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Side valve flathead diesel - theoretically possible ?

Side valve flathead diesel - theoretically possible ?

(OP)
Given a first-half-of-last-century-side-valve-flathead configuration. Add turbocharging and direct injection. Would it be theoretically possible to achieve sufficient compression while still maintaining enough transfer area for the air to enter and exit the cylinder?

Of course, the additional combustion chamber surface area and inefficient air flow would limit power, but has any thing like this ever been done? Any practical reason it couldn't be done?

jack vines

RE: Side valve flathead diesel - theoretically possible ?

It's really hard to get a high compression ratio and decent volumetric air flow efficiency out of a flat head even for spark ignition. To get enough compression to ignite direct injection would be much harder. The link mentioned a rotary pump which in WWI would have meant indirect injection and a pre-chamber combustion system, even worse efficiency. I think only the military would want such a beast but in WWI they still had plenty of gasoline powered vehicles and all airplanes were gas (no jets for another couple of decades) so they should have had plenty of gasoline around to run a gen set.

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RE: Side valve flathead diesel - theoretically possible ?

Study the difference between Miller cycle, Atkinson cycle, Otto cycle, and Diesel cycle and you will understand a lot. Specifically focus on the Atkinson cycle and it's attempts alto make a smaller combustion chamber without raising compression to emphasize how obsolete side valve engines are.

RE: Side valve flathead diesel - theoretically possible ?

Obviously it is possible to do, but does not seem like a good idea. One consideration with side-valve, flat-head engines is that the combustion chamber space must provide enough clearance for the valves to fully open and provide sufficient transfer port area between the combustion chamber volume and cylinder bore for gas flow. Given these basic requirements it is difficult to design an efficient CIDI combustion chamber configuration. The huge surface area/volume ratio of this cylinder arrangement would also result in poor thermal efficiency.

RE: Side valve flathead diesel - theoretically possible ?

A history lesson: The clerestory (clear story) engine could, if you wanted to, be described as a "real" side valve engine, although not of the "flat head" variety. In the clerestory combustion chamber, so-called because there was some slight similarity to the clerestory building architecture, the inlet and exhaust valves approached the chamber from the sides. The inlet valve was typically in a cage, which when removed, gave access to the exhaust valve immediately opposite. To make the combustion system work, bulk air swirl was necessary, and this was provided by a poker piston and by positioning the swirl chamber off center so that the air entered tangentially. The initial premixed burn impinged on the reduced diameter of the poker, then the main expansion acted on the full piston diameter, thus reducing the diesel knock noise.

Many British engines (and maybe others) from the 1930's up to through the 60's used this system, usually in naturally aspirated form in which case they would typically develop about 7 bar BMEP. One of the limitations of the concept was the flow restriction at the throat into the cylinder bore. The concept is fully disclosed in the Blackstone patent GB433838, and a couple of views from different engines is shown below; the first is a Gleniffer marine engine, and the second is a Russell-Newbery engine.

PJGD




RE: Side valve flathead diesel - theoretically possible ?

And some engines used an overhead valve for intake and a side valve for exhaust. From memory possibly some Rover and RR engine?
What is the CR of these side valve diesels? I think some early diesels were as low as 10:1.

RE: Side valve flathead diesel - theoretically possible ?

The Rolls Royce engine was a large overhead valve and a side valve exhaust, when they went away from sleeve valves. Later engines were just overhead valve.
B.E.

You are judged not by what you know, but by what you can do.

RE: Side valve flathead diesel - theoretically possible ?

(OP)

Quote:

if you wanted to, be described as a "real" side valve engine, although not of the "flat head" variety.

Yes, a given in my initial post. The question was can it work at all?

Quote:

I think some early diesels were as low as 10:1.

What is considered the minimum CR for reliable compression ignition?

Quote:

if you wanted to, be described as a "real" side valve engine, although not of the "flat head" variety.

Very interesting, although most would consider that an OHV head with 180-degree included valve angle.

jack vines

RE: Side valve flathead diesel - theoretically possible ?

Automotive diesel compression ratio has been trending lower, with most modern designs having 16-and-change:1. Glow plug operation is required for cold starting at that level, many of them keep the glow plugs on after engine start for a period of time during warm-up (or until the coolant temperature reaches a threshold) to assure ignition, and I've heard (but never verified myself) that some of them turn the glow plugs on after a period of coasting (e.g. down a long hill) in order to ensure reliable ignition when the engine has to take up the load again.

