Power Loss

[Tigerv8]

Does anyone ever consider how much power is lost between the engine and the road in your car?
My car was advertised as having 220kw of power. This translated into something like 170kw at the rear wheels. Quite significant. I have a 6 speed manual gearbox.
My neighbour has a restored 1957 Chev and had the engine built to run 400hp (300kw) but he tells me he loses around 100hp (75kw) running his GM400 auto transmission.
So our cars aren't really as powerful as we think. That's why it means more to talk about power at the wheels as this is where it does the business. If you have more power at the rear wheels than your stated engine power (usually measured at the flywheel), than you have truly made a good gain to overcome the effects of powering all that thrashing metal in your transmission and turning the immensely heavy driveshaft and differential.

[thumpin!]

Well with my car, I'm now pulling 248rwkw, myself and Blackone have worked out that it converts to 297kw at the fly wheel, making my car pretty much the same as a VZ clubbie and a lot cheaper.:faq:

[Tigerv8]

Thumpin,
What was the "before" figure on the dyno prior to your mods and what was the advertised engine power of your car? You can then see the actual original loss of power.
I wouldn't be surprised if you have more power at the flywheel than you think.

[BlackOne]

The advertised flywheel KW for his car was 250kw, which equates to around 190kw at the rear wheels.

[Tigerv8]

[QUOTE=BlackOne;3746]The advertised flywheel KW for his car was 250kw, which equates to around 190kw at the rear wheels.

OK. That means a loss of 60kw between flywheel and road.
Now he has about 248kw at the wheels, so add 60kw for the power loss and his flywheel power is about 308kw. That is about the same as the VE Clubsports have now.

Not bad.

[thumpin!]

[QUOTE=BlackOne;3746]The advertised flywheel KW for his car was 250kw, which equates to around 190kw at the rear wheels.

OK. That means a loss of 60kw between flywheel and road.
Now he has about 248kw at the wheels, so add 60kw for the power loss and his flywheel power is about 308kw. That is about the same as the VE Clubsports have now.

Not bad.

The actual rwkw before the work was done was 200. Therefore 50kw loss from flywheel to road. Now with 248rwkw, would take it to 298kw at the flywheel.
Will be interesting to see the difference when the cam goes on.:chewydance:

[BlackOne]

[QUOTE=Tigerv8;3763]

The actual rwkw before the work was done was 200. Therefore 50kw loss from flywheel to road. Now with 248rwkw, would take it to 298kw at the flywheel.
Will be interesting to see the difference when the cam goes on.:chewydance:

I was referring to the KW on a stock SV8 not with cold air intakes etc... hence the 250KW I mentioned.

[Tigerv8]

Yes, that's what I meant. Cold air intakes make no difference on a dyno anyway, only when you have a travelling airflow.

[EVLSS1]

Yes, that's what I meant. Cold air intakes make no difference on a dyno anyway, only when you have a travelling airflow.

ummm i beg to differ, that is why the dyno operators run a fan in the front of the vehicle to simulate travelling at the speed the dyno operator sets it too otherwise the readings wouldn't add up and could possibly do damage to your engine by not having enough air to mix with the fuel.

my first run before tune but with full exhaust was 191rwkw when tuned with a vz maff, mcai and full exhaust was 223 rwkw. stock they were quoted as being 225 fwkw

now the cam is in it has jumped to 287 rwkw. same exhaust for now, otrcai & a stall convertor robbing some of the power...... hmmmm but still a nice little increase!!!!

[thumpin!]

ummm i beg to differ, that is why the dyno operators run a fan in the front of the vehicle to simulate travelling at the speed the dyno operator sets it too otherwise the readings wouldn't add up and could possibly do damage to your engine by not having enough air to mix with the fuel.

my first run before tune but with full exhaust was 191rwkw when tuned with a vz maff, mcai and full exhaust was 223 rwkw. stock they were quoted as being 225 fwkw

now the cam is in it has jumped to 287 rwkw. same exhaust for now, otrcai & a stall convertor robbing some of the power...... hmmmm but still a nice little increase!!!!

Hi Jason, what sort of gain do you think I could expect if I put a Cam in my car?

[EVLSS1]

Hi Jason, what sort of gain do you think I could expect if I put a Cam in my car?

haha, a massive one!!!

you should see somewhere in the 40-60 rwkw range from the right cam & the increase in torque will see you frying the tyres with anymore than 1/2 throttle off the lights when properly tuned. but, it'll depend on what you want out of it. a lumpy cam say 108 or 110 lsa is an aggresive cam, (sometimes can be a handful in traffic) a 112 or 114 would be less obvious untill you boot it (will keep mr plod away!!). it all boils down to what you want. but it'll leave you smiling without a doubt whichever you choose.

i can't remember if you have an a4 or an m6 but you'll probably need to look at beefing up the trans a bit + adding a stall convertor or looking at a new clutch (tex z grip) to handle the new found power.

i don't regret doing mine for a second now that all the issues have been sorted out after my trans blew up, but i am contemplating buying a daily driver now as the k's are getting higher and higher on the SS and it is costing me $150-$200 a week in fuel!!! but hey, you don't modify a V8 for the fuel economy now do you??

