Looking at the pictures in the LSA pics thread, does that pulley look removeable?

http://gm.wieck.com/forms/gm/*query?09lsaKimble&sort=&source=all

Seen it, up close and personal. It's not.

Just change the crank pulley. It's keyed too!

I know someone else was talking about fabricating a new crank pulley, but I'm not sure anyone knows for sure just how much room you have to work with.

pulley can come off and will be making one:) very soon also have dimensions on the zr1 too.

oh yeah the stock pulley is 2.89'' t.o.t.

From those nice high-res shots of the exploded engine, it "looks like" the pulley is a press-fit. So, it "should" be replaceable. The problem "may be" that minimum pulley diameter may be an issue. There's a minimum required to assure proper positive drive of any belt-driven accessory, and a supercharger would tend to be a fairly high-drag item I would think. For that reason, even if you DO manage to reduce the pulley size, you "may" not realize the benefit of the ratio change due to slippage.

If the pulley were not removable there would be no way to assemble it in the first place.

Hmmmm interesting. Its much harder than you might think. A mechanical change will be corrected by the computer. Not trying to rain on anyones parade, just wanted to let you all know that the computer is in control. Not the pulley.

Huh? A Supercharger is belt driven, so boost is a function of crankshaft rotation relative to the pulley, not computer controlled like a turbo. The PCM might try to pull timing if it's been programmed to do so under boost spikes (referenced from the MAP sensor), but that can be tuned out.

If the pulley were not removable there would be no way to assemble it in the first place.

:lol: :highfive:

Correct, but can't boost ultimately be controlled by the computer? A blow-off valve of sorts?

Chris , thanks for reminding me. My 1999 Regal GS that went from 14.7 stock to 13.2 with a 3800 SC was tuned by Delphi engineer for the speed limiter and trans shifts, would accelerate right up to GPS mid 130's under full throttle and stop accelerating. Never did find out what in the pcm was holding it back but this was 10 years ago. Should be interesting what hurdles they have now!


Norm

Correct, but can't boost ultimately be controlled by the computer? A blow-off valve of sorts?

Boost can be controlled by a computer... They already have a system that is used on the STS-V and XLR-V for controlling supercharger boost pressure.

Boost can be controlled by a computer... They already have a system that is used on the STS-V and XLR-V for controlling supercharger boost pressure.


Thanks for posting James :D :lildevil:

Thanks for reminding me about that, Bill. It's true that there's a bypass valve that can be closed under certain conditions (based on reading from the IAT sensor or MAP), but it's still akin to "pinching the hose" to control boost- the level of boost is determined by Supercharger RPMs, unless the PCM sees a need to reroute the air. Retune those parameters for closing the valve (or eliminate it and replace it with a fooler, sort of like an o2 sensor so it doesn't see an open circuit) and you're golden.

It wouldn't be wise if you're planning on having Warranty work done, but a pulley change will work for those people who want to crank the boost.

Agreed... Just because it's computer controlled doesn't mean that you can't do anything with it... :D

It's not really like "pinching the hose"... More like poking a hole in it... :lildevil:


BTW... This isn't Bill... :D

Curse you and your better analogies! :lol:

Sorry about the mix-up. I see the Lindsay Logo above a techy post like this and assume it's Bill.

I couldn't help it... :D

It wouldn't be wise if you're planning on having Warranty work done, but a pulley change will work for those people who want to crank the boost.

Big boost changes come from very small pulley size changes. A properly made pulley will look just like the stock unit. I used to go from 3.8" pulleys to 3.4" on the 3800's. Nice boost increases, no ECU changes. You could get more out of the change with a tune though.

All the first name stuff. Do you all know each other? My real name is Peter North by the way.