RooTBeeR

iTrader: (4)

boost =the failz it's all about the flow

Terminator2

It is all about the flow, timing, and the A/F mixture, that is the recipe for power. I will say though that my car flows way more air at 24-25 psi than it does at 21-22 psi

RooTBeeR

iTrader: (4)

pffttt, oh quiet you!

vinman66

since the car maxes at 260.. you said its in the 30s... the air is more dense.. thus needing less boost to get to 260hp.

mikej

stock they are set at 15psi...so i went and put on the gm performance stage 1 kit that opens that up to 20psi

rukkee

iTrader: (3)

Stock they are set to a target air load that is capable of making 260 hp ...... no less no more with the nanny. They can boost anywhere from 13 - 20 PSI stock depending on how dense the air is ..... at sea level in cool dense air it will boost lower (13-14 PSI) than it would in a high elevation with less dense air (19-20 PSI) to hit those air load numbers.

GM Stage I raises the target air load so that is why you see more power with higher boost.

RobMc3

So what's the max I can tune to my car to boost safely on stock internals?

RoadconeTuning

ive seen 12.8lbs when it was 19* outside and i've seen 17.8lbs when at 6k feet of elevation and it being 70*... when it gets over 80 or 85 boost starts to drop back down it seems but generally seems to be in the 14-16 range. i've only seen over 17.8lbs a few times on a stock tune and that was with my boltons.

emiller

Stock turbo around 23-24psi. You can go higher but don't expect it to last.

RobMc3

Do you mean the turbo wont last?

ingram57

iTrader: (1)

I run 27 lbs with stock k04 built internals no problems here I just watch my temps

cranemaster

Weather is HUGE for these cars, I thought I had a boost leak as I would hang around 18/19 psi all spring.

Now it holds 21PSI like I remember from last summer. At least where I live it truly does fluctuate the 4 PSI margin due to weather. I have a cell pic of my car RPD showing 22PSI which is usually doesn't stay at for more than a second.


Cobalt turbo stock and GMS1 PSI details are as follows. Correct me if im wrong anyone..

Stock (least 13 PSI) (target 15 PSI) (max 17 PSI)

GMS1 (least 18 PSI) (target 20 PSI) (max 22 PSI)

being outside those values means either your temperatures/enviroment are extreme or something could be wrong.


I hate when people say more PSI doesnt mean more power, when it clearly does lol.
As the PSI goes up, and you get out of the intended efficient range of the turbo - the amount of airflow compared to the increase in PSI and the power increase that is created gets more narrow and you see diminishing returns. So usually from the perspective of the car being tuned correctly, and not overheating, etc. More PSI does mean more power..

22PSI HP tune can make more than a 26PSI trifecta tune, but of course this doesnt ACTUALLY prove the statement more psi doesn't mean more boost, they are being tuned differently, obviously - SO the HP vs Trifecta example is not very scientific..

For example:

1 PSI 5 HP +5HP
2 PSI 10 HP +5HP
3 PSI 15 HP +5HP (Range of efficiency ends)
4 PSI 19 HP +4HP
5 PSI 23 HP +4HP
6 PSI 26 HP +3HP
7 PSI 29 HP + 3HP
8 PSI 30 HP + 1 HP (if the turbo was still efficient here at higher psi we would see 40 HP not 30, but power sill continues to increase regardless)

Easy concept

TY8425

What actually happens when people say "the turbo won't last"? What goes out? The bearing? The oil seals? And what will watching the temps help with? And is it the coolant temps or the o2 housing temps? Or oil? I'm still learning so any help is greatly appreciated.

Nfamous60

iTrader: (11)

I was holding 27psi in elpaso when I came down to sea level OMG lol,