240 High-Amp Alternator Belt Idler Pulley Project

[dbarton]

This idea has been stuck in my head for a couple years. The 240 alternator was designed to run two belts, in my opinion because the poor belt-to-pulley wrap with this design made BELT-SLIP a problem if the alternator has higher than stock (low) output. So for all these years we've gotten along with the poor belt wrap as long as we didn't try to improve the weak 35 to 55 amp alternator.

So then we start putting 100 amp Bosch and Densos in there. Soon we find that we need to tighten those belts tighter or we get slippage.

I didn't stop at the 100 amp Bosch or Denso. I installed a high-performance Mechman years ago, which made me tighten those belts even more.

What did I do then? I bought an even badder Mechman and installed it in the last year. It's a 170 amp large case GM type with a hairpin style stator. It came with a dyno sheet showing it puts out 145 amps at idle. I don't need 145 amps at idle (few cars do), but it's nice to finally have an alternator I don't think I can slow down. It's the first alternator I've ever seen that can maintain 14.7v at idle no matter what accessory is turned on. No matter what!

Except of course belt slip is still something to work on. Belts are tight right now and working, since they're brand new. But I went through a set of belts during my trip to Davis and back in April (4,000 mile round trip) and they began slipping badly on the way home and would no longer respond to over-tightening without some slip.

So my idea is simple. To build an idler pulley to do this below (yes, back-side V-belt idler):
Dave B
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[dbarton]

So . . .
Before i see someone jump in and say "just do a serpentine," please stop and think about it. I've see a number of people do variations of serpentines, but so far I have not seen anyone do it for alternator, water pump, power steering and AC using RED BLOCK accessories or with a proper tensioner. Sure, you can cobble together some parts to adapt these things, but what are you going to do for a B21 crank pulley or a B230 crank dampener? And are you really going to do all of the needed bracketry with idlers? And in the end, will you get a better belt-wrap on the alternator than I am with my simpler idea? I'm thinking probably not. But we'll see. It's an experiment.

Conclusion: There's a lot going on with a serpentine. I have no intention of going this direction.
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[dbarton]

For those who don't have a 240 close by to look at, here's the alternator pulley belt wrap situation. Bottom pic is the Mechman in my car. Belt wrap is bad. There's no wondering why it slips.

After a careful look, moving the alternator a couple inches away from the engine does not seem to be a problem in a 240. I can't see anything that would interfere with that. So moving forward.
Dave

[dbarton]

So I began experimenting with a bracket design. Luckily I have an engine on a stand to play with.
This is a model made of plastic. It's rough, but it's a tool for seeing how things can fit.

The idler pulley pictured below is a flat belt type. I bought it to try the fit, but I don't think I'll be going with this pulley in the end. I think it might be a bit too light-duty. I'll go into more on this later.
Dave

[Jerd]

Interested! Looking forward to results.

[dbarton]

Another pic of the prototype model. This shows the alternator swung out to the max setting. Those belts turned out to be too long, but this give a good visual of how this will work.
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[Marvelous3]

Super cool Dave!

[gsellstr]

Ahh, the wonders of not having that issue on the 7/9 setup. lol

In all seriousness though, similar issues exist on the B20 setup. I haven't had slippage issues yet but I just did the e-fan install, don't have a lot of miles on it with a fan that'll load it down. I definitely like where this is headed though.

One question though...could you just run a single belt for the alternator, single belt for the water pump? That would more than double the coverage on each, which should allow you to run with just a single belt. The 7/9 setup runs singles for each without issue, but they have more wrap on each accessory.

[Harlard]

Originally Posted by gsellstr

Ahh, the wonders of not having that issue on the 7/9 setup. lol

In all seriousness though, similar issues exist on the B20 setup. I haven't had slippage issues yet but I just did the e-fan install, don't have a lot of miles on it with a fan that'll load it down. I definitely like where this is headed though.

One question though...could you just run a single belt for the alternator, single belt for the water pump? That would more than double the coverage on each, which should allow you to run with just a single belt. The 7/9 setup runs singles for each without issue, but they have more wrap on each accessory.

The 7/9 setup is very easy to adapt into a 240, FWIW.

[RvolvoR]

simple...just throw the redblock in the trash and install, well, almost anything modern

[Texas240]

Originally Posted by RvolvoR

simple...just throw the redblock in the trash and install, well, almost anything modern

There was a guy years ago offering a serpentine belt style but had zero spring type tensioner like on most modern cars. If you could adapt a wider belt setup with a spring loaded tensioner this would solve a lot of problems and no need to trash it. Use it as a door stop.

[Harlard]

Originally Posted by RvolvoR

simple...just throw the redblock in the trash and install, well, almost anything modern

Yet Asher here went with...

[Cwazywazy]

740 alts only use one belt right? Would a single belt from crank to alt and a separate belt for water pump have more contact area than the standard double belts?

