Modular 2 & 4 stroke engines (inline, boxer & V alignments) is this possible?

tuprox · May 23, 2017

I'm not a real engine guy, I know enough to work on them a little, but don't have a great visual comprehension in my head to look at all the necessary parts for a 2 or 4 cycle engine to know if this is possible or not.

I was looking at basic engine design and was wondering if there is any way to make an engine where the cylinders can be stacked in a row, each cylinder being a modular unit and the cam shaft being modular as well where more cylinder lifters (IDK what they are called) can be added as per cylinder and have a terminating end with the modules going in the middle. IDK if a cam shaft could be done this way (for 4 cycle) and if not, a specific cam could be purchased for cyinder # used.

Basically I'm wondering if it is possible to make an engine in either flat/opposing cylinders (boxer type), inline, or V type where the engine block doesn't exist as we think of it now but as multiple cylinder modules bolted together. So an engine of any number of cylinders could be made (even number for boxer or V series).

I would think that one of the major difficulties would be the oil pan(s).

Milland · May 23, 2017

It's possible, might be easiest in a boxer configuration due to balance issues. But the biggest problem might be torsional stiffness of an "infinite" crankshaft, either you'd need a massive standard crank for a given displacement, or you'd have a longer one flexing as more cylinders are added, which means extra vibration and erratic cylinder firing. Not good for NVH or lifespan. Ditto camshaft twist.

Some Porsche engines had their power takeoff in the middle of the crankcase, allowing longer cranks with more cylinders but minimizing torsion issues. A prototype flat 16 was made but never raced.

michiganbuck · May 23, 2017

Seems that I saw such an engine that employed stackable cylinders. I can't now remember who made it or if a test engine or in production. Stacking error would make crank shaft thrust clearance difficult, and heat transfer and absorbtion anothe problem. Thought it was a Man marine engine but can't find the the like in the Man catalog. Use to be so very difficult to make a special engine but now with CNC machining not so difficult. I have a few engine designs, one for a racing engine and one for high economy...likely never will get built.

One big problem was variable valve timing.. yes I had that on my Jaguar 6 but one had to pre-set the timing and that was it..so not variable on the fly. Now some engines can do that.

Monobloc or en bloc engine (casting the cylinders and the head of one part) offers some advantage...higher oct fuels and higher compression could be used..

DDoug · May 23, 2017

Loco engine, cylinders are "power assemblies" and camshaft is in cylinder width pieces.

moonlight machine · May 23, 2017

Milland said:
It's possible, might be easiest in a boxer configuration due to balance issues. But the biggest problem might be torsional stiffness of an "infinite" crankshaft, either you'd need a massive standard crank for a given displacement, or you'd have a longer one flexing as more cylinders are added, which means extra vibration and erratic cylinder firing. Not good for NVH or lifespan. Ditto camshaft twist.

Some Porsche engines had their power takeoff in the middle of the crankcase, allowing longer cranks with more cylinders but minimizing torsion issues. A prototype flat 16 was made but never raced.

I'v never seen a Porsche engine that took power off the center of the engine, which engines are like this? I know the 16 cylinder 917 drove off the end as in any normal engine. I have seen this car in the Porsche museum in Stuttgart.

michiganbuck · May 23, 2017

OT: not multiple cylinder modules bolted together
Flat engine - Wikipedia

Opposed-piston engine - Wikipedia

https://en.wikipedia.org/wiki/Junke...kmuseum_Hugo_Junkers_Dessau_2010-08-06_01.jpg

Milland · May 23, 2017

moonlight machine said:
I'v never seen a Porsche engine that took power off the center of the engine, which engines are like this? I know the 16 cylinder 917 drove off the end as in any normal engine. I have seen this car in the Porsche museum in Stuttgart.

A quick search says that it was done for the flat 12, I would guess something similar for the longer engine. http://forums.pelicanparts.com/pors...um/481416-mating-two-911-engines-917-how.html At the least, cams were driven from the middle, and there's a reference to a central power takeoff.

If you can confirm that it was an end-driven crank I'll trust your experience...

Milland · May 23, 2017

Here's another reference to the central takeoff: http://www.autospeed.com/cms/article.html?&title=The-engine-of-the-Porsche-917&A=113244

moonlight machine · May 23, 2017

Milland said:
A quick search says that it was done for the flat 12, I would guess something similar for the longer engine. http://forums.pelicanparts.com/pors...um/481416-mating-two-911-engines-917-how.html At the least, cams were driven from the middle, and there's a reference to a central power takeoff.

