I was talking to Ryan'* uncle and he said that he has had gains of 20-40 WHP depending on the extent of the build with vacuum pumps on LSx engine. He went on to talk about the other added benifits of running a vacuum pump that all really sounded almost too good to be true.

You ask what is a vacuum pump?
FYI Vacuum pump are designed to pull higher crankcase vacuum which should boost power by Improved piston ring seal and the relief of positive crankcase pressure.
It should also reduced stress on reciprocating components and lower intake-charge contamination.

You can either run a belt driven pump or a electric pump. The electric pumps are higher in price but you can find belt driven pumps for $100 or so. Ryan is looking into a deal on a electric pump while I'm looking to setup a belt driven pump in the AC location.

I was just wonder your thoughts on a setup like this... Is it worth it? Has anyone had exp. with a setup like this?

Ron Vogel (sp?) on CGP is actually running one. He also said that the a/c compressor could possibly be made into one. There hasn't been any dyno or track testing yet. though.
link: http://www.clubgp.com/newforum/tm.as...de=&*=#3174120
Very good info on there explaining why he actually went ahead and tried it. I'm very anxious to see what #* he comes up with.
There are also alot of power that can be reclaimed though the oiling system too. (crank scrapers, one way directional screen windage trays, larger oil pans and modified pick ups to lower the oil past the crank, etc.)

Ignorant question. are these for forced induction car or can the be used on NA cars?

This is a quote from the link I posted:

OH, missed that part

Hmm thanks for the link 95naSTA... I thought that I was the only one whole has thought of doing this on a 3800. I very curious to see what his numbers are - maybe I'll hold off until then.

This is quite interesting. How much vaccum do you think our cars would need? And I am assuming the PCV system is off while this is running?

Seems like a cool idea.

But, how would the A/C compressor work as a vacuum pump for long? Oil is added to the R134a to lubricate the compressor, and I would imaging that the compressor wouldn't last for long sucking air out of the engine (not to mention the problem of most Bonnies having a V5 variable displacement compressor)

I would think the best solution would be to replace the A/C compressor with a dedicated vacuum pump designed for the job and drivven of the acc. belt. That would be neat (except for the fact that I'll never have it because there'* no way I'm giving up my A/C!!!)

I do think that getting a pump designed for the purpose would probably be better.
But, while sucking air from the crank case it will be pulling misty oily air. Maybe that will lubricate the a/c compressor??

An oily mist would come out through the A/C compressor, but I would think that it would be enough oil to keep the compressor happy. I mean how much oil floats around in the A/C system? Maybe 16 oz. I think that should circulate around the system every couple of minutes. So, to keep the compressor lubed, it would need to draw 1/2 qt. of oil out of the crankcase every few minutes. Better bring a few extra gallon size jugs of oil to the strip.