The design above is an interesting one that I've never seen before. Thanks for posting that!

RE: Side valve flathead diesel - theoretically possible ?

PackardV8- Out of curiosity, what is your fascination with a side valve recip diesel engine?

RE: Side valve flathead diesel - theoretically possible ?

(OP)

Quote:

PackardV8- Out of curiosity, what is your fascination with a side valve recip diesel engine?

Merely random train of thought while examining yet another flathead design and wondering "What if?"

I build obsolete engines and am at present doing a '41 Studebaker Champion flathead. Naturally, the convoluted, restricted flow path and large chamber area means low efficiency; only 90 gross horsepower from 170" (2.8l). So, think about removing fuel from the intake passage, then air under pressure finds its way more easily, thus turbocharged with direct injection might be interesting. The large surface area of the combustion chamber would benefit from two spark plugs per cylinder and add knock detectors and computer control of ignition and fuel. Sort of like a stone axe with a titanium handle.

The last and greatest of automotive flatheads is the Packard nine-main bearing straight eight from 1954. Obviously, that bottom end can withstand more pressure than the intake flow can generate, so could it become a turbocharged diesel?

jack vines

RE: Side valve flathead diesel - theoretically possible ?

Maybe with a big supercharger..

Mike Halloran
Pembroke Pines, FL, USA

RE: Side valve flathead diesel - theoretically possible ?

(OP)

Quote:

Maybe with a big supercharger.

With a sidevalve, the intake and exhaust are conveniently located for twin turbos.

Which brings up another question. At what boost level does an intercooler become necessary?

jack vines

RE: Side valve flathead diesel - theoretically possible ?

There's no line in the sand for that. I have a supercharged motorcycle, it runs pretty high boost (~1.2 bar approaching redline) and it's not intercooled because there's nowhere to put one. Compression ratio is lower than a comparable normally-aspirated engine, and it has a knock sensor and uses it, and since it uses a centrifugal supercharger, it inherently has less boost pressure in the circumstances where detonation would otherwise be more prevalent (low revs). But this is a DOHC pentroof with central spark plug layout, certainly not a flat-head and not a diesel.

Beyond about 0.6 - 0.8 bar, it's worth using an intercooler if you have the space to put it.

RE: Side valve flathead diesel - theoretically possible ?

Intercooler or not - depends a lot on whether the engine is diesel or SI. Then for SI engines the question of "wet" or "dry" air through the compressor makes a lot of difference.

je suis charlie

RE: Side valve flathead diesel - theoretically possible ?

If you are really going deezul, I wonder if having the turbos make the intake charge all toasty would be a help?

As far as supercharging the inline 8, didn't Packard to that for one of the concept cars that actually ran? Maybe the Panther Daytona?

RE: Side valve flathead diesel - theoretically possible ?

(OP)

Quote (As far as supercharging the inline 8, didn't Packard to that for one of the concept cars that actually ran? Maybe the Panther Daytona?)


Correct, sir. The Packard engineers used a McCulloch variable speed supercharger blowing through the Carter WCFB 4-bbl carburetor. The Caribbean 8.7:1 compression 359" engine made 212 gross horsepower. This is the highest horsepower and compression ratio I've ever seen in print for a sidevalve passenger car engine. Since it was prone to pre-ignition, the estimated 250 horsepower supercharged engine would have had to have the carburetor jetted bog rich to drown the pings.

jack vines

RE: Side valve flathead diesel - theoretically possible ?

Speaking of formidable flathead engines from the fifties, the Hudson 308 cid wasn't too shabby. IIRC, the 308 powered Hudson Hornet dominated NASCAR from 1952-1954, against determined competition from Oldsmobile, with its OHV V8 of more modern conception. Of course the underlying vehicles, and the respective team development efforts played a role in the outcome; i.e. the powerplant was by no means the only factor in success.

"Schiefgehen wird, was schiefgehen kann" - das Murphygesetz

RE: Side valve flathead diesel - theoretically possible ?

Quote (PackardV8)

The last and greatest of automotive flatheads is the Packard nine-main bearing straight eight from 1954

Nice! The side-valve flat-head recip auto engine has seen its day, and I doubt it will ever be resurrected for new applications. However, I love the fact that there are a few hardy souls such as yourself having a good time pushing these old flat-head engines far beyond what their designers could have imagined.

RE: Side valve flathead diesel - theoretically possible ?

