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Robert M

I think my 912E actually handled a bit better than my 911S when tackling twisties. Might have been something vehicle specific.

The early 2.0 liter 911S "fixed" the "happy tail" by installing steel weights in the front bumper. Factory fix. So yeah, the 912 DID handle better, until they lengthened the wheelbase(which the 912E certainly had).

@Stan Galat posted:

Which Porsche factory 4? The 356? The Type 4? The new 718 turbo motor?

I can easily make an argument against the first and the last options. It’s the one in the middle that legitimizes the question.

The only real advantage of a 911/4 over a good Type 4 is the “cool factor”. It’s not more powerful, lighter, or anything else. It is hypothetically able to rev higher, but not in practice.

A big T4 is hard to argue against.

I agree, kinda. The 911/4 has better breathing, having straight crossflow cylinder heads. Straight in from the top, straight out the bottom. The type4 is crossflow too, but it takes a LOT of work to equal the 911 cylinder head. The flat-top type4 pistons are not as efficient as the 911 domed pistons and chamber, plus the valves are offset from the direction of flow. Plus the 911/4 is dry sump(which is more efficient AND cooler).

Still, the hopped up type4 is a GREAT motor. I'd love to have the 911 in any form, 4 or 6.

Every platform makes some compromises, for sure. The canted valves in the 911 are nice and the T4 ports are less ideal… but in my limited understanding of what’s happening in the combustion chamber, a domed piston is something necessitated by the 911s nearly hemispherical chamber, which (while state of the art in the 70s) is no longer “the ideal”. A heart-shaped chamber with flat-tops and “quench pads” are the new(ish) preference. Old air-cooled big-bore 911s use twin plugs because the shape of those chambers isn’t great for a quick flame-front.  

Everything cool uses OHCs, but I’m the weird guy who would prefer pushrods, assuming an equal redline. The complexity is a lot higher with a 911 or 911/4, but there’s no question that an OHC arrangement offers a higher hypothetical redline.

… but the main argument for them is that they are really, really cool, and make some awesome sounds, and have a far more robust bottom end. The bottom end is what gives me pause. No T4 can equal that.

@El Frazoo posted:

I'm stumbling a little on the idea of going from six to four cylinders. Seems like an lot of very special work with industrial tooling, not a Sawzall --- to what end?  I was just getting down with more is more, and now it's not??  WTF??

to @Stan Galat and @DannyP as well:

From memory ... didn't Chuck make that prototype 911-4 back in the 1980s, somewhat before Jake Raby was learning to work magic on the Type IV platform? If I recall this right, The engine was made for a Beck 904 because the other guys were claiming the flat 6 in Chuck's car gave him an unfair advantage on the track and so, being Chuck, he created the 4-cylinder version in order to shut them up... And did. And basically invented what is now known as the Polo engine?

I mean, I love that story. I think it might be somewhat true?

And, was this not said circa 2017 when that very engine was offered for sale on this very website?

Ed, I'm not sure about any of that history. But I'd bet if you asked Carey and Kevin Hines they could fill you in.

I do know that sometime in the 80s(maybe?) Dean Polopolous(sp?) was making/building these for not a lot of money, considering the work involved. Hence, the "Polo" motor.

I believe they were always built using early aluminum cases(before they switched to Magnesium).

Think about it: case cut in two places and welded together, then machined back to spec. The two cam carriers cut and welded(or maybe merely shortened). Include running a drill through oil passages(in both the case and cam carriers) to ensure they're open and clean. The crank and cams both get shortened.

I think the only parts not messed-with are the heads, pistons, and cylinders. And cam and crank sprockets and chains. I'm curious if they merely shortened the oil pump drive shaft(intermediate shaft).

Custom intakes, custom exhaust, custom shroud.

LOTS of work, but VERY, VERY cool.

Unrelated totally but many years ago I cut a 1600 cc case more or less in half to make a two cylinder engine for a small airplane and it ran fine. Stranger indeed, one year at the Sun n Fun airshow / exhibit I saw a guy running a 3 cylinder vw 1600 variant at the experimental engine exhibit area. One big cylinder and piston on one side ( can't remember front or back ) and two smaller ones on the other side. It ran as smooth as silk and he admitted to a very serious amount of balancing and further reinforcement on the crankshaft. I asked why he did this and he said " I couldn't get to sleep one night".....  :-)

@DannyP posted:

Ed, I'm not sure about any of that history. But I'd bet if you asked Carey and Kevin Hines they could fill you in.

I do know that sometime in the 80s(maybe?) Dean Polopolous(sp?) was making/building these for not a lot of money, considering the work involved. Hence, the "Polo" motor.



It’s all in Carey’s classified ad in Ed’s post. Chuck designed and built the first one, sold the tooling to Dean.

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