Just going back to the original thread,"are 4 SU's better than 2 Webers?"

I reckon the answer is NO, without doubt

I reckon that L18_B110 is dead right.
Some of the older farts (like me) may recall the weird double throat SUs that were fitted to Coventry Climax 2 and 2.2 litre engines of the late 1950's. They worked, just.
50 and 58 mm DCO Webers were so much better that it was unbelievable, the 2.2L engine increasing its BHP by about 20.

The second thing is that the lunatic (= a good mate) over the road has fitted EFI to his---wait for it---Harley and had pretty impressive results, in spite of the crap I throw at him. He uses a modified Delco ECU, and has proven to me that this is the way to go.
Worth thinking about!

So that Jag six must have had Motorbike carbs that resembled sus like the early honda bell tops as someone pointed out in a conversation to a Jag freak. For if sus only run each with the help of 2 cylinders then yes theres no point.

Twin SU's on a 4cyl, 4 stroke engine are only ever feeding one cylinder at a time (alternately) anyway, and as 89mm explained, that constant delivery will probably work better with this type of carb than one veturi per cyl which would generate pressure fluctuations requiring a very rapid piston response.

That principle of feeding one cyl at a time changes a little at high engine speeds with long duration cams where inlet charge momentum can keep supplying air fuel charge into the cyl even after the piston has started moving back up on the compression stroke, but SU carbs simply won't run with genuinely big cams required to generate this effect, so there's little point really.

That's my thoughts...

With bike injection and carb the only limit is the size of the carb at 40 in most cases. Ive seen many bike injected engines on magazines and heard of them in speedway A series and suzuki gti engines.

could you use motor bike injection in the same way described and use a fuel only computer? or is that just silly

My opinion is that 4 SU's would be a monster to keep in tune. I know that some of the pre WW2 Rileys tried it out with some success, but then again, there are some Brits that will try anything.

The facts are that SU's/Hitachi's/Stromberg CD are all Carbs that rely on the "constant depression" type which is an auto engineers way of saying constant pressure drop across the Carb. In fact this rarely happens in practice but the piston can usually react pretty quickly. They are not like Bike Carbies ( Amal, Dell'Orto etc) in that in these carbs, the slide (or piston) acts as the flow controller as opposed to a butterfly in the SU type.
If you are looking to go down this path, have a look at some of the 1000 to 1200 cc in line bike engines. I reckon some of their set ups could be adapted and would probably work quite well. I know of at least one Sprite (a few years back) using 2 X 1-1/4" GP Amals that went like the clappers

Hey guys Im wondering if anyone would know if four sus would be a superior setup for drivability compared to webers or similar?
Reason is that in japan I saw a six cylinder jag with six of them. Also I know the poms still use sus for everything but wouldnt it make sense to use four of the critters as they resemble the mechanical design of most motorbike carbs????
Any of the wisemen care to do the maths?