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Opinions/Experiences on Judson Supercharging 948's

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chrpark

chrpark

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Grateful for all the information/advice on the Forum. I am restoring my '62 Sprite MKII, and plan to keep the existing 9C (not 9CG) motor, but would like to produce as much power as practical for a street car. Current plan is to install a Folchi-rebuilt Judson supercharger, and I wanted to ask about other motor changes that might make sense. George has told me (and others have said) that keeping the 948 stock makes the most sense; increasing compression ratios etc not smart. George did suggest a LCB exhaust header as a good idea, but I am wondering if others have opinions on changes that would add HP without screwing the supercharger. Lightened flywheel? New cam? Other head changes?

Please no advice to bail on the 948 and swap it for a 1275; I'll take a little more cost and less power in exchange for not having a spare block/head lying around in the garage; and the Judson kit just looks like a lot of fun to show off.
 
You might want to pop over to Sprite Spot and ask Dom (d_valentino, here's here sometimes as well) about the supercharger. He's got one on his Bugeye, and is very familiar with its pluses and minuses.
 
Opinions from others who've gone down this road before, and I'm not one of them just a reader of this forum and others for the past 8-9 years, is that we do not have sufficiently high enough octane in our gas to support a Judson. Our gas is crap compared to 1958-60 when the Judson was designed for this car. Unless you plan on adding Octane booster with every fill up a 1275 is the better way to go. Just my humble opinion.
 
Go for the Judson. Available back in the day so will not diminish car resale value. Keep the original carbs, etc in case you want to revert.

Header would be good. SC pumping more air in so you want to allow it to get out. Header will reduce back pressure.

Leave comp ratio alone. Higher octane gas available at selected locations, at least here in NC. If not in your area, use highest available. You could try booster to see if it improves performance. Watch (or listen) for pinging. Back off octane or retime to eliminate ping. It will knock holes in the pistons.

I would run a test using 89, 90, 91, higher if available, and booster to see what works best. Takes notes. Have fun.

Jim
 
There is lots of discussion and historical discussion on this topic on Sprite Spot under the Supercharger Topic. Look there as well as do a search on this forum for Superchargers. Sprite Spot is a different forum with different ideas. Not updated as frequently as this site
 
I'm thinking you should spend cash on some custom forged pistons to lower the CR just a bit and modern rings. Then you do not have to sweat the octane as much.
 
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