Lm7 5.3 underdrive pulley question
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On The Tree
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Lm7 5.3 underdrive pulley question Lm7 2wd truck with cam, headers, 3200 stall converter, 4.10 rear, looking at underdrive pulley kits, i see two available. I have a company truck so this is not a daily driver.
One includes a 23% underdriven alt pulley
The other includes an overdriven alt pulley
Both have the same underdriven crank pulley
My question is, does overdriving the alternator offset the difference from underdriving the crank?
Which kit would be better for performance?
One includes a 23% underdriven alt pulley
The other includes an overdriven alt pulley
Both have the same underdriven crank pulley
My question is, does overdriving the alternator offset the difference from underdriving the crank?
Which kit would be better for performance?
Thread Starter
On The Tree
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My thought was that The overdriven alt pulley will offset the effect of underdriving the crank. Which is unappealing to me. Correct me if Im wrong.
Underdriving both pulleys would be best for loss of rotational mass - but the alternator would struggle with keeping up with accessory demand. Again, correct me if im wrong.
Just trying to understand better before i pick one or the other.
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A smaller crank pully underdrives EVERYTHING - water pump, power steering, alt, rad fan, etc. It MIGHT cause charging cooling or steering problems at idle.
A smaller alt pulley overdrives the alt only.
Not sure about "offset the effect". Although, if you mean that by downsizing both pulleys you can maintain more or less equivalent alternator performance, then yes, they do more or less "offset".
"Better for performance" is kinda wide open. A crank underdrive only (no alt overdrive) will result in the least power being drawn off by the accessories. Hard to say whether this would even be noticeable. However a truck sitting along a trail somewhere with a dead battery or spewing radiator or in the ditch because the driver couldn't correct it in time is probably not considered particularly "high performance" in any case.
If your truck has a clutch fan, you'll get more results BY FAR by putting in an electric fan, and leaving the pulleys alone (keep your money in your pocket). If that's an option in your particular truck.
A smaller alt pulley overdrives the alt only.
Not sure about "offset the effect". Although, if you mean that by downsizing both pulleys you can maintain more or less equivalent alternator performance, then yes, they do more or less "offset".
"Better for performance" is kinda wide open. A crank underdrive only (no alt overdrive) will result in the least power being drawn off by the accessories. Hard to say whether this would even be noticeable. However a truck sitting along a trail somewhere with a dead battery or spewing radiator or in the ditch because the driver couldn't correct it in time is probably not considered particularly "high performance" in any case.
If your truck has a clutch fan, you'll get more results BY FAR by putting in an electric fan, and leaving the pulleys alone (keep your money in your pocket). If that's an option in your particular truck.
Thread Starter
On The Tree
Joined: Feb 2018
Posts: 163
Likes: 2
A smaller crank pully underdrives EVERYTHING - water pump, power steering, alt, rad fan, etc. It MIGHT cause charging cooling or steering problems at idle.
A smaller alt pulley overdrives the alt only.
Not sure about "offset the effect". Although, if you mean that by downsizing both pulleys you can maintain more or less equivalent alternator performance, then yes, they do more or less "offset".
"Better for performance" is kinda wide open. A crank underdrive only (no alt overdrive) will result in the least power being drawn off by the accessories. Hard to say whether this would even be noticeable. However a truck sitting along a trail somewhere with a dead battery or spewing radiator or in the ditch because the driver couldn't correct it in time is probably not considered particularly "high performance" in any case.
If your truck has a clutch fan, you'll get more results BY FAR by putting in an electric fan, and leaving the pulleys alone (keep your money in your pocket). If that's an option in your particular truck.
A smaller alt pulley overdrives the alt only.
Not sure about "offset the effect". Although, if you mean that by downsizing both pulleys you can maintain more or less equivalent alternator performance, then yes, they do more or less "offset".
"Better for performance" is kinda wide open. A crank underdrive only (no alt overdrive) will result in the least power being drawn off by the accessories. Hard to say whether this would even be noticeable. However a truck sitting along a trail somewhere with a dead battery or spewing radiator or in the ditch because the driver couldn't correct it in time is probably not considered particularly "high performance" in any case.
If your truck has a clutch fan, you'll get more results BY FAR by putting in an electric fan, and leaving the pulleys alone (keep your money in your pocket). If that's an option in your particular truck.
