[pgfpro]

Originally Posted by stonebreaker

You guys are barely touching engine mods. Coming from a hotrodder background, there are a lot of mods the rodders do specifically to increase the efficiency of their engines - and by that I mean get more power out of a pound of fuel. The difference is, they do it so they can go faster, you guys do it to go further. OEM's often can't afford these mods due to the expense of putting them in millions of cars, but I just have to do it to one car.

Many racing classes allow the "rollerizing" of the engine. They replace all engine bearings with roller bearings to cut internal friction. While this is prohibitively expensive for most folks, what a lot of us do is replace the OEM rockers with roller bearing versions. This is good for a peak 5hp gain all by itself, simply by cutting internal friction. I don't know what that translates to at highway speeds, but many of my friends see mileage even better than stock when using a fairly mild cam.

Exhaust: OEM's have to meet strict noise standards. Hotrodders replace their exhaust partly to improve the sound of their car, but also because the stock exhaust has a lot of backpressure. Swapping the stock exhaust on a V8 to a performance exhaust can pick up over 20 peak horsepower, simply through the reduction of pumping losses. Again, I can't say what kind of improvement you'd see at eco speeds, but at least your car will sound cool!

Intakes work the same way. Going with a K&N or some other low restriction intake can reduce engine pumping losses. We have recorded as much as a 10 peak hp increase simply by swapping the air filter.

Matching fuel injectors: The fuel injectors from the factory have flows to within +/- 10% of rated flow. The tune on the stock computer has to be able to account for this. Installing a set of flow matched injectors, which are within +/- 1% of each other, will allow a tuner to clean that slop out of the stock tune. This will allow more precise fuel metering and more spark advance, and the tuner can get real aggressive with the tune if you have the car tuned on a dyno.

I agree there isn't much on here in the Master list of 65+ proven mods for increasing MPG for engine mods.

I'm not to sure why? If its a money thing or knowledge thing?