Opinions on Underdrive Pulley Install during cam swap?

Low01silveradO

Low01silveradO

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Nov 27, 2012
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I've heard some good and some bad. Is an Underdrive pulley really worth the ~200ish? I don't wanna cause excessive vibration or bad harmonics and shorten engine life, but if it will make a legit 7-10 rwhp like what I hear (without problems), I just might do it.
 
bgray said:
There are small gains, But usually its one of those mods that its only worth it if EVERYTHING else is done
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Yea, I figure since it'll be off, it might be worth changing, but it's a tough decision whether it's worth it or not. And I could use every little bit being it's a 4.8. I won't have EVERYTHING done but I'll have what's listen in my sig, cam/heads/intake. And soon after will be trans cooler/gears/stall and that gonna be all.

I could shop around and try to find one used, I've just read that some people say the only ones that are worth it are ATI, which is either stock or 10% Underdrive, and apparently due to less vibration they can make 10hp using their stock size one. But I won't pay $400 for that. And If I did get one, I'd get the overdrive alt. Pulley too

Need more opinions tho, it seems about 50/50 at this point.

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I wouldn't bother. I don't know anybody with them on LS trucks, but I know several people that have had them on Mustangs and Camaros/Trans Ams. You MIGHT see 5-8ish hp, but 9 times out of 10 from the people I know personally and what I've read online, they're more trouble than they're worth. Bad harmonics/killing the engine early, especially if you don't buy quality billet ones, overheating cuz the water pump gets underdriven or not enough charging power if the alternator is underdriven. The ONLY way I'd EVER run underdrive pulleys is on a dedicated drag car cuz it doesn't matter for that short of a distance if the water pump/alternator are not operating at 100%.

There's way more negatives than positives, just stick with the stock pulleys. They're the most reliable option IMO
 
Mines been on my ls trucks for like 7 years problem, I have no complaints. If its not in the budget no big deal, if you cna afford it why not!
 
Yea I've heard alot of bad things. But I think I'll probly just pass on it. Because I can't afford a $400 ATI one, I don't wanna cheap out on something like that. And it can always be done later if I decide to get one. But u also don't wanna sacrifice charging when I hook up my Sundown SAX1200D one day

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