During two different dyno tests on two different types of dynos my 2005 Cobalt SS never achieved peak horsepower, the power curve was almost flat and slightly inclined upward. Peak horsepower was at whatever point I let up on the gas near redline. My tune file is a stock GM stage2 tune with COT and Piston protection disabled. Anyone have any ideas WTF is going on?
GM Stage2 kit with a 2.8" pulley
K&N Cold Air Intake
ZZP Headers
do you have a copy of the dyno sheet so we can see what you are talking about?
It doesn't have to be perfect, it just needs to be done in two weeks...
A wise man once said "google it"
Unfortunately this last dyno run was more of a data gathering; air flow modeling, knock retard, and to see if disabling COT and piston protection made any improvement; therefore I didn't think to ask for a printout. I do have a printout from the previous time back in April on a different dyno; however there have been some changes since then, mainly headers hardware wise. It does show horsepower at about a 40 to 45 degree angle that never peaks out and falls back before redline, I can scan that and attach is you like.
I was planning on going back sometime after I make some changes, but at $80 an hour, it won't be anytime soon.
Lol. What are you asking? If you're at a 6500rpm redline still then you're going to crash into that before you make peak horsepower.
RSG Offroad
Jeeps. Jeeps. And more Jeeps. Oh and Jeeps too.
What's happened is the first pull I let up on the gas just a little over 6K and saw I hit peak power at that point, about 222HP, so the next pull I decided to go a little closer to redline and same thing peak power was at that point about 4horses higher. On a stock Cobalt it is rated at 205HP @ 5200RPM and after that it drops off, so you have a curve; not so on mine it's almost flat all the way to redline. So I'm trying find out why it's flat; i.e. tuning issue, mechanical issues, etc., what am I suppose to do shift at redline?
Shift at redline on the dyno!?!?!? I really think we need to see the graph before any assumption can be made.. The reason it may look "flat" to you could be for many reasons. Your power curve could be normal as can be, but the settings for how the dyno is plotting the chart may not be set to show what you are looking for. it could also be a "sampling" error... Without the dyno sheet we will never know.....Originally Posted by Rush
P&P Tuning
its a super charger, you will tend to see it making peak power at red line. I had a 06 ss/sc and with the GM stg 2 plus some I would make peak power at red line (7200)
Two different dynos (load and inertia) basically showing the same thing, a steady inclined up to the point of letting off on the gas? I'll see about getting those graphs.Shift at redline on the dyno!?!?!? I really think we need to see the graph before any assumption can be made.. The reason it may look "flat" to you could be for many reasons. Your power curve could be normal as can be, but the settings for how the dyno is plotting the chart may not be set to show what you are looking for. it could also be a "sampling" error... Without the dyno sheet we will never know.....
its a super charger, you will tend to see it making peak power at red line. I had a 06 ss/sc and with the GM stg 2 plus some I would make peak power at red line (7200)
That seems strange why the PE table has AFR at its lowest around 5200RPM and stock peak is also there, why would a stage2 kit make the curve almost flat to redline? I can see where your coming from though, the higher the rpm the faster the SC is turning and the more boost it produces. I think I would need to see Eaton's specs on my SC, to see if it is flat as well or if it peaks out at a certain speed.
It would appear that you may be right, I contacted someone at CA who sells their own stage kits and he says that's what SC Cobalts do make power all the way to redline but start to flatten out just before, he says that the torque will have a curve however. I just wonder what a stock SS/SC HP curve looks like, is 5200 RPM where it starts to level off rather than near redline?Originally Posted by trolltuner
its a super charger, you will tend to see it making peak power at red line. I had a 06 ss/sc and with the GM stg 2 plus some I would make peak power at red line (7200)
Your car is performing perfectly normal, see how the LSJ would benefit from increased redline?
Yep, I beginning to believe this is the case, I have a one mile shootout (as they call it) to atend next month and was trying to decide on a good shift point, I usually think that peak power point is the best place to shift, but that's redline. My biggest problem with this kind of event is the fact that being a FWD car I usually spin my wheels thru first and second gear before I even start to move and loose about two seconds, fortunately this event is not based on ET, but top speed at the finish line.
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