Re: Judson S/C For Sale - MG TC now "Blowers 101"

[Ray]

Blowers 101 A normally aspirated engine has about 80% volumetric efficiency, Tuning via cam timing, valve sizing, porting, etc. may raise that to slightly over 100% at certain engine speeds. This is not really practical for street engines, and really not obtainable with the XPAG engine. A compressor may be added before or after the carbs. Either way, the capacity of the blower must be greater than that of the engine to force more air into the engine that it would normally be able to inhale. There are two types of compressors (blowers): Positive displacement and dynamic displacement. Positive displacements are piston type (not used to my knowledge) , vane type (some old Centrics), and lobe (Rootes) type. These are crank driven, and of low efficiency (less than 50%) which heats the fuel/air mixture causing thermal stress on the engine such as pre-ignition (pinking). The Lysholm lobe compressor approaches 90% efficiency, but still has the above problems. Vane type compressors require oil mixed with the fuel to lube the inner workings, which drops the octane number. Then there are dynamic compressors such as the axial flow units. These require multiple stages of compressor sections and are for sustained high speed usage only. Big bucks, too. Then there are the centrifugal compressors such as were used in the twenties and thirties. These work OK if you accept large horsepower variations with small engine RPM changes. This is because the centrifugal blowers run around 100,000 RPM (and that's no typo) at max RPM to put out the power. To do so, they must be overdriven to a very large degree. Thus small engine RPM changes = large RPM changes in the blower. Not suitable for XPAG's. In short, the sliding vane type, or the lobe type works for our cars. They both have the same drawbacks as well as the same advantages. PS- The vanes may chatter because of lube failure or excessive wear on the housing. The lobe type just wear out and give less performance. Best, Ray

----- Original Message ----- From: "R. Zwart" zwart@earthlink.net> To: "Ray" Spook01@comcast.net> Cc: "Alan Moote" AlanMoote@cox.net>; "Jeff & Merryl Redman" redcigar@ozemail.com.au>; MGVADICK@aol.com>; mg-tabc@yahoogroups.com> Sent: Thursday, July 25, 2002 1:28 PM Subject: Re: [mg-tabc] Judson S/C For Sale - MG TC > A Judson is a vane type, clattering supercharger; the Rootes type has > intermeshing gear driven lobes that pump air by having very close tolerance > fits and low mechanical noise. That is a neat mechanical compressor. Costs > more, but has low maintenance, if kept clean..... > BOB > > Ray wrote: > > > Turbosuperchargers are "turbos", the Judson unit is a positive displacement > > engine driven unit. They both act to force air into the engine, but are > > VERY different animals. > > BTW, the P-38's smoked a lot of engines, too! > > If anyone knows the location of the correct unit for a P-38, or of parts > > please write. > > Best, > > Ray > > ----- Original Message ----- > > From: "Alan Moote" AlanMoote@cox.net> > > To: "Jeff & Merryl Redman" redcigar@ozemail.com.au>; MGVADICK@aol.com> > > Cc: mg-tabc@yahoogroups.com> > > Sent: Wednesday, July 24, 2002 11:07 PM > > Subject: Re: [mg-tabc] Judson S/C For Sale - MG TC > > > > > > > > Here's a reason you might want to keep it! > > > Fighter Planes in WWII were fitted with Superchargers to give them the air > > > they needed at altitude. One reference states that the P-38 was equipped > > > with two 1150 hp Allison V-1710C twelve-cylinder liquid-cooled engine with > > > an exhaust-driven turbosupercharger. > > > > > > Alan Moote > > > Oceanside, CA > > > TC7915 > > > > > > > > > > > > At 10:01 PM 7/23/2002 +1000, Jeff & Merryl Redman wrote: > > > >G'day Dick, > > > > > > > >Without knowing ANYTHING about this Tahoe/ Reno place's elevation - (I > > > >presume it's up-a-bit from sea level?) - think twice before ripping the > > > >blower off such a heavy old barge as a YT. > > > >My experience at altitudes is that a S/C is a definite advantage - > > cramming > > > >more thinned-air into each charge. You may regret going back onto carbs > > > >when in the clouds. > > > >Your choice. Your call. > > > > > > > >Regards > > > > > > > >Jeff > > > >TC3306 s/c > > > > > > > >----- Original Message ----- > > > >From: MGVADICK@aol.com> > > > >To: mg-tabc@yahoogroups.com> > > > >Sent: Monday, July 22, 2002 3:26 PM > > > >Subject: [mg-tabc] Judson S/C For Sale - MG TC > > > > > > > > > > > > > I have a complete Judson super charger package with oiler, carb, > > pulleys > > > > > etc., currently running on an MG YT, which is to be removed and sold. > > > >Unit > > > > > runs good, and carb is properly jetted to run clean at sea level. > > Reason > > > >for > > > > > sale is car is going to be used in Lake Tahoe/ Reno area and the > > original > > > > > carbs are easier to work with at that elevation. Looking to get > > $1500 > > > >for > > > > > the package, any takers on the lists before it goes to EBay. Please > > > >contact > > > > > off list - Dick Duncan, Phone (925) 229-2500 > > > > > > > > > > > > > > > > > > > > Your use of Yahoo! Groups is subject to > > http://docs.yahoo.com/info/terms/ > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > >Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/ > > > > > > > > > > > > > > > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/ > > > > > > > > > > > > > > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/ > > > > > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/ > > [Non-text portions of this message have been removed]