I wish I could give you the hard data. Time and old man winter will most likely not allow it :[ I sometimes got a solid 25+ mpg out of my AX15 Cherokee Sport. 4X4 4.0L 3:08 axles. Flat lands of Ohio 65 mph cruise speed. The same mileage was experienced down in Virginia in the flatter areas between 24 and 26 loaded. I have no doubt my American does similar or better. -- Mark Price markprice242ATadelphia.net Morgantown, WV ---- Tom Jennings <tomj@xxxxxxx> wrote: > > On Nov 2, 2005, at 1:24 PM, <mail@xxxxxxxxxxxx> wrote: > > > IIRC my tires [25560R15] are about 26.5 tall and I have a Spirit > > T-5 with 3:31 gears. It cruises on the highway just great. I have > > no real idea of what RPM it pulls as I've never mounted a tach. > > Fuel Mileage? I've not checked it offically, but it is real good, > > I'd estimate 25-30 mpg highway easy. I wish I could drive it more > > to get and official read on it. The 3:31's seem to be about perfect > > with my current combo. > > > > Yours is turning 2500 at 60, 2900 at 70; mine's somewhat less, 2200 > and 2550 or so. (see below) > > I'd be really interested in hard mileage data on your car. I'm > getting a solid 22 mpg highway at 60 - 65 mph, 19 mpg at 70 - 75 mph, > and around 18.5 in-town. That's 7800 miles, 400 gals of data (every > single fillup and mile since I ran the car in June 2005. I drive 300 > mi/week (100 mi/day 3 days) on I5, I605, I405, LA to Irvine. > > Long ago we had a thread about mileage, engine efficiency, cruising > 'sweet spot', torque peak, etc. Never got resolved to my > satisfaction. The old and general consensus is that best mileage is > under 2000 rpm, and that torque peaks are spec'd under 2000 rpm for > the motors AMC used. Clearly, you and I, and nearly all of the > numbers I've seen in TSMs regarding GEARING (not engine rpm/hp/torque > specs...) puts 60 - 70 mph cruise will over 2000 rpm. > > I don't believe the TSM engine torque and HP specs, at all. Net or > gross, it's half marketing and tax issues. I'd love to hear actual > dyno numbers on actual factory-stock motors, but I don't think many > people do that. > > Clearly gearing is all a compromise even in the fuel-spree 60's, but > still, factories tended to know what they were doing, if only be > large-scale trial and error. > > > > Mark's car, hacked up from my Hornet spreadsheet, I included on 3rd > gear (1:1). > > > RPM CFM MPH TIRE DATA > 1000 60 24.3 > Axle ratio n:1 3.31 1100 66 26.7 Width: 255 > Tire diameter 27.05 1200 72 29.2 Aspect: 60 > 1300 78 31.6 Wheel: 15 > 1400 84 34.0 Diameter: 27.05 > 1500 90 36.5 > 1600 96 38.9 > RPM interval 100 1700 102 41.3 > 1800 108 43.8 > 904 Auto 1900 113 46.2 > First 2.54 2000 119 48.6 > Second 1.55 2100 125 51.1 > Third 1 2200 131 53.5 > 2300 137 55.9 > 2400 143 58.3 > Engine CID 258 2500 149 60.8 > VE 0.8 2600 155 63.2 > 2700 161 65.6 > 2800 167 68.1 > 2900 173 70.5 > 3000 179 72.9 > 3100 185 75.4 > 3200 191 77.8 > 3300 197 80.2 > 3400 203 82.7 > 3500 209 85.1 > > > > > >