underdrive pulleys

[Blacktank]

anyone ever use them? how much did they affect alt charging and cooling?

the pulleys i'm looking at are no longer in production so i can wait for some to show up on ebay,find the right 85-87 gm to pull them off of or i can buy new but for racing which are underdriven https://www.andysautosport.com/products/bbk__1598.html v belt and serpentine,power steering stays the same just serpintine for alt/waterpump

[mudbunny]

Never have used them but I have installed an electric fan on the back of the radiator. Picks up the same hp, maybe 10 hp or so by getting rid of the factory fan. In the similar price range too. If you are out for a lot more power think supercharger. You'd have to cut up the top of the doghouse and run an air duct through where the radio is now. Think of the cool factor and the compressor whine. Arh arh arh. But really, the electric cooling fan lets you get rid of the viscous fan while keeping the rest working like they should.

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[sternwake]

Are you just wanting to go to a serpentine drive, or is your SBC just not powerful enough?

I have tried a smaller alternator dual v belt pulley attempting to get more low rpm amperage, 71 to 67mm diameter, and could not notice any improvement, but my ability to measure it was not then what it is now. When the alternator with the smaller pulley on it failed I kept my smaller pulley, but did not transfer it to the replacement which even with the larger pulley outperformed the previous alternator with teh smaller one when it was still healthy.

AS much as a fan enthusiast that I am, and my contempt for flat bladed metal fans is that rely solely on angle of attack of the blades to move air, I've never really considered going for an electric radiator fan on my Dodge. More power is not really a big deal to me, more MPGs would be nice.

[Blacktank]

i want to get a serpentine belt on the alt so it wont squeal like a banshee,currently unusable on a depleted house battery,certain 85-87 gm have serpentine for alt/fan but keep v belt for power steering making it real easy to switch over

85-87 are getting scarce and nobody makes stamped steel but still used in hotrods and a few make them in aluminium just underdriven https://www.bbkperformance.com/gm-5-0-5-...5-87.html# they have extra v belt slots for a/c,smog but would be simply change out the pulleys to get serpentine on alt

[sternwake]

Ah the squealing single V belt issue. I have dual V belt grooves but only run one V belt as my AC compressor is not aligned well and my one attempt to align it did not help enough.

I just lower my voltage trimpot until the squealing stops.

Try wirewheeling the pulleys you have, a single depleted flooded house battery should not be able to pull so many amps that the belt has to slip. either the pully surfaces are compromised or the belt is not tight enough.

Mainesail has a pretty good read:

“Industry Accepted” Recommendations for V-Belts
3/8″ V-Belt = 80A
1/2″ V-belt = 100A
This guidance can be a truism, to some extent, but it will require;

Impeccable Alignment
Near 180 degrees of belt wrap
Extremely clean pulleys
Relatively short bulk charging duration’s
A high quality belt
More Realistic Maximum Amperage Recommendation
Single 3/8″ or 10mm V-Belt = 70A
Single 1/2″ or 13mm V-Belt = 85A.
Limitations of V-Belts
Lower HP drive capability – When compared to flat style multi-rib belts

Prone to over tightening – Many a boat owner or marine techs have over-tightened a v-belt in an attempt to minimize slippage or belt dust but in the process damaged a water pump or other accessory drive. Over tightening a v-belt does not really aid in less slippage and can actually have an effect that is opposite the assumed outcome.

Excessive frictional heat – This heat can actually damage the alternators front bearing and transfer excess heat into the alternator. Frictional pulley heat can also be exacerbated by the use of cheap stamped steel pulleys (see image below) which tend to expand the V gap as they heat up. This can cause the belt to become loose under load. Using billet machined pulleys can help to minimize this.

