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Sun Jul 04, 2010 8:38 pm

Hi yall. I remember a pic floating around here somewhere about a motor that had twin judson superchargers on it (can't remember if it was a 40 horse, or a 36 horse). I can't seem to find the pic, but it was an old black and white pic (i'm guessing from the 50's or 60's). I was just wondering if anyone seems to have any more info about it, or if anyone had done, or even attempted this mod before?

I've heard that with a judson, you are pretty much limited to a stock motor, or else you'll surpass what the blower is capable of. But if you were to add two of them, i would think this would open up possibilites to larger heads, better cam, larger displacement, etc. Thanks in advance
-Mike

Mon Jul 05, 2010 12:34 am

It's been asked many times here on The Samba...the picture's in the Samba Gallery:

...every time someone has asked for more info on this set-up there has been no response.

That set-up is not from back in the day...zip ties have been around for 30 years but it's not '60s or '70s.

Mon Jul 05, 2010 4:02 am

so who has the guts to do it?? :D 8)

Mon Jul 05, 2010 4:16 am

kai wrote: so who has the guts to do it?? :D 8)

The late David Mayes was working on twin Pepcos for his Type 2 DC but sadly cut short.

Mon Jul 05, 2010 7:50 am

kai wrote: so who has the guts to do it?? :D 8)

It's about time you stepped up and show us your skills Kai... sell a few of those plate frames and ........ :wink:

Mon Jul 05, 2010 8:54 am

56OvalRHD wrote: kai wrote: so who has the guts to do it?? :D 8)

It's about time you stepped up and show us your skills Kai... sell a few of those plate frames and ........ :wink:
I'd have to sell all of them, and then still would come up short Eric..

It would be a cool project to do though, once the Speedwell kit is in the ghia.
My girl Luna has been saying for years that double Judson's can (and should) be done..

Mon Jul 05, 2010 9:22 am

Thanks so much. But whats with the generator nuts? it seems the shaft is so long, that one of those early big nuts are installed, as well as a later model cap (the piece that holds the extra shims), is backwards, and a regular nut over. whats the deal with that?

Anyhoo. It seems that now you have double the airflow, that would open up possibilities to larger heads, and other things.

Mon Jul 05, 2010 10:48 am

BugMan114 wrote: Thanks so much. But whats with the generator nuts? it seems the shaft is so long, that one of those early big nuts are installed, as well as a later model cap (the piece that holds the extra shims), is backwards, and a regular nut over. whats the deal with that?

Anyhoo. It seems that now you have double the airflow, that would open up possibilities to larger heads, and other things.

Perhaps he had to backspace the fanbelt pulleys to allow room for the dual belts for the Judsons?

You wouldn´t necessarily need the biggest valves or wildest cam with a blower(s) as there is already a pressurised fuel/air charge building up in the inlet, just waiting for the valve to open. Big valves couldn´t hurt though, I suppose... :twisted:

Mon Jul 05, 2010 12:23 pm

at first..twice the parasitic power makes no sense with judson also double bad in fact of the fan cantact to the housing. at the end this all is more stress to the crank + thermal overkill in compare to the power it gives.
but it looks cool for sure!

big valves are the supercharger's best friend.

for example: my 1200cc 36er and 17psi of boost the same power i could build with a 40hp 1200cc and 1300dp heads(35,5x32mm valves) and half of boost at same rpm.

Mon Jul 05, 2010 5:18 pm

kai wrote: so who has the guts to do it?? :D 8)
I've got the guts, but not the money :lol:

Seriously though, the parasitic losses would be a major problem like stated by grueni; twice the friction, twice the strain on the crank and bearings. You could reduce the strain by using a single serpentine cogged belt with cogged pulleys, and just line up all the pulleys. But, there is no way to reduce the internal friction of the Judsons unless you coat the internal housing surface, vanes, and vane slots. The cogged belt would kind of ruin any hopes of appearing vintage though.

Paul

Mon Jul 05, 2010 5:41 pm

a triple belt instead of two would look badass :lol: .

I mean if one judson increases power, its also taking away from the motor a little. But with two, sure you have twice the parasitic loss, but then again, you have twice the gain. Can anyone give an approxamate HP on a motor like this? if i an hearing this right, a judson on a stock 36hp motor gives about 57 to the wheels. so with two and maybe some big valves, you might be around 80hp?

Mon Jul 05, 2010 6:01 pm

BugMan114 wrote: a triple belt instead of two would look badass :lol: .

