Routing v-belts for onboard air

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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....

https://www.aulro.com/afvb/images/im...013/02/120.jpg

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....

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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

Quote:

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Originally Posted by Vern

Or just buy an electric compressor like the rest of the world, scrap the endless air idea, and just get the damn thing going.:p
Hmm think I may have mentioned that earlier;)

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The offer in the turbo+manifold thread is still valid :wasntme:

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Originally Posted by steveG

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

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Thanks Steve for the suggestions - it's not that I plan on plumbing in either compressor right now, but rather so that I can decide where the alternator needs to be right now, so I can run the compressors in the future. As has been mentioned, I have other things to worry about, such as getting the thing running....

Factory A/C Counties have two belts. First is crank-water pump-alternator, second is crank-ac-idler. The idler is a well known weak spot in this set up.

Do you have or can you get dual row pulleys for the air con compressor in the photo of your original post?

If so, i'd consider running three belts: first belt crank-waterpump-aircon, perhaps with an idler for tension or pivot the aircon. Second belt crank-air compressor (pivoted for tension). Third aircon-alt, (alt on pivot ideally).
That's all a theory without any measuring...

I'm about to add a second alternator to my V8, which will give me five belts in total. It's messy, but it works, and the original four belt design has worked fine for the last thirty years.

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