rollingsband1

yes its been beat to the ground..

My question is really is the ls1 that superior in power?

Given the ls1 will make 350 at the wheels, and in the same car we have a rotary producing the same 350hp

the torque will be different yes but would the ET's be any different? and would the ls1 be faster still or would it be a balance out etc..

this is assuming the same drivers same weight same launch same car etc.. just different motors.

burtoncr

Area under the curve helps

rollingsband1

so the ls1 in general will be wuicker in the quarter mile, light to light etc over the equal rotary of the same power?

jimlab

That depends. Peak power to weight ratios don't account for gearing, the rest of the power curve, or traction, among other things.

There is no rotary of the "same power". They may make the same peak numbers, but that's only one point on the curve.

What burtoncr was referring to was the difference in the torque curves. "Area under the curve" refers to the shape of the torque curve. The broader the curve (rpm range) and taller the curve (output), the faster the car will accelerate overall, all things being equal (gearing and weight, for example).

Even rotary vs. rotary, there can be a difference with similarly rated engines (peak horsepower). A 13B-REW turbo engine has a broader torque curve than a RENESIS, for example. Even with similar peak horespower numbers, the 13B-REW will be quicker overall, all things being equal.

rollingsband1

i understand so pretty much a rotary can hang with a ls1 in a fd given the power and turbo produce the correct torque to do so, while keeping the hp roughly the same?

twokrx7

iTrader: (1)

Don't consider the swap for hp or speed alone, you can make a ton with a 2-rotor and be fast as stink. Get a ride in both and experience the difference.

jimlab

You can't change torque without changing horsepower.

Gearing multiplies torque, which is why you have to factor in the difference in gearing, among other things. An LS1 may make more torque over a broader range, but the gearing in the T56 6-speed that most people use is taller (lower numerically) than the gearing in the OEM 5-speed. Compare the first gear ratios of 2.66:1 vs. 3.483:1, for example. With the same 4.10:1 ratio in the differential, first gear in the OEM 5-speed has a 31% advantage over 1st gear in the T56.

Let's say peak torque for the LS1 is 400 lb-ft. In first gear, with drivetrain losses, that's about 3,708 lb-ft. at the axles (4.10:1 differential). For the rotary to produce the same peak 3,708 lb-ft. at the axles, it only has to produce about 260 lb-ft. at the flywheel. Now do you see why you can't compare cars based solely on peak power? Even if the vehicle weights and aerodynamics are the same, the difference in powerbands and a difference in gear ratios can totally change the outcome.

The answer is "it depends". A rotary engine will have to produce less power to keep up, but throughout most of the powerband, the V8 produces significantly more torque. It's likely that the V8 will dominate on the lower end, but at higher speeds, the rotary has an advantage. The only thing that you can really count on is that the V8 will probably last longer producing the same power levels.

rollingsband1

actually Jim you totally clairified this for me.. I totally understand now.. the motor is only part of the answer.. you have to go through the drivetrain loss, gearing, etc to come up with final torque.

this makes me want to just stay rotary and not be like 99% of the other cars on the road with pistons :-) and ust get a killer turbo setup to school them at the road course and drag strip.