Engine choking belt dust – Many v-belts contain abrasive materials such as Kevlar or Aramid fibers. When these abrasive fibers are turned into belt dust it can actually cause damage to engines. Diesels use and need lots of fresh air for the combustion process and that air needs to be free and clear of abrasive contaminates. The idea that a marine diesel does not need an air filter can be an engine damaging old-wives tale. The image below illustrates why a quality air filter on your marine diesel is a good idea.

https://marinehowto.com/marine-alternato...ps-tricks/

You should be able to get your single v belt to stop squealing at the amperages a single flooded marine battery can ask for.

[mudbunny]

I've got good news and bad news. My 86 g20 has the serpentine on the alternator, bad news is you can't have it. I've found good luck finding oddball parts with partsonline.com. Its a national wrecking yard site and has phone #'s too. Also not sure if a truck system is the same as a van system, a lot more room under truck hood. Might be tucked in differently.

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[mudbunny]

Sorry Gary its partshotlines.com.

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[sternwake]

Serpentine is certainly the way to go. I might do some serpentine dream shopping for my 318, before I go through the effort of replacing my useless AC compressor with second alternator

One potential solution of the squealing belt is to reduce the current the depleted battery can draw on start up through your 2 AWG (?) cable.

Run in a parallel + circuit from alternator to solenoid to fuse to house battery. Have this second solenoid also manually triggered, by a rocker switch next to the existing one you already employ.

10AWG will likely limit the 50% charged battery to accepting 35 amps or less when your voltage regulator inside your internally regulated alternator is still seeking mid 14.5v while it is still cold.

With just one healthy flooded group 31? marine battery it would only be able to accept 30 amps for about 25 minutes with VR seeking 14.5v whereas with 2awg it is likely to accept double that for 8 to 10 minutes before reaching 14.4v at which point amps taper.

Once the belt and pulleys are warm and dry, the V belt is less likely to slip, and you can then trigger the existing circuit's solenoid, and these dual parallel circuits will then allow more voltage to reach the battery and it can then recharge faster as amps taper from 60? downwards as it climbs in state of charge.

The question mark is I forget how much amperage you measured going into the battery just before it starts squealing , or just after it stops squealing.

Expect the 'during squealing' amps, to be lower than non squealing.

Huge amperages can really return a healthy well depleted lead acid battery quickly to ~75% state of charge, and while a flooded marine battery should likely not see this every single day on every recharge, one must factor in the damage to battery if it only gets 87% charged 5 days in a row via solar alone. Compare this to whetherf huge alternator amperages first thing in the morning, when it is most depleted, do then allow the solar to get it closer or preferably to 100% state of charge by afternoon. Meaning the alternator can do in 10 minutes what will take the solar 2 hours when the battery is well depleted.

The additional parallel circuit is a nice redundancy, as you will have a second solenoid should the primary one fail out in the stix.

Your internally regulated 1 wire alternator likely drops the max allowed voltage once it warms up.

Once it is warmed up and the max voltage drops, so does the amperage the battery can accept, and the slower it charges.



Mainesail explains it well here:
https://marinehowto.com/automotive-alter...batteries/

So you might only need a few minutes of engine running before you can flip both solenoid trigger switches, and let her rip.

The less healthy the battery, the less amperage and lesser times are required to bring the depleted battery to absorption voltage. So your existing belt squealing, when well depleted, could be a sign your battery is still pretty healthy, as you regularly charge it via solar.

But collect the actual data with your ammeter, as it will help you learn what you can expect from your system, and as you learn, you will then easily be able to notice when the battery is aging and its capacity and performance becomes limited, and wont be surprised having to battery shop during some crazy event, like the after effects of a protracted Pandemic MadMax world.

[Blacktank]

3/8 belt trying to turn a 150 amp alt,it just doesnt slip it gets smoking

when the world opens up i should be able to find a stock set if not i'll just have to pay up for aftermarket,dont want underdrive but looks like it wont hurt anything

[sternwake]

I'd want to know that running the water pump slower with an underdrive pully on the crank is not going to push the rest of the cooling system to its limits, rather than just hoping or assuming it wont. Those running underdrive pulleys are running 1/4 mile runs wanting to free up some HP and torque, not dragging an overweight RV up a mountain pass at 50mph.

