Posted by Charlie on May 03, 1999 at 20:48:42:
In Reply to: Need better gas milage in W-100 posted by Garrett on May 03, 1999 at 13:17:38:
First of all, the speedometer is probably calibrated for 31" tires or thereabouts, so your actual mileage is 6 X 36/31 = 7 mpg. You are, however, undergeared: rpms at 60 = 576 X 3.55 = 1950. Your transmission probably downshifts to 2nd at the slightest provocation. Assuming the motor is properly times, plugged and carbureted (a big if, there's probably lots of gas engine/carburetor guys out there who can tell you how to improve things 25-50%), you should do the following: change gearing to 4.10 or 4.56, install a 4spd auto or better a NV4500. That way (with the 4500) you'll be turning 1940 at 60, no downshift without your command, have much better low end, start in second, no torque convertor loss, etc. What you should REALLY do is buy the Mitsubishi 6DR5 from the guy in Flagstaff that advertised it in Feb. or March, put a turbo on it, keep your 36s, use a NV4500 (ratios=5.61, 3.04, 1.67, 1.00, 0.74), use 4.88s or 4.56s. I promise you if the motor is in good shape and your 36s are radials you will get >20 mpg at 65, 25 mpg at 55, and 17-23 mpg in general city/suburban driving. No bullshit. The motor was $1000 for two of them, the NV4500 would be about $1500, a bellhousing and clutch etc would be ~$1000, gears about $600. $4000 for triple the mileage. I estimate that motor turboed (turbo kit would be another $1800 out of Australia) would put out 150HP@3700, 250-260 ft-lb@2000-2200.
Charlie