Depends on whose Dyno you are on that day.

 

I thought today's horsepower numbers from the manufacturer are measured at the rear wheels, not the flywheel like the olden days. So, I would think the answer to your question should be 707 HP (give or take a horse or two). Isn't that why the M6 cars and the A5/A8 cars have different HP numbers ? Does someone know for sure ? :scratchhead:

 

I believe Motor Trend reported something like 630 rwhp in a comparison with a Camaro. I've still got the article here somewhere.

 

Don't think so TorRed Jim.

 

Wow, really ??

 

Advertised HP is not a rear wheel HP number, it is taken at the engine with all install accessories and emissions controls. Old measurements were "gross" hp readings meaning it was on a engine dyno, no accessories, no exhaust and set for optimum power, but not how it would be in a production vehicle. Modern engines are tested to "net" hp meaning basically engine on the dyno just as it would be in the car, all accessories, and emissions controls in place to it gives a real world number. But no manufacturer sells by rwhp as that can be different from transmission, wheel weight (to a point) and other driveline losses (even chassis flex to a point)

 

Again, the rwhp results depend on whose dyno you are on that day.


Are we talking a Mustang dyno or a Dynojet?


Mustang dyno's traditionally read lower than Dynojets.


Ex: Mustang dyno = 590 rwhp vs. Dynojet = 630 rwhp.


Plus, each shop's dyno is going to read different depending on how the shop sets it up.

 

630WHP is what we have seen on our mustang dyno

 

dynojets are in the 660-670 range. the 6-speeds show higher numbers generally.

 

Watched a You Tube video that showed the HP at rear wheels to be 671 that makes the engine HP close to 820?

 

I had my car tested on a Dynojet dyno a week ago. A8... 3 pulls... best was 635 RWHP 650 RWTQ. All 3 were plus or minus 1 compared to other pulls.

But... it depends on DA, temp of the engine, correction and smoothing factors for the pulls, etc. Then, you will get variations from manual to auto and even from car to car.

Edit: sorry. Confirmed it was a dynojet dyno, not a mustang.

 

If you want to know checkout You Auto Know with Dave Serio and you'll see his HC on the dyno being tested. 6 speed manual hit 200 mph in 5th gear and measured 635 at the rear wheels.

 

That has to be one of the lowest HP dyno pulls ever seen for a Hellcat.

R.K.

 

Yea... something that they pointed out in that video... kind bummed me out too... the 2000hp/tq dynojets are only good to 200 mph. They will go past 200... but it will be one hell of an expensive pull.

 

Sweet! Can't wait to see what she puts down for track numbers once a new shaft is in.

We were inside a building for my pulls and had about 20 minutes per cool-down. But it was fairly warm and humid in the garage. I didn't even think about switching modes. All 3 of my pulls were in default (street). we just killed the traction control. Maybe I'll find another dyno-day soon and see what the changes are for mine.

 

My a8 pulled 637.9