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Author Topic:   Need input on alternater Idea
02 Blewbyu
Dirt Full Roller

Total posts: 48
posted April 21, 2005 12:29 AM  
I was thinking about installing a toggle switch inline with my alternater hot wire. I run 2 electric fans for the radiator and 1 fan on my oil cooler. I have heard that it takes about 8 horsepower when the alternater is working. The cool part is in the class I run in we are required to have a passenger so all the guages and switches are monitored and operated by the passenger. Is this a good idea or not?

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Stomp and steer racing

Steve Dupree
Dirt Freak

Total posts: 316
posted April 21, 2005 04:30 AM  
Hey there well we use to run a alternater and i think it is more like 25 horse power. We can really tell a difference sense we pulled ares,But in your case i might run one if i had all those fans in there. Maybe set up a switch to turn it on only when you are not racing.

Rookieracer76
Dirt Freak

Total posts: 289
posted April 21, 2005 05:24 AM  
there was a circle track issue awhile back and it talked about ignitions and altenators and they said an alt. robs less then 1 horse power so i dont know how you came up with 25??

rico 08
Dirt Forum Champ
Total posts: 1139
posted April 21, 2005 06:09 AM  
I was thinking about running a switch on the throttle for the field wire...
when you are in the gas the alternator just idles but when you let off for the corner it starts charging..just a thought

MetricMonte
Dirt Maniac

Total posts: 111
posted April 21, 2005 07:46 AM  
quote:
Originally posted by Rookieracer76:
there was a circle track issue awhile back and it talked about ignitions and altenators and they said an alt. robs less then 1 horse power so i dont know how you came up with 25??


Seems like I have heard that also...

Racer0
Dirt Maniac

Total posts: 149
posted April 21, 2005 07:53 AM  
I have a switch on mine and it works well. I have actually seen a 300 rpm increase when running without it. I leave it on while warming up and pack the track. ect... then shut it off while racing.
Putting a switch on the throttle might be a bit of over engineering imo.

02 Blewbyu
Dirt Full Roller

Total posts: 48
posted April 21, 2005 10:35 AM  
Thanks for all the imput. I think I will throw a switch inline so I can turn it off while racing

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Stomp and steer racing

M1
Dirt Freak

Total posts: 257
posted April 21, 2005 10:58 AM  
dont forget it on (the switch), or you will burn the alternator up....

340duster
Dirt Maniac

Total posts: 195
posted April 21, 2005 12:11 PM  
If you are running electric fans I would definitely leave the alternator on all the time. Because if you forget to flip the switch on during a long race with lots of cautions, the fans may take enough power away fom the battery to effect your ignition, or if you get in a wreck and stall it it will make it harder to start with lower battery voltage.

The alternator will use 1hp at full output (stone dead battery), much less when the vehicle is operating. When racing it will only draw what is being used in your system (ignition and fans).

To calculated the draw:

power = voltage X Current

So if you have a 12V system and a 60 amp alternator (12x60=720 watts) you get 720 watts.
there are 746 watts in one HP so it is roughly a 1hp loss.

But with all fans running and your ignition system it would likely use about 15 amps,

15ampx12Volts = 180 watts, which is about 1/4 HP


Steve Dupree
Dirt Freak

Total posts: 316
posted April 22, 2005 04:53 AM  
Ok well thats the best one horse power i ever got lol. You ever hooked up jumper cables to jump a car listen to motor or onse you get your car started listen to the belt sqeel even though it is tight. We gained 400 rpms with alt off and yes it was a good alt and acually was a low amp to boot. Well i think the switch is a good idea for that extra 1 horse power lol " Live and learn but dont spin em in the turn "

340duster
Dirt Maniac

Total posts: 195
posted April 22, 2005 10:40 AM  
When the car is idling, the horse power output is low, so the draw will seem significant. Ever try and dyno an engine at idle? When the engine is cranking out 400HP at full throttle it won't be an issue

teenwolfnorcator
Dirt Roller

Total posts: 21
posted April 23, 2005 08:03 PM  
i run an alt. on my 350's, with tranny cooler, seems to work good for me, but i have the big pulley so it doesn't start to charging till 3000 or 3500 rpm seems to work good, helps keep belts on also

redneck racing
Dirt Forum Champ
Total posts: 860
posted April 24, 2005 11:19 AM  
I have never ran an alternator on my car because of the loss in horse power, or so they say, was thinking about one off of a geo metro because they are small and have also thought about running it off the rear end. Eddie

02 Blewbyu
Dirt Full Roller

Total posts: 48
posted April 24, 2005 11:32 AM  
I never thought of running a geo alt. sounds like that might be a good idea if its not to much work to mount it and get the pullys lined up.

