bigdaddyvtec

Id assume around 10-15% parasitic drivetrain loss in a fwd... Maybe a BIT more in a rwd...

TorganFM

Ummm a BIT? On rwd you have a rear end and on the driveshaft you have u-joints which eat up energy. I'd put a good fwd at 10-15%, a good rwd 15-25%.

J-SMITH69

percentages don' t apply.

it takes a certain amount of torque to spin it all and no more.

20% of 300hp is 60hp

20% of 8000hp is 1600hp

why would it take more power to turn just because the motor makes more power?

fe3tcourier

you are partly right, straight percentages do not apply, but neither do straight frictional losses. it is closer to a fixed percentage of the stock power though. ie, up the power, and the amount lost in the box doesnt increase all that much. closer to that than double power = double loss.

uni joints eat nothing at all when they are in a straight line (well setup car under heavy engine load) and minimal the rest of the time. the big killers for rwd apps are these :

hypoid rear drive instead of helical gear front drive
two pairs of gears for any gear except 4th compared to fwds 1 pair.

i've written a fully comprehensive simulator for this ----, i do know my stuff.

when you put it like that with the torqueower pathetic ratio, you have a point. ie, if you made the same power with less torque, the box could be of lighter duty and survive and thus use less. when i was thinking its your boxs that suck, i was wrong, its like i always knew, the engines suck. bucket loads of box smashing torque and no power to show for it ;-)

bigdaddyvtec

Ok Ill buy that, but when ujoints are set up.. correctly...They arent in a perfect line anyways (they are off set from the factory to keep the cups from spinning), and... USUALLY there's most always some degree of angle to them... add to that the driveshaft itself that eats tq... I do agree with that its not a straight linear relationship though, when I gave my percentage "educated" estimate, I was attempting to simplify it for (lack) of argumments sake.....
Kind of like an inverse function of the law of diminishing returns.. You know what im saying?

Granted the loss isnt linear, but the more power you make, the more is lost, its not a simple as saying that you lose athe same at 1000 whp as you do at 500 thats retarded.....


I dont know, I do huff alot of race gas....


I could be a bit twisted...


LOL

J-SMITH69

you twisted niggga

BigD

How about some dyno numbers and time slips? Maybe the guy in the Mustang was a super shitty driver. Then again racing from a roll is gay as hell anyways.

J-SMITH69

met a guy last night, he was holding his steering wheel in his hand, someone else asked him whats up, he says his civic is mad tyight and it'll get stolen.

hes getting removable pedals next.

then he says hes got a 350whp NA h22. i asked him how he got 350whp out of it, he said type r pistons and vtec. i laughed and asked if he wanted to race and he says whatta got a ls1 or something LOL... i laughed and said yes and he wouldn't race

even if he just had a h22 in his civic it would've kept up for a bit

losesomethinbra

On what? Id only care about the last 1.5k rpm before redline if I'm going all out. Should I care about more area under the curve around 3k-5k rpm? Especially from a roll you put that ---- at the rpm you want, brake boost a little if you want, and from there its ALL top end

sohcpwr

^^^^^^