[turbojose]

I need a setup like this Dave. keep going with this. My Mechman gets belt slipage about once a month.

[dbarton]

Originally Posted by Harlard

The 7/9 setup is very easy to adapt into a 240, FWIW.

Easy? No. But I agree it could be a better setup. Better to have the alternator on the non-exhaust side.
Parts needed from my imagination: New mounting bracket for alternator and AC. New PS bracket to mount PS on exhaust side. New PS pump. New PS hoses. Introduce a PS reservoir where there isn't one in my car now.
Anything else?

Still, is there anyone who can say for certain there will be NO BELT SLIPPAGE with a 740 single belt using a monster alternator pushing millions of amps?

For now, I'm moving forward with this. If it works like I expect, maybe it'll help a few others in a similar situation instead of suggesting they rearrange all their accessories.

[dbarton]

Originally Posted by gsellstr

One question though...could you just run a single belt for the alternator, single belt for the water pump? That would more than double the coverage on each, which should allow you to run with just a single belt. The 7/9 setup runs singles for each without issue, but they have more wrap on each accessory.

A single belt from crank to water pump? How would it get adjusted/tightened?
Dave

[dbarton]

I mentioned changing to a different idler pulley. That steel flat belt idler I showed above might be a good choice, but since it's designed for a lawn tractor, I just don't know about it's durability. I was looking through the Dayco idler Pulley catalog: http://www.daycoproducts.com/stuff/c...lley_guide.pdf

Since I know these Dayco idlers are actually designed for automotive use, I was thinking I should choose one of these. There are not many choices for a FLAT pulley with side flanges that's actually WIDE enough for two v-belts. But I'll try a ribbed pulley with side flanges as long as it's wide enough.

The width for the two v-belts should be about an inch, plus maybe a bit extra for some clearance.

Plus I noticed that some of these have DUAL ball bearings, instead a a single bearing. Even MY finely tuned brain can see that's a more durable design.

So I bought one of these BELOW.

[gsellstr]

Hmm, good point on the adjustment Dave.

I can confirm, with a Mechman 170, running a single belt, and an underdrive pulley, the only time I have slippage is with a wet belt or extremely high load at initial engine startup. Anytime it's running, as long as I have reasonable belt tension, I've had no issues. I'm running a DR44 based Mechman as well.

[Harlard]

Originally Posted by dbarton

Easy? No. But I agree it could be a better setup. Better to have the alternator on the non-exhaust side.
Parts needed from my imagination: New mounting bracket for alternator and AC. New PS bracket to mount PS on exhaust side. New PS pump. New PS hoses. Introduce a PS reservoir where there isn't one in my car now.
Anything else?

Still, is there anyone who can say for certain there will be NO BELT SLIPPAGE with a 740 single belt using a monster alternator pushing millions of amps?

For now, I'm moving forward with this. If it works like I expect, maybe it'll help a few others in a similar situation instead of suggesting they rearrange all their accessories.

I literally just did the conversion. It involved bending stock power steering lines and adding a 90⁰ barb at the reservoir return, plus a couple of shims here and there to get a DR44 alternator and 240 R134A AC compressor to line up. It was cake.

[Wren]

I agree that swapping to a 7/9 layout is relatively easy. An added benefit is that the alternator gets relocated to the cold side of the engine.

[dbarton]

Originally Posted by Wren

I agree that swapping to a 7/9 layout is relatively easy. An added benefit is that the alternator gets relocated to the cold side of the engine.

Ok, then how about I just like doing things the hard way?

I have the bracket now in steel. 1/4 inch plate. had a local shop with CNC plasma cut it. Not the prettiest and not as accurate as I had asked for. Damned hillbillies. But it'll serve its purpose for proof of concept or not.
Dave
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[Harlard]

Originally Posted by Wren

I agree that swapping to a 7/9 layout is relatively easy. An added benefit is that the alternator gets relocated to the cold side of the engine.

Biggest benefit in my view: also more room for turbo stuff.

I hated it when my stereo went into undervoltage protect mode because the alternator was barely hanging on for dear life in traffic during a hot day.

[dbarton]

Originally Posted by Harlard

Biggest benefit in my view: also more room for turbo stuff.

I hated it when my stereo went into undervoltage protect mode because the alternator was barely hanging on for dear life in traffic during a hot day.

You're preaching to the choir.

Anyway, my temperature related voltage drop has been cured by the new Mechman.
Now it's zero change in voltage output. 14.7v all day.
Dave

[Broke4speed]

OT: I always thought the double belt was due to the mechanical fan.

[dbarton]

Originally Posted by gsellstr

I'm running a DR44 based Mechman as well.

Can you or anyone else school me more on the alternator these Mechmans are based on? Ok, DR44? So it's a GM or Delco unit? Anyone know what cars the DR44 were/are used on?

Mechman was tight-lipped on any of this and what they did to make it fit the Volvo. Were there actual modifications done to the case? It's hard to tell.
Dave