MSefi.com read only forum (Jan.15,2018)

anyone know if its common for people to have to upgrade the alternator when mega squirting?

Whitethunder wrote:anyone know if its common for people to have to upgrade the alternator when mega squirting?

I doubt there's ever been a car made with an alternator so small it couldn't cope with the extra current of the injection system. I suppose it's possible with some old cars fitted with a dynamo, though.

Had alternator / battery problems on a bike.
Bike was a carburated type , so it was never intended to run a fuelpomp and O2 sensor heating.
Replaced the headlight with a ledtype, now it seems fine.
Driving around with no lights is big no no on bikes.

PWM fuel pump control can be a major source of watts savings as well, especially since most commonly available in-line pumps are seriously oversized for most bikes.

Whitethunder wrote:anyone know if its common for people to have to upgrade the alternator when mega squirting?

For a factory EFI car, not unless you've put a bunch of other parts on there.

Cars that predate EFI sometimes had very marginal alternators. My Dart could have been ordered with a 23 amp alternator from the factory - barely enough to run everything on the car before EFI!

Matt Cramer wrote:

Whitethunder wrote:anyone know if its common for people to have to upgrade the alternator when mega squirting?

For a factory EFI car, not unless you've put a bunch of other parts on there.

Cars that predate EFI sometimes had very marginal alternators. My Dart could have been ordered with a 23 amp alternator from the factory - barely enough to run everything on the car before EFI!

Yehbut, it would still run the EFI ok until you switched on the headlights, etc.

Don't think even Joe Lucas ever made an alternator that small...

anyone know if its common for people to have to upgrade the alternator when mega squirting

Yes, I did. Special case though. Megasquirt is fitted to an old Nissan 4WD with a heavy duty winch. One day after a lot of heavy winching the voltage in the dual batteries dropped so low that it affected the ecu. The alternator could not keep up with the charging. Lots of leaning out and backfiring before I realised what the problem was.

I subsequently upgraded the batteries to AGM, the alternator to 140A, and fitted a third motorcycle AGM battery to feed ignition and ecu. This third battery although connected in parallel with the other two is prevented from backfeeding to them by a HD diode, so the megasquirt always has 13V+.

Have had no problems since.

Whitethunder wrote:anyone know if its common for people to have to upgrade the alternator when mega squirting?

Early alternators put out almost nothing at idle that 63amp alt may only make 15 or 20 at idle most GM,FORD,CHRY were all the same in that regard. Frequently engine speed had to be above 2500 to make even half it's peak rated output systems with external regulators were even worse. I can tell you a good solid power both (amps & volts) supply can cure a number of gremlins.
Years ago I was driving my 69 dodge Charger w/a 440 in it running an ACELL DFI6 TBI INJECTION SYSTEM using a combination of Holley/ ESM and GM PARTS/ 454 TBI.When the alternator began to fail the system struggled to keep running all the way down to about 10.5 volTs when it stumbled and died. The next day a reman alternator and an over night charge of the battery had me back on the road. I also let a friend upgrade my voltage regulator to the then relatively new electronic style did 0ne other thing bought an alternator for the m440 motor home chassis which comes with a smaller pulley to spin the alt faster more charging at the same engine speed the system ran noticable better after the charging system upgrades mild as they were.

up graded to a 140 amp alternator on a 79 Pontiac TA.
Of course will be running electric fuel pump and fans.