Thread: Alt. or Just Battery?

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I've got a mudd racer truck that's about ready and was wanting too know is everybody running just battery's or alt? Was wanting to run one battery for the ign and one for the other electrical stuff.

We run an air cooled drag car. It has an MDS 6AL ignition system, a MSD ignition retard box, two electric "squiral cage" cooling fans, three nitrous soleniods, as well as the engine starter.

We also tow the car back from the end of the track. We run the two electric fans to cool the heads down while we are towing the car back to the pits. We use the tow truck's "trailer terminal" on the seven way trailer plug to charge the race car's battery while it's on the tow strap. This allows us to go rounds with the V8 guys when they start "hot lapping" us during eliminations.

Racing this system over time, we have found no measureable performance drop when running a small Nippendenso alternator. I believe the horsepower lost in driving this accessory is more than made up in the performance gained with a hotter spark. The MSD system is a heavy draw. My vote would be run the alternator.

Thank's guy's my engine builder is a drag racer also and he suggest the same as you guy's, just don't have much run up front and will have to fab some kind of bracket to put where it needs to be.

Post some pics of the truck. I'm more into rocks but I still like to watch mud racing.

There was just an article on this subject in one of the magazines I was reading. Bottom line was that the increase in HP was so negligable that it made no measurable difference in the times turned, and as John mentioned, the added voltage really helps out the cooling and spark.

Don

One of my other friends is a big time drag racer and he runs two batteries all hooked together +to+ -to- and he has never had any problems. He told me that way he had alot of stored power in the back of his roadster, custom made cables that hook them together. Just got home for the weekend and will look tomorrow too see if I got any room up front for a alt bracket.

I'm running a 60A alternator with an over-sized pulley. I do believe it is more reliable to have alternator especially if you get into situation where you don't have time to recharge between rounds. However, I do not agree that there is no "significant" power to be had.

I found out (accidentally) that I can pick up over a tenth when the field wire is unplugged (external regulator). I wired in a relay to cut out the field wire and consistently saw about a tenth faster ET. I have not done this for a while because this will cause big voltage spikes when you cut it back in and I had lost an ignition box in this time frame (maybe coincidence, maybe not).

Anyway, this works out to be about 10HP gain for my vehicle with alternator field wire disconnected. Mind you there will be more to be had taking alternator out altogether without the mechanical load on the belt. I know many who would go to great lengths to find 10HP but I will not ditch my alternator because it is hard to power a race car (ignition, fans, fuel pump, maybe water pump) from battery alone without considerable charging between rounds.

two cents,

-Chris

Like I said I'll check tomorrow to see how much room I have up front for a alt, I'll be running electric water pump, fan, fuel pump.

10-4 it's all good. Talked to my friend today that has the roadster and he said he was going to put a alt on his along with the two batteries, he said when they really get into it he don't want to have to worry about power issues. Ran into a problem with mine today with space I'm going to have to pull the radiator back out just to get a socket on the crank bolt so I can turn the engine over to time it for the dist.

I've watched a lot of guys on Pinks All Out who get into the finals and then run into a problem with their batteries getting too low to either crank the car or run the MSD box. They apparently are running their electric fans between rounds, trying to cool it down, and drain the battery.

I've always said that if I built a car for Pinks I would run a 4 D or 8 D battery (Diesel truck/marine stuff) and then have a second group 27 as a back up, on a selector switch. Lots of reserve amperage in those, and the weight could be helpful in the back for traction.

Don

Originally Posted by skids72

I'm running a 60A alternator with an over-sized pulley. I do believe it is more reliable to have alternator especially if you get into situation where you don't have time to recharge between rounds. However, I do not agree that there is no "significant" power to be had.

I found out (accidentally) that I can pick up over a tenth when the field wire is unplugged (external regulator). I wired in a relay to cut out the field wire and consistently saw about a tenth faster ET. I have not done this for a while because this will cause big voltage spikes when you cut it back in and I had lost an ignition box in this time frame (maybe coincidence, maybe not).

