Field wire turn off

[RJRENTON]

Well I have been able to feel some dragging when alt is providing power on a "high" load stage. 1HP per 50 amps? Hell I don't know. I think could be a bit more, but can't say it certainly. Instead of meaningless guessing, do the calculations and KNOW the results. Its not strictly amps to HP calcs, but includes rotational (frictional + windage) losses. Since there is USUALLY a common drive method (fan/water pump + alternator) each driven device losses must be factored separately and the redults added to determine total losses and includes belt losses

Net vs Gross power makes a big difference, sure not because just the alt, but adding water pump and... steering pump too? Dunno if we talk about cars without power steering. You're referring to just alternator losses. The other items mentioned, use different loss calculations. Pump losses vary as the square difference between RPMs from first poiht to last point of RPM scale used for evaluation.

Accuracy depends on calculations. Supposition depends on NOTHING. Best thing to do is engage brain b4 writing.....
BOB RENTON

 

[451Mopar]

The 1hp per 50 amps is actually if the alternator was about 100% efficient, more like 1 HP per 25 Amps with all the losses.
What I was trying to point out is the mechanical losses from the alternator cooling fan(s) and rotor windage likely produce more drag (maybe 5HP?) than the electrical load (maybe 2 HP?)
Need a dyno comparison of engine with alternator belt disconnected, then with the belt connected and no electrical load, and then again with a large (measurable) electrical load.
The mechanical losses should increase with RPM, and at higher RPM, the alternator should be slightly more efficient.
I think how we notice the alternator drag (or A/C Compressor) is when the load is applied at idle / low rpm where the engine is only making a few HP to balance out the engine/transmission losses to maintain idle speed. Add an additional 2 HP electrical load at low rpm (throttle blades mostly closed), and you notice the RPM dip.
If the throttle blades were WOT, engine accelerating, not sure the load would be noticeable to the driver? It is still a load so it should result in slightly slower performance, but I don't think it would be very much.

 

[69a100]

Don't delete!
We still need to know why you need more hp at the track!

So he can still be a loser at the track!!!!

 

[bearman]

Well went from asking about a alt switch to tic for tac and loosing at the track. Wonderful info thank you all for the different inputs. I won't be sending any updates on if it worked or not because to be truthful it really doesn't matter.

 

[Nacho-RT74]

out of topic:
definitelly frustrated Love... no doubts
sorry, I like women.

 

[kiwigtx]

Best thing to do is engage brain b4 writing.....

Accuracy depends on calculations. Supposition depends on NOTHING. Best thing to do is engage brain b4 writing.....
BOB RENTON

How about you try and work with Nacho on these problems, instead of always running his suggestions down?

Remember, English is not his first language....and he is trying to help people.