Does anyone know the differences between a 2005 Cobalt 2.2 eco versus the 2005 Cavalier ecotec.
I have one of each and put it on my dyno and the Cobalt in stock form is measuring about 130 to the wheels where as the cav (with header and dumped exhaust - race car) is doing ~120 to the wheels.
The only difference that I know of is the Cav is using speed density. Where as the Cobalt is drive by wire and Maf tuned... Technically the cobalt is rater 5 hp more...
Oh also the Cobalt must have EPS where as the Cav has the power steering driven off the cam. I suppose that may eat up some power as well.
Now that I think about it. I guess those numbers are probably about right. But I guess I thought with the exhaust work on the race car it would be better.
Cavalier uses Alpha N fueling. The jbody pcm is an abomination. 10whp could be accounted for by anything. Maybe the cobalt's leakdown is a little better for 100 different reasons (valve seats, carbon build-up, rings). Mechanical power steering plays a role for sure. The transmissions are different, so they definitely have different sweet spots.
The tune is 100% different. I haven't looked side by side but I wouldn't be shocked if the cobalt ends up running better timing numbers because its tables and multipliers are infinitely better; knock and dwell settings definitely are. Fueling is definitely better for the cobalt with a MAF sensor and speed density as a backup. Jbody pcm being alpha n. It just is what it is at 100% throttle. It can't take altitude or air density into account.
"In Oldskool we trust"
Interesting, I haven't plugged in HPT to either yet to see exactly what's going on but sounds like I may need to steal a cobalt PCM for the Cav race car.
Last time I checked the compression on the race car it was 200+ psi for cranking compression, so I am fairly confident the motor is decently healthy. It does have about 35 hours or endurance road racing on it though.
Yeah that sounds like a great plan until you realize that you have to re-wire the car all the way to the tail lights to make it work. PCM, BCM, cluster, electronic throttle body, electronic gas pedal, and all other various sensors that the jbody doesn't have. And hell, if you go that far run a 2.4 LE5 bottom end if it's going to be an n/a circle track car. Slap a 2.2 L61 head on top of it and no one will have any idea.
"In Oldskool we trust"
Yeah my car is already gutted. No windows.. taillights are a custom harness and switched independent from the original harness Swapping over a PCM and unlocking it with HPT to avoid linking to BCM is easy. Add a MAF and couple connections can be done. Might be a cheap enough way to add 10 hp.
2.2 blocks are dirt cheap in cavs on CL... finding a cheap 2.4 to work with seems pretty hard. Maybe in a few years.
I'm shocked at the power on the cavy. I have seen bone stock 2002 LS Sport 5 speed make 129whp. then gain 8whp from a tune.
I believe the communication used on the jbody ecu compared to the cobalt ecu is different so actually swapping wiring would be needed.
FU Tuning
Addicted to meth wrote:I'm shocked at the power on the cavy. I have seen bone stock 2002 LS Sport 5 speed make 129whp. then gain 8whp from a tune.
I believe the communication used on the jbody ecu compared to the cobalt ecu is different so actually swapping wiring would be needed.
Correct. Class 2 data via serial vs. a mix of serial/high speed lan for deltas.
"In Oldskool we trust"
Addicted to meth wrote:I'm shocked at the power on the cavy. I have seen bone stock 2002 LS Sport 5 speed make 129whp. then gain 8whp from a tune.
I believe the communication used on the jbody ecu compared to the cobalt ecu is different so actually swapping wiring would be needed.
Every dyno is a little bit different. Mine is mustang style with PAU - if i run the dynojet correction factor the numbers would be a few ponies more.
Also I beat the hell out of this car (has 40+ hours of endurance racing on it)
Interestingly enough though I was playing around on the dyno today with the HPtuners hooked up this time.
I realized that the speedo cut was happening on the previous dyno pulls (107mph).
So I decided to pull the speed sensor and run her..
The differences were amazing. For some reason the car goes in to power enrich mode with no speed sensor input commanding 12.9 afr rather than 14.6
So the line was much smoother and much more power under the curve- and no speedo cut.
see latest attachment.
So anyone racing one of these cars... there is a good trick for you.
- Attachments
- catvalier.jpg (149k)
That is PE enrichment, from the factory on the Ecotec is usually around 5900-6200. Dropping that engagement down to around 3k helps.
FU Tuning
When I get home I'll open a stock tune to confirm but what John said is correct. Power Enrichment mode comes in pretty late. I think that's what you were seeing. The only criteria that's looking for is throttle position and RPM. It doesn't reference the speed sensor at all. There's also a PE delay but I believe it's pretty low stock.
"In Oldskool we trust"
