Thread: Routing v-belts for onboard air

Originally Posted by mike_ie

Set the problem aside for today, to concentrate on the more basic task of adding all the bits to actually get the engine running. Main reason I was nutting this out was to figure out the final position of the alternator so I could make up oil lines to suit.

I've come back to it tonight to pass the time, and while the setups that I have seen had the A/C compressor slung underneath the alternator, according to this pic the 4BD1T at least comes in a variation where the alternator sits midway up the engine, and the A/C compressor on top again....



First off, it answers the question re. acceptable belt contact area - the fan pulley and the alternator couldn't be getting more than 50 degrees contact... second, it may be possible to squeeze a second compressor under the alternator....

To me that pic looks like there is a dual row pulley on the alternator, and the compressor is run off a second belt, therefore your theories on belt contact area don't apply.
I'd guess the alternator is in/near the position of a Stage1 4bd1 alternator (which is the lower of the 2 types of mount brackets in truck terms).

Lengthwise clearance to the engine mount was the issue when I was looking at mounting a compressor down low, but a shorter compressor might be an option to get around that (if they exist).

Not sure if its already been suggested:
- put the alternator in roughly the standard (center) position, and run it and the water pump off the standard belt.
- Run the lower compressor off the second row in the crank pulley
- Run the second compressor (above alternator) off the alternator using a short belt and double row pulley on alternator.

As I see it, advantages are that you'd probably be able to stick with the standard belt (and its a heavy B section belt) for alternator/water pump which is your critical one, and the other 2 belts are relatively short and easy to work with, ie not having to get one run to avoid multiple touch points on longer runs.
Lower compressor will also be slightly further forward than the main crank belt (to pick up the next row forward on crank) and therefore give you a bit more clearance to the engine mount.

Steve

OK now its my turn, can anyone see a problem with running 1 belt around all 4 pulleys (balanced,water pump,a/c,alternater),, so each pulley gets about 90degrees of belt contact?
I'm up to this stage on my engine and want to Fab up the a/c bracket, I don't have a two row balanced pulley or the idler.
Cheers