Lorax

I knew the spoolup was less than perfect on this car, but I did some side by side comparisons and did some searching about the spoolup others are getting with the vitesse stage II, and i think its pretty bad. Im getting 15psi by 3800-3900 rpm's. The response is lacking. It still pulls very hard, just spools slowly.

Ideas:

Gigantic exhaust leak?
Collapsed down pipe?
Something wrong with the turbo?

This is the old version vitesse turbo.

76 911s

All of the above; what wastegate do you have? Boost leaks around intake and intercooler couplers?

Lorax

I have the Tial 38mm. I dont THINK Im leaking boost from the IC couplers, because the car has been spooling slow since before I bought it, and it had stock pipes then.

lee101315

compression test?

xsboost90

what are your egt's? Could be a collapsed crossover pipe. What exhaust are you running?
cracked header? I believe kevin had a similar problem.

Lorax

I havent done one, but that doesnt seem like it would be the cause. The engine was rebuilt a few 1000 miles ago, and while the rings weren't replaced, im pretty sure the PO checked the compression when he bought this motor, and it was good.

Lorax

Im definately thinking that it could be a collapsing x-over or down pipe, it seems to have gotten slightly worse since I bought the car. Im running stock exhaust with no cat. I cant test EGT's.... yet.

fast951

Start with the simple things before proceeding the the PITA to check components.

Which Boost Controller are you using?
Is the Boost control system working properlyn (boost controller, WG, lines,..)?
Is the BOV holding pressure?
Any vacuum leaks?
What is the fuel pressure? (It must be 3bar static)
What position is the FQS?
Is the car running rich?
Is the air filter clogged?

If none of the above! Test backpressure in the X-over pipe, this will tell you if there is a restriction.

On your turbo, 4th gear, you should be hitting 1bar boost around 3200rpm.

Lorax

AFR is about 13.5 - 14.0 on full boost through all rpms.
Air filter is a bit clogged.
Fuel presure is at 3.0 bar.
I have tried two different BOV's and that didnt seem to change anything.
vaccum seems to be fine at idle, -15 or -16 usually.
I havent looked to see what position the FQS is in.


How can I test pressure in the x-over pipe? If been thinking about doing this anyway, along with an EGT monitor.

special tool

What means did you use to measure the spoolup?
Its been an exhaust leak 80% of the time in my experience.

Lorax

I was hoping you would chime in. I think it would have to be either allot of leaks, or one very big leak to affect spoolup so greatly correct?

I used my excellent cross-eyed surveilence skills to guage the spoolup.
Im not sure exactly when im getting 15psi, but im sure its close to 4k, so I know thats not right. I am dying to go hunting for exhaust leaks, but i cant find my stupid jackstands.

schwank

Whoa, did you know 500-600 was the secret code used to indicate to troops that they should kill Che Guevara after his capture 40 years ago today?

http://news.bbc.co.uk/2/hi/americas/7027619.stm

fast951

Before you worry about the spoolup, fix the AFR 13.5-14:1AFR under boost is very lean!
Fix the AFR FIRST!

Lorax

Wo i didn't know that was too lean. I just went out ofr a quick run to verify that, and it sitting right at 14.7 on idle, and sticks at about 13.8 under full load. What should the AFR under full load be?

fast951

You need to be around 11.8:1 AFR under load!