[thumpin!]

I've got a 6speed manual and a tex x grip clutch, I only do about 150-200klm a week in my car as I hardly drive it and it only has 64,000klm on it. I've worked out that in the last year I did 9,500klm.

[EVLSS1]

well a mate in practically an identical car (VXSS s2 same colour, exhaust set-up and otr) recently converted to an m6 as his a4 was nearly knackered. we have the same spec cam installed and tuned by the same w/shop and with the m6 he produced 310 rwkw and when he had the a4 in it we were within 3 rwkw (he made 284) of each other. so that'll explain a bit more about drivetrain losses for you too....

[wazza]

costing me $150-$200 a week in fuel!!!

G'Day Jason , I know a few builder's over here who used to own SS ute's , used them as trade ute's , as they looked so good , with the sign writing all over them , their tax acc , told them to piss em off , because they cost to much to run ! now they are running around in 4cyl jobs , one bloke told me that he would spend $300.00 / $400.00 a week easy on fuel for the SS's & that is without any mod's done to it . They sure do like a drink !.

[thumpin!]

well a mate in practically an identical car (VXSS s2 same colour, exhaust set-up and otr) recently converted to an m6 as his a4 was nearly knackered. we have the same spec cam installed and tuned by the same w/shop and with the m6 he produced 310 rwkw and when he had the a4 in it we were within 3 rwkw (he made 284) of each other. so that'll explain a bit more about drivetrain losses for you too....

What sort of cam does he have and do you think I could expect the same sort of gain?

[EVLSS1]

costing me $150-$200 a week in fuel!!!

G'Day Jason , I know a few builder's over here who used to own SS ute's , used them as trade ute's , as they looked so good , with the sign writing all over them , their tax acc , told them to piss em off , because they cost to much to run ! now they are running around in 4cyl jobs , one bloke told me that he would spend $300.00 / $400.00 a week easy on fuel for the SS's & that is without any mod's done to it . They sure do like a drink !.

it all depends how you drive it wazza!! stop-start city traffic plus probably having the tray loaded and also pulling a trailer it'll cost heaps.

if i drive mine sedately, HUH!!! i can get nearly 400ks out of a tank around town. on the open road pulling my jet-ski i recently did a 340km round trip to the river (morgan) doing the speed limit too i might add on a whisker over half a tank. so it goes to show that they can still be economical, sometimes!!

[EVLSS1]

What sort of cam does he have and do you think I could expect the same sort of gain?

it is a crow cam, 226/231 110lsa. that's all i know about it as it is a custom grind designed and tested by my tuner so i am unsure of the degree of lift in it.

:shocked:i think you'll be pleasantly suprised with the results you could get with the right cam choice and the right tuner. but it'll pay you to talk with them to give them an idea of what you want out of the car. e.g. a torque monster with lots of low down power or a high revving max kilowatt angry beast or something in between. it might pay you to ask if someone could take you for a drive in a cammed car or 2 to get a good feel of what to expect. i'm sure your tuner could arrange that for you. then all you'll need is the :money:

we also did in our cam package - otrcai, valve springs, retainers, push rods, and 25% underdrive balancer. we both already had larger throttle bodies and full exhaust systems. and both being auto's at the time we had pwr trans coolers and 3000rpm hi-stall convertors put in aswell. and since, he has converted to an m6 with a tex z grip clutch and i have upgraded to a 4l65e fully built brand new trans and reduced the stall to 2800rpm. haha smokes them everywhere, it's killer!!!

[GMMAD]

thew reson why everyone quote rwkw is that is what a dyno reads
the only way to get fwkw is pull the motor out and use a engine dyno
the only people who quote fwkw are w@#ker trying to look like they have massive HP
as for fwkw to rwkw power loss

fwkw x loss% - = rwkw

(Auto 30% or Man 27%)

385 fwkw x 30% - = 269.5 rwkw

[Red_Ice]

thanks for the info there gmmad

great stuff

[Blown355]

Here's one for a huge drive train loss......

Did you know that the blower off a top fuel dragster @ full song takes about 500hp to turn......... That's more power than most street cars will ever have without spending some bucks.

[FAVSSS]

in autos they say you lose about 30% and in manuals its about 25%