RWHP Dyno Numbers?

[LOVEAZ]

If you change your differential from 2.62’s to 3.09’s will it effect your RWHP dyno numbers?

 

[Blkout]

I've been told it will typically lower your numbers slightly by several tuners, I believe it's about 10-20whp if I recall.

 

[16GoManGoHC2]

Agree, The deeper the gear the more the loss. A good portion of drivetrain power loss happens in the rear end.

 

[coolblue]

I don't understand that. NOT saying it's not true, I seriously just don't understand that. In my mind the rear is also a constantly moving fulcrum. So if the lower rear (higher numerically) has a higher mechanical advantage wouldn't the edge go to it, and not the higher (lower numerically) rear ?

 

[LOVEAZ]

I don't understand that. NOT saying it's not true, I seriously just don't understand that. In my mind the rear is also a constantly moving fulcrum. So if the lower rear (higher numerically) has a higher mechanical advantage wouldn't the edge go to it, and not the higher (lower numerically) rear ?

That’s kinda what I was thinking. 🤷🏼‍♂️

 

[Blkout]

It is what it is.

 

[Temporarily Insane]

So my 2019 HC Redeye with the Demon 3.09 differential has less than the 797 advertised horsepower??

 

[coolblue]

So my 2019 HC Redeye with the Demon 3.09 differential has less than the 797 advertised horsepower??

Oh man total mind Fu%^. LOL. Don't worry about it. You still got the full boogie RE/Demon motor and those 3:09's are really gonna make you scoot if you can even hook up. Don't get hung up on numbers. And it may very well read those number's even with the 3:09's.
We're just batting thing's around.

 

[Temporarily Insane]

Good answer!!

Oh man total mind Fu%^. LOL. Don't worry about it. You still got the full boogie RE/Demon motor and those 3:09's are really gonna make you scoot if you can even hook up. Don't get hung up on numbers. And it may very well read those number's even with the 3:09's.
We're just batting thing's around.

 

[Blkout]

So my 2019 HC Redeye with the Demon 3.09 differential has less than the 797 advertised horsepower??

No, it has 797, it will just dyno slightly less to the rear wheels than a 2.62 gear car. The HP at the engine is the same, it's just the way the chassis dyno measures it.

 

[16GoManGoHC2]

The 3.09 will give you more torque multiplication in all gears, Torque is Time, HP is speed. When I switched to a 2.98 first M6 the torque multiplication was instantly felt and with a heavy car is needed,and be quicker IF you can get it to hook up. Like the other guys said don’t worry about the HP loss you MAY see on the dyno, it doesn’t mean much with 800 on tap unless you just dyno party your car and are interested in the highest dyno numbers possible for bragging rights but there are ways to manipulate that like pump your tires up to 40 psi and you’ll get that 15 hp loss back.

 

[Temporarily Insane]

^^^another good answer^^^
Dyno party! That made me laugh! I like that, lol. Yes I did forget about the torque multiplication and torque aspect of it all.... so true

 

[16GoManGoHC2]

I don't understand that. NOT saying it's not true, I seriously just don't understand that. In my mind the rear is also a constantly moving fulcrum. So if the lower rear (higher numerically) has a higher mechanical advantage wouldn't the edge go to it, and not the higher (lower numerically) rear ?

Any time you increase mechanical advantage there’s loss due to friction. A 3.09 gear has more teeth then a 2.62 gear, each tooth engagement friction occurs, so the more teeth the more friction loss that occurs per revolution, the higher the rpm the more this happens. For the same rear wheel speed with a lower ratio rear the input shaft, the drive shaft, has to turn faster. This is why one needs to take into account not going too low and the transmission shifting into a overdrive gear before your 1/4 is over as over driven gear ratio’s loose even more power to friction.

 

[16GoManGoHC2]

This is one of the reasons A8’s have better luck with aftermarket drive shafts vibration wise compared to M6’s with 3.73 or lower gears, the A8 DS spinning much slower at 140 then a M6 car. Also why a stock M6 DS can take a bit more abuse, it’s turning faster at the same torque which decreases time at load at critical points in its rotation.

 

[coolblue]

This is one of the reasons A8’s have better luck with aftermarket drive shafts vibration wise compared to M6’s with 3.73 or lower gears, the A8 DS spinning much slower at 140 then a M6 car. Also why a stock M6 DS can take a bit more abuse, it’s turning faster at the same torque which decreases time at load at critical points in its rotation.

It's almost like you know what your talking about. . LOL. Very good and clear answers on both. Thank you.
But wait...If your so smart, why do you still drive an M6? .

 

[16GoManGoHC2]

Because I have a pair

 

[16GoManGoHC2]

Just landed home
YAAAAYYYYY Cat time

 

[16GoManGoHC2]

What a trip!!

 

[16GoManGoHC2]

Next stop Island Drag way

 

[DGatzby]

It is certified at 812hp at 6300, so we have 14 ponies to spare with the bigger gears. Add that to the dyno talk to further confuse the bench racing debate.