rg171352
Samba Member
Joined: November 16, 2018
Posts: 1
Location: USA
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 Posted: Fri Nov 16, 2018 9:25 am Post subject: Pepco blower or Judson? |
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I am new to the forum, but have been lurking for a long time. I'm working on an OT car (American Bantam) but have a keen interest in supercharging the engine. The base engine is 50 cu. in. featuring 2.260" bore and 3.125" stroke and around a 7:1 compression ratio. I believe that puts it at around 819 cc's, quite a bit smaller than a 36 hp VW engine.
(For more on the engine, feel free to click here: https://trustinrust.com/library/literature/brennan-imp-advertisements/ it would be the latest 40 hp version of the Brennan Imp).
In my quest for building it, I've picked up an MG Sprite Judson, which is supposed to be nearly identical to a 36hp VW unit, except for the required manifolds and a Pepco for a 36 hp as well. I've been trying to read up on as much as possible, but I'm not sure which would be the better unit to run. The Judson is an NOS unit which needs to be rebuilt and the Pepco is a used unit in unknown condition.
Are there performance characteristics of the vane style versus the roots style assemblies that are preferable? Do either of these set ups last better? I'm sure there are other questions I could ask, but it may be better to just see what your thoughts are generally. I'm not looking to beat up the engine too much, but would like to increase the driveability of the car while hopefully keeping it from dwelling in the high RPM range for too long.
Thank you very much for your help! |
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FritzCP
Samba Member
Joined: October 23, 2005
Posts: 463
Location: Wisconsin
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| Posted: Sun Nov 18, 2018 5:23 pm Post subject: Re: Pepco blower or Judson? |
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The Judson is a centrifugal type blower and builds more boost as rpm increases with small gain at lower RPMs. Ricardo makes rebuild parts for the VW Judsons.
Pepco is a Roots type blower and produces more boost consistant boost at varying rpm ranges. nobody builds these that i know of, unless Speedwellusa can as he also makes a repro of the pepco blower.
Pepcos were also used on Crosley engines of the same era, but had a pulley snout to run the belt. You might want to check with those engine sizes and rpm ranges and use for comparables as well.
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