under-drive pulleys
Race Director
Joined: May 2003
Posts: 10,956
Likes: 409
From: California
Safety Car
Joined: May 2004
Posts: 4,363
Likes: 1,588
From: los altos hills california
You might look into serpentine, worked out great for me.
Last edited by ignatz; Apr 24, 2019 at 04:17 PM.
Race Director
Joined: May 2003
Posts: 10,956
Likes: 409
From: California
The under-drive pulley being larger at the crank, and smaller at the other locations, ie power steering, so the engine work less, thus having more top end HP
Safety Car
Joined: May 2004
Posts: 4,363
Likes: 1,588
From: los altos hills california
although the serpentine belt looks (IMHO) mush better, and it is easier to R&R.... There is no HP gain or loss as compared to the standard multi belt design.
The under-drive pulley being larger at the crank, and smaller at the other locations, ie power steering, so the engine work less, thus having more top end HP
The under-drive pulley being larger at the crank, and smaller at the other locations, ie power steering, so the engine work less, thus having more top end HP
Last edited by ignatz; Apr 24, 2019 at 05:16 PM.
Team Owner
Joined: Oct 2004
Posts: 81,241
Likes: 3,063
From: altered state
St. Jude Donor '05
I have an ultralight underdrive set up, pulleys have to be sized right. I dont think youll notice 1 bit of gain its more of a "want every little bit real or imagined"..Pulleys gotta be sized right.
Theres cheaper stuff on speedway, turn one KRC?? Wanted bearings that wont pop at high rpm;idles around 1200 rpm so charging isnt a worry
Waste of $ probably oh well lol
Kinda wanted AC but was afriad of belt issues or spitting a compressor out.
Have an RCR system (discontinued)which is pretty much the same thing as
http://www.jonesracingproducts.com/
Theres cheaper stuff on speedway, turn one KRC?? Wanted bearings that wont pop at high rpm;idles around 1200 rpm so charging isnt a worry
Waste of $ probably oh well lol
Kinda wanted AC but was afriad of belt issues or spitting a compressor out.
Have an RCR system (discontinued)which is pretty much the same thing as
http://www.jonesracingproducts.com/
Last edited by cv67; Apr 25, 2019 at 03:18 PM.
Race Director
Joined: May 2003
Posts: 10,956
Likes: 409
From: California
From ls1 tech:Originally Posted by DamianYou gain more area under curve rather than peak HP with a pulley.
I've seen a solid 1-2 tenths/1-2 mph from a pulley swap. I actually swapped one @ the track once
Yes that is what my dyno comparison showed as well. I think torque & hp were up well over 10 up to peak and 7-8 at peak.
I've seen a solid 1-2 tenths/1-2 mph from a pulley swap. I actually swapped one @ the track once
Yes that is what my dyno comparison showed as well. I think torque & hp were up well over 10 up to peak and 7-8 at peak.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Drifting
Joined: Aug 2015
Posts: 1,939
Likes: 477
From: NSW, Australia
C3 of Year Finalist (track prepared) 2019
I have a CVF Racing underdrive crank pulley. It was the only way I could stop the car throwing the power steering belts at high revs and steering effort on the track.
Le Mans Master
Joined: Jan 2006
Posts: 6,506
Likes: 139
From: Butler Pa
Le Mans Master
Joined: Jan 2006
Posts: 6,506
Likes: 139
From: Butler Pa
I'm aware of the so called advantages of under drive pulleys claimed by the manufacturers, but was more interested in the OP's reason for wanting them.
Drifting
Joined: Aug 2015
Posts: 1,939
Likes: 477
From: NSW, Australia
C3 of Year Finalist (track prepared) 2019
Drifting
Joined: Jun 2011
Posts: 1,704
Likes: 27
I went with an underdrive pulley on my LS years ago, could not tell any difference in performance from a "seat" perspective. In defense of the pulley, didn't notice any of my accessories performing any worse. I wouldn't waste you time or effort unless you were building a track car with an engine from scratch and plan to squeeze everything out of it you can.
Last edited by htown81vette; Apr 25, 2019 at 01:54 PM. Reason: sp
Melting Slicks
Joined: Jun 2016
Posts: 2,979
Likes: 332
From: Woodinville WA
Stock style alternators already have a hard time at low RPM, my fear would be the alternator.
My steeroids rack also doesn't like my stock power steering pump at low RPMs and I'd hate to make it worse.
