olds 307 and 403

I am talking a modified sbc truck set up a diesel water pump vs a factory V belt set up. Is there any difference in power lost through accessories? Running electric fans with both.

Koda

Not enough to worry about. I will grant that, upon startup, a v belt may slip more than a serp belt would, but, once you are running, those belts do not slip, and the life before they wear out is similar. Were a V belt to lose power, it would slip, and that slip would be friction, and that friction would cause the belt to wear out sooner. The only performance thing I see about serp belts is that they will not slip on startup when cold and damp like a looser v belt will. They also will maintain tension better. However, if you lose a V belt, or your power steering or AC or smog pump goes and locks the pulley, you cut the belt, and drive on. If you lose your alternator, you cut the belt and drive on for a while, maybe you can get home, or at least get safe. If you have a serp belt, and lose any of those, or an idler, or the tensioner, you are dead right there.

Serp belts are less cost to the OEM, and maintain themselves a little better, but, when some accessory goes, they all go. Not a trade I am interested in spending time and money pursuing. If you want less power loss, delete AC, delete power steering, and run a water pump and an alternator.

joe_padavano

The OEMs went to serpentine belts because 1) it's less labor to assemble, and 2) the tensioner controls the HP loss, which is critical when every fraction of an MPG matters to CAFE ratings. The problem is that no aftermarket or self-made serpentine system has anywhere near the factory level of engineering and test. The result is that usually this is a whole lot of effort for at best no performance improvement and more likely an increase in drag and HP loss. The high dollar aftermarket systems are the worst, as they don't use a reverse rotation water pump and thus require a boatload of idlers to force the belt into contact with the pulleys. The result is friction and HP loss.

olds 307 and 403

Thanks guys, I was hoping Joe would chime in on this. Like I said, factory sbc system using the brackets guys are making to adapt to the Olds block with the diesel reverse rotation water pump. I may put this on the 260 in the 88 since I just need an alternator and the adapter brackets. Yes, I am looking for maximum mpg out of this car.