Bill Gunshannon wrote:
> On Thu, 23 May 2002, Nolan Penney wrote:
>
> > Lots of wrong myths about the DCOE abound. Two 40 DCOE, even with the
> > smallest venturi's available, flow far more air then the most highly
> > reved Spitfire engine can pull. Translation? Far more carburetor then
> > engine, and typical lousy fuel mileage and poor lower rpm performance
> > when operating anywhere but on the race track. A single 40 DCOE will
> > perform better. Look at the Weber information for selecting venturi
> > sizes and you will see what I mean.
>
> So, is this unique to the Spit?? I drove an old Alfa-Romeo for
> quite some time when I lived in Europe (back in the days when you
> could still go fast in most places) and it not only had better
> gas mileage than my Ford Capri, but performed quite well at both
> low and high speeds. (As an aside, while difficult to do things
> like valve adjustment it was one of the best engineered engines
> I ever ran or worked on.)
It is certainly true that the single will give you more Torque low down. In fact
there was a guy writing in the TSSC magazine about SUs on spits that compared a
single HS4 to a twin, and found that around town the car was much better with
the single. Better pickup from the lights and much better economy.
I have twin DCOEs and haven't noticed any difference at the low end, but it
certainly gets to the rev limit much quicker than the twin SUs. However the SUs
were a bit worn. I had the car Dyno tested last week and with twin Webers and a
free flow 4-2-1 exhaust as the only changes, they were getting 80 BHP at the
wheels (1500 engine).
As hs been pointed out however, this is not using the carbs to their true
potential, but the next step (next winter) will be a new cam and stage 2-3 head,
then they will come into their own!!
Cheers
Tim
>
>
> >
> > The notion that you have bad fuel distribution problems running the
> > single DCOE...hogwash.
>
> Glad to see someone say this. It would be real hard to believe that
> the guys designing the manifolds knew so little about their job.
>
> bill
>
> --
> Bill Gunshannon | de-moc-ra-cy (di mok' ra see) n. Three wolves
> bill@cs.scranton.edu | and a sheep voting on what's for dinner.
> University of Scranton |
> Scranton, Pennsylvania | #include <std.disclaimer.h>
>
>
--
Tim Dafforn
University of Cambridge
Structural Medicine Unit
Cambridge Institute for Medical Research
Hills Rd, Cambridge CB2 2XY.
UK
Tel. (01223) 763230
Mob. (07876) 624238
Fax. (01223) 336827
http://smokeroom.cimr.cam.ac.uk/
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