Underdrive pulleys

patooyee · Nov 6, 2008

My LS2 is internally balanced and therefore does not have a harmonic balancer on the outside of the engine. The crank pulley is just a cast iron pulley with no soft material on it. I need an underdrive pulley and I can't find any that aren't harmonic balancers. I guess I don't see how running a harmonic balancer would hurt anything but I'd prefer just a plain old pulley with no soft material or weights to throw or anything like that. (Not to mention that I would imagine that harmonic are more expensive than cast iron.)

So do I run the harmonic on the internally balanced engine or does someone knwo of somewhere that has something that isn't harmonic?

J. J.

YOUNG · Nov 6, 2008

LG Motorsports has what you need. Here is the description of the pulley and a link to their site.

ASP C6 Corvette Underdrive Crank Pulley

$329.95
ASP Underdrive Pulley (SFI Approved) 25% Harmonic Dampner Crank
What do Underdrive Pulleys do? Underdrive pulley systems increase engine horsepower by reducing the amount of power required to drive external engine accessories. For example, the alternator, power steering, water pump and air compressor rob horsepower from the engine. By replacing factory-sized crank and accessory drive pulleys with a resized pulley, the accessories are slowed, resulting in more horsepower available to the drive wheels. Typically, a set of Auto Specialties street pulleys will increase horsepower by 12-15, and increase mileage by 2 to 3 MPG. All pulleys are manufactured from Billet Steel or Aluminum, exceeding factory quality.

ASP LS2 underdrive pulley kit reduces parasitic power losses associated with high accessory speeds, freeing up additional HP. It also reduces the rotating inertia on the front of the crankshaft allowing for faster revving. We have seen just over 13 rear wheel hp increase with this kit installed on stock LS2s.

Includes belts and Redline Power Steering Fluid

http://www.lgmotorsports.com/catalog/product_info.php?cPath=343_372&products_id=1750

patooyee · Nov 7, 2008

That one is a harmonic balancer, too. I've found them on Summit for under $200. Still wish there was just a cast iron pulley available that would cost less than $100 probably. Oh well ...

J. J.

blacksheep10 · Nov 7, 2008

YOUNG said:
LG Motorsports has what you need. Here is the description of the pulley and a link to their site.

ASP C6 Corvette Underdrive Crank Pulley

$329.95
ASP Underdrive Pulley (SFI Approved) 25% Harmonic Dampner Crank
What do Underdrive Pulleys do? Underdrive pulley systems increase engine horsepower by reducing the amount of power required to drive external engine accessories. For example, the alternator, power steering, water pump and air compressor rob horsepower from the engine. By replacing factory-sized crank and accessory drive pulleys with a resized pulley, the accessories are slowed, resulting in more horsepower available to the drive wheels. Typically, a set of Auto Specialties street pulleys will increase horsepower by 12-15, and increase mileage by 2 to 3 MPG. All pulleys are manufactured from Billet Steel or Aluminum, exceeding factory quality.

ASP LS2 underdrive pulley kit reduces parasitic power losses associated with high accessory speeds, freeing up additional HP. It also reduces the rotating inertia on the front of the crankshaft allowing for faster revving. We have seen just over 13 rear wheel hp increase with this kit installed on stock LS2s.

Includes belts and Redline Power Steering Fluid

http://www.lgmotorsports.com/catalog/product_info.php?cPath=343_372&products_id=1750

I just want to say that I love your posts because you only jump in with tech, and your avatars are awesome

YOUNG · Nov 7, 2008

patooyee said:
That one is a harmonic balancer, too. I've found them on Summit for under $200. Still wish there was just a cast iron pulley available that would cost less than $100 probably. Oh well ...

J. J.

Why are you needing the other style pulley? Are you trying to find something to run the hydraulic gear pump? If so, then just find the correct v-belt pulley, drill the correct holes and bolt it to the front of your current set-up. That is what we do with the gear pumps on the LS series engines.

patooyee · Nov 8, 2008

I'm not needing a v-belt pulley. The one you posted will work fine, albeit there are cheaper ones available. I was just looking for something that wasn't a dampener. I guess it doesn't exist so I'll just run the dampener. Thanks, though.

J. J.