Goin to the boneyard, again.

I need to get a water pump and crank pulley for the mixed serpentine/v-belt setup as my engine didn't come with them. will these pulleys be different depending on if the car had AC? Do I also need an idler or tensioner pulley for this setup?

Alternatively, since only my alternator has the serp. pulley and the others are v type, can I just get a v pulley to replace the serp. one on my alternator and then get the much more common v belt crank and water pump pulleys? I have AC so how many grooves do i want on which pulleys? the AC and steering pump each have two grooves.

Does anyone have diagrams of the mixed and V belt belt routings? Thanks.

 

U-Train,

Personally, I wouldn't be too concerned about underdriving the alternator, or even the A/C compressor - just the power steering and coolant pumps. The A/C compressor is basically an idler when the A/C is not running, so you won't save a single watt of "wasted" power there. The steering pump does take a little power when the gearbox is in recirculation mode, but not a lot. You could potentially save 1-2 HP at high RPMs with an underdrive setup. The coolant pump is another user of power at all RPMs, so you could benefit a little there, but you could do the same by cutting down the impeller of the pump.

The alternator and underdrives, however, are a complete joke to me. The alternator will electrically load the engine to whatever level of output is required at any given RPM. The alternator is NOT a constant load device like the steering pump or A/C compressor. The load varies depending on the voltage regulator forst, then RPM. Once the battery has been recharged, load on the alternator will be negligible, and it becomes in essence another idler. Underdriving it will only force it to output more watts at a lower RPM, potentially overheating it. If the regulator wants to get 20A from the alternator, it is going to load up the rotor accordingly, regardless of its speed. That means that it's going to take 250W of power to turn it (assuming it is almost perfectly efficient device with 5% losses). You can take that 250W (or 1/3 HP) at any RPM - it will just run hotter at the lower RPM to make that output.

Given that, if you can find a double- 'V' belt sheave for the water pump that is larger than the current one, you will have achieved almost the same thing as the complete underdrive set.

Another thing to consider - have any of you guys with aluminum sheave experience looked at how fast the aluminum wears out? It's amazing how much longer the steel lasts in industrial applications, and I've been the victim of aluminmum sheaves more than once. Personally, I would prefer to lighten up the steel sheaves with holes instead of installing aluminum - even heat treated T-6/356.