[jlm69]

So I'm trying to narrow down on some things and one of them is whether or not I want to run an alternator.

The Car...1969 Firebird
The Engine ...RAV

The car will only be run on the track only. I'm still trying to finish up on the long block, so I haven't had it on a dyno yet. I'm assuming that the engine will cross the traps at a 7000 to 7500 RPM if not more.

I'll be running a vacuum pump just not sure which yet.

I'm looking for the pro's and con's of running the alternator and if I do run one which pulley's would be best to run so that I don't throw a belt??

Would running an underdrive or overdrive pulley be best.

I have a ATI damper on the crank now.

Looking to hear what the community is doing and thoughts on this.

[johnta1]

Running an electric water pump?
(I do and run the belt from relocated alternator to the crank pulley)

Use an under-driven pulley.
They made a bigger pulley aftermarket (Moroso?) It had deeper groove.
I find a smaller crank pulley that also helps the alternator RPM's.

I usually only charge the battery before race day and when done.

[25stevem]

If your do run a Alt you can wire in a cut out switch and charge the battery up some after a run while on the way back to the pits.
Also if your just in your pit spot already and checking timing you can have it charge then.

[Scott65]

I'd run an alternator. Do the math on the pulley sizing to keep the alternator below it's redline at max engine rpm.(usually <18000 on Delco stuff but find out for the one you use)

[Dragncar]

Originally Posted by 25stevem

If your do run a Alt you can wire in a cut out switch and charge the battery up some after a run while on the way back to the pits.
Also if your just in your pit spot already and checking timing you can have it charge then.

I did some testing on this. Made a run. Pulled the field wire and made another run and the times were the same.
But it was with a 36 amp alternator.

[Jack Ferris]

Always ran one. Fuel pumps, electric water pump, MSD ect all take some amps to run. And if you get into the late rounds, there's rarely any productive charging time.

[Half-Inch Stud]

How about running off of the drive shaft ?

[aaronman]

Both KRE and Butler sell the proper pulleys for an alternator in a drag race application. They are deep groove and if properly aligned you will not throw a belt. Most of the competitive bracket racers I know run alternators. If you are a heads up racer or on a budget then buy the best batteries you can and a good charger.

[Mike S]

I run an 63 amp alternator. I have the car on a trickle charger when I am not racing. I never have to charge it at the track. Ran with out and never see any difference in et. I ran the charge wire back to the battery so the kill switch would still shut the car off. I am using the stock crank pully and a deep alt. pully.

[jlm69]

I was asked about electrical items I was planning on using:

-QuickStar Maga Fuel Pump
-Meizer water pump
-MSD Power Grid
-O2 sensors
-Line- lock
-Car is wired for headlights, rear lights and markers for night runs, one interior L.E.D light
-guages with lights
-Switching for electrical componets with L.E.D lighting
-electrical activated shifter
-12 volt electrical fan in the interior
-Dual electrical radiator fans
-trans brake
-possibly NOS solenoids

[gman005]

I have run one for years. You don't want to miss a run because you are still charging your battery.

[25stevem]

A 36 amp Alt is plenty for a true race vehicle that you don't have a 2000 watt 4.1 stereo in along with a 3ft X 8" 2 farid capacitor in.

[Scott65]

Originally Posted by jlm69

I was asked about electrical items I was planning on using:

-QuickStar Maga Fuel Pump
-Meizer water pump
-MSD Power Grid
-O2 sensors
-Line- lock
-Car is wired for headlights, rear lights and markers for night runs, one interior L.E.D light
-guages with lights
-Switching for electrical componets with L.E.D lighting
-electrical activated shifter
-12 volt electrical fan in the interior
-Dual electrical radiator fans
-trans brake
-possibly NOS solenoids

I'd find the rated amp draw of those items (or check them yourself with an amp clamp). Then do the math. The big pulley will likely diminish the alternators output, especially at low speeds. Easier way: get an alternator that puts out twice what your current draw needs are. Then when you slow it down it should be fine. IMHO

[Half-Inch Stud]

I recently read that the late 60s 37A alternator put out a specified 6 amps at idle. 6 Amps is a number that sticks in your head.

I do remember my ole 68 LeMans (37A in an AC car?) would go dim to bright, when going off-idle.

[johnta1]

I do remember my ole 68 LeMans (37A in an AC car?) would go dim to bright, when going off-idle.

I'd say that is from the external regulator?

Use an internal regulated alternator. (less wiring also)

[Half-Inch Stud]

Yes, Ext Click Solenoid Regulator. That was 1981. Went to Int REG Alts on all my PMDs by 1986

[AG]

I use a 100 amp one-wire alternator with an oversized pulley for a 62 amp electrical load (Mark VIII fan pulls 44 amp).

[Scott65]

Originally Posted by AG

I use a 100 amp one-wire alternator with an oversized pulley for a 62 amp electrical load (Mark VIII fan pulls 44 amp).

Similarly, I went with a 150 amp, with a ~3 1/4" diameter pulley. I have to be more particular with idle amperage due to efi. This way the charge is great at idle and I don't worry about over speeding the alternator. (Which I have had happen in the past. Fiberglass hoods and exploding alternator fans are bad...)

[Dave Polichena]

Originally Posted by jlm69

I was asked about electrical items I was planning on using:

-QuickStar Maga Fuel Pump
-Meizer water pump
-MSD Power Grid
-O2 sensors
-Line- lock
-Car is wired for headlights, rear lights and markers for night runs, one interior L.E.D light
-guages with lights
-Switching for electrical componets with L.E.D lighting
-electrical activated shifter
-12 volt electrical fan in the interior
-Dual electrical radiator fans
-trans brake
-possibly NOS solenoids

If you be running all of that, you will need an alternator. I see at least 60 amps of draw there. If running 2 Deep Cycle batteries, you may get away without one in early rounds.
If you run 16 volt, get an Alternator! They don't have the Amp Hours or storage capacity of good 12 volt stuff and keeping them charged is mandatory.

[Probird]

It looks like I’m in the minority. I don’t run an alternator. There is usually plenty of time to charge batteries between rounds. When I did run an alternator with an oversized pulley it didn’t charge at idle, only going down the track and I needed to charge anyway. I rarely double enter but have and didn’t have any issues. I run a 16v battery. I have a small portable generator I can take to the lanes when at a track that runs round robin and want you to cool in the lanes. My brother runs an alternator and occasionally it will lose the belt. You know to look for the belt when his car picks up a tenth out of nowhere.