So its evident looking through google that there are a lot of dumb people that have no clue what compressor surge is. So im going to try this. I have BTF's KO4+ turbo and had it tuned to about 20.5 PSI. For supporting mods i have the dejon intake, synapse turbo intercooler and piping, synapse turbo downpipe, and synapse engineering BOV. Stock exhaust rest of the way down though. Im going to be working with BTF on my tune to eliminate the surge BUT what can i do to maybe clear it up some. I'm thinking that maybe eliminating the restrictions of the stock exhaust by getting a 3" exhaust with muffler delete. Thats really all i see other than reducing boost. Any help would be much appreciated

 

3" catback may help. lower your desired airload in the lower revs (3500 and under) a little. You can still command 20+ psi in the upper revs. The surge window is 3500 rpm and under I believe.

 

that sounds about right, i was noticing it up to about 3700 rpm. Thanks

 

Your welcome. You should probably command 18 psi below 3700 and once you get above that slowly ramp it up to 22 psi.

 

Do you happen to know what kind of power your puttin down with the wheel upgrade? Havent really seen any threads about the actual power they can produce with mods and tuned properly.

 

301 whp and 310 wtrq. It is in his signature. Pretty low numbers at 20 psi. It should be at least 330 whp or so. The upgrade is supposed to flow 25% more air than stock. So it should be capable of 360 whp when maxed out at 22.5 psi.

 

oh sorry I didnt even see that, that is pretty low people have been gettin that with just a tune. He better get that exhaust and open that beast up.

 

He has a catless DP. The stock Catback flows pretty well but. It must add some power because since I installed my 3" catback I can spin in third gear now if I roll into it at 50-60 MPH. I am getting new dyno numbers in a week or so. I made 253 whp and 247 wrtq stock and 307 whp and 330 wrtq tune only, and I have the stock turbo. I am hoping that I will see 325 whp and 350 wtrq with Intake, DP, Catback, chargepiping and some more tuning.

 

Yeah I will be getting tuned shortly and I have charge piping, intake, 3 in catless DP and 3 in exhaust and was wondering what numbers I could expect.

 

If you are on 91 octane expect 18-20 whp less. I made 289 whp and 311 wrtq on the stock timing tables which you will definately have to use if you are not on 93 octane. Get an intake too. Those are worth approx 15-20 whp in most cases. I got my Dejon for $158 shipped but I already had a filter for it.

 

I always put 93 in it. I have the dejon intake and bypass spring best mod under 200 bucks.

 

Sorry, I did not read your signature. Before I posted that. With a good tune you should be able to acheive 325 whp or so. Hahn did and their car was tuned with the PPC tuner wich adds only about 30 whp to the car by itself.

 

I actually just added my sig, lol. I live close to Hahns shop but have been hearing good things about trifectas tuning, not sure which to go with.

 

If you can, get a custom dyno tune. My only criticism of trifecta's tune is that I believe it to be too rich at 12.4-11.8 A/F. It seems that Psychostevo and Area 47 and my tuner found that 12.6-12.8 is the best A/F for max power and it way richer than the stock tune at 15.7- 13.4 A/F. Just my two cents.

 

k04+ makes 320 whp you have to have full supporting mods to flow the 42lbs/min people are running into problems on hpt forum, give it a sec to be worked out it will break through and make power generously especially after stage 2 kit

do remember that 12.6-12.8 afr can only be ran on vehicles that have a catless dp. someone will get mixed up im sure and read that wrong is all. i have a factory cat still so im running 12.1 at top end to keep catalyst from overheating.

 

I have this friend right, and he wants to know what compressor surge is. what a newb right? so can you tell him

 

i am getting hp tuners and that work with Rick from BTF to get my numbers where they should be and than get rid of the compressor surge. Im going to assume in my head that the dyno i was one was reading low that day... helps me sleep at night to think that. But if anyone has anymore thoughts on upgrades, or what i should have looked at on my tune i would love you forever

 

http://en.wikipedia.org/wiki/Compressor_stall

 

Thanks so it just seems like it builds up alot of pressure and it cant use that pressure fast enough so essentially it starts to back up and cause pressure surge. Thats what im getting out of it

 

It's really a hammering oscillation. But you have the cause right.
Too much pressure at low rpm, the pressure wave (one is created by each compressor blade tip) looses intertia and reverts back tward the inlet.
Pressure drops, intertia of incomin charge once again reverses the direction of that pressure wave until the pressure builds up. repeat.

Folks, when it comes to dyno numbers your taking them as gospel and they are not! A dyno is a tuning tool. Not the be-all end all of respective output. WAAAAAY too many variables.

If you took 50 stock cobalts and dyno'd them on the same machine and the same day (whew that's alotta strappin') ,You would have a bell shaped curve representing the output. Some are really high (we call them wringers's) some are really low, most are average in the middle.

So if you increased the hp of one of the low ones by 65hp. That would be a substantial gain. But it would be "close" to the best stock numbers out there.

Conversly speaking, the best numbers out there are NOT representative of what the CBSS "should" be making. You simply cant benchmark off the highest numbers anyone has achieved.

Jerad, once you get your module PM or call me. I'll help you fix your midrange compresor surge issue.


Also, CHris found the overboost/underboost tables. It will be in the beta in the next few weeks.
I'll break you off with 265kpa and 7200rpm. Let the billet wheel shine!

 

thanks Rick, i be calling u next week, it should be in

 

As soon as I get my catless dp and intercooler on I will be street tuning my car. I think it will be better than a dyno tune.

 

Definately unless you have access to a loaded dyno like a mustang or dynocom. They are just as good as street tuning because you can put a greater load on the car.

 

Calling all Cobalt tuners!! Can somebody give me the HP/RPM numbers in each gear for the stock Cobalt ECU?? I just installed my shift light and would like a base line for setting it to each gear. I can fine tune it on track days but with out aplace to start I'm sure I'd be all over the place. I don't have a clue where to look other than here. PLEASE HELP!!!

 

Shift at 6K in each gear that seems to net the best acceleration. Power falls off after 6K stock and after 5600 usually if you are tuned. Anything higher and you are out of the turbos efficiency range.