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Dewey

Super charger on 81

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Can I get a super charger under the hood on an 81 with a 305 short block and is the performance worth the cost?

 

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I think you can get a blower under the hood but I'm not sure about what modifications may be necessary to clear the inner fender aprons and maybe some of the emissions and exhaust plumbing.  Vortech makes low mount systems for a carbureted small block Chevy buy it looks like a different carburetor box might be necessary.  

While a blower would certainly give better performance and some real bling to your car, I think a higher performing crate engine would be much easier and less expensive.  The 305 may not be the best candidate for a supercharger.

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According to Bob Johnston’s registry, my 83, RQB 3771, once had a blower. It wasn’t on it when I got it and I have no history on it. A crate motor might be more practical but a supercharger on an Avanti is kind of neat!  Mike

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As above, the 305 has all the "wrong stuff" for a performance engine, small valves, low cubic inches, two bolt mains. Get a crate engine or an LS pulled from a performance car to upgrade performance. You are starting with 165 HP give or take. If lucky, 7-8 PSI will give you about a 50% increase all the way to possibly 250 if the engine can do that. I'd spend my money on the new engine. But get a set of noisy cam gears, they will sound like a blower.

If you are looking for a quick, cheap upgrade - get a decent set of rearend gears and posi. It won't help a lot but it'll feel better.

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The issue I had, regarding putting a blower on a GM powered Avanti ...was finding a mount for it.   The one I used  ( in 1997) was for an early 80's Chevy and used three 7mm drive belts.  I ditched the "mm" belt system and fabricated a dual belt system like the 63.  It may be a moot point now with S'chargers being in the mainstream, but you still have to do a lot of tweaking.  Clearance below the hood will not be a problem on an Avanti II. 

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I investigated upgrading the 305 in my '82. People here who sell rebuilt 350 and 400 and crate suggested I first look at tuning and carburation in the 305. I did that and improvement was satisfying. 

While I have a free ride here I'm looking for AOAI Houston members for fun and games. So far no joy.

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