Re: Improved 24v alternator pulleys and turbo heat shield
Hi Alain,toggle quoted messageShow quoted text
This is copied from my email to the forum back 2020.
I found on eBay Leece-Neville part number K176101466, priced $30. This is a K section 8 groove pulley with 63mm diameter. The bore is 7/8 inch with keyway to fit the alternator. The pulley was new and unused.
Micro v belts can go round much smaller pulleys. I think for the K section it is a minimum of 45mm. So no problem going round a 63mm pulley.
I then took the original 230mm double groove pulley, that bolts to the Volvo crankshaft to my local machine shop in the UK who milled it down to match the Leece-Neville one I bought. He did a superb job for £60.
Please see the photos of the big pulley that has been machined down from 230mm to 200mm.
So I calculate that I now have a pulley ratio of 3.14 whilst before it was 2.7. Thus at idle (725 rpm on the engine) the alternator now runs at 2300 rpm and will be charging nicely. Where as before in idle it was running at 1957 rpm. The alternator only kicks in at 2000 rpm. So in the boat manoeuvring situation we will now have proper charge, and we all know how much power the Bowthruster uses.
The alternator is rated for a maximum RPM of 8000. The Volvo D3 has maximum rpm of about 2700 so I calculate that the maximum engine rpm will have to be 2547.
Seeing as that is really thrashing the engine and I never run it it that level apart from the once a year blast out. I will put a small sticker at the helm saying Max RPM 2500.
Total cost in US$ including new Gates Fleetrunner belt about $125.
Obviously when I get back to the boat I will have to align the alternator, but note how now both pulley are exactly the same width. It will be much easier than before where one pulley was 47mm and the other 52mm. The machine shop supplied me with a few spacers, washers of different thickness, to help but I may well have to have a washer made for the final alignment.
So now that I have it fitted I can report that it works well. The only thing is that small pulley required a small spacer about 5mm for the nut to clamp it to the fan.
I also report that the belt that I am using fits nicely Gates FleetRunner Micro V 8PK1255HD