Wheel Kw's to flywheel kw's

[Rock ape]

Ok guys how much power do you lose from the flywheel to the wheels with a manual box? Can it be worked out? If i make 279kw on a dyno whats that at the motor??? Do auto's lose more?

[groops]

Ohh...I think I can answer this one...I was talking about this to mate the other day...you have to find out how much drivetrain loss there is, how much gearbox loss there is and then add those 2 figures to the atw kw rating and that should be in the ballpark of your KW at the flywheel.

I'm happy to be proven otherwise, like I said, just going off what I was told.

Mike

[feebs]

How are you Terry... you still smiling after the weekend..?

Some say that FWKW = RWHP, but that's with an auto not a manual, so perhaps your engine is making 340KW peak.

Either way with a factory tune, it is very good. :-)

[Rock ape]

FWKW= RWHP yes thats what i have been told aswell. 279rwkw=374rwhp=374fwkw???
Is that right???
Yes feebs im still smiling.

[Fair302]

That is what i have been told. So 279rwkw x 1.341 = 374rwhp = 373fwkw

Not bad is it?

PS I got your PM and I'll contact you when DVD ready

[Rock ape]

Not bad at all , these Boss motors do make good power. I am hanging out for the DVD.

[gtfpv]

Originally Posted by BAGTp001

FWKW= RWHP yes thats what i have been told aswell. 279rwkw=374rwhp=374fwkw???
Is that right???
Yes feebs im still smiling.

thats what i was told when i had my dynograph done . but another mechanic in the same shop said he didnt really believe that, and believed that the ba MKII MAN loses around 60kw through the driveline .

so i got 2 conflicting figures from the same shop.

one was 264 RWKW = 354 RWHP = 354 FWKW.
the other 264 rwkw + 60 = 324 fwkw. i tend to believe the latter.

as mine is stock and if you add my bolt on claims you get
290kw engine
15 kw BMC fltr
5 pwr pipe
10 kw catback
total = 320 kw.

[feebs]

The FWKW = RWHP works better for AUTOs than Manuals.

So your engine may not be making 375KW, but either way it is doing well!

Saving up for a s/c kit then??

[Bent8]

Motor mag tested a bunch of FPV's and HSV's on the dyno and they averaged out the figures and came to the conclusion that the auto's lose about 22% at the wheels and the manuals about 17%. Utes were a little more.

279rwkw equals about 336fwkw (17% power loss) That's only 14kw short of the supercharged AMG E55!!

[feebs]

^^^^^^^^^^
Speaking of boss motors.. how is yours?

[Bent8]

^^^^^^^^^^
Speaking of boss motors.. how is yours?

Hi Feebs, just got my car back this afternoon, she's purring great but I'm not gonna thrash it just yet, got let it run in first...

[feebs]

Yeh.. let her run in for a couple of minutes huh??

[Bent8]

Yeh a few minutes should do it

[3vXT]

Originally Posted by Bent8

Motor mag tested a bunch of FPV's and HSV's on the dyno and they averaged out the figures and came to the conclusion that the auto's lose about 22% at the wheels and the manuals about 17%. Utes were a little more.

Thats more like it.

Flywheel kw = rear wheel hp is a load of crap. There are far too many variables in different gearboxs and drivelines for this to be a reliable way of working out the loss. Its the same as the people that claim cars lose a uniform 30% through the driveline.
By pure coincidence, it may work out to be accurate in some cases, the way a broken clock is right twice a day

EDIT: Assuming the dyno was accurate and that its flywheel kw were the same as ford have quoted (a pretty big assumption) my BA lost almost exactly 20% with no mods, thats with a T5.

[Fair302]

Originally Posted by Bent8

Motor mag tested a bunch of FPV's and HSV's on the dyno and they averaged out the figures and came to the conclusion that the auto's lose about 22% at the wheels and the manuals about 17%. Utes were a little more.

279rwkw equals about 336fwkw (17% power loss) That's only 14kw short of the supercharged AMG E55!!

I must admit that the above does sound more realistic. It would make some of the BOSS motors absolute beasts otherwise.

In my case: 273.2 / 0.83 = 329.2fwkw
290 to start with
helix + 5
BPRD CAI + 15
Pacemakers + 10
APC SS Twin 2.5" + 10

290+5=295+15=310+10=320+10=330
329.2 x 1.341=441.5fwhp

That sounds realistic enough to me.

[HLC]

i normally add about 50kw to get fwkw from a rwkw figure :

[TZENU]

Originally Posted by BAGTp001

Do auto's lose more?

