Originally Posted by seth
You can try this:
Be careful though, I got this for my boat and the spacer that came with the kit was wrong! Spent a whole day burning belts and eventually took it into the shop and spent $100 for him to talk to PCM who couldn't figure it out either. I eventually sent it back. But everyone else who has put it on doesnt seem to have a problem.
Seth, if you have a 2 inch foot alternator than that 100 amp replacement should pop in with no spacers needed. It should line up just fine. The measurement from the front of the 2" foot to the middle of the belt should be the same as a Prestolite or smaller Delco.
To the OP, you aren't going to want to go more than 100 amps unless you want to spend serious dough. Your boat probably only uses a single 1/2" v belt. You will burn up belts like crazy if you go much bigger than 100 amps. Also consider that you will have to upgrade all your cable's to be able to handle the extra output.
If you want to do around 100 amps with an OEM quality unit you have a couple of options. One is the Delco 11SI. This is the unit that is pictured in the link. The OEM Delco unit is a 95 amp unit with a 2" foot. To upgrade to it you will need to add or increase the cable's some. It also requires a pigtail. The one I carry comes with a serpantine pulley. If you have a prestolite alternator now the pulley won't be able to swap over. I do have some single V pulleys that should work. This is a great unit and not too expensive at around $220.
Another option is to get a Prestolite(Motorola) 90 or 105 amp unit. Some of these require an adapter to fit in a 2" foot location but that isn't a big deal. They may or may not have to be wired slightly different depending on how yours is currently wired. These units have been around for a long time and are a very good inexpensive option. The 90 amp is about 200 and the 105 amp is about 230. Again you may need to upgrade your cables.
You can do what "G" has done and get a 200 amp balmar but after buying custom machined crank pulleys, upgrading cable, buying an external regulator you will probably spend over 2k and that is if you install it yourself. I am guessing you don't want to do this.
Your best bet if you want to get a good reliable system is buy one of the alternators I was talking about, upgrade your cables, add a voltage sensitive relay(assuming you don't already have one), buy new batteries that are suited to how you are going to use them and get an onboard charger.
If all you do is upgrade your alternator slightly and abuse the starting/charging system you are going to have problems and shorten the life of the batteries, alternator, starter and most other electronics.