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There seem to be a few folks out there making stepper pulleys these days. I'm not clear on exactly what they are and how they work. Rather than post all my guesses I was wondering if one of you fine folks would explain one to me. Sounds like it'll give me a few choices of boost level. I'd like to go with a little more boost that's still safe for a totally stock engine setup. I'm running 6psi now with JR BTC. The folks at Jackson seem to think I can go to 8 psi without beating up my stock internals, but they have this big crank pulley that overspins everything else in it's path, which sounds like it'll be hard on the air conditioning, power steering, etc. Comments on experiences with installation and maintenance would be helpful - are they more prone to belt slippage, for example?
Thanks much.
Bone stock except for JRSC 6psi, JR BTC, and JR Fuel Pump.
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The stepper pulley:
With the JRSC kits we get a dual ribbed alternator pulley. What the stepper pulley is, is this same dual ribbed alternator pulley with the blower side of the pulley actually increased in diameter to increase revolution speed, in turn creating more boost, approx. 3psi on a GSR.
It works great and is fairly simple to install. By simple I mean less of a bitch than taking the blower off to install a new blower pulley. It can be done in under 2 hours by someone who has done the install before.
For a pic of a stepper see this picture, the stepper pulley is the one to the bottom left. Stepper Pulley
<font color="#a62a2a" size="1">[ May 06, 2003 07:40 PM: Message edited by: CROM ]</font>
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Thanks CROM, that was very helpful. Anyone else with experiences (good or bad) or pearls of wisdom to offer please chime in. I'm considering having one of these things dropped in when I go for the timing belt, which is due to be changed soon (about 9k miles from now). I'm guessing that since they have to go in there anyway it might be a good time to do that too. I was also considering adding the JR field controller to kick in the big cam under boost. The way the car is now in terms of response is not very different from stock aside from the additional power, which is substantial (and very nice). I just don't want to end up with a car that has uneven transitions and bumps in the torque curve as I ease the throttle open. It's the pool shark theory - with a sleeper, ya' never want to show 'em more than ya have to... just edge them out by half a car length.
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I have Motorvations (jrcivic on here) stepper pulley. It increases boost to about 9psi which is still safe. It is a very good quality kit and it actually comes with a belt that fits.
The only downside with increasing boost stepper pulley is that the supercharger belt might be a little more prone to slipping. I know with my car I sometimes get a little belt squeal when I floor it at a low RPM. It's not really a big deal and IMO the stepper pulley is still the best option.
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B18C, does that squeal you are talking about sorta sound like a whistle? I get that sound also (at low rpms sometimes). I always thought it was air resonating in the intake.
Petie, you can't go wrong with Jim's stepper (oops, MVM stepper). I bought the Endyn stepper first. Let's just say that was a BIG MISTAKE. After switching to Jim's, I couldn't be happier.
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There seems to be an ongoing debate about injectors and FP. Am I going to need bigger injectors? If I do that will I then need to have a new fuel map to manage the different injectors? I have discovered that aftermarket components (such as the blower)don't upset the insurance types provided they are "origional dealer installed". It's when you have a third party do the mods or do them yourself that the rates start going through the roof here in NY. The upshot of all this is I want to be a little cautious about doing something that looks simple but ends up requiring several other components worth of support. So how tough are those stock injectors anyway? Ever had 'em fail on ya'? What happens when they do? Simple loss of power? (not so bad)... melted piston? (freighteningly bad)... etc., etc. I was pretty cautious about installing the blower in the first place, but I'm really glad I did it. I hope to remain glad without going broke.
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Petie: What kind of car do you have and what year?
I have a set of Venom 320cc High Impedence injectors for an OBD1 car. IF you can use them and want them email me for a GOOD price [img]smile.gif[/img]
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217gsr: Yes, I guess is does kind of sound like a whistle. I'm pretty sure it's the belt because it got better once I tightened the belt a little more. It actually went away at one point when I had the belt really tight but when I recently got the belt replaced the squeel came back.
