yeah the 2004 have dynoed around 255 to 260 rwhp and some are always a little different. I wish their was a dyno around here, if their is one in okc someone let me know. thanks.

 

hmm so that means my 03 Sierra, with AS&M headers, a UPD intake, 3" Corsa with and without Predator tuning only made about 8hp more than a STOCK 03 Avalanche. Sorry but I find that very hard to believe. Either that or my Sierra came from the factory a real wimp .

 

I made 276 rwhp with a stock LS1 in my 03 Silverado

 

The 2003 Avalanche has 285 flywheel horsepower, so you're talking 8% drivetrain loss on an automatic transmission. That's pretty impressive. Especially considering my 2003 Avalanche only did 235 RWHP/265 RWTQ at the same RPM's.

What kind of dyno is this, and who owns it?

 

The same one you had your truck tested on

 

I had my truck tested at a dyno facility in Phoenix, AZ, before and after the blower install. If you're talking about Magnuson's dyno, yes, I had some tuning done there, but you have to wonder about the numbers it produces. They have a Mustang dyno 'calibrated to Dynojet specs.' This leads me to believe that the dyno is operating out of cal. As far as I know you can't calibrate one manufacturer's equipment to another's specifications, which would explain your lofty numbers. As far as I know, no automatic transmission out there is capable of 8% drivetrain loss....17% - 22% is more the norm. But I'm willing to be wrong on this if shown otherwise.

 

Have you ever considered that GM's 285 HP Claim may be off?

 

04 5.3 extended cab made 232 rwhp saturday with it being 95 degrees, afr was 11.0-1 this was with hypertech tuning. changed afr to 12.2 got it to 256.0. still some left but ran out of dyno time.

 

That's certainly possible. Hell, anything's possible.

However, my 2003 Chevy Avalanche's initial dyno run falls right in line with what you would expect from a stock 5.3L ....285 FWHP x .17 Drivetrain Loss = 235 RWHP. That makes perfect sense. Is it possible that my truck is putting 300 HP to the flywheel, and I'm seeing 22% drivetrain loss - which would give me that same 235 RWHP? I guess so, sure.

But if that's the case, then the 2003 Chevy Avalanche you tested must have the same drivetrain loss, correct? Same year, same motor, same tranny. With that same 22% drivetrain loss, your truck would have to be putting 335 HP to the flywheel in order to make the 261.9 RWHP you measured. I have a hard time buying that.

Even if we go so far as to say that the drivetrain in my 2003 Chevy Avalanche has a 22% loss, while the drivetrain in your 2003 Chevy Avalanche has a 17% loss (not likely, but possible - I guess), my AV would then be making 300 HP to the flywheel, and your AV would be making 315 to the flywheel. Do you really think that's possible?

I'm more inclined to think your dyno is off.

 

As I said before I think something is way off here. There is NO way a stock 5.3 is putting out some of the power people are claiming. I think the dyno settings have got to be way off.

A minimum of an 18% driveline loss should be found on just about any rear wheel drive car. With this loss then a truck making 270hp to the wheels would be making 330hp at the flywheel from the factory. There is NO way Chevy is over 35hp off when claiming stock hp numbers. Why would they do that? Especially when competing against the 300hp Ford, 345hp Hemi, and 340+hp Nissan Titan.