You have a couple things working against you at the dyno. The 12-bolt and 3.73's will rob power and lower the HP numbers a bit (artificially for the gears??) The !cats will decrease torque on the low end with the loss of backpressure. I learned this from experience recently with my LT header stall and !cats.

With the 12 bolt and other mods your best estimation of power would be trap speed at the track. My car actually flt a bit slower after the header !cat install, but is gained a consistent 3mph at the track.

Schantin
1997 Camaro Z28

 

My car pretty much stock, just the hypertech and 3.73's is running 262 rwhp, and about 295 off the fly. Is this good for a basically stock LT1?

 

imo the dyno is just about right for his mods.
a bone stock A4 lt1 should dyno about 245rwhp on a dynojet
CAI-8rwhp
shorties-10rwhp
cutout-8rwhp
ud pulleys-3whp
!cat-3rwhp

equal approximately 32rwhp over a stock A4, which should be roughly 277rwhp, but then take into account what the 12 bolt and 3.5 DS rob him and you have 260rwhp.....

if you were an m6 i would think you was slightly down on power.
JIMHO though.
Jesse

 

Hot Rod television did a dyno comparison with a supercharged late model Mustang. On the Dyno jet it put down a little over 300 RWHP. On the Mustang dyno it only put down about 240 something. Their reason was the Mustang dyno simulates rolling resistance and wind resistance. It's suposed to accurately tell you how much power your putting to the road minus the power required to propel the vehicle.

Thats BS, I want to know how huch power I'm putting down, not how much power I have left over.

 

When Ywo Guys Garage did their last show on emission tuning a Blazer, they used a Mustang Dyno because they could simulate "real world" performance on it better.
The Mustang Dyno may give lower values, but at least they're "real" in the sense that they don't assume that you'll be driving your car on Teflon in a vacuum.

 

JPSartre12, don't feel bad. I was at DSI at the dyno day when you were there. Same story for me, my TH400 sucked up some serious power. Also, Phil even told me they're typically like 20rwhp lower than other shops in the area, even those who have Mustang dynos. Like you said, the car pulls strong. So who cares how much power you have? I think dynos are being taken too seriously these days. They're a good tuning tool, and they're good for seeing measurable performance gains in mods. If you wanna know how fast it is, take it to the track and it'll tell the whole story.

 

Numbers sound about right to me. Like everyone else has said, the 12-bolt, stall, and gears are robbing your power numbers there but are most definitely good for your quarter mile timeslips.