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Old January 2nd, 2022, 05:17 PM
turbobill turbobill is offline
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Default Re: The fuel efficient GMC V6

This is my take.

The not so great fuel mileage in my opinion is mostly the result of the not so favorable "surface to volume" ratio of these very oversquare engines. Large bore engines tend to have greater surface area at TDC for combustion heat to be lost through. A helpful fix there is the heat barrier coatings.....for the piston heads, combustion chamber surfaces and at least the valve faces. This can be done to the stock pieces.

Next up is compression. The higher the compression ratio, the more the thermal efficiency (everything else being equal). Within the confines of stock parts, head and deck milling along with the thinnest possible head gasket. Other than that, custom or different pistons.

Engine friction.....friction coatings, low tension rings, smaller piston skirts, roller lifters, roller bearing rockers with roller tips, synthetic oil, but most important of all.............reduced engine RPM.

These engines make good low RPM torque so an axle ratio change, taller tires or overdrive transmission would probably be a lot cheaper than some of the custom parts/fabrication/modification required for different rods, Chevy pistons etc. Each ten percent increase in engine speed increases parasitic (friction) losses twenty percent. Cut RPM in half, engine (and anything turning with it) friction is reduced to 25% of it's previous value at twice the speed.
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