Hi Martyn, Scott, list,
The engine in my car is a 1275 (1312) and I have run a single back box RC40 on
it for years. It is a little noisy - because RC40s become less effective at
the higher power ouputs but it's cheap.
The 948 is not going to making the kind of big bhp (100+) that would require
big carbs - in my opinion anyway. Over here only some of the mini racers use
the small block engine (998cc) and I am not sure what carburation they run.
What Scott says about venturis is true. However, a 45DCOE with 34mm venturis
is probably making less brake horse power AND making less torque than a single
1.75 HIF6 carb - or so some well respected experts advise me. The reason for
the big SU working so well is that has the advantage of being a variable
venturi carb, whereas the DCOE is a fixed venturi carb albeit one that can
have the venturi changed from one size to another.
There is a phrase in England 'Horsepower sells engines but Torque wins races'.
On the engine in my car I pick up fistfuls of bottom end torque with a David
Vizard designed, Janspeed produced Controlled Vortex manifold. I also pick up
some torque with Full Radius rams on the DCOE.
BUT,returning to my question of is the SU better than the DCOE, the only thing
I am not so sure about is whether top end BHP aside (where the DCOE is
superior) does the Weber DCOE whether or not 'choked down' with small venturi,
gain over any SU setup by virtue of the acceleration pump jet system. In
other words when the pedal hits the metal does a Weber DCOE carbed engined rev
quicker (not revs more) than the SU? I suspect it does and that this is why
there is more to performance carburation than dyno and flowbench figures
suggest?
Comments welcome
Daniel 1312
PS. Is this the Scott that made the cover of Tom Colby's newsletter a few
years back?
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