Reply to "ZF Losses"

The power loss will always be a percentage, not a set figure of 75 or 80 hp etc.
The more power your engine produces the more power you will lose through the drive train.

More power equals more friction in gears, bearings & driveshafts, as well as the tyres.
The lost energy turns into heat, hence the requirement for items such as transmission oil coolers on high output engines.

As George has stated, from his experience it has always worked out at around 19%, which is pretty good.
That equates to a fairy efficient transmission.

It’s possible if you had 930 CV joints instead of the Uni’s the losses may be a touch less.
As with better synthetic oils decreasing the friction.

So a 500 hp engine would have around 405 hp at the rear wheels, (95 hp loss).
A 350hp engine would be around 284 hp at the rear wheels, (66 hp loss).

If your engine was down a few cylinders & you filled it up with diesel by mistake & it was running like a real pig, put out only 90 hp, then the losses through the ZF would only be 17 hp.

Going to the extreme, if you had a twin turbo 427 monster pumping 1000 hp at the crank your ZF & drive train would be sucking up a good 190 hp & leave you with 810 hp at the rear wheels.
(still going on the 19% loss)
That’s why gearboxes let go with lots of power & torque.
Too much torsional twist on materials that were not designed for the increased power, too much friction on gear tooth faces leads to prematurely worn gears, shearing of teeth or bearing housings split from too much outward pressure & oil overheating & failing to do the job required.
So you need to beef up the transmission to handle the power, wider gears, bigger bearings, heavier shafts…..gearbox now holds up, but friction has increased, as has the inertia of the heavier rotating parts & so losses increase.
Gearbox is now good, but you start to suffer from a loss of traction, so fit bigger sticker tyres……….more power lost due to the increased frictional loading of the tyres.
And because your now loading the engine & not spinning the wheels, yep, more power is again lost due to increased friction in the drivetrain.

It’s said that a 7000 hp Nitro drag car requires 450 hp just to drive the supercharger.
It’s all relative.
You want more, you have to lose more…….it does not come for free.

But remember, your only losing all that power due to friction when your on full noise, & really, how often are you producing full power when you go for a Sunday drive?
5%.........10% of the time?
So the heat generated by the transmission is relativly low.........unless your on the race track, & thats when your losing 19% power 80% of the time.
As opposed to the Sunday cruise..... 19% of the power 5% of the time.

Regards,
Tony.