Curious...how many racers run an alternator?

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flyfish

flyfish

C8H18+N2O = :-D
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Just curious to see...any major draw backs to not running one other than the obvious need to charge between rounds? I know a lot of guys that run an alt and charge between rounds as well...

Main reason for this question is last week I was running a 10.5 index race and spun my alternator belt off. I was able to put it back on, but since it threw it once it would not stay on....so I just pulled it off and ran the car...and the car picked up a tenth in the 1/4 mile. Kinda fun, because I had a new best for the lousy density altitude (3400' and humid).
 
If I was bracket racing I’d run an alternator. Especially when you start hot lapping. And, regardless of what the all the ignition manufacturers say, a drop in voltage is a power loss.
 
yellow rose said:
If I was bracket racing I’d run an alternator. Especially when you start hot lapping. And, regardless of what the all the ignition manufacturers say, a drop in voltage is a power loss.
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Yes to running an alternator ! For years I fought electrical problems including not charging sometimes having to charge between rounds. Over this past Winter my car was rewired finally after 37 years. Everything works great now except on the first outing it wasn't charging properly , turns out the Advance Auto parts alternator wasn't putting out enough voltage ( third time this has happened ) I swapped to a Powermaster one wire alternator and the car now charges and runs at 14 volts , perfect and no need for between run charging and the worry of not starting. The only time I charge the battery is when the car is home for an extended period of time its put on a Battery Tender
 
At various times i have pulled the alt belt off to try and gain a little ET
Mainly on a car i used to own running 10 flat index on really hot days where i couldnt quite get to the number. Think i did it twice
Never saw anything just pulling that belt off.
Did the same on my little 11 sec 318, saw nothing.
Have seen a tenth going to electric fan and water pump on two different cars, from stock setup.
Seen a few hundreds getting rid of power steering pump too.
 
I’ve run a single wire Chevy alternator I picked up off a table at Norwalk for years. I will never race a car without one again. I charge my battery about once a month if I remember.
 
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I run a single field Mopare alternator turned around since I run a motor plate. I have a cut out switch that I flip off when I start my burn out, when I make the turn out, I flip it back on to charge on the return road. This has worked well for me for 11 years & counting.
 
Demonracer said:
I run a single field Mopare alternator turned around since I run a motor plate. I have a cut out switch that I flip off when I start my burn out, when I make the turn out, I flip it back on to charge on the return road. This has worked well for me for 11 years & counting.
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I always wondered about that (switch on the field wire). Does it give a small bump in ET like not running a belt?
 
Was your belt driving the water pump too? The little bit of research I did says 1hp/25amps out of the alternator. So, four lousy hp if the alternator is actually putting out 100 amps, and even if it was, It wouldn't last long.
I think your tenth improvement came from something else.
 
I have a Moroso electric water pump, my alternator is driven off of the lower pulley only with a 5" pulley on the alternator. Fortunately, I've never had a problem with the belt coming off as I run a narrow belt that sits deep in the pulleys.
 
There is no noticeable difference at all in ET, it's just less chance of any parasitic drain, of over revving the alternator under load.
 
That big pulley on your alternator means you are turning it slower than most, so the horsepower required to turn it should be even less.
(Unless the bearings are complete garbage. That could also be the cause of the belt throwing)
 
You can think about this with an easy 10:1 ratio. The system should run at 13.5--14V charging. The battery is less than 12 with a load on running

Imagine this in terms of 120VAC. If your appliances were down to 100V or less they would not perform very well.

In other words a 2V change in a 12V system is as bad as a 20V change in your 120V system
 
Run a single wire and use a "normally on solenoid" to shut it off in the water box. Charging the battery at RPM's throw the belt. If you ever throw a belt, Throw it out its junk after that. Always ran an alternator. Optima battery flip the switch and listen to the radio on the return lane "Radar Love". Never charged the battery ever! Race cars had to be driven to the money races. Trophies didn't pay the bills. The streets did.



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33IMP said:
Was your belt driving the water pump too? The little bit of research I did says 1hp/25amps out of the alternator. So, four lousy hp if the alternator is actually putting out 100 amps, and even if it was, It wouldn't last long.
I think your tenth improvement came from something else.
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No belt on the water pump (electric Moroso drive unit). I know my car quite well, and it normally does a 48 (10.48) in 3400' air...and I have done the with/without thing a few times and on my car it really is a tenth (10.38 no belt). Your results may vary, this is what it does on my car (maybe my alternator has a lot of drag, idk).

The car ran really consistent without the belt, but it is a little bit of a pain to charge it. Mainly curious of how many use/don't use and alt.
 
33IMP said:
Was your belt driving the water pump too? The little bit of research I did says 1hp/25amps out of the alternator. So, four lousy hp if the alternator is actually putting out 100 amps, and even if it was, It wouldn't last long.
I think your tenth improvement came from something else.
Click to expand...

An electrical hp is roughly 750W, roughly, 750/14 is about 50A but an alternator is maybe 50% efficient, so yeh, 25A / HP is fairly accurate I'd guess
 
I'm a dirt track guy and haven't seen an alternator on a dirt car for 40 years.

We do charge the battery in the pits and some guys run a 16V battery these days.
 
3 cars have powermaster one wire alternators.....75 duster has stock mopar alternator with regulator...
Using moroso underdrive crank pulley to turn alternator only.....moroso electric water pump...
 
Demonracer said:
I run a single field Mopare alternator turned around since I run a motor plate. I have a cut out switch that I flip off when I start my burn out, when I make the turn out, I flip it back on to charge on the return road. This has worked well for me for 11 years & counting.
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If I remember correctly, if the car is running and the field in the alternator has voltage to it, just switching off that power does not stop the alternator from charging. I think once the field is excited by voltage and the alternator spinning it will produce its own voltage to excite the field.
 
That being said I just tested this. I ran a gutted alternator. Pressed off everything but the fan and put it back together. No change in et. I have picked up 2/10’s when it threw both the power steering and water pump belts about 10 ft out, but no more power steering and no gain from removing alternator. Especially compared to the low voltage/having to charge the battery hassle.
 
If you guys are seeing .10 change in ET from an alternator either you have the wrong one or something is wrong. I’ll take the extra voltage my alternator gives me any day of the week being a bracket racer.
 
Yeah, I just have a stock replacement Autozone alternator...gotta a lifetime guarantee on it back in 1993...probably have replaced it 4 times over the last 27 years, lol.

Sounds like everyone runs one, cool beans. I always have as well, so I guess I'll save the "remove the belt" trick for in case I'm throwing the kitchen sink at it on a cool TNT night with a 30mph tail wind going for a 9 second time slip :-D
 
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