2 Stroke 911?

[ClickClickBoom]

Has anyone tried to make a 2 stroke 911? It seems that the individual exposed barrels would lend it to a Detroit Diesel type of system. Use a turbo to force the induction. 2 times the power strokes.
https://www.youtube.com/watch?v=yR9I1x2Ix-0&list=RDQMrynMoZ5QhbA&index=2

[manbridge 74]

There was something about this in Italy back around 1970. Supposedly it was the last dream of a top fabricator there but I think he passed before attempting. I will look for it. With today’s new fuel injected KTMs etc, it could even be clean running. Provided you had unlimited resources and wallet.

[2jmotorsports]

Stretch your R&D budget and try the concept on an aircooled VW flat 4 and if it works kick it up 2 more cylinders...

[Fly911]

A modern two stroke is superior to four strokes in most areas. Better power to weight ratio, fewer moving parts, way more torque, better fuel economy, less maintenance, cheaper to build, sound better, etc. etc. But a horizontally opposed two stroke will have to fire two and two cylinders simultaneously, making a flat six sound like an inline three cylinder. The boxer principle was used by Evinrude in the 20's and 30's, mostly to get a better balanced engine. For modern two strokes, inline or V-configuration is the only option that makes sense.

[Quicksilver]

A major problem would be heat. If you double the power production you will double the quantity of heat that needs to be removed from the engine to keep it from melting down.

[slingshot-930]

Hi folks,

the Italian engine wizzard, Gabriele Gottifredi, was a very good friend of mine. He developed
some pretty nice projects, such as the 3-valve head Porsche engine (Neat Post of the day: Porsche 911 3-Valve Engine! an own MFI injection pump.
He also built some nice cars, such as Once upon a time... MFI ST Racecar or even an own Group C car.

But today, we want to talk about the Porsche 2 stroke experiment. In the very first years of his carreer, Gabriele worked in the engine development department of Italian go-kart manufacturer
Parilla. They sent him to the USA, as the Parilla engines were under pressure from the competitors.
He started studying every possible type of two stroke engines, from big diesel 2 stroke turbo engines, to marine engines and even chainsaw engines. Back in Italy, he built a 2 stroke DOHC
kart engine for Teo Fabi (who later became pretty famous as a racing driver also in the US) and his
brother.

[slingshot-930]

Over the years Porsche engines became Gabriele‘s absolute passion. At a certain point, he started
a 2 stroke project for a race car, but also due to some changes of the rules, it was abandoned.
I don‘t know how far the whole engine configuration was really developed or even tested, but I
have some pics of a cylinder and an intake of that project.
Unfortunately, we can‘t ask Gabriele anymore, as he passed away some years ago and he took some of his secrets with him to Porsche heaven, in order to discuss them with other maniacs there...

[piscator]

Slingshot,

Thanks for your contribution here, that lead me to your other thread, which was fascinating. Certainly among the most interesting I've ever read here on Pelican. You have a wonderful writing style and I hope you share more of your stories and great photos!

[2jmotorsports]

This is fantastic content. A very much appreciated deep breath of fresh air.

[ClickClickBoom]

Proof,
No matter how fantastical an idea, its probably, not jut been thought, it might even have been tried.
My theory is, while 2 strokes have traditionally been thought of dirty and inefficient, the lure of an increase of power strokes by 100% seems like a relatively inexpensive way to increase HP. Add Direct Injection an ECU and some sensors. The 935 block is good for 800+HP, so with some minor mods a 2 stroke intake system is not a Mars shot.

[Mocker]

As the owner of a Yamaha RD350 and a Lambretta SX200 (as well as a '79 930), I approve of this discussion!

[manbridge 74]

Water cooled P/Cs like on KtM etc would be required for heat management. Six expansion chambers might be tough but what an engine sound this would be. Remember Kenny Roberts? He called all four strokes diesels. 250s make about 50hp so 300hp for six. The bottom end lubrication and fuel injection would be another issue to overcome.

[ClickClickBoom]

Originally Posted by manbridge 74

Water cooled P/Cs like on KtM etc would be required for heat management. Six expansion chambers might be tough but what an engine sound this would be. Remember Kenny Roberts? He called all four strokes diesels. 250s make about 50hp so 300hp for six. The bottom end lubrication and fuel injection would be another issue to overcome.

Look at a Detroit Diesel, the bottom end is like a regular 4 stroke. The only difference between a Detroit and a 4 stroke is the induction, instead of valves they use the piston, along with forced induction either with a mechanical supercharger or turbo(s). It’s not that a big of a stretch. Expansion chambers are not required there are 2 perfectly useful valves in that head. Not saying that this is a home shop project, it is a thought exercise.

[manbridge 74]

Oh yeah, total thinking out loud here too. I thought the Detroit diesel wasn’t a revver though? Getting rid of the valves makes for simplicity...

[ClickClickBoom]

Revisit, I can’t pry it out of my head...
For a fixed displacement there are 2 ways to make power, BMEP and RPM. RPMs cost a lot to make signifantly more, BMEP is limited by octane, but doubling the powerstrokes could be easier. Turbos have become almost ubiquitous, direct injection is already here. Cylinder heads have space for a second plug, injector would be simple.

[ClickClickBoom]

Ferrari:
https://www.youtube.com/watch?v=enW9ajxi0lE

[Marc Bixen]

Teo Fabi's brother was Corrado I believe. Quite a good driver himself, made it to F1 for a couple of races.

[ian c2]

There’s rumors of formula 1 going 2 stroke ...

Saab did it years ago irc

[dicklague]

Originally Posted by ian c2

There’s rumors of formula 1 going 2 stroke ...

Saab did it years ago irc

I learned how to drive on a 1959 Saab 93b......3 cylinder 2 stroke....the I had a 1960 95 2 stroke station wagon.......and later a 1966 Saab 96 2 stroke......kept that through 1979.

Great little cars and guys like Tom Donney and others are keerping them alive.

[ian c2]

Yip .
Will be interesting viewing of f1 go that route in “the formula” ...

When the world wanted low cc high efficiency cars , They went 1.6 turbo ...
Other technology ground to a halt apart from aero .
No need for transmission Progression when you can use whatever ratio you like and have forced induction power to pull you back into power .

Now they’re committing to lowering carbon footprint , 2 stroke is being touted as the key .

Will they make it work ?
Damn right they will !!
They’ve allways made the formulae work .
I see advances in transmissions , reliability , and gas usage having to be top priority .
After all with twice power strokes you have to use twice fuel , right ?
They’ll work that out , but hopefully change the fuel flow and amount rules to give us some exciting sounds again .
Can’t wait to hear f1 cars that scream like the older v10s as they allways sounded The most cool and screaming to me , like a 2-stroke 125 getting its balls wrung out

I’m hoping it will take us in the direction of the cars that played music * , rather than the old days where your executive family saloon car was faster ( the days when they realized they had to do something )


*
I’ll go find a video on my iPad of the best example of this and report back