Serpentine Belt Advantages

[jaluhn83]

Thanks all, that's about what I was thinking but figured I'd see what everyone else thought.

I certainly don't have a lack of other things to do to this truck, though I'm also going to be pulling the cam at some point to put typ4's in, which will require stripping most of the accessory drive gear if I recall correctly.

I do think the serp belt looks cleaner and I like the 130 amp alternator idea.

Production vehicles use serpentine belts mainly because they're cheaper and easy for production and allow more compact engine arrangements. They are also somewhat more efficient though I doubt it's noticeable on an engine this big.

 

[SparkandFire]

I used to believe the redundancy idea behind V belts, my dad and grandpa preached that to me "Oh son, if you loose one belt you keep right on rollin, you've got other belts to run the water pump"

uh huh..

Well, the problem with that, at least for me, was when I lost one V belt (a cheap Auto Zone alternator belt with about 7 and a half miles on it) it smacked the underside of the hood hard enough to dent it, got all tangled up in the other belts, popped all of them off and made an aweful smelly belt-mess that took me a couple hours on the side of the road to detangle with a pair of *****. Im happy I had kept my old worn goodyear belt, I drove the truck home with just the alternator belt on.

Serpentine belts are more efficient, quieter, self adjusting, easier to change. I had debated for a minute keeping the V belts on the 6.9 when I dropped it in my '94 truck. Then I came to my senses and moved all the serpentine stuff over...

 

[franklin2]

Like I said, most cars and trucks now have the very large alternators, and the serpentine belt is the only single belt that will turn one of those large alternators without slipping. A dual v-belt system may do it, but then you need room for that underneath these new hoods where everything is crammed together. And most cars now run electric fans, all kinds of other electric gagets, and A/C is standard, so they need those big alternators.

 

[Old Blue]

A single v belt can transmit far more hp than a 130 amp alternator can use. It is dependent on pulley wrap, RPM of the faster shaft, and pulley diameter. There are tons of engineering books available for download that you can play with numbers online, but you can reliably transmit just over 2 hp on a 3" pulley at 1750 RPM (alternator speed.) At 80% efficiency at full load, a 130 amp will need just over 3 hp for full output. At 3000 RPM shaft speed (< 1500 RPM engine speed), a single v-belt can transmit about 20 hp - but with a small 2-3" pulley you may only have half that transfer if you want 100% duty cycle - and most alternators aren't taxed at 100% for long because they themselves aren't designed for a 1.0 service factor at full load. The faster your belt speed (RPM) the more HP can be transmitted.

I'm having a local alternator guy put a 165 amp rotor and stator in my 1G, and I asked him just to be sure how much I'd be able to get with one v belt. So he threw a 200 amp unit on his test bench with its single v belt. There was no problem making 200 amps at above about 5500 rpm shaft speed - that would be no more than 1500 or 2000 engine RPM by my SWAG. That being said - a 5 or 6V serpentine belt can obviously transmit more power! The bottom line is you don't need to consider switching belt types to get the rated power from any "3G" setup in normal circumstances, with the exception of if you want to make 130 amps for hours on end at idle speed - and I'm not sure you'd be making enough magnetic flux at that speed to hit your max amperage anyway! However, it is true the v-belt will not last as long under any high amperage, low RPM "abuse" when compared to a serpentine setup.

I wouldn't change a truck one way or another just for the sake of doing it, or for an alternator swap. If the parts were just sitting there and all known good (idler and tensioner) I'd consider it if you're pulling the front end apart anyway, like for a cam swap. Not as a sole modification though, there's not enough advantage to me personally to justify the work. I certainly wouldn't pay money to buy parts to switch over. If I had a serp truck I'd keep it that way - my truck has the v belts, and I plan on keeping it that way as well. OEM's pick serps because that is the best tech for the price and they have to buy something to build the car/truck with - you on the other hand don't have to buy/do anything, so the cost benefit analysis is considerably different if you're into that kinda thing. We'll like it whatever you pick!