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Old 11-05-2012, 02:37 PM   #13 (permalink)
3-Wheeler
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Quote:
Originally Posted by nbleak21 View Post
.....In theory I'm looking at a 7% increase in displacement resulting in a 12% (relative) decrease in TPS.....
1) A bigger engine will have more surface friction due to piston area, longer skirt length, and so on.

2) It will also have higher heat losses to the outside world because of the larger surface area.

3) A bigger engine will require more fuel because there is also more volume to fill, due to the larger displacement.

4) A larger engine usually weighs more, so there will be more losses when accelerating due to higher mass.

5) An engine with a lower TPS value will have more pumping losses because of the higher vacuum level in the intake tract. This is an inherent advantage of diesel engines; i.e. those with no throttle plate.

All things being equal, the larger engine should consume more fuel than a smaller one.

Jim.
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