Just do a search on willwren or Jeffery10x2 and take a look at there signatures, that pretty much speaks for itself

Series 1 and Series 2 pulleys are NOT compatible. Series 2 are pressfit (tapered shaft) and Series 1 are keyed. Advantage to series 1 for ease of swap.

92/93 L67'* use a 2.55" pulley, 94/95 L67'* use a 2.85" pulley. 2.2" is good for 92/93, 2.5 for 94/95, assuming you've done at LEAST the intake and 180° thermostat. All of these years produce the same basic boost levels stock, it'* just that the 92/93 spins faster to produce the same boost. I'm running 12psi on a hot, dry day. Winter I probably run 13psi. This is with relatively few mods. Jeffrey is in much the same boat, but I think he'* running another pound higher than me. BTW, my SC is now running at nearly 14,000 rpm'* when I'm at redline.

Anyone who tells you a Series 1 will blow gaskets at high boost is full of ****. There are virtually no differences between them, even though they use different SC models.

Thanx for the info
I have the JET stage 2 , air intake been replaced , removed TB screen .
I need to go to lower temp thermostat. What pulley would you recommend to not worry with KR. I need to change thermostat and colder plugs , Msd is on the way . I thought about the 2.2 but do you think I will be ok with the 2.0 pulley?

Sorry to bother you guys @ the Bonnie club , being mine is actually in a fiero. But I have been reading alot of posts here and learned alot about the engine.

On my stock 1992, I can peg the boost gauge. Maybe the gauges are not always that accurate. Take my fuel gauge .... please !!!!!


Will, I did a very quick measurement of my main pulley and it looks to be about 6.5 inches in diameter, give or take.

So the ratio for a stock setup would be 6.5/2.55 =2.55 (you can do this because the circumference is directly proportional to the diameter) (interesting that the SC diameter is the square root of the main pulley)

so at 5500 rpm, the SC would be at 2.55x5500 =14025 rpm.

With a 2" pulley like yours, 6.5/2=3.25 ratio.. 3.25 x 5500=17,875 rpm !!!!!

oops, Will you are at 2.2 inches, so 6.5/2.2 = 2.96 x 5500 = 16,280. If my measurement is correct, of course.

You're a LITTLE off. It'* a straight 2:1 ratio for a 92 or 93. 5500 rpm'* on the engine is 11,000 rpm'* on the blower. You can reverse solve from there.

Will, I am sure you have good information but I am finding it hard to believe that I could be that far off in my measurement. That would mean that the main pulley would have to be 5.1 inches, where I thought I measured 6.5. Maybe it'* just me. It was a quick measurement, I could have made a mistake.

I might have bogus info. I do know the M62 is rated at 11000 rpms at engine redline, but that doesn't mean GM set them up that way.

I'd love to put a digital laser tach on my pulleys and figger all the diameters out.

I will attempt to get a better measurement from my engine. You really don't need the special tach if you know the diameters.

The tach can TELL you the diameter