40 or 46 IDA Webers on 2.8 twin-plug ?
 

I have a 2.8 twin-plug engine built from:

'73 2.4S case
'S' cams
Mahle 92mm RSR pistons/cylinders
twin-plugged 2.4 'S' heads
custom-built billet distributor with Marelli twin-plug cap & rotor

On the dyno the engine produced 217 bhp at the rear wheels (estimated 255 bhp at the flywheel) running on 40 IDA Webers with a twin-outlet sports exhaust.

Would the engine produce significantly more power on 46 IDA's (enough to warrant the extra cost of the carbs/manifolds) ?

On the dyno you might see a higher peak HP number (7400 rpm or so), but overall the driveability will suffer. I wouldnt spend the money there unless you can sell the 40's to offset most the cost.

Don't mean to steal the thread, and hopefully this is along the same lines, but John, do you have a baseline venturi size recommendation for a 3.0 with 46 mm Webers w/ tall manifolds, RSR cams, 10.2 comp., mildly ported heads, twin plug, and 1 5/8 headers and megaphones in a race only application shifted at 7500 rpm? Thanks!

Joe, I would baseline it with 42mm venturis.

Thanks so much, John!