DYNO numbers

[pietran30]

20% loss seems extreme. My challenger put down 426 hp on a dynojet. At 20% loss, I'm looking at 530 hp. The factory rating is 485.

FCA has stated that there is only a 12% loss from both the manual and the new A8. This would put my A8 Scat pack right around 485.

I know that the original poster said it was on a Mustang dyno, but 20% seems like a hell of a lot.

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[pietran30]

20% loss seems extreme. My challenger put down 426 hp on a dynojet. At 20% loss, I'm looking at 530 hp. The factory rating is 485.

FCA has stated that there is only a 12% loss from both the manual and the new A8. This would put my A8 Scat pack right around 485.

I know that the original poster said it was on a Mustang dyno, but 20% seems like a hell of a lot.

On second thought. It really doesn't matter. As others have said, just use the same dyno whenever you add mods to your car. That way you can see how much your car has improved on the same dyno.

 

[10splaya22]

Your math is a bit off. If you want to assume a 20% drive train loss it's 342/.8 = 427.5 flywheel hp. OP your numbers are fine. You should be more concerned with the change from the tune/Cai then the actual numbers. Ive had many different cars on many different dynos from 380rwhp on dyno jets to 1225rwhp on Mustang dynoes. They all read different, it's just a tuning tool.

+1. This is right. You divide by 0.8 to get back to the original number. You can't multiply by 1.2. Its not the same. You would have to multiply by 1.25 to add back the original 20% lost.

Also dyno numbers means absolutely nothing. You could put your car on 2 different dynos and get 2 completely different numbers. Just because it read high on one dyno doesn't mean your car is more powerful.

OP please do some reading on dyno numbers and what they mean. Before and after dyno numbers (on the same dyno) are all that matter.

 

[Mark5825]

Here, this should make you happy.

http://www.mustang6g.com/forums/showthread.php?t=21292

Ha, thanks for that. I got my final tune done and have the Mustang dyno and still didn't get close to 384, can't do final DynoJet until next week so I'll go post my final Mustang dyno on there.

 

[Daytona Coupe]

Dyno drivetrain losses aren't a fixed percentage. They are variable depending on a lot of factors. That 15 - 20% BS has been all over the internet for years, but it is wrong. it just keeps getting repeated over and over...

From my experience (15 years professionally in the dyno industry) a typical Mustang (car - not dyno) usually loses about 40 - 50hp in the drivertrain on most popular dynos. Mustangs (dyno) tend to read low, Dynojet tends to read high, all others tend to fall somewhere in the middle. A LOT of factors can lead the numbers to go up or down. If you guys want a detailed list of the things that can have an impact, I can go into it further.

 

[Burningcoals]

Dyno drivetrain losses aren't a fixed percentage. They are variable depending on a lot of factors. That 15 - 20% BS has been all over the internet for years, but it is wrong. it just keeps getting repeated over and over...

From my experience (15 years professionally in the dyno industry) a typical Mustang (car - not dyno) usually loses about 40 - 50hp in the drivertrain on most popular dynos. Mustangs (dyno) tend to read low, Dynojet tends to read high, all others tend to fall somewhere in the middle. A LOT of factors can lead the numbers to go up or down. If you guys want a detailed list of the things that can have an impact, I can go into it further.

Agreed,

Just so original poster knows...

- Altitude
- Ambient temp
- Humidity
- Octane
- Dyno Fans
- Dyno configuration/calibration

And probably a lot more can factor into your dyno number.

You can't say your car is low dyno compared to others, unless you take 2 cars that are the same on the exact same day using exact same process in exact same temps, using exact same octane, etc.

 

[valentinoamoro]

Summary
- Dynos are not comparable unless u r comparing using the same dyno to see if power is gained with mods - ideally under the same conditions (ex: broken in engine, temp etc). Even then, multiple runs on the same dyno are needed to establish the variability in the dyno readings and car.
!! You did do a pre-and post mod, and unless conditions changed dramatically or the dyno was recalibrated in the interim, you picked up some SERIOUS hp. So much I'm having a difficult time believing its possible from the minor changes you did.

- to get an average that is comparable between dynos and cars you will have to sample multiple runs on the same car under the same conditions on multiple dynos - not happening due to complexity.

Ultimately, the 'butt dyno' and trap speeds are good indicators of a cars output. I havent done the trap yet, but my butt dyno tells me my car is dang fast stock, comparable in acceleration but feels faster than (<110mph, I havent tested above) my recently sold 500HP V10 BMW. My GT is totally stock, and so was the BMW (except catback)

 

[foghat]

Summary
- Dynos are not comparable unless u r comparing using the same dyno to see if power is gained with mods - ideally under the same conditions (ex: broken in engine, temp etc). Even then, multiple runs on the same dyno are needed to establish the variability in the dyno readings and car.
!! You did do a pre-and post mod, and unless conditions changed dramatically or the dyno was recalibrated in the interim, you picked up some SERIOUS hp. So much I'm having a difficult time believing its possible from the minor changes you did.

- to get an average that is comparable between dynos and cars you will have to sample multiple runs on the same car under the same conditions on multiple dynos - not happening due to complexity.

Ultimately, the 'butt dyno' and trap speeds are good indicators of a cars output. I havent done the trap yet, but my butt dyno tells me my car is dang fast stock, comparable in acceleration but feels faster than (<110mph, I havent tested above) my recently sold 500HP V10 BMW. My GT is totally stock, and so was the BMW (except catback)

Agree with most you said. Though I find butt dynos are a terrible way of judging a cars output and are deceivingly inaccurate. Simply changing the throttle response and a car will feel faster/slower.

 

[valentinoamoro]

Agree with most you said. Though I find butt dynos are a terrible way of judging a cars output and are deceivingly inaccurate. Simply changing the throttle response and a car will feel faster/slower.

Butt dynos are a terrible way of judging real or relative output for sure (though trap speeds are much better). My point generally is, given the uncertain and wildly inaccurate and/or varying readings we get for HP, the manufacturers SAE rating + real world validation through trap speeds is the best we have to work with.

Beyond that, given the thrill of speed is mostly associated with the feeling it elicits within us enthusiasts (given the exception of some people who compete in track and are at a point where a slight HP advantage can make or break a race or the rare drag race, where again, a ton of variables apply) one could argue that the butt dyno is ultimately what matters to most as its experiential.

Along those lines, I will say that tunes mostly change throttle mapping, making cars feel more aggressive (or at least thats a key factor in the difference people feel from tunes). I will also agree with you in the sense I have driven cars which seem much faster than the numbers would indicate (a 328i for example with the 8 speed auto). I have also driven cars that felt slower than the numbers would indicate (2012 Camaro SS, Dodge Challenger 2013 Hemi R/T 5.7).

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