Running an alternator
 

Do you think running a alternator has any effect on consistency (charging rate changing while racing). Also how much Et do you think it takes if any just been thinking. I've run one for years just never done an A-B-A test with it.

Re: Running an alternator
 

Robbie, I think it is a good idea and provides consistent voltage. If you charge the battery as time allows the alternator load is small. In addition, use pulleys that limit the alternator speed to no more than about 20% overdrive.

Re: Running an alternator
 

Makes more difference with an EFI car. Voltage level effects how fast the injectors open. I found when my 12 volt batteries were a little low, my logger showed it running leaner. That, of course, effects consistency. I had a button under the accelerator pedal, hooked to a relay, that shut the alternator off @ WOT.
Going to two 16 volt batteries cured all that. With no alternator. Had to lean it down with 16 volts batteries. The injectors opened faster, of course.

Re: Running an alternator
 

I run a 16volt battery and the alternator is a16volt . I charge the battery between rounds also I have a 75% reduction pulley on the crank. Just been thinking about the possibility of consistency issues because the alternator may be changing charge rates while racing. Anyone ever trace a consistency issue to running an alternator? Thanks for the response's

Re: Running an alternator
 

I have never run an alternator. I also have a 16 v battery. I have a lithium battery. They are more stable with the voltage over the charging state. The race car does not run enough to charge the battery with the alternator so I don't see any reason to run one. You still have to charge the batteries between rounds so there is no advantage

Re: Running an alternator
 

My kid runs 12 volt stuff, bracket car, lights, dial boards, ect. He runs an alternator and very rarely charges his battery, lots of times double entering the car. So from my perspective I'd say they do a fair job of keeping up with the demand. Car prints tickets so I'd say an alternator does not cause inconsistent E.T.'s. Merely my observations.

Re: Running an alternator
 

Don't you have to run an alternator in Stk?

Re: Running an alternator
 

By NHRA Rules - you need an alternator in Stock -

Re: Running an alternator
 

Yes, it has to be in place, and turning with the engine ;-)

Re: Running an alternator
 

I've used Ed's idea with the micro switch. I also use it to un-ground the fan relay on the run. Not so much as a speed secret, but to keep the voltage consistent during the run.
Does it help? Can't say, but it can't hurt, as long as you charge between rounds.
We are talking about carb'ed combos here.

Re: Running an alternator
 

I have one of those.:)
Mike A114
P/SA

Re: Running an alternator
 

Back in the day we ran a alternator, under driven, charged up for Friday nite then ran Sat and Sunday, had no battery charger at track, 12 volt system. Never a problem starting or running. Let the fan motor run awhile, spray it down, set around waiting with no hassles for the next round, everyone else like ants on candy. Same procedure I'll use on the new car.
Might add, main purpose was to keep 13 volts to run the components not to keep battery charged, alt ran everything, not the bat. Bat just for starting.

Re: Running an alternator
 

Oh the good ole days....remember it well the springnats in Columbus ,Ohio...after rd 2 the techman checked all the winners for a functional working alternator....guess that was before the hollowed , stripped out alternators stated showing up....LOL.......

Re: Running an alternator
 

Thanks again for the response's. My concern is load on the alternator possibly changing during a run and the affect it would have (if any) on the run.

Re: Running an alternator
 

Isn't there a way to have an alternator configured for full charging at low rpms? According to a municipal mechanic, police and EMT vehicles charge 100% between idle and 2500 rpms. At those levels, much move effective charging in the staging and return lanes. Cut off switch for racing.Best of both worlds.

Re: Running an alternator
 

Years ago we calculated that an alternator consumed approx. 3 to 5 hp. I would kill the field wire with a switch before the run. The battery supplies power to all the electrical devices and the alt. replenishes voltage back to the battery. So, IMO, if you maintain your batt. voltage to the same level before each run and let the alt. do it's job, then basically your run charge cycle will always be the same and the variables don't change. So it should not make any difference on the et.

Re: Running an alternator
 

Yes that will work great.
An rpm window switch and a relay will turn the field off consistently every time too.

Re: Running an alternator
 

Imo if using 12 volt battery the loss of volts, during the run, will lose as much as an alternator using hp. 16 volt bat is another thing. With all the different electrical components on the cars today that bat will go down quick. An example, run a fuel pump at 12 volt than at 11 then 10, see how much it drops off. Now add the fans-computers-data loggers-ignition and other things, keeping 13-14 volts supplied the whole run is better and far out weighs the 2-5 hp loss (depending on how fast the alt turns at speed). Furthermore setting in the staging lane for hours makes it hard to recharge your battery. I for one will never run a car without an alt.

Re: Running an alternator
 

Robbie, not sure what type of alternator you're running but most of the one wire units are set up for a specific voltage and amperage target. With that one would assume the load being exerted by the alternator on the engine would remain fairly constant. As I stated about my sons bracket car (has a one wire alt.) there is no effect on E.T. with his set up Alt. is active at all times (not being shut off during the run) many runs per race. This is a big block combo so maybe that makes a difference of that I'm unsure.

