hp loss from crank-rear?

trkmotorsports · Oct 1, 2009

whats the most common hp loss from the crank to the rearend? my crank hp is estimated to be around 500, woundering what i rough estimate can expected ar rear.

bentley429isBAC · Oct 1, 2009

What trans? Depends on a lot of things just dyno it if you feel the need.

cenok is family · Oct 1, 2009

yeah it really depends on the rotating mass of your drivetrain including flywheel, clutch, transmission, driveshaft, etc. it's roughly 15-20% though.

trkmotorsports · Oct 1, 2009

im going to dyno it once i got it ready, just need a rough estimate so i know what clutch to get

5.0Torx · Oct 1, 2009

the clutch doesnt grab the rear wheels, it grabs the flywheel. So if youre making around 500 fwhp, you should buy the clutch according to that.

Now, since youve implied that you have a manual transmission, figure roughly 15% driveline loss. +/- 2%.

Shaolin Crane · Oct 2, 2009

from what i remember for a manual 8% +/- and an auto is 15% +/-

MAC'n89Blckstng · Oct 2, 2009

I'd say your putting any where from 410-430 at the tires.

90lxcoupe · Oct 2, 2009

trkmotorsports said:
im going to dyno it once i got it ready, just need a rough estimate so i know what clutch to get

Clutch ratings also have to do with how much the car weighs, if you have a car thats 3500 pounds with 500 hp, and a car thats 3000 pounds with 500hp, then obviously the 3500 pound car is gonna need a stronger clutch. Torque ratings are more of a deciding factor in clutches than hp also.

If you give us more info on the motor somebody could steer you in the direction of a good clutch

Dino Dino Bambino · Oct 2, 2009

trkmotorsports said:
whats the most common hp loss from the crank to the rearend? my crank hp is estimated to be around 500, wondering what i rough estimate can expected ar rear.

About 430-435.

mikemac58 · Oct 2, 2009

Real HP... a question on the how's and why's of ratings

All this leads to another question I have had.

A 1984 5.0 was rated at 175 HP and the 1989 5.0L was rated at 225 HP. Was that at the rear wheels? Has the industry gone back and forth on if to quote HP at the crank vs. rear wheels for insurance purposes? If these 5.0L HP figures were quoted at the rear wheels would I assume a 20 - 30% bump at the crank?

My 2009 normally aspirated 3.5L in a Lincoln MKX is quoted at 265 HP... is that at the crank or rear wheels? Despite the huge differences in technology I would think my 5.0L's would still out HP my 3.5L... they certainly "feel" that way when driving them both. The 5.0L's are certainly more fun!

Just curious more than anything else

90mustangGT · Oct 2, 2009

When the advertise the hp they always talk about how much power the engine makes, not the "car". That rating does not include acesories such as PS and AC. Now at least they include the alternator and waterpump.

The 1984 engine was pathetic but about all engines were back then. That's what happens when you let the goverment have control of anything.

cenok is family · Oct 2, 2009

mikemac58 said:
All this leads to another question I have had.

A 1984 5.0 was rated at 175 HP and the 1989 5.0L was rated at 225 HP. Was that at the rear wheels? Has the industry gone back and forth on if to quote HP at the crank vs. rear wheels for insurance purposes? If these 5.0L HP figures were quoted at the rear wheels would I assume a 20 - 30% bump at the crank?

My 2009 normally aspirated 3.5L in a Lincoln MKX is quoted at 265 HP... is that at the crank or rear wheels? Despite the huge differences in technology I would think my 5.0L's would still out HP my 3.5L... they certainly "feel" that way when driving them both. The 5.0L's are certainly more fun!

Just curious more than anything else

all advertised HP ratings are at the flywheel. that "feeling" you're getting is the torque. your mkx probably has more horsepower, but it weighs more and definitely has less torque.

NIKwoaC · Oct 2, 2009

Manufacturers have never rated HP at the rear wheels- its always been at the flywheel/crank. Since 2005, to certify an engine power claim with the SAE, testing conditions must include everything the engine would have in the car; full accessories, exhaust and intake, IIRC.

A lot of people misunderstand horsepower on a fundamental level. Horsepower is nothing but a function of torque and engine speed. It defines nothing but how fast your engine is spinning when you measure the torque output. It can get pretty hairy when trying to define why some engines perform the way they do, but suffice to say that the 5.0 is fast because of its solid torque numbers, not because of its peak HP.

SVT32VDOHC · Oct 2, 2009

15-18%.

hp loss from crank-rear?

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