Quote:
Originally Posted by Prowbar
Here's something I've been tinkering with for a while. I've been reading that old post from James Cleary and he mentions outstanding fuel economy from an engineering standpoint. Well, as we know, these V6's are anything but fuel-efficient.
Which got me wondering, is it possible to improve the mileage on these V6's? I believe so, by reducing the internal friction that these have. The main advantage we already have is 2 cylinders less than a V8, meaning less friction.
Some ideas I had: (which apply to a 305E)
1. Custom (longer) connecting rods and the use of 4.250" big block Chevy pistons with thin, low tension, piston rings. Modern materials make this possible. This would reduce the massive friction of the thick piston rings and the large piston skirts.
The longer connecting rods are needed because of the higher wrist pin location.
Does anything know what length the stock rods are, and what the deck height is?
2. Another advantage is the compression gain, with a flattop or even a slight dome design. Up to 9.5-10:1 static. Maybe even higher, given the rod ratio.
The disadvantage would be to have everything rebalanced.
Of course, the mains and rod diameters are larger on a V6 than a comparable engine, adding to the friction, which is a given. But I have a hunch this (different piston) will improve the efficiency of the engine significantly.
Reducing additional friction could be done by the switch to a roller camshaft.
Another idea is to change the intake manifold, but I'm not sure how good or bad these are. Optimized and equal fuel distribution to all cylinders is the idea.
I'm no engine builder, just a student on the subject, but I'd love to hear your ideas. It is not my idea to write off the base design, just some thoughts to improve on it.
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Stock rod length: 7.17825" C-C;
Piston Deck Height 0.000"
Not for sure on the Piston Dished Volume but I believe it is around 10CC.
Plans for my 305:
To increase the compression ratio I am planning on offset grind the crankshaft to increase the stroke, going from stock journal size to 0.030" undersize. Then mill the head of the piston (will be 0.030" oversize) to get it back to a zero deck height, this will remove most of the dished from the head of the piston.
Also in the works I have been flow testing the heads to improve the flow. Been getting mixed results from this. Still in progress. I will be targeting high swirl and all the flow I can get. Stock head has no swirl and badly shrouded valves.
I had already modified the intake manifold to be equal to the Magnum engine and had installed the Holley 2 barrels carb. I need to schedule time on the chassis dyno, this will show the change from the totally stock dyno reading.