Pulleys
01-27-2003, 01:31 PM
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Car: 91 Camaro RS Convertible
Engine: 10:1 355 L98
Transmission: 700R4
Pulleys
I've been told by numerous sources that changing the underdrive pulleys on a motor will increase horsepower. Makes sense to me, because smaller lighter pulleys have less rotating mass and things like that. One of my friends is selling his 95 Z28 and has an underdrive pulley kit that was never installed. Would those LT1 pulleys work on my L98? Or is there too much of a difference in the belt system?
01-27-2003, 08:22 PM
#2
Acutally it's not the pulleys themselves that are the horsepower robbers. It's the accessories.
Take the water pump for instance. Typically on stock pumps, the impeller is most efficient at low engine speeds, once above that "sweet spot", the faster the impeller turns, the less efficient it becomes (particularly at high rpms) and the more horsepower it takes to run. By putting a larger pulley on it, it changes the pulley ratio between the pump and the crank, lowering the rotational speed of the pump at all engine rpms. So, for any engine speed, your pump is turning a little slower and therefore not robbing as much power.
There's a limit to this however, and that's when you slow down the pump so much that you start loosing necessary block pressure and you end up with overheating problems.
The same principle applies to the alternator and it's ability generate power effectively with a reduction in it's speed.
As far as compatibility of LT1 and L98 pulleys, I'm not really sure. I do know that the LT1's merged the crank pulley with the harmonic balancer, but other than that, I couldn't tell you much more.
People usually do not have a problem with street level underdrive pulleys, and the power gains are not often felt. It's when they try to run race pulleys that they encounter difficulties.
Take the water pump for instance. Typically on stock pumps, the impeller is most efficient at low engine speeds, once above that "sweet spot", the faster the impeller turns, the less efficient it becomes (particularly at high rpms) and the more horsepower it takes to run. By putting a larger pulley on it, it changes the pulley ratio between the pump and the crank, lowering the rotational speed of the pump at all engine rpms. So, for any engine speed, your pump is turning a little slower and therefore not robbing as much power.
There's a limit to this however, and that's when you slow down the pump so much that you start loosing necessary block pressure and you end up with overheating problems.
The same principle applies to the alternator and it's ability generate power effectively with a reduction in it's speed.
As far as compatibility of LT1 and L98 pulleys, I'm not really sure. I do know that the LT1's merged the crank pulley with the harmonic balancer, but other than that, I couldn't tell you much more.
People usually do not have a problem with street level underdrive pulleys, and the power gains are not often felt. It's when they try to run race pulleys that they encounter difficulties.
01-27-2003, 08:27 PM
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Wow that was some good info. Now to answer the question Would those LT1 pulleys work on my L98?
NO! You might be able to use the alternator pulley from the set but pretty sure the rest are different.
NO! You might be able to use the alternator pulley from the set but pretty sure the rest are different.
02-20-2003, 10:45 AM
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