mhwarner

This may be a dumb question, but I'm gonna ask it anyway:

Peripherally-ported engines can produce amazing NA power at high RPM, but they suffer from poor low RPM performance, and are essentially useless on the street. Rumor is they can't idle below 2-3k and really don't come alive until 6-7k, right?

A stock side port system, on the other hand exhibits essentially the opposite behaviour: good idle and street characteristics, but runs out of breath at upper RPM.

So... why not try a hybrid port system; i.e., one that uses traditional stock side ports for low RPM idling and "street" RPM ranges, with a P-port system for upper RPM work? A staged intake system that switches from side port to P-port would have to be designed/built, of course, but wouldn't this offer the best of both worlds?

I was just wondering...
-Mark

Klar

Search for semi-pp.

I thought about the intake thing as well, but pushed the idea aside for it was way too much for a street car and too unnessasary for a race car.

peejay

No. Not too high... well below five figures.

No. They make power everywhere.

Mine will idle at 600 if I wanted it to. The carb I have on it is way too big, and it won't idle by itself for very long unless I turn the idle up past 1200. It'll do 600 easy, I just have to tap the throttle every few seconds because the engine doesn't pull enough vacuum to keep the carb flowing fuel. EFI would definitely solve this. (So would using a carb that wasn't stupid large )

It also spins the tires from a roll at 2k in First. Fuelling issues are preventing me from doing much more than that, my fuel pump is woefully small.

OTOH, cruising in-town is right out. You can't drive it in the city below 2500 unless you're accelerating. Otherwise the bucking is just insane.

Michael_Rudy

peejay i read all that stuff about your little engine there, quite the neat project, will be neat to see some dyno info on that little beast

peejay

As soon as someone ponies up the money for dyno time, maybe. But the dragstrip is the best place to tune an engine, so dynos don't matter much to me. Plus dyno time is *expensive*.

Curtisleeyoung

Hey PeeJay, how much torque are the P-P engiens putting out at low and high rpm?