> James Arnold writes >
>
> > But I'd be very interested to hear what a 3 carb setup looks like on a an B
> > series head, as it only has two inlet ports. ( Or did you mean a single
> > 3 inch SU? )
>
> Let me guess: The air first goes through the three carbs. Then
> through the Roots blower, which is connected to the B cylinder head via a
> manifold similar to the one used to put one large SU on a B.
> I have never seen an SU run pressurized by a supercharger, and I don't
> think I would want to try it. I have seen an SU feeding a supercharger on
> a prewar MG. Roger surely has more detail on that :-)
Well, you certainly couldn't presurize an SU and have it work, so that
sounds reasonable. But 3 carbs? All the supercharged installations I can
recall only have 1! (well, maybe 2, but not 3) You get more flow than normal
due to sucking through it to begin with. If you need more, just fit a
bigger carb. (And, I don't think SU's come bigger than 2")
On the older cars, the blower is often driven off the front of the crank,
resulting in a carb mounted in front of that, This is why cars like the K3
have a "power bulge" in the front apron, with the top of the dashpot
sticking through. A long manifold is then run back to the engine.
Top mounted installations, either belt or gear driven, can have more room
for carbs, especially on "modern" cars. On prewar cars, there just isn't
much room between the engine and the bonnet.
On a related note- Most of the MMM MG's didn't come with *any* air filter!
There's maybe an inch or 2 between the carb and the closed bonnet, hardly
enough room to fit a filter. Here in the modern world, we all know that
any gains in air flow due to lack of filters are soon lost to the
additional engine wear from all the dust you suck in... I'm thinking about
building some kind of filtered air box. To look right, it will need
artistic lines, and will probably need to be fab'ed out of Aluminium, with
a K&N element hiding inside.
Roger -Blower? No, I rake my leaves by hand- Garnett
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