Red-GT500

That number seems rather high for a stocker... are you sure they used the correct adjustment values? it should be 350 ish maybe 360 on a good day but 383 rwhp is a lot. Maybe you got the sleeper boss engine by mistake hehe.

kev152

When I look at everyone's results, I am still surprised. I would have always thought that an automaker would over-rate, not underate, their engine's hp.

dacobra04

He had all the adjustments correct. You must account that I live in Washington our air density is greater than most area's, and the fact that it was 6o degree's out. Plus I did a correct break-in of keeping it under 4,000 rpm for the first 1,000 miles and only ran 92 octane. There was another completely stock 2011 mustang GT that also dyno'd 379 hp. So maybe where you live 350-360 is the standard but correct break-in, air density, octane used and temperature are factor.

Red-GT500

Im not saying you are a liar, i was just thinking that was kinda high. Also i really dont think the way you break a car in is going to effect rwhp that much. Maybe if you start the engine up for the first time and peg the tach then yeah it will be weak but 33-23 rwhp is not going to be effected by a break in procedure.

412 hp X 12% loss for power train is 363 rwhp.

435 hp X 12% loss for power train is 383 rwhp.

If this is true then ford has underestimated the HP number on the mustang. Which is a great thing if they did... only pay for 412 but get 435. All i ment by my former comment was the math seemed a little odd. There are other cars out there that have reported the same. I did a search while posting this, and it seems its about average for the car to get 380-390 on the dyno. It seems to be lower if you do a 4th gear pull rather than a 5th but thats just a few articles i was looking over.

steve b.

i have 378

Burns331

Where is the 12% loss come from. Seems kinda low. I have have alwasy been told 18% on an auto, and 15% on a manual.

siggyfreud

I think you guys are putting too much faith in Dynos, even of the same brand, to give the same results.

dacobra04

I agree, I also would had thought that Ford would had not underestimated
the power output since we are basiclly in the new era of a muscle car wars. But as far as I have been told that in the mid 60's through 70's. That there were some muscle cars (forgive me I can't remeber the specific ones that were told to me) that were were putting more power to the wheels from the factory than claimed at the crank. So hopefully this was just a tactic that Ford is using. So when all the magazines do the VS. testing they say well the mustang is faster than the rest with less horsepower. Plus what a better way to build a more loyal buyer than giving him more power than he suspected. Lol. Buy the way very jealous of your GT500. If they didn't have a $20,000 dealer markup at every dealer around here that would had been the mustang I'd got.

siggyfreud

I believe that back then, and perhaps now, they were underrated for insurance reasons, and to make the car more affordable. Insurance companies take into account power to weight ratios.

Falcon Fixer

Most of the time ,yes.

My 2006 Cobalt SS/SC was rated to the ground.
Underrated actually.
GM said 205 at 5900, but redline was 6500.
Most were putting 210-215 to the ground stock.