i've researched a lot and it seems that everyone is boosting 23 to 25psi with gms1. I'm hitting 20 to 21 psi at most, but its usually around 17. Stock i would hit 12psi and it would climb to 15 and hold that till redline. car feels a lot stronger. Is that normal? i'm in nj and its pretty cold right now...if that has a impact on boost level. thanks!

 

im in ohio and i hit 20 to 21 normally sounds about right to me, idk bout the 17 tho

 

iirc it'll boost to whatever is needed to make the rated HP and TQ ratings. So boosting lower is better.

 

Out of curiosity where did you end up getting it installed?

Anyway that's the exact same way mine operates. Stock mine operated the same as well. Either both of a cars are fine or they are both screwed up lol.

 

You don't hit full boost all the time... and actually, I'm pretty sure GMS1 peak boost is 20. People going 23 to 25 are aftermarket tuned.

 

I may be way off here and anyone who knows better can correct me and chime in.

I have a "canned" tune and I'm fine with that. I'm not all power crazy. Mine is boosting maybe... 1.5-2 lbs lower than in warmer weather. But I think the ECU takes in readings from the MAP, MAF, IAT, etc, etc and uses an algorithm (math calculation) to figure out what the air load is. In other words how much air EXACTLY is going in. It shoots for a predetermined target and will boost to that. With custom tunes, well I'm not so sure. People may be setting it to hit a certain boost no matter what, even if it means overspooling the turbo to reach it. I could be wrong.

Another factor with that would be that even my car will drop a couple pounds as it approached redline, even in warmer weather. That only means that since it's flowing faster into the engine the turbo isn't holding the psi like at lower rpms. But actual flow is more, which equals more power. So if that's the case, no big deal bro.

 

green brook buick, gmc, (pontiac) on rt 22 in green brook. they charged me 2 hours labor and I was the first to get the kit installed. they both probably similar cause we're close. I was curious cause i read that people were hitting 24 or 25psi with gms1.


thanks...i was happy with the gains, just wanted to make sure it was correct...cant wait for warm dry weather to really try out the new power.

 

I'm getting 15 on my GMS1.

 

Lol. That's stock pressure. I bet your PCM didn't take the tune.

 

im hitting about 20psi on gms1 and my trifecta tune...gonna raise the psi on trifecta in the spring, My tune dealer didnt wanna risk anyhting getting f#cked up

 

the dealer i work for had to pay for a gms1 kit because they only put the sensors on and didnt install the tune. and needless to say the manager wasnt happy at the tech lol

 

walking to my car, you can FEEL the air density in this cold weather. Possibly one of the coldest winters here. Im boosting 17psi regularly on gms1.

 

Something's not right.

 

I'm pretty sure if the PCM didn't take to tune you would be throwing CEL's like crazy. Stock tune doesn't understand the 3 Bar MAP's.

 

what was mentioned earlier about torque rating was pretty much bang on.

as I've understood it either the stock or stage1 tune do have target air volumes that are relative to torque output, and you will boost to the point that your engine needs to hit those targets;

With this in mind, the boost rating for a stock car is 15lbs, and the stage1 is (going on memory here) 20lbs ~ but I have heard of stock cars being observed @ 20lbs (I have personally observed 18), and stage cars going beyond 20... so it really all comes down to temperature and air conditions.

does that help clear things up any?

this is 100% correct.

Look at it this way;
Does that make sense?

this is why if you do the stage kit install you are supposed to baby it, to the dealer, and not get into boost (but you are recommended to have it towed iirc) ~ putting the car into boost without being reflashed will put the car into limp mode because it is unable to know what is going on...
If you're not running the stage tune, then getting any boost would put you immediately into limp mode.

 

Its not really looking for a set torque number, but is limiting boost as required to keep the turbo inside what GM considers the "safety zone". Remember, boost is relative to a number of factors, including the amount of reisistance the air is experiencing and the air density itself. Certain mods could raise or lower the resistance in the air's path. Air temperature and altitude affect the air density. GMS1 watches the turbine and adjusts boost as necessary to not overspin the turbo. This is how they maintain warranty.

 

I Would get that checked out... I'm getting 13psi and it's -19c outside "stock"

Summer max I get is like 18..

 

repeating incase you missed it.

 

actually gms1 is 22psi norm. but it differs from altitude to altidude.

 

lol thats funny, should talk to vince instead of ur dealer, nothing will get f'ed up as long as u stay under 24. been running 22 for a long time with no issues. i ran 21, then 24, then 22, i like 22 cause its safe and more power than 21, 24 is great but i dont trust it.

 

ya ur car didnt take the tune, go back and get them to do it again, im thinking u were pretty dissapointed in the results wernt u. its cause ur still on stock tune. lol if u arnt spinning ur tires threw second gear in summer, ur still stock tune

 

I don't know how helpful this is, but I'll contribute.

I have ZZP ECU tune which is supposed to be better than GMS1, but similar in conservativeness.

My boost was set to 22psi, GMS1 is set to 20 from what I understand.

When I WOT, I go from 24-25 then drop to about 16 psi. Now ZZP told me it's because I have too much back pressure since I have stock downpipe and the turbo is slowing down due to that. I have a downpipe on the way to see if this is indeed true.

Anyway, the point i'm trying to make is I could be very well normal that you're dropping due to extenuating circumstances like myself.

 

I boost 17lbs on GMS1, its -35 here in ND, i used to boost 21 when it was warmer.

 

I have HPT tune. Boosts just over 20LBS and HOLDS steady to around 6K RPM..drops to 17 after. This was before and after adding DP. DP had no effect on holding boost.

 

IM hitting 21-22 psi on gm stage 1 best investment ever i love it so much!