My engine builder installed a pretty nice 55 amp unit marked ND50. I am not sure that is big enough. I know it was pretty pricey but with AC, MSD, and Fans I am not sure it can keep up. Any thoughts?
Alternator size?
- Thread starter Dlampe
- Start date
Ron Earp
Admin
AC is about what, 10 amps tops? MSD is about 1 amp per 1000 RPM from their data and what I've measured as well. Depending on the fan probably 7-9 amps each. So you have maybe a 40 amp draw in the worst case at max RPM with AC on and assuming some other stuff on like lights. I'd think you'd be okay.
R
R
Alex Hirsbrunner
Lifetime Supporter
I agree, I think the only benefit from a larger alt will be quicker reserve capacity recovery after starting.
Al
Al
Ian Anderson
Lifetime Supporter
Also need to allow for Electric fuel pumps - amazing current draw on some - especially if running EFi
Ian
Ian
Dean,
Bill D. is on the right path. A marginal alternator is second best. With an alternator that is just enough, you will wear out batteries and alternators.
Add up all the amperage requirements of your harness, then add 30% to top the battery.
Its always better to bring a gun to a knife fight!
Cheers,
S
Bill D. is on the right path. A marginal alternator is second best. With an alternator that is just enough, you will wear out batteries and alternators.
Add up all the amperage requirements of your harness, then add 30% to top the battery.
Its always better to bring a gun to a knife fight!
Cheers,
S
Lights, dual fans, a/c, fuel pump, ignition, wiper can easily consume that alternator. Also, consider the impact of counter EMF on start up of electric motors, particularly dual fans. You are better off with at least 100 amp alternator in my opinion for long term reliability. I run 140 amp in my coupe and have the same one wire set up on my GT40 engine.
You will easily need a 100 amp alternator, at idle w/ AC, rad fans, inside fan, any lighting, elecric fuel pumps etc, your battery voltage can easily drop into the 10V range and most ignition systems are not happy there, definetly not good for fuel injection. Everything runs slower.
Summit sells single wire alternators that will work just fine.
If you don't have aircond you can go to pic a part and get an alternator from a 86-89 Mazda RX7, it is only 65 amps but will put out at idle and take very high RPM. The last one I got for a Tiger cost $20.00.
IMHO
Summit sells single wire alternators that will work just fine.
If you don't have aircond you can go to pic a part and get an alternator from a 86-89 Mazda RX7, it is only 65 amps but will put out at idle and take very high RPM. The last one I got for a Tiger cost $20.00.
IMHO
