[fastboy]

AFR is 11.7 not more at wide open throttle.
Could it be the vanos mapping? We did it 15 degrees across the from 3500rpm and off at 5000rpm

[crazyyardie]

What size turbo housings ?? What cams ?? Aren’t you on standalone. Do you have the log ?


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[XnWarden]

Im no expert but that hotside sounds small and those cams sound slow.

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[dburt86]

Everything in here

Or the vanos is staying active

- - - Updated - - -

Wait, i just read the comments in here

The VVT settings should be set to ON/OFF. Meaning you wont be specify a certain number of degrees, but rather when the vanos solenoid should be on or off

Generally speaking, your gonna want the vanos active at like 1200rpm and off around 4k.

You can easily find this out by making back to back dyno runs with the vanos on all the time and then another pull with it off the entire time. See where the 2 graphs would cross if you layed them on top each other

[das Boot]

That .63 housing is waaay to small get somthing atleast i. The .9x range and watch what happens.
The differance in spool will be a few 100 rpm.

[fastboy]

Thanks guys for the input really appreciate it.

@Dburt we actually did all Zero's in the vvt table for a few runs the car lost over 50 whp and TQ and then did a few run with the vanos activated from 3500rpm and off at 5500 rpm @10 degrees all the way up 20 degrees, no real change happened at the 20 degree so we left it at 15 degrees. the car lost power at the 5500rpm so we decided deactivated the vanos at 5000 rpm the car gained a bit of power in that area. when we go back to the dyno we will try the earlier activation of the vanos.

@ DasBoot I am in the process of looking for the bigger housings

[Butters Stoch]

Its the cams causing the drop in power up top. Not the small back housing. Sure a bigger back housing will flow a bit more, but those shit cams are killing your top end.

[dburt86]

Thanks guys for the input really appreciate it.

@Dburt we actually did all Zero's in the vvt table for a few runs the car lost over 50 whp and TQ and then did a few run with the vanos activated from 3500rpm and off at 5500 rpm @10 degrees all the way up 20 degrees, no real change happened at the 20 degree so we left it at 15 degrees. the car lost power at the 5500rpm so we decided deactivated the vanos at 5000 rpm the car gained a bit of power in that area. when we go back to the dyno we will try the earlier activation of the vanos.

@ DasBoot I am in the process of looking for the bigger housings

Your VVT settings should be ON/Off, not PWM. The vanos solenoid in the older 24v stuff is not meant to PWM.

Meaning, you shouldn't be targeting an angle in your tune. You should be targeting at what RPM and load the Vanos should be on or off.

But either way, ur cams suck.

[fastboy]

@Dburt noted I will be revisiting the targets as was suggested for the vanos angles as soon as I can get back on the dyno, also noted on the sucky cams lol, I am thinking of getting the schrick camshafts 264/256 would that be a better choice?


As for Timing what's a medium timing figures compared to a high timing figures?.

[Robocop]

pretty interesting i thought twin cams rev out WAY more that's like an m30 powerband.

[pbonsalb]

Its the cams causing the drop in power up top. Not the small back housing. Sure a bigger back housing will flow a bit more, but those shit cams are killing your top end.

A little turbo E36M3 trapped 135 mph this year with 0.63 JB PT 6262, comparable to GT35R. Yes, it was running more than the 15 psi of the OP’s car, but I would think it was also doing better than 350 STD Dynojet at 15 psi.

Log boost and AFR for a start.