Help please!

[peterallen]

Hi everyone, I know I'm not the brightest spark and this instance proves the point. Can someone tell me what goes where when upgrading the TR5 to an 18acr alternator.  

All the information I can seem to find refers to changing from a dynamo, with a five contact control unit, or the '6' with a looped wire on the alternator and no control unit. 

Mine is as the good book shows , and is wired through a four contact control unit, I have an idea, but would feel happier if someone with more knowledge could supply a diagram or say what colour wire should go where. 

Thanks, and stay safe.

Pete.

 

 

 

[RobH]

As it is now:

 

As it needs to be:

 

 

Some users like to uprate the ammeter also, or replace it with a voltmeter.  

Edited November 25, 2020 by RobH

[John L]

Rob,  I have a CP with the 15AC alternator and the separate control box, I would like a bit more output, currently it has a 2 3/4" pulley, if I fitted the the 2.5" pulley, could this give me a slight increase in power out put, bearing in mind I'm not revving the that much and cruise a lot at 60/70mph.

This would be a much cheaper option and keeping the original parts, perhaps than changing to an ACR alternator?

John

[RobH]

A  smaller pulley won't really make any difference above about 3000 revs John but it should certainly help a bit at lower speeds, though you are still limited by the standard maximum output.   You are looking at a 10% speed increase so the charge you get at any given speed should be the same as you get now at 10% higher, i.e the output at 1000 rpm should be what you now get at 1100 with the bigger pulley.  That doesn't sound much but at very low speeds the output curve is rising steeply so it might represent as much as a 30% greater output. As the revs rise, the relative  gain tails off so by 3000 there may be  nothing more to come.  It's certainly worth a try though.  

The only concern is the alternator speed when the car is flat out. The Lucas alternators seem to be rated up to 15000 rpm (alternator speed). The standard pulley gives approx. 1.88 speed ratio so the max engine speed is 15000/1.88  or about 7900 revs.  The smaller pulley will lower that by 10% to just over 7000 rpm so you should still be fine.  

Edited November 25, 2020 by RobH

[peterallen]

Brilliant, exactly what I was hoping for, perhaps I'm not as dim as I thought as it confirms my thinking, but I'm always uncomfy with electrics, and it's reasuring to have the backup. Thanks Rob.

Stay safe everyone.

Pete.