Also the 71 to 67MM pulley amperage difference being negligible on my alternator, does not translate into an underdrive pulley on the crank having a negligible effect on alternator output and the quarter mile crowd can even get away with NO alternator, as a abttery has more than enough capacity for a 1/4 mile run. I drove 120 miles with no functioning alternator and arrived with more than 12.2v, at night, with headlamps on.

a 150 amp alternator can only attain that rating briefly, when cold and spinning fast and when fully fielded by the voltage regulator. It cant do it when hot, at engine idle speeds, and often higher rated alternators perform worse at low rpm than their lower rated brethern.

And your flooded house battery is never going to ask for anything close to 150 amps. It squealing at whatever amperage it is providing, is more a sign your pulleys are misaligned, and/ or your pulleys are dirty, and or the belt is too loose, and or the belt and pulleys are glazed from slipping so much from misalignment or being undertensioned.

My group31 AGM battery is way greedier than any flooded lead acid G31 battery when depleted perhaps even 4d or 8Ds, and I can get 90+ amps from my alternator into it from a single V belt,, unless its wet, and My AC compressor pulley is not properly aligned. 134 amps of plug in charging source was not enough to instantly being my depleted battery to 14.7v, and there is no way any flooded marine battery is going to approach the amp sucking ability of a TPPL AGM battery when it is depleted.

I doubt my belt is overtightened, and Mainesail says overtightening it does not really help it to not slip under high load, it just causes more friction and heat.

By all means upgrade to serpentine or Dual v belts, but don't think your '150 amp' alternator is just too powerful for your current limited battery capacity, as there is no way you have asked that alternator for its supposed 150 amp rating.
And if your depleted battery and other loads have asked it to provide even half of that, it has been only very briefly.

You got other issues with your existing belts an pulleys besides an alternator which can theoretically overpower them.

Until you get more battery capacity, I bet you can stop the squealing with a properly tensioned new V belt and running a wirewheel in the grooves of the existing pulleys and perhaps a solvent to get all the squeal inducing baked on shmegma from their mating surfaces. Whether this effort is worth it to you is another matter entirely.

I get that you are thinking ahead, and this issue is not really even an issue at the moment as you are neither deep cycling your limited battery capacity, nor even asking the internally regulated alternator to provide its cold rating and I am not arguing that a single 3/8 inch V belt is totally inadequate for a fully fielded 150 amp rated alternator.

I totally get not expending effort into fixing something, only to upgrade it later, but you might find misalignment now, which will still be misalignment when you install new pulleys.

Fixing potential misalignment/ improper tension now and wirewheeling the pulleys and ordering a new quality V belt, cleaning pulleys of Schmeg, and properly tensioning the V new belt and then again after some use/breakin period, could allow you to push off that serp/ dual V belt upgrade until something shows up in your junkyards, or you find a NON underdrive set online.

As I wrote I can get 90 amps from a single V belt, and just checked and it is a 3/8, not a 1/2. My belt does no where near a 180 degree wrap around the alternator pulley either, and your single flooded battery is not going to be demanding 90+ amps of charging current even if you draw it down to 30% SOC. What other DC loads does your engine have? No high PSi electric fuel pump, no computer, only the ignition. Mine with a 15psi pump requires 8.2 amps to run the fuel pump and ignition at idle and 12.2 amps at 2K rpm.

So you got issues other than a single 3/8" V belt trying to turn a '150 amp' alternator, as it has been slipping at less than half that output, and Mainsail's 70 amps continuous amperage recommended rating for a 3/8" alternator V belt assumes a much larger and depleted battery bank than what you currently have, and 70 amps for 30+ minutes, not 5 which is all your depleted battery would likely be able to accept.

You can likely fix this squealing issue, for the cost of a new V belt and your labor to clean the pulleys, and perhaps a washer or two to fix any potential misalignment.

The most expensive V belt rock auto lists for my Van is 12$, the cheapest is 75 cents.