Down 15whp/20wtq

Stock 2004 Corvette with LT headers & tune. That means LS6 intake.
Installed MMS ported FAST92 intake & MMS ported TB and 10% UD. Butt dyno says car feels much stronger.

@99 Black Bird T/A
Thoughts?

 

Nobody? Nothing? Guess I'm the first to lose HP with a mod.

 

No you're not the first. But I can't follow whats going on in the other forum. I see you have a shift ****, that prob didn't contribute to the power loss.

 

What was the weather like on each dyno?

 

Both dyno runs show to be STD corrected, so I wouldn't think weather would have an impact to the final numbers. That said, the weather for the 2nd run was definitely hotter, by about 40-50 degrees, as well as more humid. 50*-60* vs 100*

The first dyno run was stock LS1, tune, LG long tube 1 3/4" headers and Callaway Honker CAI (considered the best for this platform). 349/372

Second dyno run was the addition of the ported FAST intake & ported LS2 throttle body with a re-tune; same tuner. 335/350

Before the first dyno, I had complete fluid replacements, new spark plugs & wires, new air filter. Car had 65,500 miles on it. I've put about 2,000 miles on it since.

To add: The previous owner had the LTs & CAI installed and tuned. He had a dyno with I think about 370whp, but I'm certain that was uncorrected and obviously a happy dyno.

 

New mods are junk, Ill buy the fast 92 off you, probably only worth a couple hundred since it looses power

Id say take it to the track and see, 50-60 degrees vs 100 in my eyes would lose some power. Plus dynos can be off, they need to be calibrated every so often, maybe it was out at one point.

What did the tuner say about it?

 

Yeah, I'll be running at Texas Motorplex Sat night. Weather should be a bit cooler than the 100s we've been having.

Haven't followed up with the tuner yet.

 

50 degrees hotter and 40-50 percent more humidity will absolutely make a difference. So it feels stronger, which means it’s more fun to drive probably. I personally don’t put a lot of “give a crap” in what a dyno reads. They are only good for tuning on. If your going to use a dyno to compare numbers, it must be consecutive days or days very close together, with similar weather.
Track times will tell the truth, again assuming weather/DA is favorable and comparable.

 

Big Supper,

Apologies on slow reply - had carpal tunnel surgery last week and not typing much.

I think as others said running at the track will be a better evaluation of power gain/ loss. The conditions were very different. And as mentioned dyno should be calibrated from time to time.

Looking the dyno graph posted on the Corvette Forum, seems to me the last 1,200 rpm gets a little wavy - if the car has the original stock valve springs they might be getting tired.

Hopefully some of the others will take look at the graph and comment.

 

Thanks for taking the time to reply.

Yes, stock valve springs. That's a good observation.

My baseline run is 12.64 @ 110. I'll need to correct my best run Sat but that will be as best a comparison I will be able to do.

 

Just reflecting on your post here... 1.8 Rockers???