Quote:
Originally Posted by GregWeld
So here's a more important question that which brand....
Have you done the calculations required to see exactly where you'd be with different ratios.
My experience is that you can drop ratio and get WORSE gas milage because you're too far out of the torque band of the engine/cam combo. This can happen with rear end gear change or a transmission gear change.
My "info" has always been that you want to be CRUISING at (pick a speed - 60 /65/70 mph) about 200 RPMS UNDER where your cam starts to make torque. Anything farther out than that and the motor is lugging - and wastes fuel.
There's a point at which the carb (air flow) is pulling in enough air and it get properly atomized etc... so it's not just all about rear gears.
Just talking out loud here. I'm no expert - but I have experienced the exact opposite of what I was trying to achieve!
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Hey Greg .... no, I have to say that I haven't considered the gas mileage. The car is at a little over 3000 rpm at 60 ish, and all that I've thought about is dropping that to 2300 - 2500 rpm at that speed. That's interesting though ... I built the current motor a little over 10 years ago, so I'll have to dig thru the files to get the cam specs.