86 951 Driver

I don't know if this is how a 944 Turbo should act, but When you go wide open on it boosts up to 1.5 bar then the closer you get to redline it starts to bleed off, and at 6,000 RPM its at about 1.1 or 1.2 Bar. Is that right? Just wanting to make sure as I have a new to me diverter valve. It is a Forge one. Just making sure its working properly. The car seems to run a little better than it has been lately after replacing that. Seems to pull harder.

Van

No, it should be a bit higher.

On my Turbo S, it boosts up to 2 bar on initial, then drops off to about 1.75 bar at red line.

Even for a regular turbo, I'd expect the initial boost to be pretty close to 2 (maybe 1.8 bar) then taper off to about 1.6 bar.

ArthurPE

factory curve, non-S:
1000 ~1 bar
1750 ~ 1.5
2500 ~1.75
3250 ~1.72
4000 1.7
5000 1.6
>5500 ~1.55

86 951 Driver

I'm curious if maybe I don't read the gauge right or if my car is not making the boost it should be. What should the boost gauge be reading like line wise? I have an 86 951

Van

The middle line, with the "1" above it is 1 bar. the right most line, the the "2" above it is 2 bar. The lines between are equal to 0.2 bar increments.

xboostx

1 bar factory gauge is 0 psi . 2 baron gauge is 14.5 psi or 1 bar of boost . its stupid

Paulyy

if you want to hold boost better, time for a new wastegate

Van

Or get rid of the intake/vacuum leaks... or get rid of the exhaust leaks... or make sure the cycling valve is functioning properly... or make sure the BOV is functioning properly... or make sure the turbo vanes are in good shape.

86 951 Driver

I think I may be reading the gauge incorrectly. I just replaced the stock Diverter Valve with a Forgee 007 that was off a Audi 1.8 LTR. Seems to be in good shape. Spring hold tension. Not sure what boost it set for.

How would I check for a working cycling valve?

Exhaust leaks could be a problem since my cat and what not is jerry rigged. I will be replacing that with a test pipe.

I will be looking at redoing the vacuum lines with a venturi delete, but right now I need to focus on an alignment and tires.

odb812

Get an aftermarket boost guage. The factory one is not very accurate or precise.

TurboTommy

It's actually pretty accurate up to about 13 psi if there is no leak from the line going to the KLR.
There's probably something up if it acts like you describe. Probably not your diverter valve, though. Also, usually not the wastegate either.

86 951 Driver

I am wanting to do the fuel lines and the vacuum lines, but I can't do both at the same time. So I may do the vacuum lines first and venturi delete and see if the car runs better then.

ArthurPE

>2500 rpm should be close to the 4th tick mark (between 1 and 2)
>5000 should drop to ~ the 3rd mark...

86 951 Driver

So here is what its doing. It is 1.4 bar most of time and drops off to 1.2 bar towards redline. What could it possible be?

Van

Start by checking the things in posts #8 and #7.