Alternator drag

lcorriveau3 said:

I was reading a thread on reducing ET's, it mentions that an alternator can take upto 35 hp from your engine and that a switch can be added to the field so it can be turned off when you drag race. Does anyone have a link or a source to explain this concept. I just find it interesting and would like to find more info on it. THanks

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That is standard equipment on aircraft charging systems. Its there so the pilot can deal with an malfunction which causes an over voltage condition. But it also helps the starter crank the engine a little faster or at all if the battery is low.

If the battery is fully charged, there will not be a 35 HP draw from the alternator. If you installed a switch to open the field circuit, the alternator would then free wheel sparing what ever HP it would have used for other purposes. Hopefully the battery would have the capacity to run the engines electrical load for the duration of a 1/4 mile race.

60 amps x 12 volts = 720 watts. thats about 1 horsepower. id guess power steering eats more power than the alternator. does make a difference, thus the market for underdrive pullies, but i wouldnt bother with trying to turn off the alternator. my .02.

Ok I was reading the thread in the drag racing section and that was printed in it. I was checking. Do a/c compressors draw HP when they are turned off?

lcorriveau3 said:

Ok I was reading the thread in the drag racing section and that was printed in it. I was checking. Do a/c compressors draw HP when they are turned off?

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Does it draw noticible HP when it is turned on?