Anyway, this works out to be about 10HP gain for my vehicle with alternator field wire disconnected. Mind you there will be more to be had taking alternator out altogether without the mechanical load on the belt. I know many who would go to great lengths to find 10HP but I will not ditch my alternator because it is hard to power a race car (ignition, fans, fuel pump, maybe water pump) from battery alone without considerable charging between rounds.

two cents,

-Chris

--and I never hit the switch unless I'm out on the other lane, at about the 1000 foot mark it will give a few hundredths cushion on my dial in...Hey, had to do something when the starters got so dang nasty about deep staging!!!! the left front has about 3/4" lead, must have been an engineering error!!!! Honest!!!!

Did you go to a 16V battery with the dual connections yet Chris????

Hey, Dave - still just 12V optima red-top. Thinking of switching to yellow-top for next year. I've pondered ways to use the alt switch to advantage in "fender racing" situations but haven't really messed with it due to risk of voltage/current spikes. If I get motivated I'll come up with an electrical choke/filter arrangement for that. Would be nice to have an "add horsepower now" button in some situations. A racer here in 14s Vega wagon has N2O system he uses only when someone puts a fender on him early... give away the stripe and push the other guy out

Who would want to stage deep? An extra 3/4 - 1" of roll-out is a good thing! Longer head start and harder to go red so long as you hit the tree right. Pro tree maybe another story.... or 19s truck (leave on the 2nd amber )

Originally Posted by skids72

Hey, Dave - still just 12V optima red-top. Thinking of switching to yellow-top for next year. I've pondered ways to use the alt switch to advantage in "fender racing" situations but haven't really messed with it due to risk of voltage/current spikes. If I get motivated I'll come up with an electrical choke/filter arrangement for that. Would be nice to have an "add horsepower now" button in some situations. A racer here in 14s Vega wagon has N2O system he uses only when someone puts a fender on him early... give away the stripe and push the other guy out

Who would want to stage deep? An extra 3/4 - 1" of roll-out is a good thing! Longer head start and harder to go red so long as you hit the tree right. Pro tree maybe another story.... or 19s truck (leave on the 2nd amber )

Ooops, you don't run a Pro Tree, forgot... When you get old and slow on a Pro Tree the deep stage thing sometimes equalizes things with the young-uns!!!! Deep stage almost by accident the first couple times, then kept doing it...too old and slow to go red maybe??? Probably going back to the long tree next year, might do some nostalgia running... Haven't had problems with a voltage spike---yet...hadn't even thought about what could happen to the electronics if it did spike... Haven't done the switch to 16v yet either, wanting to talk to some who run it.

Yeah, you super-streeters and stockers need all the help you can get Not sure that I have had problems with electrical spikes but makes sense that they should be there. The fact I had an MSD box go south was enough for me to shy away from it... any spikes like that could be mitigated with a PI filter or some similar arrangement... maybe just a big filter cap... at the same time you don't want to starve the ignition of the instantaneous current it needs so any choke needs to be chosen/placed carefully.

Didn't know you had a similar arrangement to cut out the alternator. Did you do it the same way with relay on field wire or something different? As for 16V, that will be an investment and weight adder... the battery is one thing but then you need to add a bunch of extra wiring and/or step down converter... I like to use 00 welding cable from the back to the front so doubling that probably an extra 20lbs at least. Then you need a new battery charger and/or alternator and that can get spendy real quick. I don't personally know anyone that is running 16V but I'm sure some of the super pro guys are. If "most" everything can run at 16-18V then just a small step down box for the stuff that can't handle it (like tachs, gauges, ignition box, etc).

I know a few here that are running two 12V batteries with an isolator such that one is only used for the starter but both get charged by the alternator.

Sorry for the hijack, streak! I'll crawl back under my rock now

-Chris

Yeah, same setup on the alternator. Just a single wire alternator on the drag cars so no big deal to hook up.... Got to look into the filter thing for the alternator, haven't fried anything yet but maybe I've just been lucky...

Ok Streak, we're done now. Sorry about the hijack.....