Experience with Under drive pulleys

[don4life]

Getting parts together to get my car running and was considering ordering a set of under drive pulleys. Was wondering if anyone here has any actual experience with them and how much they effect charging and power steering ( have hydro-boost)

Thanks
Don

 

[FE3X CLONE]

In my opinion, for the tiny little bit of HP you might gain from them it's not worth worrying about charging issues, etc.

My brother and his friends went through that craze with their Mustangs. They didn't leave them on there for long due to charging issues, cooling issues, etc.

 

[565bbchevy]

For my BBC I originally bought a set of March underdrive pulleys since I thought it would help since I was shifting at 7600 RPM.
They had very little effect on the power steering but I was having charging and cooling issues when I was at constant idle and I ended up replacing the alternator and water pump pulleys with smaller diameter ones to help them spin faster while keeping the underdriven crank pulley.
While this helped I still ended up replacing the crankshaft pulley to a stock diameter one and realistically everything works better even my crankcase evacuation pump.
If my car was a race car then I could see them being beneficial but for a street car I wouldn't bother and one thing I found when buying a high amp alternator is they base their ratings on either a 7" crank pulley or a 3:1 pulley ratio which neither can be done in an underdrive set up.

 

[pencero]

If your typical driving experience is agressive city driving / traffic underdrive pulleys are definitely the way to go. They save your breaks and prevent the car from upshifting at times you are trying to hit the breaks. If your driving experience is usually very backroads / highway oriented it's just a huge waste of money and going to starve your charging system on the highway.

 

[565bbchevy]

If your typical driving experience is agressive city driving / traffic underdrive pulleys are definitely the way to go. They save your breaks and prevent the car from upshifting at times you are trying to hit the breaks. If your driving experience is usually very backroads / highway oriented it's just a huge waste of money and going to starve your charging system on the highway.

Please explain how underdrive pulleys can save your brakes and prevent the car from upshifting when you are trying to hit the brakes?
Underdrive pulleys slow all your accessories down so it uses less power to spin everything so if they were going to cause any cooling or charging issues it would be at slow driving speeds such as city driving/ traffic and if your on the highway your accessories would be spinning faster because of your engine RPM which would make them function normal at those speeds.

 

[don4life]

If your typical driving experience is agressive city driving / traffic underdrive pulleys are definitely the way to go. They save your breaks and prevent the car from upshifting at times you are trying to hit the breaks. If your driving experience is usually very backroads / highway oriented it's just a huge waste of money and going to starve your charging system on the highway.

Please explain how underdrive pulleys can save your brakes and prevent the car from upshifting when you are trying to hit the brakes?
Underdrive pulleys slow all your accessories down so it uses less power to spin everything so if they were going to cause any cooling or charging issues it would be at slow driving speeds such as city driving/ traffic and if your on the highway your accessories would be spinning faster because of your engine RPM which would make them function normal at those speeds.

i was just gonna leave it alone 🙂

 

[CWPottenger]

I have a set of March pulleys on my Regal and have not had any adverse affects. How much they help I can not be sure since never ran this motor without them.
My charging system runs fine @ idle or at speed, Cooling is also fine, and I have hydroboost and have no problem w/ steering or braking using them.

 

[-83MONTESS-]

If your typical driving experience is agressive city driving / traffic underdrive pulleys are definitely the way to go. They save your breaks and prevent the car from upshifting at times you are trying to hit the breaks. If your driving experience is usually very backroads / highway oriented it's just a huge waste of money and going to starve your charging system on the highway.

:lol: I think your on the wrong subject here

 

[olds307 and 403]

Don't buy under drive pulleys. They charged really poor with the big alternator pulley and just passable with a 100+ amp alternator with the stock alt pulley. Cooling was awful with my 403 and was never acceptable till I used the crank pulley as a floor jack extension 😀. Put your money elsewhere. I should have bought a decent rad and not ran those pulleys in the first place, my 403 would have probably survived much longer.

 

[pencero]

I looked into installing under-drive pulleys on a 328i bmw. I always heard bad reviews of under-drive pulleys on a sbc / bbc so I would never even consider installing them on my cutlass tbh. bmw makes a great clutch but not such a great automatic. On the 328 in chicago traffic it would always shift into 3rd when I really needed it to stay in second gear. This would cause me to waste so much breaks b/c the car is always trying to shift into 3rd. I rode w/ a friend in his 328i with the under-drive and noticed when he was in 1st or second gear if he took his foot off the gas his bmw would just coast and remain in w/e gear he was in before he took his foot off the gas and it would continue coasting in that gear. This looked much more enjoyable / easy to drive in Chicago traffic and was therefore very appealing to me. I never got around to installing the under-drive pulleys on the car b/c my brother crashed in it. I can't imagine any situations outside of Chicago traffic where this would be very helpful. It looked like a huge improvement for driving on highway 94 to downtown chicago, IMO. Idk anything about horsepower gains and charging and all that, I'm a driver not a mechanic.