Donuts

07 C6 is heading into the shop soon for a cam swap and was wanting to know if there's enough of a power increase to justify spending $250 on UD pulley. I'm trying to exhaust all of the bolt-ons on this trip to the tuner.

C6 DVL

it's good for 10rwhp.......every little mod helps

Donuts

is there one in particular thats better than the others?

johnodrake

Powerbond is as good as any....

k0bun

If you're going to do it, during the cam swap is the ideal time.

Fasrdnu

Its been argued on this site that the uderdrive pulley causes the timing chains to break on the stick cars. It causes a harmonics problem.

Donuts

Is this something that's been happening to guys at the strip/track only or happening under normal driving conditions?

BornSUPERCHARGED

There are also reports of the underdrive pulley throwing error codes because the car isn't maintaining voltage levels. It was suggested that a better mod is an electric water pump.

Fore58

So, the electric water pump makes about the same hp or it just a better mod?

C6FirstVette

When Lingenfelter did the 366 package on my C6 the package included ASP underdrive pulley system ("ASP 10 % Underdrive Pulley Kit increases engine horsepower by reducing the amount of power required to drive external engine accessories. The alternator, power steering, water pump and air compressor together reduce engine horsepower. The ASP Kit also reduces the rotating inertia on the front of the crankshaft allowing for faster revving. By replacing factory-sized crank and accessory drive pulleys with a this resized pulley, the accessories are slowed, resulting in more horsepower available to the drive wheels. All pulleys are manufactured from billet steel and aluminum, much improved quality and construction over OEM pulleys")

I have experienced NO issues with this system... no engine lights and all systems work fine
Michael

1.8t

Well, I will say this. My car with an underdrive pulley made 483whp and 435wtq. I then had a timing chain failure which was attributed to some number of reasons, but the UD was one of the scenarios discussed. I rebuilt the car with all stock parts(the heads are unported and were only shaved 5 thousandths to ensure they were completely flat) while using the stock balancer this time around. I then went and re-dyno'ed the car and it made 480whp and 442wtq. Both of these dyno's were on the same dyno, in similar conditions, with the same tune. I attribute the loss of 3whp to the balancer. I attribute the increase in tq to a now knock free tune(we removed all carbon build upon the pistons when the heads were off) and the slight increase in compression.

Take that for what its worth. IMO, UD pulleys are nothing more than another product for vendors to make money off of. The only one I would ever use is the ATI 10% pulley. It is the only pulley with data to back its claims, which are more affective harmonic dampening as opposed to increased hp.

BornSUPERCHARGED

Claims of 7-10hp gained by using an electric water pump, are about the same as claims of gains using an UD pulley.

8850

How would an underdrive pulley break a timing chain? I think somebody was guessing.

The ASP has a molded outer ring and no O-rings. O-rings can slip. ASP has been around a long time and offer the best underdrive on the market.

I've been running underdrives for many years now without any problems as long as you use good common sense in heavy traffic. Might have to turn the AC down to one of the lower fan settings to maintain battery charge or put the car in neutral and bring the rpm up for a few seconds assuming a discharge is occurring. Underdrives are good for 8-10 hp. Definitely the difference in winning or losing!

1.8t

^ There has been discussion that they do not dampen crank harmonics affectively. If you call ATI and speak with them about their 10% UD pulley, they will give you data that supports this theory.

8850

True some brands are not true harmonic balancers. I can only speak for ASP. Theirs is SFI approved as a harmonic balancer.

TCW

Count on a dead battery if you're idling around town at night!

Tom

C6FirstVette

No dead battery here...like I a said all is quite well so do not understand some of the comments other that they are IMO

old motorhead

If you're doing a cam, chances are that you'll also come away with a slightly higher idle. Probably more than enough to overcome any possible charging deficiencies. I have more than a few thousand miles on mine with no problems.

8850

Some of the comments I hear sound like they are coming from people that have never even had an underdrive pulley on their car or don't use good common pulley sense if they have. Under some conditions you can have a problem but if using good common sense you won't.

Kinda like the guys who down a product that they have never seen, know nothing about it and have never used it. As an example is the "Chinese" Ebay headers.

StoplightWarrior

I always ran underdrive pulleys on my mustangs, and had one on my camaro z28 ls1 also. Never had any serious issues.

It's concerning to hear about some of these potential problems on the c6. i'd like to hear more, because I was planning on doing an UD pulley at some point in the future.