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Old 10-30-2007, 02:02 AM   #1
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Default Smaller Pulley?

1994 Bonneville SSEi

I would like to get a smaller pulley on my supercharger soon and was wondering what size pulley I should be most inclined to go with.

I was thinking about the 2.5 and would like to know if this would be a substantial yet safe increase in boost. I think it would put me at around 10 or 11 pounds of boost, compared to the 7 or so stock.

Also wondering if I put this smaller pulley on do I have to get a new tensioner pulley that is bigger? Or does the tensioner itself have enough play to take up any slack that is created?

Hope I can get some guidance!
Thanks, Josh
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Old 10-30-2007, 03:02 AM   #2
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do you have any other mods? also, have you scanned for KR yet?
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Old 10-30-2007, 08:11 AM   #3
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You need to scan for KR(Knock retard) Also, do you have a CAI installed yet? Have you done anythign to your exaust yet? If you boost to much without the supporting mods, you will not get the gains your looking for.
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Old 10-30-2007, 08:33 AM   #4
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Here'* the Techinfo Faq about smaller pullies.

http://www.bonnevilleclub.com/forum/...charger+pulley

Things to note are testing fuel pressure and knock before changing pulley size.
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Old 10-30-2007, 01:32 PM   #5
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As of right now my mods include a high flow cone style intake and a hole that formed naturally in my cat. I would like to replace it soon with a high flow cat. What would be a few improvements for my exhaust system?

I also need to get new spark plugs and was wondering what would be a good brand or type to get. I have rough idle every now and then after I start up.

What should I look for if I scan for Knock retard?
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Old 10-30-2007, 01:54 PM   #6
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That cone style air filter..it'* open to the heat of the engine bay?

The hole in the cat is priority #1 before a pulley. You should never mod a broken car. Overall the exhaust is quite good on your car for flow. The cat should be all you need to worry about unless there are other problem areas in the system.

Plugs..TR55'* are a commonly used plug here. The copper based one. Or autolites..I can't remember the heat range ...maybe a 106?

Knock retard is the parameter you will be looking at in the scan. Normal driving and WOT runs all need to be looked at.

Check the fuel pressure as well to ensure your pump is not getting weak.
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Old 10-30-2007, 02:06 PM   #7
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Quote:
Originally Posted by BillBoost37
Or autolites..I can't remember the heat range ...maybe a 106?
Use the Autolite® 605 spark plugs (one heat range colder than stock) if you have a 3800 Series II or III engine engine with up to 6 pounds of boost. At this level, we recommend reducing the spark plug gap to .055", or .035" with nitrous oxide.

Use Autolite® 104 spark plugs (two heat ranges colder than stock) if you have a 3800 Series II or III engine with 6 to 12 pounds of boost. At this level, we recommend reducing the spark plug gap to .050", or .035" with nitrous oxide.

Use Autolite® 103 spark plugs (three heat ranges colder than stock) if you have a 3800 Series II or III engine with 12 to 18 pounds of boost. At this level, we recommend reducing the spark plug gap to .045", or .035" with nitrous oxide.

*the following is from www.intense-racing.com and is directed to series II/III motors
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Old 10-30-2007, 06:48 PM   #8
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So, when I check for knock retard what is it that I want to see? Or do I have to compare it after I put the smaller pulley on?

I was also wondering whether I can just throw the new pulley on and go or if I have to get a larger tensioner pulley also.
????
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Old 10-30-2007, 10:52 PM   #9
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KR:

If you have KR on your current setup, don't change the pulley until you have zero KR.

Scan again if you pulley down. If you have more than 1-2 degrees, run it for the winter, then take it off for the spring/summer or fix the issues causing the KR. KR will almost always be FAR worse with hotter air temps. This isn't the time of year to pulley down, so I'd suggest waiting for 80 degree weather to even be thinking about it. More boost will make the car less driveable in the winter.

Pulley:

On 94/95'*, the larger diameter tensioner idler is strongly reccommended. On the 92/93, it'* required.



The S1 L67 doesn't have as much natural belt wrap around the SC pulley as the S2. As the S1 pulley gets smaller, the wrap circumference becomes less, allowing for more belt slip. Belt slip translates into higher belt wear, less boost under accelleration, and unpredictable PCM response in fueling.

This is the very reason I added another idler pulley on my 93.
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Old 10-30-2007, 11:30 PM   #10
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So i do not want to have any knock retard before or after switching pullies?

And I wasn't planning on doing this pulley mod untill next spring when I have the entire summer to try it out. I do need to get a new cat though, the dang thing is pretty loud right now.

Thanks
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