What power does a V8 Supercar make on a chassis dyno

[Shonky.]

Anyone know?

[Fpv V8]

I think I have read the ford and holden engines are about 480kw.

[patrickian11]

Thats about right http://www.v8supercars.com.au/champi...ehicle-details

[Shonky.]

Cheers, for that.

But does anyone know what they put down at the tyre?

[GT2]

I remember they ran a 10.80 @ around 135mph. That should give you an idea.

[Sprint]

650hp

[Shonky.]

That's @ the flywheel though

[Sprint]

- 40 hp then

[FTe342]

Originally Posted by Sprint

- 40 hp then

I wish my cars only lost 40 hp thru the drivetrain !

[BIONIC MAN]

gee shonky... lots of people posting.. but no one has the answer!?
we can all guess/work out drivetrain loss etc etc, but has anyone got figures of actual runs on a dyno and RWKW recorded!

[GS608]

Originally Posted by BIONIC MAN

gee shonky... lots of people posting.. but no one has the answer!?
we can all guess/work out drivetrain loss etc etc, but has anyone got figures of actual runs on a dyno and RWKW recorded!

You won't find exact rwkw/dyno results, not of the current cars anyway..those are kept very close to the chest.

[BIONIC MAN]

yeh, that's a fair point, you would think someone like a privateer or a car in the development series being dyno'd.
just an actual recorded figure would be nice. they may have less drivetrain loss than a regular road car due to gearbox design but it would still give an idea.

[sbutler]

Almost all cars lose 50kw through the drive train..

[DJR MAN]

Generally allow 20% less than flywheel HP.
That possibly the most accurate answer as no supercar team will publish that figure.

[Sprint]

Originally Posted by sbutler

Almost all cars lose 50kw through the drive train..

no way mate unless you have the hand brake on or seized wheel bearings.

Race cars also have a super efficient drive train, 50kw is about 70hp, about as much power as a std ford escort makes.

You can get figures from many people that also have flywheel vs rwkw and take a average.

[Spammy]

Originally Posted by sbutler

Almost all cars lose 50kw through the drive train..

So a 1200 VW Beetle which has less than 50kw at the flywheel will have how much at the wheels.

I think you will find its a percentage of power, rather than a fixed number.

[Xauterus]

I believed that they all used a torque sensor on the drive train so that they were all capped at a maximum horsepower to keep them more even. Of course the trick for a team would be to get the most useful power curve under that maximum limit.

[FPV GTHO]

PM CAT600, I recall a post he made about this related to drivetrain loss and what he'd seen a V8SC pull on a dyno vs what one had run at the strip

[sbutler]

Sorry a balls up on my part between HP & KW
I was meaning most cars lose 25kw drive train loss..
We have done the percentage thing a thousand times & it doesn't work.

[Spammy]

Originally Posted by sbutler

Sorry a balls up on my part between HP & KW
I was meaning most cars lose 25kw drive train loss..
We have done the percentage thing a thousand times & it doesn't work.

First you tell me drive train losses are a fixed amount and now the conversion from kw to HP is 2x rather 1.341022x

What else has changed since I did Mechanical Engineering at UNSW?

[sbutler]

Originally Posted by Spammy

First you tell me drive train losses are a fixed amount and now the conversion from kw to HP is 2x rather 1.341022x

What else has changed since I did Mechanical Engineering at UNSW?

If what I say bothers you so much, why reply?

[Spammy]

Originally Posted by sbutler

If what I say bothers you so much, why reply?

Somebody has to enforce the laws of physics.

[stevefreestyle]

Originally Posted by Spammy

Somebody has to enforce the laws of physics.

Thanks Spammy, as a former Mech Eng myself, I got a smile out of that !

[sbutler]

Originally Posted by Spammy

Somebody has to enforce the laws of physics.

So when did you become the physics police?

[mik]

A big vehicle with lots of torque and big bearings drive shafts and gears is going to need a lot more power to turn wheels compared to vw or an escort.

[Road Games]

*koff* 135 mph @ 1350kg ... do the math ...

[Franco Cozzo]

If the rule is 20% for RWD cars, what about for FWD cars as they are more efficient at getting their power to the wheels?

[zilo]

Originally Posted by Big Damo

If the rule is 20% for RWD cars, what about for FWD cars as they are more efficient at getting their power to the wheels?

yep...12-15%

Also why most manufacturers making fuel efficient cars settle on a FWD platform.

(not to simply kill the joy of drifting as some would think)

[Road Games]

http://www.tciauto.com/tc/racing-calculators/

[madmelon]

I read a year or more ago in a Motor magazine that they put down about 620hp at the wheels. Going off about 650 at tje flywheel, that's only a 5% loss. Given the tech that goes into a racing transmission and diff, I figured this value to be reasonable.

I work in transmission design and development and have seen efficiency curves for transmissions. Generally, for a particular transmission, the higher the input torque the higher the efficiency. This is because there are losses in the transmission that are not closely related to input torque- as it rises significantly, the losses may rise slightly or remain constant. The peak transmission efficiencies I saw in those curves were around the 95% mark.

Hypoid type diffs suck a reasonably large amount of power- the axis of the pinion does not intersect the axis of the crown wheel. This necessitates a tooth design which results in sliding contact, as well as rolling contact. Normal gears have rolling contact only, so their mechanical efficiency is very high- on the order of 97-98%. Hypoid bevel gears have a mechanical efficiency of 92%. So if it was done right (and I'm certain it is!) a driveline loss on the order of 5-10% in a racing car is not unreasonable.