I mean if one judson increases power, its also taking away from the motor a little. But with two, sure you have twice the parasitic loss, but then again, you have twice the gain. Can anyone give an approxamate HP on a motor like this? if i an hearing this right, a judson on a stock 36hp motor gives about 57 to the wheels. so with two and maybe some big valves, you might be around 80hp?

Nope, doesn't work that way.

There is a limit to the amount of air you can cram into the engine without bad effects. To use some round numbers, consider that your compression ratio is 8:1. If you run 7PSI of boost (1/2 atmosphere) you will get an effective CR of 12:1 which is getting into detonation territory.

The only purpose to running two S/Cs is if one S/C cannot supply the flow you want at the boost you want. That would imply that you either have greatly increased displacement or are running at much higher RPMs.

So, you might want to run dual Judsons on a large type IV where the increased displacement might require more flow.

I think in this case the goal is more aesthetic than practical. Two Judsons makes someone the Alpha Dog of the show from the moment their car rolls out of the trailer until they push it back into the trailer.

Mon Jul 05, 2010 9:20 pm

well the idea would be to increase displacement, as well as use larger valves. if one jusdon was good for 1200cc's, wouldn't 2 be good for 2000-2400cc's, if airflow was the main issue here? perhaps this could be used on a late model 1600 increased to 2000cc's (perhaps a 2074cc, or 2110) i would think this could be made to be streetable. just a thought

Mon Jul 05, 2010 9:24 pm

BugMan114 wrote: well the idea would be to increase displacement, as well as use larger valves. if one jusdon was good for 1200cc's, wouldn't 2 be good for 2000-2400cc's, if airflow was the main issue here? perhaps this could be used on a late model 1600 increased to 2000cc's (perhaps a 2074cc, or 2110) i would think this could be made to be streetable. just a thought

That's why I mentioned the type IV engine. However, going that way kinds of corrupts the whole Judson vintage speed mystique.

Mon Jul 05, 2010 9:31 pm

yeah, but cmon, if you see a 1600 based motor, with TWO judsons, you know you'd stop and drool all over it, lol. 1600, 25hp, their all the same, 1600's are just cheaper, and faster, 36hp's are older, slower, expensive as hell to mess with, but much MUCH sexier :lol: . besides, a 40 horse looks almost the same as a 1300, or 1600. I personally can't tell the difference, unless i see the case numbers, lol

Tue Jul 06, 2010 12:18 am

BugMan114 wrote: yeah, but cmon, if you see a 1600 based motor, with TWO judsons, you know you'd stop and drool all over it, lol. 1600, 25hp, their all the same, 1600's are just cheaper, and faster, 36hp's are older, slower, expensive as hell to mess with, but much MUCH sexier :lol: . besides, a 40 horse looks almost the same as a 1300, or 1600. I personally can't tell the difference, unless i see the case numbers, lol

Just standing there drooling in the uneducated "bigger is better" state of mind , after the great explanations of why 2 would not work, you would be a fool standing there drooling over something that did not work.

Is that why people love chrome? :wink:

Tue Jul 06, 2010 12:33 am

All I can see you getting from Twin Judsons is a BIG headache. If you know how tight it is under the decklid with one Judson just imagine the problems with two. At least it will be a quick way to fry an engine.

If you want more flow get a bigger Supercharger not two small ones. If it has to be vintage use a Shorrock C142, you'll have to fabricate an intake manifold but the C142 worked very well on The Inch Pincher.

Tue Jul 06, 2010 1:03 am

John Moxon wrote: If you know how tight it is under the decklid with one Judson just imagine the problems with two.
Stick it in a barndoor ;-)

Tue Jul 06, 2010 8:07 am

krusher wrote: BugMan114 wrote: yeah, but cmon, if you see a 1600 based motor, with TWO judsons, you know you'd stop and drool all over it, lol. 1600, 25hp, their all the same, 1600's are just cheaper, and faster, 36hp's are older, slower, expensive as hell to mess with, but much MUCH sexier :lol: . besides, a 40 horse looks almost the same as a 1300, or 1600. I personally can't tell the difference, unless i see the case numbers, lol

That's just standing there drooling in the uneducated "bigger is better" state, after the great explanations of why 2 would not work, you would be a fool standing there drooling over somthing that did not work.

Is that why people love chrome? :wink:

That's why people use dual 48's :roll:

Tue Jul 06, 2010 12:39 pm

If you are going to use 2, at least stack them.....