Thread: Routing v-belts for onboard air

Not sure I like the setup. I would drop the onboard air comp down enough to leave the a/c and water pump on one belt, then drive the endless air and idler (if needed) off the crank separately. Otherwise your idler cops a pounding with all the belt load and its failure will stop you. Idlers aren't generally found on drive sides of a/c compressors. Does your a/c swivel for tension adjustment?

Remove the idler, Move the Ac compressor (or the endless air compressor) down to the Idlers position and use that as the idler/tensioner

you could do it with the alternator but I like the electrics up high and dry.

you current setup doesnt really put enough angle on the belt for the lower compressor, Generally you dont want an angle of more than 120 degrees on a v belt pully that drives something and ideally you want closer to 60.

IF thats all the room youve got and you cant get to the other side of the engine, thats about as good as your going to get.

Yeah, I'm not 100% sold on it either, but I'm trying to work within the confines of the defender bonnet space. Onboard air compressor can drop down maybe another half inch before I run the risk of it doing a tap-dance on the engine mount. A/C compressor can be made to pivot, within reason. IT'll have to pivot upwards, which potentially raises the position of the alternator, which potentially puts it out through the bonnet...

just hang the onboard air on a PTO out the back of the Tcase....

Or convert it over to direct hydraulic drive with a small capacity motor and plumb it onto the powersteering pump.

Done.

Originally Posted by bee utey

Not sure I like the setup. I would drop the onboard air comp down enough to leave the a/c and water pump on one belt, then drive the endless air and idler (if needed) off the crank separately. Otherwise your idler cops a pounding with all the belt load and its failure will stop you. Idlers aren't generally found on drive sides of a/c compressors. Does your a/c swivel for tension adjustment?

x2, you do not want to have an idler on the drive side, if you use one at all it needs to be on the slack side of the crankshaft pulley.

I'd want a directly driven alternator for sure, I'd go with an electric compressor or even the hydraulic compressor idea, rather than have drive belt issues.

someone been playing the same game, serpentine conversion (4bd1t in jeep) http://www.4btswaps.com/forum/showth...ine-conversion

Originally Posted by Blknight.aus

Remove the idler, Move the Ac compressor (or the endless air compressor) down to the Idlers position and use that as the idler/tensioner

you could do it with the alternator but I like the electrics up high and dry.

you current setup doesnt really put enough angle on the belt for the lower compressor, Generally you dont want an angle of more than 120 degrees on a v belt pully that drives something and ideally you want closer to 60.

I took a look, and assuming that I can fit the compressor where the tensioner pulley is in the above diagram, it's going to be sitting pretty low - at least underneath the engine mount. Not sure how much of a problem that would be. Transfer case option is out, as I have a hydraulic winch sitting at home whose pump will be occupying that space.

Originally Posted by mike_ie

As part of my Isuzu swop I'd like to have onboard air and retain the Defender aircon, and I'm trying to figure out the best way to route the v-belts to drive the system.

The only setup I can come up with that belts won't rub against other parts of the engine is as follows:



Orange belt driven by the crankshaft pulley drives the compressors and the fan pulley, red belt driven by the AC pulley drives the alternator. Alternator tensions the red belt, tensioner pulley tensions the orange belt.

Physically, I can fabricate this and make it fit under the bonnet (I think), but is there anything wrong with this setup?? In particular:

a) Anything wrong with the alternator not being directly driven by the crankshaft pulley?
b) Belt contact area on both compressors is about 60-70% of total circumference. Possibility of slippage???

Additionally, what v-belt does a 4BD1 take? I have a v-belt driven compressor, but the belt will barely sit in the groove. This would be so much easier with serpentine belts.... :/

If you are going for this set up, how about a custom idler pressing on the back of the belt. Gives a better drive angle. Use bigger bearings and carry spare.

Didiman

Originally Posted by mike_ie

I took a look, and assuming that I can fit the compressor where the tensioner pulley is in the above diagram, it's going to be sitting pretty low - at least underneath the engine mount. Not sure how much of a problem that would be. Transfer case option is out, as I have a hydraulic winch sitting at home whose pump will be occupying that space.

Knowing that.

use the powersteering pump to power up the hydraulic winch (saves on line/pump costs in the short term and can be replaced later) then use the PTO to drive the Compressor