Dyno after MODs complete - Bad Numbers
Thread Starter
Burning Brakes
Joined: Feb 2005
Posts: 752
Likes: 1
From: Tulsa OK
Dyno after MODs complete - Bad Numbers
I recently completed several mods - blackwing w/airbridge and smooth coupler, Kooks LTs, Corsa exhaust, BPP X-pipe weld into a stock Z06 h-pipe. The headers are connected to the stock cats.
I did a few dyno runs last week to see how the car was doing. Its been driven about 100 miles after the mods and before the dyno - no custom tune yet. It felt strong.
The first run was a disaster. The curve looked like a mountian range the car was so rich it dropped off the scale - started at Air/Fuel of 11 and fell from there. At 4,300 rpm it was below the scale. Hp about 305 and Trqe 310. The dyno guy said that he never saw a car running so rich. Disconnected the battery so the tune would go back to stock.
Air Fuel was better - started at about 13.5 and leveled out between 12.5 and 12.8 at mid range.
The horsepower was 310.1 and the trqe was 315.6. There a noticeable drop of about 5 hp and 10 Ft lbs. trqe at around 5,100 rpm and then it came back up.
Any ideas or help on what might be going on? The dyno shop showed me a run for a bone stock C5 that only had a Cold air intake mod at it had a much smoother curve and the same numbers as my car with the headers and exhaust.
Needless to say - I'm disappointed.
I did a few dyno runs last week to see how the car was doing. Its been driven about 100 miles after the mods and before the dyno - no custom tune yet. It felt strong.
The first run was a disaster. The curve looked like a mountian range the car was so rich it dropped off the scale - started at Air/Fuel of 11 and fell from there. At 4,300 rpm it was below the scale. Hp about 305 and Trqe 310. The dyno guy said that he never saw a car running so rich. Disconnected the battery so the tune would go back to stock.
Air Fuel was better - started at about 13.5 and leveled out between 12.5 and 12.8 at mid range.
The horsepower was 310.1 and the trqe was 315.6. There a noticeable drop of about 5 hp and 10 Ft lbs. trqe at around 5,100 rpm and then it came back up.
Any ideas or help on what might be going on? The dyno shop showed me a run for a bone stock C5 that only had a Cold air intake mod at it had a much smoother curve and the same numbers as my car with the headers and exhaust.
Needless to say - I'm disappointed.
Team Owner
Joined: Mar 1999
Posts: 22,025
Likes: 192
From: At the beach in little Rhody
Are you comparing your untuned with mods curve to a basically stock curve? You have made enough changes at this point that some tuning is required. You should be up around 330 when done.
As for the bump in the curve, likely knock retard that will be corrected with the tune.
As for the bump in the curve, likely knock retard that will be corrected with the tune.
Racer
Joined: Dec 2004
Posts: 355
Likes: 1
From: Bergen County NJ
Originally Posted by shurite44
I think you will be fine after you have a dyno tune done buy a good shop. 
I was only making 318 rwhp with more mods than you with an mn6, after dyno tune it produced 345 rwhp!!GET A DYNO TUNE!
Thread Starter
Burning Brakes
Joined: Feb 2005
Posts: 752
Likes: 1
From: Tulsa OK
I plan to do the tune soon - in fact it would have been this week but the dyno shop thought that there might have been some other trouble like a clogged cat or bad MAF. The guy was surprised that the computer did not produce better Air/Fuel ratios and horsepower on its own after 100 miles or so. I am bringing the car into Chevy for a check of the PCM and an efficiency reading on the cats.
