Pre war supercharged Comet..........Zoller supercharger.

Gene Nehring

Well Known and Active Forum User
VOC Member
Greg this is a book that you might like to find. It has allot of information about setting up and types of superchargers. Maurice Brierley owner of the super charged Vincent Methamon wrote it. Lots of good pictures etc.
20210124_150235.jpg
 

greg brillus

Well Known and Active Forum User
VOC Member
Thanks for that Gene, I've always had a thing for supercharging........when I was studying for all my aircraft engineering exams years ago, my highest mark was for supercharging. I have built a few......not many engines with them on.......If this one runs any kind of "Boost" it will be on the low side, probably 6 to 8 Lb's at most........and it will need to run on methanol I think, given the original ones suffered over heating quite badly.......enough to turn the piston rings "Blue"......... The cylinder head design is too flimsy.......the alloy ones look like exact copies of the cast iron ones, very weak........I am currently rebuilding one of the 2 factory 'Big fin" head TTR's .........same bike as in J B's "Original Vincent" These oversized fins were simply welded on to the original fins to add extra surface area, however, the welding has made the head like plastercine.
 

Robert Watson

Well Known and Active Forum User
VOC Member
When Smith spent a bit of time looking for the blower for his Velocette Roarer project and found nothing, he just scaled some dimensions from pictures etc and as one does, went over to the lathe and built one. He might chime in but boost was not excessive and was in the range Greg is talking of (I think) Also it was a roots type one..... again I think

No doubt he will get on here in a day or so and tell me I am full of it!
 

greg brillus

Well Known and Active Forum User
VOC Member
Thanks Robert, I think that might be the bike that is in Virgil Ellings bike museum in Solvang CA.......Cathy and I visited and met both he and Gill at the museum back in May 2019........He took me out the back and showed me the workshop with many more bikes and parts/engines......just amazing.......Actually, he might be worth a call........a lot of his bikes are exotic race bikes, so he might know or have information on this early supercharger.
 

delboy

Well Known and Active Forum User
VOC Member
Greg,

I have some photos and Phil Irving's notes on the supercharged bikes. Of course, one of them, ST29, was reported to be in Victoria. I wrote about Frank Pratt in an earlier Lightning/Grey Flash review and his partner was the well-known racer, Norm Osborn. Norm is shown here racing STT29 in Australia:

View attachment 39778

I believe the supercharger was removed when Norm was racing the bike. Many years ago it was said that the bike was in Victoria in pieces.

Close up photos of the supercharged engine are in the PDFs.

Zollers seemed to be the favorite of MG, so there is some general information available on MG sites:


View attachment 39781

View attachment 39782

David
David,
excellent definition Series "A" close ups.
This is the sort of thing us [sad] "A" nuts long for. [Especially close up details of road-goers.]
Thanks, Delboy.
 

Monkeypants

Well Known and Active Forum User
Non-VOC Member
This is reminding me of a recent Supercharged Norton purchased on another site.
The bike came complete with 2 large boxes of spares, including 4 sets of broken crankcases! :)
 

greg brillus

Well Known and Active Forum User
VOC Member
Yes I guess due to the over heating issues, luckily these engines returned to a naturally aspirated state before any further abuse and/or poor tuning resulted in mechanical failure. Interestingly, this TTR that I am rebuilding (engine, gearbox and primary only) it was evident that it had indeed suffered a broken con rod at some point.
 

vibrac

Well Known and Active Forum User
VOC Member
My friend built supercharged a Norton twin (it is allowed in the BHR regs!) he only raced it once he said it was great till you closed the throttle then it was like a vast brake was pulled on, and he couldn't obtain that fine control of retardation that is so necessary in Road Racing it it significant no others have raced a blown bike in the BHR road races since.
I seem to recall that the blown Vincent bike was never raced and only had one trial run in an IOM TT practice and was then abandoned as a supercharged racer, can someone confirm.this?
 
Top