well, I can't tell what is exactly the diffrence... but I can tell you guys this: I had a 1977 dodge polara RT wich had the stock manifold on it. OEM carburetion for this car was a large 2 barrels holley 2300, wich was blueprinted from one made by penin and then mass produced by argelite s.a. (argeninian license holder for many carbs factory). I swapped in a penin manifold (in fact, my grandfather took the car to the very inventor of this manifold, Mr. Nestor Penin) and having changed nothing besided that manifold the car started to behave VERY diffrent, more low end, nicer feel over the entire rpm range, even better economy. That's first hand experience. Unfortunately by the time grandpa died, I had to sell the car and I didn't have time to install back the stock manifold.
Supposedly penin tuned the runners on that manifold, gave them some sort of taper... he modified the cross sectional areas all over the piece, intalled the divider and reworked the plenums area... I can't tell what or how he modified cuz I was a young boy by that time (very young, I even had hair on my head, now that hair has either gone or moved to my body
) and even though I enjoyed fooling around motors, cars and good mechanichs, I wasn't able to fully understand what was going on....I think that a good M1 intake can serve as a pattern so we can get a closed manifold so everybody can have their own custom setup machined without adapters... carters, holleys, solex, whatever carb one could want to install on a slant.
I'll try to get one penin manifold, as I've been trying hard for the last 5 years, but it's a long shot.
) with that.
