Turbo boost question
 

you don't get full boost in 1st gear for the sake of traction.

I understand that they limit the amount of boost, but is it normal for it to hover around zero in first gear unless I floor it?

Yes. I've noticed I don't build boost even in 2nd unless I am about 3/4 throttle. I believe it is to make the car more driveable and less of a gas hog

Ok. Thanks for the info. I just wanted to make sure I wasn't having boost issues.

1st gear w/5speed should limit around 5lbs, unless you have the GM Turbo upgrade.

I purchased the turbo upgrade but I haven't had it installed yet. What does it limit boost to AFTER the upgrade?

Boost is set up to come in under load..in first where the gearing is high the loads are not the same as in other gears,,and its a short gear so one can imagine the problems if it wer to go full boost...its not set up like a race car

Mines a 5spd with the LSD and the GMTU. I get 5psi in first and the other gears get about 20psi +/- depending on atmospheric conditions. You can accelerate in a reasonably fast manner to up to redline and not hit boost. However, if you push more on the pedal while accelerating, you will see the boost climb gradually unless you floor it, then it goes to full boost right away. Yours sounds like it is the same as mine. You are probably maxing on boost at about 15 psi.

I get full boost in all gears, bone stock minus the exhaust. I'm sure we've all realized that without sticky shoes anything beyond 5 psi in first gear shreds them, even with the LSD :two thumbs:

Care to elaborate on that? Is your stock SS just a freak?
The torque management system should limit the boost, especially in 1st.
Not saying you're wrong, but everyone elses seems to be limited. Why is yours not?

To the best of my recollection I've hit full boost in 1st, though it may have been with TCS disabled (track runs). We've had rainy weather here the last few days so I'll verify the next time the road is dry. I can definitely recall some hot asphalt launches over the summer where it gave full power and had significantly less wheelspin. With the colder weather, that doesn't happen much.

It was my understanding that if the tires stay grounded, the TCS system doesn't cut engine output. I could be wrong though.. if you refer to "torque management", we may be talking about the same thing, in which case, you are correct that in low traction conditions such as cold weather or rain, this car can't go much past 5 psi anyway without spinning the tires.

You get ~5psi in first regardless off traction. Unless tuned otherwise

I stand partially corrected- it will hit 7-8 psi in first, although its still spinning tires at that point.

Sounds like a stupid system to me anyway given that the engine has less load once the wheels break loose (similar to how little if any boost will build revving the engine while stationary), unless those factory guys were doing their best to keep the wheels planted.

Max. boost?
 

What is the maximum boost these turbo's make in stock configuration?
I seem to get 28 lbs., I believe that was in 3rd with my foot in it. Is that about correct/typical for these motors stock?

ThankSS
Wayne

If you're actually getting 28lbs, your's isn't stock. Stock is anywhere from about 14-22 depending on conditions.
Bone stock I saw 15 max. After the GMTU, I have seen it spike at 20.
Many variables account for boost pressures. Altitude,humidity,air quality etc.
Torque management also comes into play. According to a tech at GM Perf. that I spoke with. "How much boost you get is based on the power it is putting out.
In other words. If car "A" gets that 260hp/torque at 14 lbs, thats it. Car "B'
may need 19 lbs to obtain the same power.
Most folks get hung up on boost numbers and think that if they have more than the "other" guy that they have more power. Not always true.
If you have the RPD display, you could check your hp/torque numbers.

Thanks Firemangeorge, I'm still not sure what I have here or where I'm at with this new found pleasure. I assume the a pillar boost guages are fairly accurate, and I don't have the
RPD display. That must be what goes in the compartment as an option in the center of the dash? I just want to know what I have, and where I'm at, before I can figure out where I need to go performance wise. I have to do some more playing, and investigating with this car, I don't need to repeat what has already been done to this car performance wise. The only thing I know for sure, besides it being a whole lot of fun to drive already, is it does not have the aftermarket rear sway bar on it, and it does not have an aftermarket exhaust or cold air kit.

ThankSS for the info, I'm going to have to do some more playing around.
Wayne

My RPD (with a bad photoshop on the mph:lol:)

https://www.chevyhhr.net/gallery/fil.../0/7/8/038.JPG

I figured that was where the RPD went. BTW what does RPD stand for? Is there a part number for that, and is it very difficult to add it after the fact , or does it get wired to the pcm somehow?

Wayne

RPD = Reconfigurable performance display. I have heard it is quite complicated to put in an RPD...you may need a whole new harness.