"The last and greatest of automotive flatheads is the Packard nine-main bearing straight eight from 1954. Obviously, that bottom end can withstand more pressure than the intake flow can generate, so could it become a turbocharged diesel?

jack vines"

=============

The Packard inclined valves are pretty interesting. Look like a possible advantage.
Page 8 here (but for 5 main bearing engine )-
http://www.packardinfo.com/xoops/html/downloads/pa...
I'd like to see one of those con rods. Real broad shouldered taper toward the big end, like a FORD FE Lemans or Norton short stroke.
https://www.428cobrajet.org/sites/default/files/im...
http://i17.photobucket.com/albums/b73/Les3066/Nort...

One of the production flathead/side valve engine's appeals was simplified machining, with the bulk of the machining done making a bunch of parallel holes in the block.

I'm not sure if the pretty highly developed Harley XR and XRTT side valve race engine stuck with vertical (to the gasket surfaces) valves.
Edit - As Packard pointed out, I should have said KR , not XR

RE: Side valve flathead diesel - theoretically possible ?

(OP)

Quote:

I'm not sure if the pretty highly developed Harley XR and XRTT side valve race engine stuck with vertical (to the gasket surfaces) valves.

Assuming you mean the sainted KR racers; the most highly developed and most efficient flatheads ever. Because the KR cam lobes are parallel to the crank axis the valves had to be parallel to the bores. The auto flathead inlines had lobes perpendicular to the bores, so it is easier to incline the valve head a few degrees toward the bore.

jack vines

RE: Side valve flathead diesel - theoretically possible ?

Yeah its possible.. Hard with the most common idea of a side valve engine, but possible.

2 strokes, in essence, are side valve engines.

Even in a poppet-valve flathead, you could seal the combustion chamber from the intake/exhaust chambers and then un-shield them as the piston moves. The piston and head would form a prechamber, and this charge would compress and ignite the rest of the fuel/air charge as it moves.

The benefits to doing that are unimaginable, as in, I have no idea why you would do it exactly like that lol.

"Formal education is a weapon, whose effect depends on who holds it in his hands and at whom it is aimed." ~ Joseph Stalin

RE: Side valve flathead diesel - theoretically possible ?

(OP)

Quote:

Even in a poppet-valve flathead, you could seal the combustion chamber from the intake/exhaust chambers and then un-shield them as the piston moves. The piston and head would form a prechamber, and this charge would compress and ignite the rest of the fuel/air charge as it moves.

Interesting you suggest what had crossed my mind early in the virtual design, but I couldn't see any way to seal off the valve and transfer area before it bled off too much volume during compression. If turbocharged, it's possible there could be sufficient density in the piston chamber. However, as compression ignition occurs, what happens as the piston descends and the valve and transfer area is opened? The expansion goes there and less is available to push the piston down?

jack vines

RE: Side valve flathead diesel - theoretically possible ?

"but I couldn't see any way to seal off the valve and transfer area"

A sleeve valve? :)

je suis charlie

RE: Side valve flathead diesel - theoretically possible ?

^ Exactly. Sleeve valve like a 2 stroke.

Detroit diesel basically built what we're discussing.. And it is one of the most beloved engines that there has been

"Formal education is a weapon, whose effect depends on who holds it in his hands and at whom it is aimed." ~ Joseph Stalin

RE: Side valve flathead diesel - theoretically possible ?

The DDC two-stroke engines were uniflow designs that used piston controlled intake ports in the lower cylinder wall and cam/spring regulated poppet exhaust valves in the cylinder head. The combustion chamber was a dish in the piston crown. And the fuel injector was centrally located between the 4 exhaust valves in the cylinder head.

The only part of those Detroit Diesel 2 stroke engines that I recall anyone having a "love" for were the Roots scavenge blowers that drag racers adopted to supercharge their race engines.

RE: Side valve flathead diesel - theoretically possible ?

DDC engines certainly sound good.

RE: Side valve flathead diesel - theoretically possible ?

(OP)

Quote (The only part of those Detroit Diesel 2 stroke engines that I recall anyone having a "love" for were the Roots scavenge blowers that drag racers adopted to supercharge their race engines.)


There are myriad DD fans still out there. One quote which sums up their attitude: "When our sun is cold and dead, as is the Earth revolving around it, the only thing still living is that Detroit Diesel at its core driving the turntable."

jack vines

RE: Side valve flathead diesel - theoretically possible ?

^ and its letting off a beautiful symphony of combustions while doing it.

"Formal education is a weapon, whose effect depends on who holds it in his hands and at whom it is aimed." ~ Joseph Stalin

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