Well at 15,000rpm it look a little like this tq=hp^3
Or hp is 3 times the torque at that rpm so I have herd.

 

If HP = torque x rpm /5252,

then Torque = HP x 5252/ rpm

750 hp at 15000 rpm is 750 x 5252/15000 or 262.6 lb-ft

At 3 x 5252 or 15756 rpm, the hp number is exactly 3 times the torque number.

As for maximum torque on a 900 hp F1 engine, BMW conveniently neglected to discuss that. I'll try to simulate an F1 engine from the data they have published. My guess is around 300 lb-ft in the 14000 range.

Food for thought:

F1 car with 825 hp @ 18000 rpm geared for 190 mph at that point.

Nextel Cup car with 825 hp @ 9000 geared for 190 mph at that point.

Assume rear tires are the same diameter (which isn't far off).

If both cars are drag limited at 190 mph so they are producing the 825 hp, calculate the torque at the flywheel and also the torque at the rear wheels for both cars. Assume 90% driveline efficiency for both.

Are you surprised?

 

hp = tq/5252

at 5252, tq = hp

at 10504, tq= hp*2

at 15756, tq= hp*3

 

same hp, double rpm-
the low revver makes 2x the torque.

so if nascar makes 2T
and F1 makes 1T
then factor in .90 and you have 1.8T vs .9 T

I dont feel like doing the actual math.

tq is essentially a function of displacement, VE and compression assuming all else equal, no?

Nascar is about 1.4 VE
F1 is around 1.9sh?

1.45(?) * 5.7~~ 8.3
1.9 (?) * 3.0 = 5.7

so if you can get more than about 350ft lbs out of your 5.7, you are kicking *** and at about 100% Ve?

F1 runs higher compression and such dont they? What are the actual torque numbers? 350 and 550 ish?

8.3/ 5.7 = 1.45
550/350 =1.57

pretty close, or concidence?

 

Remebmer F1 is 3.0L and Nextel Cup cars are about 540ft lbs Max Tq.

Bret

 

How about the rear wheel torque of the F1 and Cup cars in my example? How close are they? It's not a 2:1 ratio at the wheels, BTW.

Try 26.7 inch tire diameter on both to ease the math. You can use the formulas in the sticky at the top of Advanced Tech to help.

 

at the wheels, id imagine its equal. i gotta run, i'll look into the math later but if they are geared to have the same speeds at shift points with equal number of gears and have the same hp but one revs 1/2 as high, shouldn't they have the same rwtq after taking gear ratios into concideration?


Bret, I used 3.0 in my calculations for the F1 car and used 550tq for the Nascar. 540 would make the results even closer

 

Yes, torque at the rear wheels is equal, as is horsepower because wheel speed is identical.

However, torque at the flywheel is twice as much on the Cup engine as on the F1 engine. Of course the F1 is pulling exactly twice as much gear.

No calculation is required unless you want to know rearwheel torque.

 

I'm brilliant
moral of the story, make cubes rev.


Heres an intersting one while we are talking about VE


In a cross country drive with my gen III votec silverado, I had slightly better gas milage in 3rd than 4th gear. at 85mph, i was close to WOT through the mountians in 4th, about 3/4 throttle, if that in 3rd.

I had 3.73s matched with 33'' tires so the revs were way too low to make any torque. Preak tq is somehwere around 3300 according to the ***-o-dyno.

damn high revving truck motors.