Hi all,
It has come to my attension how many arguments result between high revving low torque engines and low revving high torque engines. I just want to lay out an example to clear it up.
Givens:
(Max accel occurs at peak torque in each gear)
Tire Diameter: 24 inches
Tire Circumfrence: 6.28 ft
Engine 1: 550ft-lbs @ 2500rpm
Engine 2: 185ft-lbs @ 7500rpm
Cars have equal mass
Neglecting actual gear ratios and assuming peak torque occurs at given MPH (ideal gears)
Test Speed: 40mph
Tire Rotation: 560rpm
Engine 1:
Engine to tire ratio (4.46:1)
Torque to rear tires: 2453 ft-lb
Accleration force: 2453.2 lbf
Engine 2:
Engine to tire ratio (13.38:1)
Torque to rear tires: 2475.3 ft-lbs
Acceleration force 2475.3 lbf
Result: Engine 2 has greater acceleration
This is just an example to show that you cant compare engines purely on peak torque without considering the rpm which it occurs because the end result is the acceration force at the rear tires and that is what really matters.
Yes, i know you have to consider gear ratios and other things in real life but this shows that acceleration of a vehicle is only related to the force at the rear tires and the mass of the vehicle.
(i thought this might help some folks when arguing a point)
It has come to my attension how many arguments result between high revving low torque engines and low revving high torque engines. I just want to lay out an example to clear it up.
Givens:
(Max accel occurs at peak torque in each gear)
Tire Diameter: 24 inches
Tire Circumfrence: 6.28 ft
Engine 1: 550ft-lbs @ 2500rpm
Engine 2: 185ft-lbs @ 7500rpm
Cars have equal mass
Neglecting actual gear ratios and assuming peak torque occurs at given MPH (ideal gears)
Test Speed: 40mph
Tire Rotation: 560rpm
Engine 1:
Engine to tire ratio (4.46:1)
Torque to rear tires: 2453 ft-lb
Accleration force: 2453.2 lbf
Engine 2:
Engine to tire ratio (13.38:1)
Torque to rear tires: 2475.3 ft-lbs
Acceleration force 2475.3 lbf
Result: Engine 2 has greater acceleration
This is just an example to show that you cant compare engines purely on peak torque without considering the rpm which it occurs because the end result is the acceration force at the rear tires and that is what really matters.
Yes, i know you have to consider gear ratios and other things in real life but this shows that acceleration of a vehicle is only related to the force at the rear tires and the mass of the vehicle.
(i thought this might help some folks when arguing a point)