There were some great dyno tests of underdrive pulleys and different accessories from HotRod or SuperChevy a while back and engine-driven fans were obviously the worst power loss, but after that was the water pump, if I remember correctly. The test compared a stock water pump vs a high flow water pump vs. an electric pump. -Then they installed overdrive pulleys and the most shocking thing was that an underdrive high flow water pump was almost dead-even on power vs. an electric water pump (because of the extra load on the alternator) AND the high flow water pump spinning at the reduced rate still flowed as much and cooled as much as the stock water pump with standard pulleys.
If I'm going to do anything it would be a bigger pulley on the water pump to slow just it down by 20% (already got the high flow pump).
I know the engine masters guys did something on this, but I haven't seen that episode on the FREE motor trend on demand yet..
Adam
My steeroids rack also doesn't like my stock power steering pump at low RPMs and I'd hate to make it worse.
There were some great dyno tests of underdrive pulleys and different accessories from HotRod or SuperChevy a while back and engine-driven fans were obviously the worst power loss, but after that was the water pump, if I remember correctly. The test compared a stock water pump vs a high flow water pump vs. an electric pump. -Then they installed overdrive pulleys and the most shocking thing was that an underdrive high flow water pump was almost dead-even on power vs. an electric water pump (because of the extra load on the alternator) AND the high flow water pump spinning at the reduced rate still flowed as much and cooled as much as the stock water pump with standard pulleys.
If I'm going to do anything it would be a bigger pulley on the water pump to slow just it down by 20% (already got the high flow pump).
I know the engine masters guys did something on this, but I haven't seen that episode on the FREE motor trend on demand yet..
Adam
Race Director
Joined: May 2003
Posts: 10,956
Likes: 409
From: California
Stock style alternators already have a hard time at low RPM, my fear would be the alternator.
My steeroids rack also doesn't like my stock power steering pump at low RPMs and I'd hate to make it worse.
There were some great dyno tests of underdrive pulleys and different accessories from HotRod or SuperChevy a while back and engine-driven fans were obviously the worst power loss, but after that was the water pump, if I remember correctly. The test compared a stock water pump vs a high flow water pump vs. an electric pump. -Then they installed overdrive pulleys and the most shocking thing was that an underdrive high flow water pump was almost dead-even on power vs. an electric water pump (because of the extra load on the alternator) AND the high flow water pump spinning at the reduced rate still flowed as much and cooled as much as the stock water pump with standard pulleys.
If I'm going to do anything it would be a bigger pulley on the water pump to slow just it down by 20% (already got the high flow pump).
I know the engine masters guys did something on this, but I haven't seen that episode on the FREE motor trend on demand yet..
Adam
My steeroids rack also doesn't like my stock power steering pump at low RPMs and I'd hate to make it worse.
There were some great dyno tests of underdrive pulleys and different accessories from HotRod or SuperChevy a while back and engine-driven fans were obviously the worst power loss, but after that was the water pump, if I remember correctly. The test compared a stock water pump vs a high flow water pump vs. an electric pump. -Then they installed overdrive pulleys and the most shocking thing was that an underdrive high flow water pump was almost dead-even on power vs. an electric water pump (because of the extra load on the alternator) AND the high flow water pump spinning at the reduced rate still flowed as much and cooled as much as the stock water pump with standard pulleys.
If I'm going to do anything it would be a bigger pulley on the water pump to slow just it down by 20% (already got the high flow pump).
I know the engine masters guys did something on this, but I haven't seen that episode on the FREE motor trend on demand yet..
Adam
And I am running the March under drive pulley system as well... My Water-pump is the Edelebrock Aluminum
And I do not have any problem with ether, wether at low or high RPM.... they perform perfect.
Note: the alternator I run is a power master 140amp.... charge starts at about 750 RPM,
Last edited by pauldana; Apr 25, 2019 at 03:36 PM.
Thread Starter
Racer
Joined: Jan 2013
Posts: 300
Likes: 10
pulleys
although the serpentine belt looks (IMHO) mush better, and it is easier to R&R.... There is no HP gain or loss as compared to the standard multi belt design.
The under-drive pulley being larger at the crank, and smaller at the other locations, ie power steering, so the engine work less, thus having more top end HP
The under-drive pulley being larger at the crank, and smaller at the other locations, ie power steering, so the engine work less, thus having more top end HP