[Spridgets] LotO Autocross / Judson and 5 speed questions

Dean Hedin dlh2001 at comcast.net
Tue Jun 10 18:26:16 MDT 2008


It's actually somewhere in between.

Let's say on the best of days you get 4.5 psi from your Judson.
and atmospheric is 14.7 psi

Well 4.5/14.7 x 100 is about a 30% increase in volumetric efficiency.

It's actually a little more since the normally aspirated case is not at 100% 
volumetric efficiency.

And yes, once you get off idle, you get practically full boost as soon as 
you go WOT.
This is because the Judson is an adibiatic compressor (in compresses the air 
inside itself).
The pressure on it's output side is strictly a function of the pressure on 
it's input side and not a function of it's rotation speed.

So, once the vanes stop going clackety clack, your get full boost.


----- Original Message ----- 
From: "Lester" <oldsaabguy at comcast.net>
To: "Spridgets Group Chat" <spridgets at autox.team.net>
Sent: Tuesday, June 10, 2008 3:09 PM
Subject: Re: [Spridgets] LotO Autocross / Judson and 5 speed questions


> You personally got 45% or this was claimed?  When looking at a few
> articles written in the 50's the commentary was that the claim was
> 45% or 50% in the sales literature but actual testing was closer to
> 25%..  look down a bit on this one..
>
> http://www.infostuff.com/carstuff/mgacbc/mgajudson.htm
>
> Lester
>
> On Jun 10, 2008, at 1:14 PM, Kitterer Bob wrote:
>
>> In 1960 I had a Judson installed on my then new Sprite.  On the dyno
>> there was a 45% hp increase but this was with 100 octane leaded gas.
>> I suspect that one of the listers with a Judson installed also has
>> the pressure (boost) gage installed and could tell us about how soon
>> the pressure goes up vs rpm/gear.  It seemed to me that it came up
>> pretty quick when I go on the pedal - - - but you know every thing in
>> the past looks better when you get old.  :-)
>>
>> Bob Kitterer
>>
>> 1960 Austin Healey Sprite (Mk IV in disguise)
>> 1966 Austin Healey Sprite Mk III (Trevor) - still in boxes
>> 2
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