onspeed

Around what RPM should a Vitesse Stage 2 turbo be hitting full boost (16 psi)?

Car is 2.5L w/ 3" exhaust, MAF kit, new vac lines, Tial WG, etc etc.

I'm not getting full boost till ~3600 RPM - I'm thinking the header might be cracked..

Also - I see a MAP sensor for the MAF kit that doesn't have a vacuum hose attached... that can't be right? edit - Added a line to go to the MAP sensor, weird that AFRs were spot on with it reading constant atm pressure.

refresh951

Hey Chris, did you buy another 951?

Humboldtgrin

If a header is cracked or the crossover then that would definitely be a problem.

mel_t_vin

In what gear?

If in 5th, I would suspect an exhaust/boost leak or faulty waste gate. If in 1st, that would not be out of the realm of normal operation.

onspeed

Upper gears. Also getting slow transient boost response on gear shifts, longer than I remember these cars having.

Pretty sure it's something like a cracked header unless someone chimes in otherwise that the turbo is just slower to spool

Adonay

dont think that is normal ,My stage 3 was around 3100\3200 in 5th gear

fast951

With the Vitesse Stage 2 turbo, you should be seeing 1 bar boost around 3000RPM (+/-200 rpm), in 4th gear. Many things can cause your car not to hit 16psi till 3800rpm, some of which:

- Exhaust leak in front of turb0 (cracked headers, bad seal between Headers & X-over, X-over to turbo, X-over to WG).
- Malfunctioning boost control (WG, Boost controller,...)
- Leak on the intake past the turbo (this usually creates very rich AFRs as well).

If you have V-MAF+ software (in the DME), then the MAP sensor must be connected. Otherwise the DME will run in safe mode with reduced power (which could attribute to a slower spoolup).

If you have a PiggyBack and you are using it as a boost controller, it depends on the MAP sensor to operate.

Apparently, there are multiple things that require attention/checking, hopefully it's something simple.

onspeed

This is what I needed to know, thanks. Going to look into exhaust issues. AFRs look pretty good, car has one of your VMAF systems & piggyback. Using MBC for boost control.

Alan 91 C2

When I was working boost issue on my Turbo S car, found collapsed head pipe. But also found valve in waste gate was not sealing. A quick trip to the valve machine trued up the valve sealing to the seat.

Tom M'Guinn

I can vouch for that. Crazy Eddie's 2.5L car has the VR2 turbo and hits 15psi by 3k, probably a little sooner. I've had two variations of the VR5 turbo on my 3 liter and they both hit 15psi by 3k. So many things can slow the spool, but one of the more frustrating for me to find once was a bypass valve that was leaking internally...

Naplesguy06

I have an old turbonetics 60 hifi with billet wheels and P trim that spools at 3000 rpm at close to 1 bar so I fell pretty good right about now.

Humboldtgrin

What kind of BOV are you using?

alxdgr8

3" exhaust the whole way back or just from the cat? A collapsed cat pipe will cause this from too much backpressure.

Humboldtgrin

Or a partially melted catalitic converter. I melted mine. Lost a lot of boost. I really did.




I had to beat it out but if you look close<br/>You can see the melted pieces all over.