Anyone running an underdrive crank pulley ?

[93blackthunder]

Well with underdrive pulleys doesnt the belt size change as well.

 

[Horns]

Well with underdrive pulleys doesnt the belt size change as well.

Yes.

-Via Mobile-

 

[98slv]

You made any desicions? I've been thinking more and more about this, a poor performance problem that i've had was after a while the belt stretched and it would slip when my wheel was turned all the way in one direction and the ac is on. Fried two dashboard HVAC controllers before I figured it out. The belt thats on it now is like 3-4inches shorter than the factory one IIRC....


I got mine on summit and it was ASP-541084
http://www.summitracing.com/search/year/1998/make/chevrolet/model/c1500/part-type/pulley-kits

After looking at auto specialties website it shows that the 541084 is a 25% reduction but they make a 43% (race reduction crank and altenator pulley set.) ASP591000 really comtemplating on getting it for the new truck to see what happens. What % reduction does the March pulleys offer?


25% ASP541084 (same thing that summit has)
http://autospecialties.com/gm.html

43% ASP591000
http://autospecialties.com/domestic_race.html

 

[eric.s.t]

i dont understand why this would give you more horsepower? Can someone explain to me... since im curently building my 383, and will be in store for buying new pulleys to replace the original ones.

 

[Darkrider]

i dont understand why this would give you more horsepower? Can someone explain to me... since im curently building my 383, and will be in store for buying new pulleys to replace the original ones.

Its not so much giving you hp its more freeing up hp thats already there by reducing how much hp is lost driving accessories.

Sent from a 6.5 Detroit Diesel powered smartphone

 

[Gatorboy]

If it works so well, I'm surprised more people don't use them.

 

[BigV]

If it works so well, I'm surprised more people don't use them.

This is one of those cases where race tech != street tech. Underdrive pulleys are used to fix 2 problems with race cars. One is moving water too fast through the radiator and causing over heating. Second is over driving the alternator causing it to fail. This is all related to driving at high RPM for extended times.

If you don't live in a congested area and spend a lot of time at highway speeds you will probably not notice any downside. Upside will be a bit more power leaving a stop. IMO not enough to justify the expense.

If you spend time in traffic, drive a lot of city streets or spend a lot of time at idle you will hate it. Overheating, dead battery and poor steering at low speeds are all things to be expected. You can offset some of this by upgrading cooling, alternator and PS pump. Again, not worth it IMO.

If you run hydro boost brakes don't even think about doing it.

I've seen several guys at the race track go to under drive pulleys. They all switch back at some point. Generally because of over heating issues.

 

[///RAGMC]

I had a set on my truck and had alot of charging issues and the power steering felt alittle lazy

 

[350VortecSSCT]

I did all my Alternator pulley and underdrive pulley, thus changing the belt size and running smaller pulleys would mean "less" work but gains in HP and top end due to less concentration of creating power for other means and focusing it towards top end and moving. At Idle, I do see my battery gauge dropping...Upgrade alternator to a bigger AMP, run a second battery, and run a top end battery as well.

 

[silverado13]

bought both the crank and the altenator pulleys and with the altenator pulley I would keep killing batteries. Removed it all was good, but I could tell a difference. RPM's climbed much faster with them installed.

absolutely agree, i got just the crank for mine and then i couldnt get more then 12 volts so i ordered the alternator pulley and already killed one battery, as soon as i finish the next few projects i have planned over the next couple weeeks, im going to be removing and getting rid of mine