Re: Running an alternator
 

All else being equal, an alternator is going to output somewhere between 13.7 and 14.2 volts on a 12 volt system, normally with a load and at idle. A well charged (100%) battery is right around 12.7 volts, so you get at least a 1 volt "boost" with the alternator running properly. It would be interesting to see what the effect of the load of a alternator would have on a vehicle with a fully-charged vs. under-charged battery. Could it be done on a dyno? From personal experience I've discovered that a one-wire unit needs to "spool-up" before it begins to charge, so it's either a small crank pulley or large one on the alternator, not BOTH!! :o

Re: Running an alternator
 

The load from an alternator occurs when there is a need for it. If you cool the car after a run without charging you are drawing from the battery. Then when you start the car and make a pass the alt is working to replenish what you drew out of the battery while cooling and to keep up with any draw while running. Better to charge while cooling and the load of the alt will be less and consistent.

Re: Running an alternator
 

Thanks again for all the response's. I was thinking of putting a RPM switch to trigger a relay in the alternator output to kill it during the run. I think when I get a chance I do a A-B-A test taking the belt off to see if there's anything to it. Thanks again

Re: Running an alternator
 

Robbie, I first put a universal starter button under my gas pedal, wired to a relay so it went open (off) when pressed. At WOT it opened the wire to the alternator. Worked fine.

Re: Running an alternator
 

Why even put an alternator on if you're not going to use It during the run? All the power drain occurs then. The only purpose of the battery, after installing an alternator, is to start the engine. The alt supplies ALL the voltage your componites require (at 14 volts not 12 or less), that extra voltage more than makes up for any HP loss that MIGHT occur.

Re: Running an alternator
 

Mine ran faster with it turned off during the run.
Even a little quicker with two 16 volt batteries, and no alternator.
Your results might vary. Don't know if you don't test.

Re: Running an alternator
 

I do it for consistency, not necessarily ET.
On my 2300 turbo, you could hear the idle pull down when you switched on the alternator.

The Monte has never had the alternator switched off. Not even on record passes.
It dials pretty well, and follows along with the big boys' ET's.
Of course, it has the stock computer (which Ed re-did for us), and also stock ignition.
Plus the trans doesn't use any juice either.
So, who knows, without a-b-a testing within a reasonable time frame?

Re: Running an alternator
 

The only advice I can give you is.....when they start hot lapping your AZZ, you will be a very happy racer IF you have a very Functional charging system. ........

Re: Running an alternator
 

I have no problem making three "hot laps" with two 16 volts.

Re: Running an alternator
 

I don't run an alternator. I have a 16 V battery. I ran 11 rounds at one of our Southern Stock Super Stock Assn races last year in one afternoon. 2 rounds of qualifying won the first race and lost 2nd round in the 2nd race. Battery was charged between rounds and I cool off with a separate battery.

Re: Running an alternator
 

Ed, my experience is limited to STOCK Eliminator with ONE 12 volt battery....I will HOT LAP with the best of them because......my charging system is top notch ....Remember , when you are hot lapping there is no time to visit the trailer and charge the battery....

Re: Running an alternator
 

I know what hot lapping is. Been doing this for about 50 years now. Mine is faster on 16 volts. I also test.

Re: Running an alternator
 

So....this should be your GOLDEN anniversary season,....Damn ...your old....LOL.......

Re: Running an alternator
 

Started in 1962. Back when we drove to the track, changed rear tires, and opened the "dumps". Be 74 next month.

Re: Running an alternator
 

The hot lapping Mr Derby City is talking about is called winning rounds late in the day. That is something most racers are never lucky enough to experience. If you have not experienced a late round push to get the racing over with for the day, then you do not know what real hot lapping is. Listen to his advice about running an alternator because he has been there and done that.

Re: Running an alternator
 

You don't think we know what that is?

Re: Running an alternator
 

Everyone knows what 3rd, 4th, 5th, or 6th round is but how many have been there and actually got to run that many rounds? Unless one has actually been there, they may not know what real hot lapping is.

Re: Running an alternator
 

Not saying that I'm any kind of a heavy hitter or anything , earlier this year I doubled up in a local Super pro and local S/ST event with my car that has no alternator but does have two battery's went 5 Rounds in Super pro and won in S/ST. There was only one class between the two classes ( motorcycle ) that was 4 time runs and total of 9 rounds that night. I would put a charger to the car when fueling but had no trouble cooling the car or starting . Towards the end of the evening I was having ( being a old guy) a little energy trouble as the gate time was 5pm and the final in S/ST staged a 2:30 in am..... LOL

The reason I have no alternator was that back when i ran with one third round of a team race the alternator split in half 600 ft out. When it did that it killed my MSD box so I was done that day and had $175 repair on the box. So I just mounted another battery out back and give up on the alternator. It kind of helped my 60 ft. removing weight off the front and putting 45 lbs in the rear..... That's my two cents....

Re: Running an alternator
 

Been there. No problem with two 16s.

Re: Running an alternator
 

I haven't bought any 16 volt batteries, but IMO, buying 2, plus the charger is a lot more $$ then one little Toyota junk yard Denso one wire alternator with a big pulley, thats maintenance free, and one less thing to worry about between rounds.
Mike

Re: Running an alternator
 

Around $1000 for two XS 16v batteries and a charger. $250 for a Powermaster Denso. I run a full size alternator and it killed all my charging issues. I bracket race and now means now.