Auto's do lose more power(not much) especially if they have a high(ish) stall converters..

[TUF270]

but then if autos lose more power? y are they faster than the manuals down the quarter? in stock form that is? not bringing modded cars into it..

[3vXT]

^^^ because they're easier

[irlewy86]

The Ford GT put out 550rwhp (either Ford defied the laws of physics or lied about the engine output)

17% is a fairly accurate figure for drivline loss on your modern barge.

Auto's have come a long way over the years and there as much of a gap between the 2 setups these days.

[T3man]

Originally Posted by HLC

i normally add about 50kw to get fwkw from a rwkw figure :

Yay, this sounds like the one for me! My old Beetle has about 25 rwkW. So if I add 50kW that means I have 75kW at the fly - 100HP - gotta be happy with that from a 40HP motor.

A good basic estimation of driveline loss (for properly matched gearbox/transmission) is 17% for manual and 18% to 22% for autos (the lower figure for modern autos and higher for the older types).

Because your engine has been modded the transmission is now being asked to work harder than before so the driveline loss wil be slightly higher than for a standard car. If you therefore used a figure of 20% for a manual and 25% for an auto you'd be pretty close. Also, autos tend to lose more of their basic efficiency than a manual does as torque is increased. Unless of course the transmission is also modified eg. higher line pressure to servos/upgraded clutches etc.

[Fair302]

Thanks for above info, I have always wanted to know this.

Also:

Holden Ute... Evoloution ends here.

It makes sense really, most of the Holden drivers I know stopped evolving a long time ago.

LOL but so true

[webby_191189]

Originally Posted by TUF240

but then if autos lose more power? y are they faster than the manuals down the quarter? in stock form that is? not bringing modded cars into it..

Because you loose a little bit of time shifting between gears in a manual where as an auto it does it automatically. Also depends on driver skill and how well they can shift

[RavenLS1]

Originally Posted by irlewy86

The Ford GT put out 550rwhp (either Ford defied the laws of physics or lied about the engine output)

17% is a fairly accurate figure for drivline loss on your modern barge.

Auto's have come a long way over the years and there as much of a gap between the 2 setups these days.

thats 550bhp not rwhp.

[Bent8]

I've heard that the GT40 makes 530rwhp because it doesn't have a tail shaft so almost all of the engines power gets to the ground.

[joe260]

Originally Posted by TUF240

but then if autos lose more power? y are they faster than the manuals down the quarter? in stock form that is? not bringing modded cars into it..

even i know the answer to that one. autos are best for dragging as u dont waste time chagning through gears lol

[prydey]

auto's faster down the strip? what era of cars we talkin here? only in the last few years has this been remotely close to being true on stock cars and even then its mostly on forced induction models where an auto is better.

drivetrain loss was always ROUGHLY 30% . there is no definitive figure as all cars will be slightly different. once again though, as the cars and the technolgy get newer and improve the loss through the drivetrain is becoming less and less. nowadays it is more likely to be somewhere in the 20's but its a rough guide as it always will be.

also when calculating, you are talking a loss so you start with fwkw and minus the percentage you choose (somewhere between 20 and 30%). because it is a percentage if you add it to your rwkw you will get a smaller figure than if you take it from fwkw. eg 200kw - 30% does not equal the same as 140 + 30%.

in my opinion, 270rwkw would be around 340fwkw using 20% drivetrain loss. this also is confirmed if you think a stock 290kw puts out around 220rwkw then both outputs are up around 50rwkw.

i also believe once you have estabished drivetrain loss on a stock car you can use that figure after future mods instead of using a percentage as loss should remain virtually the same.

[Badcooky]

From dirt bikes to top fuelers it's about 20% across the board,sometimes a little more.

[asusdragon]

the top one rwhp to flkw would bout right for my car 202rwhp so 202fwkw which working with the mods is bout what i think mine is doing plus take 50kw and you get 152rwkw which is what my car put out on the dyno

[prydey]

stock ef falcon at the fly is 157kw. 30% loss equals about 110rwkw which i think is about normal for most e series. 20% loss would give about 125rwkw which is a bit off the mark so i'm of the opinion that something closer to 30% is more applicable to that era of cars.

ba's on the other hand, being newer, seem to lose less. most stock xr8's are up around 200rwkw and xr6t's around the 170 - 190rwkw which equates to something closer to the 20% mark.

at the end of the day, its meaningless except for bragging rights down the pub.