pulleys
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Smaller underdrive crank pulleys free up a few hp by slowing down all accessories. Keep in mind the other viewpoint of having your waterpump, alternator , ps & ac turning at a slower rate. This may or may not be a problem.
Personally I think switching from a mechanical belt driven fan to an electric fan setup with reliable, high quality components is the best way to free up a few horses.
Personally I think switching from a mechanical belt driven fan to an electric fan setup with reliable, high quality components is the best way to free up a few horses.
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1,348 Posts
The engine fan does eat up a littler horsepower, although most of the time the fluid coupling makes that less of an issue.
However, you don't get anything for free. If you put on electric fans, the power to run them comes from somewhere. Guess where? The alternator. Yes, it does pull a similar amount of power from the engine, when the fans are running. If they're not running, you don't have a problem.
However, you don't get anything for free. If you put on electric fans, the power to run them comes from somewhere. Guess where? The alternator. Yes, it does pull a similar amount of power from the engine, when the fans are running. If they're not running, you don't have a problem.
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2,102 Posts
the mechanical fan can use as much as 40 hp and it takes about 1 hp to run a 100 amp alternator at full load on a test bench . really no comparison ,going to electric fans will free up way more power than the electrics use up. the biggest power saveings from underdrive pulleys on a mechanical fan car is from reduced fan drag
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326 Posts
I want to be sure I am reading your post correctly: Mechanical fans can use up to FORTY HP? How much does a flex fan use up in horse power compared to the clutch fan?
I guess a 1HP electric fan, setup to be dependable and robust, would be the best of all configurations?
I guess a 1HP electric fan, setup to be dependable and robust, would be the best of all configurations?
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555 Posts
Underdrive pulleys have a smaller crank pulley that turns quicker/uses less effort with each revolution, which in theory, frees up horsepower. Manufacturers like March claim this can be worth up to 12–15hp. The downside is that it turns all the other pulleys and accessories slower, as jlcustomz described.
I have a set of March Performance Ratio Pulleys on my 383 and don't really notice any horsepower bump (100% street driving) but do notice my headlights run a bit dimmer and the voltmeter usually reads a tad low, anywhere from low 12v to 13.1v at idle. Recently swapped in a larger water pump pulley and noticed it ran a just touch cooler.
I like the pulleys for the machined/polished aluminum look and the multi-ribbed aspect but the underdrive part, meh—i could take it or leave it. If you have a daily driver or sit in traffic for any length of time, i wouldn't bother.
I have a set of March Performance Ratio Pulleys on my 383 and don't really notice any horsepower bump (100% street driving) but do notice my headlights run a bit dimmer and the voltmeter usually reads a tad low, anywhere from low 12v to 13.1v at idle. Recently swapped in a larger water pump pulley and noticed it ran a just touch cooler.
I like the pulleys for the machined/polished aluminum look and the multi-ribbed aspect but the underdrive part, meh—i could take it or leave it. If you have a daily driver or sit in traffic for any length of time, i wouldn't bother.
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257 Posts
I would also like to know if it matters wit a flex or clutch fan. I understand mechanical is mechani
cal and that the flex will still take away HP. But will it b as much because of the 2 different ways they run.
cal and that the flex will still take away HP. But will it b as much because of the 2 different ways they run.
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