Is it really that EXACTLY?

Quote from Bob Smith :

Is it really that EXACTLY?

power = torque x rpm

let T = torque
let R = rpm

The amount of work done per revolution is torque x 2 x pi.
1 hp = (550 ft lb) / sec

power/hp = (T ft lb) x (R rev/minute) x (sec / 550 ft lb) x (minute/60 sec) x 2 x pi

power / hp = T x R x 2 x pi / (60 x 550) = T x R x 2 x pi / 33000

power / hp = T x R x (pi/16500) = T x R x (1 / 5252.113122...)

Quote from Bob Smith :

Ah lets have proper SI units:
Nm for torque
W for power
rad/s for engine angular velocity

Then by definition, the torque and power curves will cross at 1.

Or if you insist, use kW and they'll cross at 1000. Nice easy numbers.

Also if you use rpm and kW, the number is 1000*30/pi, so easy enough to calculate. Well, easier than lb ft and hp for sure.

Well said... and that from someone who lives on the island

The MRT5 is as correct as I can feel for what it is and the limits given to simulate an exact spec car like it.

I can't really say how but I have experienced the Y patch with an MRT5 and the rev's re-set to pull HARD to 12-13,000rpm.

Its much too twitchy for the normal driver to be worth tuning a laptime. A few loonatics would love it like that but its a spec car, right?

Quote from MR_B :

Are whales soft then?? I always thought they were solid lumps....

Squidgy whales, well blow me down.....

Yeah, whales must be quite soft as after skin comes quite thick layer of fat that keeps them freezing to death and as we know fat is soft.

In autocross hp is not everything, wide torque curve is best as often there is places where you are better off to use one gear.

Very informative, interesting post, thanks! Now when can me get the MRT9 in LFS? I want that extra 20hp.

Yeah, the more MRTs the better

Quote from mattgignac :

...good stuff...

Well there you go! Straight from the horse's mouth. Thanks for the insight.

MRT5 was a while ago but these days FSAE teams using larger engines (restricted 600cc 4cylinders, etc.) are making as much as 80-100 hp at the wheels. The MRT5's 68 hp figure was most likely also measured at the wheels (chassis dyno).

I always assumed that power for LFS cars was advertised at the crankshaft/flywheel (engine brake dyno). If this is true, then the LFS MRT5 has less power than the real MRT5. Can anyone confirm this error?

Quote from Cappy333 :

I always assumed that power for LFS cars was advertised at the crankshaft/flywheel (engine brake dyno).

That is correct.

Quote from Cappy333 :

If this is true, then the LFS MRT5 has less power than the real MRT5. Can anyone confirm this error?

If the 64hp is definitely at the wheels, then LFS is indeed down 10hp on the real thing.

Mattgignac, can you confirm that the 64 hp (or is it 68?) was measured at the rear wheels? I wonder if the developers would fix the MRT5 after all this time.

Quote from Cappy333 :

Mattgignac, can you confirm that the 64 hp (or is it 68?) was measured at the rear wheels? I wonder if the developers would fix the MRT5 after all this time.

It sounds about right for one of these cars at the wheels. Ours from about the same year with no turbo did 50 hp at the wheels measured at competition.

That's not much for a I-4 600 cc FSAE car. What engine was your team using?

Quote from Cappy333 :

That's not much for a I-4 600 cc FSAE car. What engine was your team using?

honda f4i iirc, was with them 2004 and besides a custom intake/exhaust and a remapping they didn't do much to the engine.