Please bear with me here:

Spent a couple hours searching in the Autocross & Racing forum, and the C4 Technical and Performance posts, and still not clear - can find tons of info on the C5s and C6s, and on the early L98s, but -

We have a 1995 LT1, being prepped for the track. Air conditioning has been removed. Water pump is electric-driven.

Questions: [1] Can we still benefit from underdriving the Alternator and the Power Steering?
[2] If so, what are you gentlemen using for this? Manufacturers? Benefits of various configurations?
[3] Any suggestions on the installation process? Any "gotcha's"?

Many thanks,
Ed LoPresti

 

Ed: I use an underdrive pulley and it does free up a few HP but it also lessens the load on the PS pump. A lot of people complain about overheating the PS fluid but I have never had an issue with the PS on my 94 LT1(with over 110 hours of track use.) No charging issues of any type. The downside is finding the proper length belt. I have had my underdrive pulley for over 10 years but I think it is a March(but I am not sure.)

 

I don't use my car (85) for autocross...so I can't be of help there. I would guess that after you have removed the air and water pump, that spinning just the alternator and the power steering would not be too much of a drag on HP. There have been others on the forum that have added a small transmission cooling unit and hooked it into the power steering lines to cool the fluid.

 

Hi Ed,

On my 92 I have been using ASP pulleys. It consist of the crank pulley and alternator pulley. I am pretty sure that the alternator pulley (although larger) further slows down the alternator. I recommend at least slowing the power steering pump as these can be a problem.

I have been running these pulleys since around 2004 with several TT events.

Regards,
Steve

 

Running ATI-917275 damper/pully....all standard pulleys, electric water pump, A/C

No problems, sure I gained a few ponies plus reduced max revs on both alternator & power steering....

Belts are available in just about any length, so that should not be a problem

 

Gentlemen,

Thanks for the insight so far. I'll try to take each one in order:

Sidney,

I was on the telephone with both Breathless and March a few minutes ago, and neither one was very helpful. Breathless, who supplied the A/C and Air Pump delete bracket and pulley for our 1987 build a few years ago, claims to have nothing for the LT1. Even more surprising, March claims to have nothing for any Corvette newer than 1982! Am I asking the questions wrong?

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John,

I did not intend to convey the impression that we are going to autocross this car. Obviously, the configuration for autocross and racing will be drastically different - your points about fluid cooling is a prime example.

We appreciate the advice on incorporating a transmission cooler. Our plans are to eventually plumb an oil cooler, a trans cooler, and perhaps incorporate a little PS cooler, although a couple other racers have told us to simply mount a heavier duty PS unit (not Corvette) with a larger fluid reservior.

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Hi Steve,

Tell me a little more about the ASP pulleys you have on your 1992. You mention the crank and the alternator pullies. Does this mean you just retained the stock PS unit pulley? From what I can tell, your point about changing out the that PS pulley is right on, since these seem to be a weak-point for sustained high revs. Do you have contact info for ASP, especially telephone number?

Thanks!

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Bud,

I am unclear about your "Running ATI-917275 damper/pully....all standard pulleys . . ." The product name and P/N are great info, but are the ATI products just a nice aftermarket upgrade, or do they actually change the drive speed, and mechanical drag of the other components? Could you elaborate?

Thanks,

Ed LoPresti

 

Ed Hi I would go with the asp underdrive pulleys. I called around earlier and they sounded like the only place to go for a mid 90's corvette, price wasn't that bad either! Their phone number is 1-877-928-8678. I would think you would want the set that underdrives the crank 22% and the alt. 15%,That way your battery still gets charged. I don't know since yours is a race car,maybe you can get away with just the crank pulley.I think guys like the 15% alt pulley because your lights won't dim as much at idle. I'm not sure if they have a smaller power steering pulley also or if just the smaller crank pulley underdrives the power steering pump instead. One problem with asp is they wait till they get a bunch of orders to make them for c4 corvettes.Guess c4 corvettes are not a big enough market anymore. I tried to order a while back and they didn't have any at the time. I was told I could put my name on a list and they would call me when they make them. I'm hoping to get a set before spring. good luck Tim

 

The ATI damper incorporates a pulley that gives a 10% underdrive to all accessories.

When I did this a few years back, I ran into the same thing you are now, which is no one made underdrive pullies for the alternator, power steering or AC...

I didn't worry about idle as with my cam I now idle about 10% higher than stock

Hope this helps....

 

Thanks to all who have responded.

We are getting some feedback, advising against under-driving the alternator, so I have started a seperate thread here:

http://forums.corvetteforum.com/c4-t...post1576107363

. . . . . asking about how to get around the simple removal of the A/C compressor and its pulley. Any additional thoughts or techniques would be most welcome.

Ed

 

What he said.

I don't know which alt pulley I have-but I have no problems at all. The power steering pulley stays the same and it is no big deal to get correct size belt.

I also had to wait to get mine.

Regards,
Steve