I got a little curious and decided to calculate the supposed top speeds of some popular CUCV drive train setups. Please feel free to correct my math if it has any discrepancies.
M1008- stock TH400, 4.56 differential gears, 235/85/16 tire size with a circumference of 95.82 inches. Also, third gear in the TH400 is a 1:1 ratio, so the transmission can be "skipped" in this equation.
3600(governed 6.2 top speed)/4.56= 789.47 Tire RPM
789.47x95.82= 75,647.02 inches traveled in one minute
75,647.02/12= 6,303.92 feet traveled in one minute
6,303.92/5280= 1.19 miles per minute
1.19x60= 71.4 MPH -Top Speed
HOWEVER, this does not calculate for the wind resistance, rolling resistance, or the extra resistance placed on the motor by the alternators and power steering pump. I have followed our M1008 with a load of firewood and saw it do 60mph on our mini van's speedo.
I did the same calculations for:
M1009 -stock with TH400, 3.08 differential gears, and 31/10.50/15 tires with a circumference of 92.68 inches.
The top speed was 102.6 MPH, again without rolling resistance, wind resistance, or accessories resistance calculated. I have had my M1009 up to 80 and it wasn't maxed out.
M1008 -with stock 4.56 gears, 700r4 overdrive transmission, and stock 235/85/16 tires.
Top speed was 102.0 MPH, again without rolling resistance, wind resistance, or accessories resistance calculated.
M1008 -With 5.9 Cummins and NV4500 transplant and 4.56 gears and stock tires.
Top speed was 73.8 MPH -Kinda disappointing because I wanted to do one of these swaps when the money came around.
M1008 -Stock 6.2, NV4500, 4.56 differential gears, and stock tires.
I didn't actually calculate this one out but the overdrive in the NV4500 was a 0.73:1 ratio and the 700r4 is 0.7:1 so the top speed would be very similar.
M1009 - stock 6.2, Nv4500 OR 700r4, stock 3.08 differential gears and stock 31/10.50/15 tires.
Top speed calculated out to be 140.1 MPH, but I very much doubt that the blazer could reach this speed without falling apart. Plus, the faster you go the more rolling resistance/wind resistance.
Please feel free to punch you own numbers and try different tire sizes. I would have tried it with 37s. However, the tire size its not actually the exact tire size. the diameter of my 31 inch tire turned out to be 29.5 inches when I measured it. Make sure you measure your tire diameter before you start your calculations, or your answer with be inaccurate.
M1008- stock TH400, 4.56 differential gears, 235/85/16 tire size with a circumference of 95.82 inches. Also, third gear in the TH400 is a 1:1 ratio, so the transmission can be "skipped" in this equation.
3600(governed 6.2 top speed)/4.56= 789.47 Tire RPM
789.47x95.82= 75,647.02 inches traveled in one minute
75,647.02/12= 6,303.92 feet traveled in one minute
6,303.92/5280= 1.19 miles per minute
1.19x60= 71.4 MPH -Top Speed
HOWEVER, this does not calculate for the wind resistance, rolling resistance, or the extra resistance placed on the motor by the alternators and power steering pump. I have followed our M1008 with a load of firewood and saw it do 60mph on our mini van's speedo.
I did the same calculations for:
M1009 -stock with TH400, 3.08 differential gears, and 31/10.50/15 tires with a circumference of 92.68 inches.
The top speed was 102.6 MPH, again without rolling resistance, wind resistance, or accessories resistance calculated. I have had my M1009 up to 80 and it wasn't maxed out.
M1008 -with stock 4.56 gears, 700r4 overdrive transmission, and stock 235/85/16 tires.
Top speed was 102.0 MPH, again without rolling resistance, wind resistance, or accessories resistance calculated.
M1008 -With 5.9 Cummins and NV4500 transplant and 4.56 gears and stock tires.
Top speed was 73.8 MPH -Kinda disappointing because I wanted to do one of these swaps when the money came around.
M1008 -Stock 6.2, NV4500, 4.56 differential gears, and stock tires.
I didn't actually calculate this one out but the overdrive in the NV4500 was a 0.73:1 ratio and the 700r4 is 0.7:1 so the top speed would be very similar.
M1009 - stock 6.2, Nv4500 OR 700r4, stock 3.08 differential gears and stock 31/10.50/15 tires.
Top speed calculated out to be 140.1 MPH, but I very much doubt that the blazer could reach this speed without falling apart. Plus, the faster you go the more rolling resistance/wind resistance.
Please feel free to punch you own numbers and try different tire sizes. I would have tried it with 37s. However, the tire size its not actually the exact tire size. the diameter of my 31 inch tire turned out to be 29.5 inches when I measured it. Make sure you measure your tire diameter before you start your calculations, or your answer with be inaccurate.