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Stomp and steer racing

Busch
Dirt Full Roller

Total posts: 46
posted April 24, 2005 06:22 PM  
We have ran an alternator for nine out of eleven seasons of racing and they are definately worth the cost of a couple of HP.

zeroracing
Dirt Forum Champ
Total posts: 1875
posted April 24, 2005 07:13 PM  
we are going to put an alernator on my mod, with a battery i can turn about 7800 no prob, but with an alternator i can turn about 9000 with a clean fire all night.
even if i am not turnign the 9000 the alt. will help to make sure at 7250 it is a full spark and not a weak battery trying to fire it.

jercer2004
Dirt Roller

Total posts: 12
posted April 24, 2005 07:31 PM  
East Coast Electric makes a racing alternator , its like $350 with all the brackets . And when we dyno'd our engine we did the 1st few pulls without it on and then hooked it up for the rest off the pulls and we seen no horsepower loss !!!! It's definately worth it , and in your case it's really worth it. Good luck !!!

redneck racing
Dirt Forum Champ
Total posts: 860
posted April 25, 2005 01:14 AM  
The Geo alternator will work, I put one on my buddies car to test it out, just had to fab the brackets hence my idea of running it off the rear end. Eddie

340duster
Dirt Maniac

Total posts: 195
posted April 26, 2005 11:46 AM  
jercer2004 - was the alternator charging a battery or running the ignition? If the belt was hooked up and no wires the horsepower loss would be near zero.

02 Blewbyu
Dirt Full Roller

Total posts: 48
posted April 26, 2005 03:55 PM  
I agree with you duster.

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Stomp and steer racing

jercer2004
Dirt Roller

Total posts: 12
posted April 26, 2005 04:41 PM  
It was hooked up properly.

97dirt
Dirt Forum Racer

Total posts: 94
posted April 26, 2005 05:04 PM  
been running alt. for 10 yrs. never had problems,have tried running without one,motor would bust up around 7300

340duster
Dirt Maniac

Total posts: 195
posted April 28, 2005 11:49 AM  
I'd be worried about running it off the rear end on dirt. You would have to build a good gurad etc to keep the mud out.

We had one of the top imca mod drivers up here doing a seminar, he was asked to look at a limited late model stock car and give suggestions/improvemnts that could be made to the car. We opened the hood, he pointed at the alternator and the first thing he said was "what is that for?". He said get a good battery charge after each night a toss the alternator, he runs his without an alt on 100 lappers no problem.

As well on my current car I had installed a fuse in the alternator wire. The fuse blew and it took me three race nights before I noticed it, the starter was slowing down. The reason I knew when it blew is I had accidentaly shorted the wire, but didn't check it at that time.

02 Blewbyu
Dirt Full Roller

Total posts: 48
posted April 28, 2005 03:57 PM  
Im sitting here after a long hard day at work wondering what I started with this post. I didnt used to get much email but now every time I look I have a something from here. Anyways thanks for all the opinions and knowledge

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Stomp and steer racing

gahainsey
Dirt Maniac

Total posts: 113
posted April 29, 2005 08:53 AM  
As I have said before: If MSD sold it as an engine driven ignition amplifier, alternators would be the trickest part going. Voltage to the distributor is increased 20 percent PLUS it is constant. All for a paltry 1 HP investment. Examples: 400 horsepower 3200 pound car equals 8 pounds per horsepower. 399 horsepower same car 8.02005 pounds per horsepower. 3240 pounds (with mud), 400 hp equals 8.12 pounds per horsepower. A gallon of mudd off is a better speed secret than removing the alternator!! The same guy who says an alternator costs power is the guy running with no collector extensions and 1 7/8 tubes on a 350 hp motor. Now THAT will drain 25 horses!!!!!

WesternAuto17
Dirt Forum Champ
Total posts: 569
posted April 29, 2005 11:54 AM  
Here's an idea - wire the alternator output on a normally closed relay. Than wire the relay to an rpm activated switch which opens the relay only when rpm's exceed 3500 (ie - when you are racing). Now everyone is happy, it automatically takes the alternator out when you need the horsepower (be that 1/1000 or 25) that it saps off most.

I run the alternator all the time, but if I didn't, that's how i would set the system up.

Now let's discuss the pros and cons of nylon brake lines.........

outlaw#03
Dirt Roller

Total posts: 25
posted May 05, 2005 11:59 AM  
I've always run an alternator. An HEI ignition (which I'm sure most of us run) requites 14.4 volts to run properly, which just so happens to be what an alternator puts out. A fully charged battery will put out almost 14 volts but starts dropping pretty quick, now that 55,000 volt coil you spent good money on is not getting the input voltage it needs so there for will not put out what it should be. I would compare it to running 5/16" fuel line and complaining your high volume fuel pump keeps running out of fuel high RPM. The mod and Late model guys can run an MSD box to boost the out put voltage and they do not require the 14.4 in put voltage like an HEI, If I'm not mistaken there designed to run on 12 input volts.

Pickel
Dirt Forum Champ
Total posts: 784
posted May 06, 2005 08:00 PM  
Ran an alt for years...the positives far outweigh the negitives.

    

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