Talk about under rating a cars HP. Thats like 900 HP at the crank if u take 15% drive train loss out.
Mclaren 780 WHP on the Dyno.
- Thread starter GNBRETT
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https://www.svtperformance.com/threads/765lt-on-the-dyno.1194111/#post-16571234
Yeah, lol, all this drivetrain loss stuff.
How could a trans that eats up 10% at 300 hp eat up more power just because you added more power to a motor? I have to believe the loss is a constant value, as opposed to a %.
If a T56 loses 15% on a stock car then you turn it up to 1000 HP, does the trans suddenly eat 150 hp?
Yeah, lol, all this drivetrain loss stuff.
How could a trans that eats up 10% at 300 hp eat up more power just because you added more power to a motor? I have to believe the loss is a constant value, as opposed to a %.
If a T56 loses 15% on a stock car then you turn it up to 1000 HP, does the trans suddenly eat 150 hp?
Has to be just a quantity of needed HP to overcome the frictional and rotational forces of the transmission.
So the percentage loss should actually decrease as the HP rises. The 765 probably has a good bit less than 10% loss
An engineer one time explained this on a different forum, but yes, the losses increase with more power.
He used an example similar to this. Take a completely stock, empty truck, drive around at 50 mph with the least amount of throttle you can use. Now do the same thing with a loaded stacker enclosed trailer. Jump out and feel the transmission after each test, it's going to be far hotter after towing (for the sake of our argument the truck could be an old 7.3 ZF6 with no trans cooler). The increased friction through the transmission increases losses from putting more power through it.
Even if you kept the truck in 5th gear for each test, it would still be far hotter after keeping the throttle open (pushing 200hp) vs lightly keeping your foot on the throttle (maybe 30-40hp).
I thought that 15% estimate only applied to front engine, RWD through a manual trans. Also, I thought automatics ate up more power. I'd think that a modern dual clutch would be pretty efficient, but I admit that I don't know enough about them to speak at all intelligently.
I thought most sports cars and supercars from the last decade on were in the 7-10% range. I remember seeing something on the Viper and it was only losing like 9% or something and it was similar or better for the FGT. The 15% number is really old and I think most performance cars have improved drastically since then. Brands are also underrating their performance cars a lot more. I am pulling these numbers from recollection so I could be way off.
This example sounds like its specific to an old school auto trans with fluid coupled clutches, etc.
I'm no physics whiz, but I gotta think a modern DCT does not succumb to those issues, and less so in a traditional manual trans.
It will still apply.
Add more power - create more heat. That's additional losses in efficiency (greater hp loss).
Same logic would apply to a differential. Take 2 mustangs, put them side by side on the same dynos, one without a load, one with a load. Same gear, same RPM, which differential are you going to touch once after they run for 10 minutes?
Also, it's worth mentioning that the percentage of loss isn't linear across the board, I've been told it's more of an average. But as more power is added you have additional losses.
In the end it should not matter, as it is a moot point. Until somebody pulls the entire engine from the vehicle with all accessories and exhaust system intact, and straps it to an engine dyno, there is really no way to know the exact loss.
Rated numbers are all over the place.
Rated numbers are all over the place.
The car is insane. What did they underrate it so much for?
Well, Brooks at Drag Times has commented several times on how the transmission in the Ferrari shifts so much faster than anything else and is one of the reasons its so fast!
I can only imagine it equates to more HP in the end which would likely mean less HP loss so yea 7-10% probably sounds more reasonable.
Pretty sick tho to buy a new sports car to today and look at the HP specs and know that ur getting actual WHP and more..... U wont have to convert it from BHP to WHP lol.
I can only imagine it equates to more HP in the end which would likely mean less HP loss so yea 7-10% probably sounds more reasonable.
Pretty sick tho to buy a new sports car to today and look at the HP specs and know that ur getting actual WHP and more..... U wont have to convert it from BHP to WHP lol.
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