If you can confirm that it was an end-driven crank I'll trust your experience...

Now there is an example of posting without thinking.....All I had in my mind was a porsche 2708 v8 engine we had apart in the dust and dirt at Phoenix in 1988. We blew up a 6 pack of them before the Germans gave up and 2 Americans fixed it the night before the race. It never ran more than 12 laps in the March chassis without flying apart. after the fix it ran the full race distance. We left the track feeling great that day, then we saw the press release from Porsche giving the credit for the diagnosis and repair to some German train drver.

WHHJR · May 23, 2017

GM did the 149 series with individual moving parts and a collection of V blocks ie 6 cyl and 8 cyl.

Milland · May 23, 2017

moonlight machine said:
We left the track feeling great that day, then we saw the press release from Porsche giving the credit for the diagnosis and repair to some German train drver.

Heh. Not the first time I've heard of such "appropriations" from that part of the world.

moonlight machine · May 23, 2017

Milland said:
Heh. Not the first time I've heard of such "appropriations" from that part of the world.

I don't remember the name of the printing haus but it is owned by Porsche and prints most of the propaganda,...err. books about Porsche. Strange, nothing but good in those books! I remember reading in Mark Donohues book, "The Unfair Advantage" about tuning the 917 engine to actually be drivable. The 2708 Indy Car program was like groundhog day. The fuel and ignition were not mapped below 6000 RPM and the battery was so small that it would only last about 12 seconds at less than 6000 revs.

Scottl · May 23, 2017

It certainly is possible but IMO the drawbacks would likely outweigh the advantages. This would not only add complexity but more seams to leak and looser overall tolerances due to stack-up. It would certainly be an expensive way to build multi-cylinder engines.

The big question is, other than intellectual curiosity, is there a point to your question?

J&H · May 23, 2017

http://www.boatracingfacts.com/foru...s-4-Rotor-Wankel-Racing-Engine-The-Real-Story

That is an incredibly long read, but it's a fascinating story told by one of the engineers of omc about their challenges in trying to stack a pair of 2 rotor wankels on top of each other for tunnel boat racing.

Bill D · May 23, 2017

I read about a early car engine that was something like a straight 16 or maybe a 12 but the cylinders were cast in sets of four. each set had its own carb and camshaft. This was demonstration model for the auto shows around 1920.
Turns out only the rearmost cylinders had pistons, cranks, rods etc. The front part of the engine was for show only. If it had made it into production the other cylinders would have been complete with all needed parts and a longer crankshaft. My memory could be wrong and it was the front cylinder that ran and longs strait crank ran the length of the block.
I believe the Jaguar v12 engine used two straight 6 cylinder heads.
Bil lD

Milland · May 23, 2017

J&H said:
http://www.boatracingfacts.com/foru...s-4-Rotor-Wankel-Racing-Engine-The-Real-Story

That is an incredibly long read, but it's a fascinating story told by one of the engineers of omc about their challenges in trying to stack a pair of 2 rotor wankels on top of each other for tunnel boat racing.

Wow, thanks for posting that. Mazda did make some successful four rotor engines, but in just the quick description you gave they went about it differently, which if I remember right was one long common shaft with two lobes and then one or two secondary lobes that slid on with keys for rotation fixing. Still the only Japanese company to win LeMans...

Milland · May 23, 2017

Bill D said:
I believe the Jaguar v12 engine used two straight 6 cylinder heads.
Bil lD

I'd bet that's what they did for their early V-12 in the E Type. The V12 in the Aston-Martin during the Ford years was two Mondeo V-6's front to back, at least in basic architecture. Not sure what Jag did for their newer 12's

Bill D · May 23, 2017

I believe aircraft radial engines could be stacked up to as many as four rows deep.
Bill D

moonlight machine · May 23, 2017

Milland said:
I'd bet that's what they did for their early V-12 in the E Type. The V12 in the Aston-Martin during the Ford years was two Mondeo V-6's front to back, at least in basic architecture. Not sure what Jag did for their newer 12's

There were a few DOHC racing v12s but the road car v12s were SOHC

Wild West · May 23, 2017

The largest engines in the world are modular component built depending on what is required. It doesn't show in detail but the crankshaft is built in small sections as is the block.

Modular 2 & 4 stroke engines (inline, boxer & V alignments) is this possible?

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