Re: OD trans, engine configurations, highway fuel mileage goals
Alright I had to calculate it for the ax15 and 275/60r15's
Currently, I'm spinning 2580rpm @ 70mph
on 28" tire, 3.07 rear, & standard 4 speed,
achieving a best of 21+mpg on an HEI/Holley 500 305D.
28" tire + 0.79:1 o.d. + 3.07 Dana 44:
1000rpm = 34.35mph
1500rpm = 51.52mph
2000rpm = 68.69mph
2038rpm = 70mph
2500rpm = 85.87mph
3000rpm = 103.04mph
3500rpm = 120.21mph
4000rpm = 137.29mph
28" tire + 0.79:1 o.d. + 3.31 Dana 44:
1000rpm = 31.86mph
1500rpm = 47.78mph
2000rpm = 63.71mph
2197rpm = 70mph
2500rpm = 79.64mph
3000rpm = 95.57mph
3500rpm = 111.50mph
4000rpm = 127.42mph
28" tire + 0.79:1 o.d. + 3.54 Dana 44:
1000rpm = 29.79mph
1500rpm = 44.68mph
2000rpm = 59.57mph
2350rpm = 70mph
2500rpm = 74.47mph
3000rpm = 89.36mph
3500rpm = 104.25mph
4000rpm = 119.14mph
28" tire + 0.79:1 o.d. + 3.73 Dana 44:
1000rpm = 28.27 mph
1500rpm = 42.40 mph
2000rpm = 56.54 mph
2476rpm = 70 mph
2500rpm = 70.67 mph
3000rpm = 84.81 mph
3500rpm = 98.94 mph
4000rpm = 113.08 mph
So my take on that is that the 3.07 would be viable to give me the absolute best 70 mph cruising mileage, but the 3.31 will be better all around & won't require downshifting on big hills or on winding country roads coming out of turns or climbing up hills. The 3.31 really would be more fun to drive at 45 to 65 mph.
The 3.54 (74.47mph@2500rpm) & 3.73 (70.67mph @ 2500rpm) would still be lower rpm's on the highway than a 3.07 + 1:1 top gear transmission (67.83 mph @ 2500 rpm), and would increase the fun factor and hauling capability
Last edited by Chuck78; June 4th, 2016 at 10:25 PM.
|