Yeah that makes more sense, although I'd say more like 416 at the flywheel (333/.8). Still a good gain over stock!

 

Yeah, great gain!

Here was the response from when it was done:
"The actual flywheel amount will not show on a chassis dyno. From the Hp increase of 36.59 at the rear wheels the corrected calculation would show 426 hp. This is a corrected adjustment through power loss of the drive train and climate conditions of the day.

To actually have an hp from the crank the engine would have to be removed from the vehicle and then tested.

Just remember all dyno’s are different and the tester can alter the information at will. It also can be altered if the operator does not know how or done several dyno’s"


So is it always 20%?-or can it vary from climate conditions as well. He seemed very confident in the 426.....this is all new to me!

 

20% has been the accepted value. That is a great gain. I need to get to a dyno to see what mine is doing with the mods I have.

 

I dynoed my car after the addition of RSC cats, RSC reflash, and K&N filters (didn't do a "before" dyno unfortunately). The result was 332 whp. With the 20% correction factor that's 415 bhp. +35 bhp assuming a 380 bhp base. Not bad.

 

That is decent gain.

 

Markesq, do you have the same mods? If so, I'd be interested to hear your dyno results. I realize there are many variables that can skew the numbers, but still . . .

 

I would think 20% is more in line with a SS car and 15% with a manual.

 

Yeah 36 whp is a good gain...equates to about 45 at the crank. I think your car was a bit underpowered stock...the 297 works out to about 371 at the crank assuming the correction factor of 20% is right. But your mods brought you up nicely. I think they got 426 because they were assuming 380 hp stock but I think that is generous given your stock dyno run.

Whatever the case, nice gain that brought you up to speed with others that did similar mods.

 

Hard to say. My car made 307rwhp stock and I have a manual. That works out to exactly 19% IF you assume that the car really makes 380 at the crank. Given some of the less than stellar performance figures in testing, I'm not sure that's a given. So you could be right and my car might have made 360 hp in stock form, but there's no way to really know.

 

Thanks for the insight. I agree that they may have been assuming the 380 number and working from there. Supprised that some stock cars are coming back lower than 380. Thats a shame. Most maunfactures of performance cars underestimate their claims (HP, 0-60 etc).

I was told at the dealer that the n400 package puts out more like 30HP, not the 20 claimed as "Aston likes to be cautous in their numbers". Why not stock then??

 

I think they're trying to save face after putting out a car that underperformed and had less than advertised horsepower. The stock tuning on the 4.3 is very rich allowing for a safety net but they left a lot of hp behind...which they corrected on the N400 tune. IMO.

 

I agree with you, I believe that based on the trap speeds and performance that most of the cars are putting out closer to 350 flywheel hp. Of course the only real way to know is if someone used an engine dyno, and thats a lot of work to attain a true baseline number!

For a comparison the roughly same weight Mustang GT which is only putting down about 270 rwhp but also putting down about 280 rwtq ( 300 flywheel hp rating) is pretty much identical in all acceleration numbers. But for what is considered a high strung V8, the gains are pretty impressive with the mods!

 

Yeah and that Mustang GT is rated at only 315 hp at the crank.

 

You have no basis for this assertion. You can't get a dyno number, 'guess' at a drivetrain loss, then from that claim that you know anything about what the engines really do on a test stand. The ONLY number that has any meaning is the RWHP number (and that itself is subject to many variables, including the dyno operator).

Car manufacturers learned their lesson very well concerning underperforming engines since the Mustang debacle. I would believe that all the Astons make at least as much power as they claim.

 

I think he may have some basis in fact, either the V8 Vantages weigh more than claimed, or they are not putting out 380 hp. The only other thing I can think of is the gearing and not having a lot of torque under the curve to get the heavy cars moving. A modern manual car, should not have more than 20% drivetrain losses. But again the only way to find the truth is on an engine dyno.

The early Maserati QP's ran 5.3 to 60 and 13.7 @ 104 in the 1/4 mile with 394 hp and 333 lb ft in a car weighing 4400 lbs.....

So 14 hp and 31 lb ft make up for an almost 900 lb difference? 11.3 lb/ hp for the QP vs 9.1 lb/ hp for the V8 Vantage. Something is not adding up here, it can't just be the 5,000 rpm torque peak that is responsible.