17% pulley on a JCW?

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Apr 27, 2007 | 08:08 PM

#26

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6th Gear

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From: SoCaL (Agoura Hills)

Quote:

Originally Posted by 70spop

I spoke with Jan this morning, and he mentioned that car. Said it pulled like crazy, and he's anxious to get some numbers on it to see what it's actually doing. We talked a little bit about pulleys. It seems that maybe a smaller pulley would do better with a higher flowing head because the extra airflow from the sc would have somewhere to go, rather than just shoving up against the intake ports and valves. If you're shoving lots of air, but it has no escape, then you're going to get higher boost. If the head can handle the flow, then shove more air through it. I still don't necessarily want maximum pulley action, though. At least not with a stock/JCW head. I'd really like to find out, definitively, what reduction the JCW pulley is that's on my car. Once I know that, I'd have a better idea of what a 15% or 17% pulley might get me.

I guess Jan's setting up a Dyno day next month, so I'm planning on heading down there for that. I'll see about getting the GP flash and then have him do some tuning on that and see where it gets me for now.

I'll be there

. As far as the pulley. When you're down here, have Danny bring a tool and measure the pulley for you, we can figure out what % it is from there

. I'm going to talk to Jan and see if he thinks it's worth going with a 19%. If I do end up going with it, i'll see what kind of IAT's we're running, etc. I'm also going to do some research through Eaton and see what they say about running the blower up at those speeds.

.

The only issue for me is the redline thing. If i'm going to be running an 8500+ RPM redline, I may have to go with a LARGER pulley, not a smaller one.

Apr 27, 2007 | 08:13 PM

#27

70spop

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From: Sacramento, CA

Quote:

Originally Posted by rustyboy155

The only issue for me is the redline thing. If i'm going to be running an 8500+ RPM redline, I may have to go with a LARGER pulley, not a smaller one.

Yeah, that's true. Good idea about measuring the pulley when I'm down there. There seem to be a few conflicting statements about the JCW pulley size. I'd like to find out what's on MY car.

I look forward to hearing what you and Jan find out about the pulley/head combos. Another month? Could get REALLY interesting by the time I'm down there.

Apr 28, 2007 | 04:45 AM

#28

BlimeyCabrio

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From: Holly Springs, NC

Quote:

Originally Posted by 70spop

I'd love to see more measurements - along with install dates of the JCW kits they came from - I'm buying into the "2 sizes of JCW pulley" theory - because I think the sources of some of the "conflicting statements" are reliable...

May 8, 2007 | 06:34 PM

#29

Grassroots Garage

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From: Piedmont Triad, NC

Quote:

Originally Posted by BlimeyCabrio

The pulley size has not changed, the one I have kicking around the shop is a very early one, I had installed in about May or June of 2003, removed the pulley for a 17% in summer of '05 and I have just installed a 17 on GP 0015. The pulley sizes were the same.
Ok, small math check, I double checked with my calipers, same one Blimey used, and I found the scrap paper we wrote on, we had written down cm's with an " decimal. So I set the calipers to what was measured and came up with 11%, then I remeasured (in inches) and came up with... get this...11.2%
Well, it still isn't the 14.4% as claimed earlier. And I believe that Randy's pulley may have been smaller than mine (I measured stock=2.576, JCW=2.287)
--Dan