Swap diff gearing for lower ratio & convert to rwd?

[Happy]

Originally Posted by Bdc101

Do you think that when you are at full throttle at 2,000 rpm it uses the same amount of gas as full throttle at 3,000 rpm? It doesn't -- you are accelerating slower because the motor is using gasoline at a slower rate (because it's at lower RPM and is pumping air and fuel at a slower rate). It's not like using higher RPMs magically gives you extra acceleration without spending any gasoline to do it.

So let’s apply this to the diff swap. 3950 rpm’s in 5th gear with the 4.10 diff vs 3525 rpm’s in 5th gear with the 3.64 diff.

At full throttle, both diffs will have max fuel consumption. However, at a cruising throttle position, fuel consumption will be minuscule. The throttle position is still key to the fuel consumption. You’ll need more throttle with taller ratios. Taller ratios deduct acceleration. That’s is why the engine speed decreases with the 3.64 diff. That speed will need to be up elsewhere.

Originally Posted by Bdc101

Partly closing the throttle restricts the flow of air (since the throttle is just a restrictor plate).

Not only does it reduce air flow, it reduces fuel flow.

Originally Posted by Bdc101

Likewise, pumping the air into the engine using a supercharger increases the volume of air that you can get into it per revolution, because it pumps it in at a higher than atmospheric pressure and thus a higher density. When you supercharge your mileage suffers because you have to inject more fuel to keep charge temperatures lower, to protect from detonating, but that is a different thing from what we're talking about by swapping final drives.

When the throttle is in a cruising position on a blown rig, boost is discarded through the valve. But depending on the type of valve setup, this parasitic loss can be harvested at a lower pressure, and redelivered. This adds more air without more throttle, resulting in better volumetric air flow rate efficiency thus raising the mpg by 2 , maybe 3 . Detonation will not be an issue because the pressure is not excessive. Again N/A, FI fuel consumption is determined by throttle position. Detonation is indeed a different subject.

Originally Posted by Bdc101

The end result is that you pay in gasoline for all the acceleration that you ask for with your right foot.

LoL.. Ain’t that the truth! Well in my case, ethanol.



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ReVELaTiON 22:21