Like above I need an underdrive pulley and I happen to need a new camaro crank hub. Looks like ATI balancers come with hubs as one piece and they offer a 7.5" and 6.75" OD pulleys. I take it the factory pulley is 7.5 and the 6.75 is their version of an underdrive pulley? Looks like its only maybe 10% underdrive though? Do I have this right, other underdrives offer 25 to 34%? Yes I know this gives me a new balancer also, which I figured wouldnt be a bad thing anyway. Thanks

 

Also, if I didnt want the expense of the new balancer and more underdrive, I have heard that the ASP underdrive pulleys come with an integral new hub, is this true? - their web site doesnt say. Thanks again.

 

The ASP is a combined damper/underdrive pulley. It does not include a hub.... just bolts to the stock hub.

 

You must mean the ASP is a combined hub and underdrive pulley - the ASP does not include a damper - this is my question, does the ASP pulley include a hub? The ATI is a damper and hub but with what looks like a minimal underdrive as an option, this is kinda my second question.

 

If you need an ATI damper, you shouldn't be worried about an underdrive ratio. Even with 35% UD, you're only going to see a fraction of one HP at the top end.... it isn't worth it. The average HP gain is better, but the loss of full charging capability at idle will probably not help performance, if your battery is not being kept fully charged.

The ASP that I owned was an integrated damper and pulley. It bolted to the stock hub.

http://www.lmperformance.com/3668/2.html

 

I understand what you are saying, but this is a pure road racing car and Im using the underdrive to slow down the power steering pump, not for HP. So if the ATI is only 10%, it wont help me. Its interesting that your ASP was a damper also, their website mentions nothing about a damper, only the underdrive pulley? I'll call them, thanks for the input.

 

will this work for a motor turning 7000-7400?
or should I use something else

will be around 650 rwhp

 

My recommendation for an engine turning in excess of 7,000 RPM would be the ATI. The ASP is not SFI-rated and does not meet NHRA specs. The ATI is.

 

This is a good thread and there aren't a whole lot of good damper threads. ATI sells a damper with aluminum hub and one with steel. what is the downfall to an aluminum hub and why would you really use an aluminum hub over steel.

Fred, I hope that you chime in on this one.

Also, for those that road race or are interested in road racing there is a company(can't remember the name) that sells a pulley and pump that spins slower. There was a article in GMHTP prolly a year ago stating a 5hp gain at the high end of the power band and cooler ps fluid

 

TurnOne makes a power steering pump for road racing. I bought it about 3 months ago. It has a nice feel to it. It has different jetting in it to not pump so much fluid. The pump has a stiffer feel to it that I really enjoy. With our cars running 6000+ rpm it is smart to not flow so much fluid. An underdrive pulley could never reduce the flow enough to make a significant difference.

I also have the big block ATI 10% underdrive aluminum hub/balancer and I noticed no difference in charging or power steering feel when I installed it.

 

I'll chime in about the ASP 23% underdrive pulley/dampner combo...I've had mine since 1996 and its performed flawlessly, no charging issues at all...Its a nice piece...Unfortunately I never dynoed it before and after install, but I've got to think that I run what I run with a wee bit of hp from a few small areas...this may be one of them...

If nothing else its a proven, durable piece..I'm not easy on my stuff and it hasn't failed...

--Alan

 

Thanks Alan, is it nhra approved?

 

Yep, this is the company that I was talking about, just couldn't recall the name. What is the point of an aluminum hub, that 's what I want to know. I know it's lighter but wouldn't it be more prone to failure?

 

The aluminum hub would reduce rotating mass. Not sure that you will see much impact, due to the fact that the mass is so close to the centerline of the crank. The aluminum hub would not be a good choice for a blower motor, where the hub has to carry the HP pulled off by the blower, in addition to the accessories. I've seen the ATI steel hub fail on two high (1,000+) HP blown LT1's. The single keyway is where it cracks. The "fix" is a double keyway and a reinforcing band around the outside of the hub.

 

I use the ATI aluminum hub in conjunction with the lightest outer shell on Stock Eliminator engines that usually don't see RPM much over 7000. My conversation with the sales rep at ATI regarding using the same set-up on my Super Stock Motor that pulls well over 8000 led me to leave the steel hub and shell on that piece. The rep said that the heavier steel components did a better job of dampening harmonics in higher RPM ranges.