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Old 10-26-2010, 01:02 AM   #1 (permalink)
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lightweight cam gears

so i've been doing alot of searching before posting this and couldn't find what i was after, so i'm thinking of buying some light weight cam gears for "ye ole starlet" (not this is a timing chain engine not pulleys so don't think serpentine pulleys) i was wondering if there is a decent FE gain from it (as rotating mass reduction has a greater effect than normal weight reduction). when i say decent i mean 1km extra to the litre or about 3.8 mpg extra, will keep searching but would be good tohere your thoughts or tests already done

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Old 10-26-2010, 07:03 AM   #2 (permalink)
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I highly doubt you'll see any gains.
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Old 10-26-2010, 10:48 AM   #3 (permalink)
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energy used to rotate a cam gear in the first place is very minimal to the energy required to move a 2000lb car along the road. Id expect that even a weightless cam gear would show no noticeable mpg improvement, using it to to time the cam on the other hand could help (if its adjustable).
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Old 10-26-2010, 10:59 AM   #4 (permalink)
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The Ford pinto 2.8 liter V6 had plastic (phenolic) cam gears, and from what I remember they would fall apart before the scheduled replacement period. The replacement part was metal.
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Old 10-26-2010, 03:11 PM   #5 (permalink)
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Quote:
Originally Posted by MorphDaCivic View Post
The Ford pinto 2.8 liter V6 had plastic (phenolic) cam gears, and from what I remember they would fall apart before the scheduled replacement period. The replacement part was metal.
they did that for noise , plastic is quiet compared to all steel .
I can't see cam gear weighing very much (probably a 1lb or so ). Now you could get light weight flywheels or crank pulleys that will reduce mass by many lbs compared to stock but still I doubt you get much improvement in FE, maybe 1-2mpg max depending on drive conditions . I think city driving would get most benefit .
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Old 10-26-2010, 03:30 PM   #6 (permalink)
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remember that a flywheel is huge compared to your cam. And that cam is only rotating at 1/2 crank speed. I doubt you would see anything. MAYBE .1 mpg.
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Old 10-26-2010, 08:01 PM   #7 (permalink)
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Also note that the diameter of the cam gear is relatively small, so the moment of intertia is also small. You'd have to have one heck of a weight savings to make any noticeable difference. (I'm guessing you'd have to save more weight than the gear even weighs in the first place!)

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Old 10-29-2010, 07:32 AM   #8 (permalink)
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fair enough then, im getting the earlier version flywheel of this car (its 4lb or roughly 1.8kg's lighter) so should still be fine with a bit more acceleration, i need to time in my cam anyway, i just finished statically re timing my hole engine.. its on 16" btdc goes alot better, will have some results up next week but cant tell ya the final result till a month or so
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Old 10-29-2010, 12:46 PM   #9 (permalink)
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you should see some gains with the flywheel. More if you drive in town, less if you drive highway. It varies in proportion to how many times you rev cycle the engine. If you want to see more, try skipping gears if your gearing allows that.

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