you can put a switch on the field of your alternator to turn off the drag during the run. an alternator can take up to 35 hp so its a good idea....but which wire should i put the switch in?? the fat one off the back of alt.? or the little red ontop??

 

35 hp?Who the hell told you that?Did you mean 3-5 hp?I don't think it should even be that much. Not enough to worry about IMO.

 

dragtrucks.com and numerous other sites

"10 tips for shaving ET this weekend"


1. More RPM - I've found that it’s just about impossible to have too much (higher number) gear in your car if your goal is the lowest ETs. Just keep adding gear ratio until you stop gaining ET, even if the MPH falls off. Remember: racing is usually ET not MPH.
2. Jetting - If I had to guess I'd say that 80% of all race engines are jetted too rich. Some of the signs of a rich setting are an engine that misses or surges. Try jetting down two sizes and see what happens. Learning how to read spark plugs is my best advice.
3. Ignition Timing – Go up or down two degrees and make a test. I’ve seen engines tuned with just a couple of degrees too much timing lose 30hp, so don’t think you can’t have too much.
4. Oil – If you aren’t using synthetic oil already, try it, it’s worked every time for me. The other big thing is oil level, on a wet sump engine too much oil is a killer. No engine needs more than 6gts, no matter what the pan manufacture says. In fact; too much oil is bad.
5. Shift Points – If you’re going to miss your shift point, miss it early. A late shift is an ET killer, especially in the lower gears. Here’s a test: If you seem to really be knocked back into the seat after the shift, you’re late. The Reason? Your body went forward before the shift because of lack of acceleration.
6. More Traction – Obvious subject I know, but here’s one I’ve seen missed more than any other traction aid: Weight. So many people are afraid to add weight to their car, but I would guess that 80% of cars could benefit from weight in the trunk. Don’t take my word for it, give it a try.
7. Lower Coolant Temp – With all other variables being the same, lower coolant almost always makes more power. There are a lot of ways to lower the temp and I can’t mention them all here, but a problem I’ve seen more often than not is low coolant level. Make sure the radiator is full.
8. Kill The Accessories – A water pump takes 10hp to drive, an oil pump takes 10hp and the alternator can take up as much as 35hp. Use a low drag water pump or electric drive and put a switch on the field of your alternator to turn off the drag during the run.
9. Aerodynamics – Now I know changing aerodynamics of your car is not a simple thing to do, but there is one quick modification that I’ve seen work more than once; Lowering the front end of your car. I’ve seen drag cars pick up as much as .01 of a second in ET and 3 MPH in speed by just lowering the car two inches.
10. Test Different Carbs – Carburetors all have their own personality and some just seem to work better than others. Buy two carbs that are exactly the same and you’ll have different results. My advice: test every carb you can get your hands on and never get rid of a good one.

 

"an alternator can take up to 35 hp so its a good idea"

That's not happening. If that were true then a simple test of pulling the belt would increase trap speed by 3 MPH. Lemme save you the trouble....it doesn't. In fact, often people see a DECREASE in HP when running without the alternator due to lower ignition power (gotta fire those plugs off ya know!)

 

I'm gonna have to agree with mister colonel.

spark be good.

 

Guess i'll bite.. 35hp, no way. Just look at how much heat it would have to get rid of if it was eating that much hp... your alternator would need a radiator of it's own. I say a few hp, maybe 5.. or if your battery was a crapper that you just put in, and was drawing a hell of a load trying to charge, maybe a little more.. (purely speculative on my part however)(also why hit the strip with a dead batt to start out with). On the issue of turning it off.. i would think that you'd have to switch off the output by putting a BIG relay on the large wire (8ga?) coming off. if it's not running into a load, there's only an inertial load on the motor of spinning it up and down, like a flywheel(only smaller). The other option would be to feed the signal wire a signal of higher than the voltage of the battery so it thinks it's fully charged. I think you'd have to rig up a regulated power supply that went to ac, then was transformed to a slightly higher ac voltage, rectivied to dc, capped so it would take the sine wave ripple out, and hopefully end up at 16 volts or so, so the alternator would think that it had no work to do.. I'd say, if you really want to do it, rig up a heavy duty realy or switch on the charge wire. As far as voltage for spark dropping, i could see that on a manually switched setup, where you have staging time that the ignition, fuel pump, and injectors draw from.. if you do a realy setup, there's no way 12 seconds(plus or minus 3) of draw on a healthy battery and an average car setup would draw you down to a poor spark level of voltage. The ls1 pcm even alters dwell, and injector pulsewidth if the batt voltage drops a little, to compensate. As my conclusion to this unfortunate thesis... don't bother. (IMHO)

 

The wire that you "break" is the small one (field). It is worth about .02 on a ten second car.

Daren

 

Going from belt to no belt at all on the dyno put 5 rwhp more out on my car. The only thing being driven is the alternator (manual rack & EWP).

I would not run a fuel injected car without the alternator, even for a pass. Your list from dragtrucks seems to focus on carb'd vehicles... which don't have much of an electrical system. Our cars are VERY dependent on electricity.

 

hey thanks alot everybody it didnt seem logical to gain so much power but now as everyone is saying i wont be doing it...thanks again

 

Take the belt off if you really want to stop turning things. You'll never break the "field" of an alternator, as far as I know, because the magnets and coils / stators / whatever are permanent ... aren't they?

 

Wicked,

You have a lot of experience with this?