First ever multi-carb draft!

[InlineDave87]

One piece cast iron 4.9 prototype.

How does it perform? And do you mind sharing its specs?

 

[THE FRENCHTOWN FLYER]

How does it perform? And do you mind sharing its specs?

With all the traditional hot rod methods - 13.4 CR, roller cam, headers, (3) 540 cfm Holleys it ran 9.0 @ 147 MPH in the quarter in an 1800 lb altered which translates to roughly 550 HP at the crank - normally aspirated on gas.
Best 1/8 e.t.: 5.60.

 

[TheFutura]

If you'd asked me before Hanuka, I'd have said three IDA Webers or three 500 cfm Holley 2300's on an POPIR intake (Port O Port, Independent Runner) intake manifold. Think early Ford GT40 Windsor 289 or Kar Kraft FE 427 induction system.

Then I rediscovered the restrictor plate two cylinders per venturi (RP2CPV) engines, such as what NASCAR used to use till 2011, and what the Austin Healy Sprite and Mini Cooper and Cooper S 1097, 1098, 1275, 970 special engines ran, Fisa Group 2 were normally trying to go back from Port On Port to something less to restrict performance. So were the power boat and Hydrofoil engines, the racing powers that be always tried to go back from Port on Port.

When you down grade from POPIR intake to NASCAR style RP2CPV With the right cam, you can drop the carb size down, and still get great power.

I'm thinking that Ak Miller actually understood the over carburation as he didn't do many POPIR engines. I know that there is a 15% peformance growth using POPIR, but with an optimized cam, you can get close to matching Port on Port, but with less fuel consumption.

The true masters of the RP2CPV carburation cam timing were American...Clay Smith, Ak Miller, and to another extent, Endyns Larry Widmer, were able to see the concept of fuel delivery differently to the classic Weber port on port Engine cubes verses rpm peak formula.

Those little Tri-Power Ford sixes, a classic restrictor plate two cylinders per venturi (RP2CPV) engine, shouldn't ever have made 220 hp as a 250 or over 180 hp as a 200 cube engine. But they did, and there was some kind of excellence going on in the way they were set up.

They did so with total carb size area and cfm rates half the amount that a Weber engined Port on Port car would need

This is such an informative thread. It’s time to bring it back for the holidays. I like the idea of two carburetors, each one feeding three cylinders. Tune for efficiency and the power will follow.

 

[twentyover]

Not mine. SU HIF-4, commonly available on ebay. Probably a better alternative would be HS-6, common on Volvo before FI became the norm. Different shape (float bowls alongside rather than under, but common, experienced rebuilders in the US. One needle for jetting per carb, adjustments are jet needle, Jet depth, vacuum chamber spring, and damper oil

No further information on this installation