underdrive pulleys??
Thread Starter
Advanced
Joined: Jul 2005
Posts: 95
Likes: 0
underdrive pulleys??
I have friends with sport compact cars, and some of them run underdrive pulleys. I've seen pulley kits for SB chevys, and was wondering who actually uses them. Do they actually add enough power to warrent the price? thanks
Le Mans Master
Joined: Aug 2000
Posts: 6,273
Likes: 14
From: Austin TX
At low RPM, you will probably discharge your battery and may encounter cooling problems.
Unless you run very high rpms frequently, probably not worth it.
I tried 'em for a while and found no gain in street use.
Unless you run very high rpms frequently, probably not worth it.
I tried 'em for a while and found no gain in street use.
Race Director
Joined: Aug 2004
Posts: 10,628
Likes: 132
From: Duvall, WA
In a sport compact, underdrive pulleys might double horsepower. That same horsepower gain in a Corvette is like a .001% horsepower gain, so I don't think it's worth it. (Maybe I am exaggerating a bit, but you get my point).
Le Mans Master
Joined: Dec 2003
Posts: 5,727
Likes: 39
From: Fremont CA
I have a Canton racing crank pulley with the factory deep groove water pump pulley on my 1972 LT-1 to drive the H2O pump at arouund a 1:1 ratio instead of the 20% overdrive GM put on it stock. Most C3 Vettes have too high a ratio if you plan on extended runs in the 6500RPM+ area. My LT-1 does fine running 180 degrees tempratures on 100+degree days thanks to Dr Rebuild seals on the radiator, a Edelbrock H2O pump, and DeWitts aluminum radiator.
Thread Starter
Advanced
Joined: Jul 2005
Posts: 95
Likes: 0
thanks for the input, on their smaller engines they do see gains. They have smaller engines, and turn just as many accessories as we do, with our bigger engines your probably right I wouldnt see nearly as big a gain as they do. thanks again
Melting Slicks
Joined: May 2005
Posts: 2,143
Likes: 0
From: San Diego California
I have an uderdrive pulley on my 78 and it works great I get more miles per gallon now and it does feel more agresive, with no problems with the electrical system (electric fan) or cooling in traffic 
Melting Slicks
Joined: Apr 2005
Posts: 2,045
Likes: 4
From: Yorktown VA
NCM Sinkhole Donor
I put March pulleys on my 76 along with a new cam, big valves and intake manifold. I've seen a hugh increase in power, but I have no idea if any of it is due to the pulleys. They do look nice though. I have only been driving it for a week since the engine was completed, so I haven't had a chance to check the mileage. Will be interesting to see if I get an increase in mpg. 
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
5 Best & 5 Worst Corvette Daily Drivers
Joe Kucinski
The Headlights of Every Corvette Generation Explained
Joe Kucinski
5 Best & 5 Most Overrated Corvette Track Packages of All Time!
Joe Kucinski
Every 2027 Corvette Engine Explained
Joe Kucinski
Designer Imagines A Corvette That Looks More Like a Corvette Than the Corvette
Verdad Gallardo
10 Ugly Corvettes That We Still Kinda Love
Joe Kucinski
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
