Serpentine Belt advantages

[a64pilot]

To my knowledge Mark Grasser is the only one to supply an Overdrive kit if you will to speed up an alternator.
I have not seen his kit, but assume it ain’t cheap. I didn’t hear of it until after I had bought my Balmar kit, but I am of the opinion that there is goodness to be obtained by speeding up our alternators as I don’t think we ever get to their designed operating RPM.
http://markgrasser.com/products.htm#pulley_kits
They appear to be much more than the standard Balmar kit

[john61ct]

If you're doing a custom mod, selecting the right pulley size / ratios is a standard part of the process.

Not cheap, quality pulleys can cost more than the alt

but also not rocket science for the guys that do this stuff for a living.

[DougR]

Here is an alternator belt tensioner that will take away all the pain of skinned knuckles and bent screw drivers. It's easy to make or buy the few needed parts, and makes it a snap to create the proper belt tension. DougR

[darylat8750]

One thing I was surprised to learn is that there are several different v belt and pulley designs. There are different widths but also different angles to the grooves. I run a SI28 large frame alt with two 1/2" belts and have no noticeable dusting. The single belt on the old/small alternator made a mess with dust. I think the pulley on the alternator may have had a different angle spec. than the belt I was using.

A tensioner that uses a bolt or screw for holding the tension is "the cat's meow" and they are not difficult to make.

[deluxe68]

Originally Posted by rgleason

A64pilot and Bruce. Thanks. On this new Yanmar I am still working out the kinks re the alternator belt adjustment. It is a nice tight & solid 3.15" dual foot, but the space and tolerances around the alternator are tight, and the adjustment bracket gives only an inch or so of adjustment. I'm cutting down an expensive balmar adjustment bracket to fit, then the next problem is actually applying the tension required. There just aren't as many leverage points as my old westerbeke.and the last time I bent my screwdriver. I am going to try a pulley pusher device that a friend gave me, but fitting that looks a little tight too. I might have to make my own cheap verson of the "belt buddy".

I will definitely check the alignment as suggested. Maybe 65 amps V does not have to dust.

Do you look at engine specs to determine the required tension? Westerbeke just had the 1/4" belt diagram.

This you-tube video explains how you determine tension. The gauge in the video is about $25 and is the one I use.

https://m.youtube.com/watch?v=qP0iZAN0KHw

[Stu Jackson]

Originally Posted by rgleason

I've done some searches and have come up with this list, it would be helpful to get some confirmation on the advantages from actual users, qualitative as well as quantitative.

Serpentine belt advantages:

1. drives larger alternators easily
2. more efficient power transfer, less energy loss to belt.
3. uses less energy, more efficient, requires less HP
4. less belt tension required, better for bearings on engine and alt
5. belt tension is not as big an issue as V.
6. less slippage, less heat
7. less dust
8. quieter

Serpentine is not necessary for up to 100 amp alternators.

rg,


I think the use of an external regulator, using either Amp/Belt Manager and/or Small Engine Mode "allows" the use of a 3/8" pulley and UP TO a 100A alternator.


Funny, that's just what I have...


But read Maine Sail, as I know you have, but many haven't.


I use Small Engine Mode with a toggle switch. I've written about it here quite often. Do a search on SEM with my name.


Fingers too tired for retyping.

[john61ct]

Ignore the max rating of the alt.

What counts is the actual output demanded for long stretches at a time.

A 100A alt only outting out 50A continuous does not require a fancy belt.

Same as a 200A alt derated by a good VR to 60, maybe 80 or even (some say, I'm sceptical, maybe some ideal setups) 100A.

But personally, if I was looking for even 60-80A actual continuous output, and was doing custom mounting etc work anyway, I'd put in serpentine while I was at it.

[Rotten Ricky]

Originally Posted by john61ct

If you're doing a custom mod, selecting the right pulley size / ratios is a standard part of the process.

Not cheap, quality pulleys can cost more than the alt

but also not rocket science for the guys that do this stuff for a living.

True, but I would have thought that at least if my new engine did not come already fitted with a larger, more appropriate driving sheave, at very small cost, then surely I could order one? No such luck. Unless someone can tell me where I can get a larger Universal or Kubota sheave, I will have to use a commercially made kit or have a sheave specially machined for me, or make my own. In the end, and being as i am handy with a lathe, I figured that I could leave everything in place, and just make my own slip-over sheave that would bolt yo the front face of the original, and will raise the diameter from 4" to close to 6" so my alternator should spin a lot faster.

Regarding using a straight-edge to check alignment of sheaves and belts. be aware that different sheaves can vary a lot as to how much distance there is between the edge of the edge of the belt and the edge of the sheave - and they may not be accurate! This will obviously make your straight-edge inaccurate unless compensated.

When I started measuring up the 6 alternator sheaves I had obtained to make my own sheave, and contrary to my expectations, the accuracy of some of those factory-made sheaves was surprisingly poor, and I am counting on mine to be a lot better!

Cheers, RR.