rocketrider2

I did search, honest (raises right hand like a good boy scout), for what the stock boost is on an 88 non-S. I am assuming 14psi but I do know what ASSUME spells.

Thanks
Lane

Bri Bro

From Clarks Garage FAQ.

5.2 What is the maximum boost I should see on my boost gauge?

This has long been a point of contention among 944 Turbo owners. For early 944 Turbos, I've heard ranges from 1.7 - 1.75 bar while the numbers for the Turbo S cars range from 1.75 - 185 bar. However, the factory shop manual clearly states that the maximum boost for both models is 1.75 bar. "Maximum boost pressure of 1.75 bar (absolute pressure) is reached at approximately 3,000 rpm. At higher engine speeds (engine type M 44.51) the boost pressure drops off again and reaches a boost pressure of 1.52 ±0.03 bar (absolute pressure) at 5,800 rpm. With engine type M 44.52, the boost pressure remains constant at 5,800 rpm (1.75 bar absolute pressure) and drops only after this value has been passed."

M 44.51 1986-1988 Model 944 Turbos
M 44.52 1988.5-1989 Model 944 Turbos

There does seem to be some variance between models, but I don't know that anyone's ever actually proven if the later model cars produce a higher maximum boost. The factory does indicate that there is a 10% tolerance at maximum indicated boost. So, that means that the indicated maximum boost could range anywhere from 1.58 bar to 1.93 bar. Start looking for problems if your maximum boost is consistently less than 1.6 bar.

Scott H

My 100% stock 88-S makes 10-11 psi right up until redline, which is right in line with the factory manual. It wasn't going to stay that way for long, though... that CV was a mess and one of the rubber lines going to the CV cracked in my hands. Thank god that whole mess is getting ripped out and not going back in... 14psi is high enough to trip the stock overboost protection.

Black51

The boost gauge on my dash barely goes over 1 bar. At the same time though, my aftermarket boost gauge tells me the car is hitting 16psi. I trust my aftermarket boost gauge more than the dash gauge. Who knows how accurate those are nowadays from one 951 to another. Just like with the AFM's, each one is different from the other as proven in tests performed by some guys on the list.

rocketrider2

OK so around 10 psi makes sense. I am seeing about 1,7 bar on the factory gauge. SO if I use the Rogue A tune how much boost will I be seeing coupled with a test pipe, Tial 38 and 3 bar FPR?

Scott H

That depends on your boost control method. Using the stock CV it will be the same boost level as it's controlled by the KLR and that won't be changed. Using an MBC you could dial it up to whatever Rogue recommends for your injector size.

schip43

+1

schip43

The stock boost gauge reads absolute pressure, someone else can explain it better than myself. I find it useful to see when boost begins but no more than that, for me at any rate.

Black51

Right. I understand once the needle goes over "1 BAR" you're now in boost.

I was just saying that beyond the "1 BAR" point, I don't really trust the reading the gauge gives me. If the needle hardly goes past that point, then it's indicating (in my car) there is barely any boost happening. Probably a leaky vac line I presume...

16 psi is 1.10 BAR. So that should push the needle up to 2 BAR on the gauge. Right?

Van

Correct.

However, you should be able to feel if it's making boost... if those are your options. At 1 bar on the factory gauge, it'll accelerate about as fast as a minivan. At 2 bar on the factory gauge, it'll push you back in the seat and feel like a rocket.