simply the wrong application for the 180 degree independent runner concept?

I often wondered how the Single plane independent runner concept would work in a 180 manifold IF only the runners were sized comparable to those of a RACE single plane and the design was applied to a heavy street/race type application....Imagine an SP2P with Max Wedge sized runners and a big tall plenum....combine the high volume of a race single plane with the strong 180 degree pulse phasing of a dual plane.
The concept was to keep high velocities in the independent runners for better VE....the only weakness to them was the port cross sections were made smaller for MPG and ultra low RPM torque and HP peaks than a conventional dual plane.


I often wondered if it was a good theory applied to the wrong (in this case an MPG) mission.

Discuss.....

Be darn near impossible to fit max wedge size runners into that configuration. Are you thinking small almost non-existant plenum also?

Naah, think BIGGER...TALLER, as tall as it needed to be to get consistent cross section.

The cool thing about a 180 would be there would be no 5-7 or 2-1 consecutive fire issues the plenum would be about the size of a single plane. it's drawback vs a single plane is it would still want a larger CFM carb and you would still have the more severe dual plane runner angles getting to the valve....and conceivably the runners could enter the plenum from underneath like a short ram.

as far as the original SP2P, I always thought a killer MPG motor could be built around one on a 10:1 273 with late model swirl heads and a modern hydraulic roller cam, it's too small an intake for a wide powerband on a 318 but on a 273 it'd be about the right size....4800rpm peak power with a 318 would be roughly a respectable 5500 with a 273. I could see an A body getting close to 30mpg with an OD 833 and maybe 3.23 or even 2.94 gears.

Thanks for posting your thought on a 273 with that intake. The next car I am building is a 69 Dart GT conv. with a 273. I have a nice set of 302 heads,and a Performer intake. I had debated on using an SP2P instead of the Performer, but haven't put a lot of thought into it. The car will be strictly a cruiser,and my wife & I plan on doing a cross country trip in it. What hyd roller would you recommend? It will have a 2.76 gear, with a 999 thransmission with a lockup convertor. What got me thinking about the SP2P instead of the Performer, was I have considered fuel injection instead of a carb. Exhaust will be early 340 HP manifolds with 2.25 pipes. Sometimes y'all get so far above my head with these engine theory discussions that I can't even look up and see your feet....lol. It will be interesting to read more about the SP2P versus the Performer on a 273 built mostly for gas mileage.

JD

I think the factory hydraulic roller they used in the late 80's 318 (mechanical fuel pump) could be fine but then I'd limit the compression with iron heads a tad to a max of 9:1.

I've been thinking about a 273 mileage machine also. Can we still get pistons for it to get a zero deck height

I am runnning almost 10 to one with 302 casting heads on my 318 miledge motor. I would run higher compression and higher octane because the higher compression increases efficency and pays for the difference in gas prices.

To run that high compression you need very tight quench witch also helps efficency.

For a 273 I think the sp2p would work great.