If you could do anything to a cyl head?

[Silverback]

As far as the actual question… I’d look at it a little differently… real world there are plenty of designs that on a largish engine will give you plenty of airflow to get you into RPM ranges that aren’t realistic for the rotating assemblies that most are willing/able to run. That being the case I’d shoot for maximum combustion efficiency (more compression, better bsfc, more tolerant of more aggressive valve timing… all with lesser quality/cheaper fuel…) and then hit it with a pile of boost to make more power then you can realistically use in most chassis.

Of course, some of this is driven by the fact that I don’t live in a world where I can spend tens/hundreds of thousands on rotating assemblies…, my fuel quality is limited…

The real problem with this question is that it’s too wide open. What works and is badass for say sub 2L engines in small chassis/bikes is totally different then what I would choose for say > then 5L and you start getting in another range with the monster motor big blocks. You’re just not going to build a reliable 30Krpm (isn’t that what Honda tested to in their “what rpm will combustion speed keep up… experiments?) >600cid engine, and the finer points of 4/5 valve head designs don’t really mean much in that range.

[ICTCrob]

No rotary valve is going to be able to flow a wet mixture as well as a poppet valve, if you look at lift through the range of the poppet valve vs. degree of rotation of the rotary valve, the rotary is slamming the air fuel mixture into turbulence at every angle except max opening(and probably there as well).

Only direct injection and supercharger will make a rotary valve even close to providing a engine with efficient combustable mixture...then you still have lame combustion chamber with the two spheres that can't be sealed.

If the rules stated only a two valve, I'd build a head much like that of the Dart Little Chief.

-Rob

WWW.ICTCengines.com

[Ron E]

One more vote against a rotary valve. I'm weak on imagination, but if two valve, the further rotated layouts, (Hemi 99,P5) but with more exhaust-valve angle would be where I'd start. If the cam was high enough, for decent rockers, I'd try to bridge the gap from the center of the chamber to near the deck with the exhaust valve angle. All this assuming we're talking a hi-compression capable engine.

[Gary Blair]

I would opt for a gas DI engine with microprocessor actuated pneumatic
valve train. No rockers, followers, lifters, push rods, or cam.

[BCjohnny]

Guess somebody's gonna post next that sleeve valves don't work either.......

John.

[SchmidtMotorWorks]

Guess somebody's gonna post next that sleeve valves don't work either.......

OK, I'll bite, can you post a modern example of a sleeve valve functioning at a level comparable to current poppet valves? How about poppet valves of 1960?

[PackardV8]

Bit of a tangent here, but one of the most interesting poppet valves I have ever seen was invented by a Kiwi named Ralph Watson, as I remember. Imagine a valve with the stem just above the head bent 90* and without a conventional vertical guide. The idea was, it swung open sideways like a submarine hatch cover, thus getting completely out of the way of the seat and port. Only the stem remained in the port. He showed great flow in the sub-4,000 RPM ranges on an opposed 4-cyl Lycoming aircraft engine. It flowed about 25% better than the low-lift OEM setup, but the manufacturer wasn't interested in the long-term durability testing necessary to certify a new aircraft engine component.

From what I remember, he could never get it to live at higher rpms or figure out how to work around the water jackets in water cooled engines. Will look for old magazine reports, but I remember seeing it in a home-built sports car at some Kiwi race back in the 1960s or early 70s. His slow-turning big four-banger sounded like a low-flying small plane, compared to the higher-revving water-cooled fours of the time. he won a lot of races down there because of the durability of his Lycoming and the lack thereof in the Brit crap of the day.

thnx, jv.

[Darin Morgan]

Guess somebody's gonna post next that sleeve valves don't work either.......

John.

The Napier Sabre Sleeve Valve engine was a bad ass design in WWII and they do work, but it is limited to a very low rpm range due to the kinetic energies associated with the mass of the cylinder sleeves and the friction power losses associated with the overall surface area of the sleeves themselves. A sleeve valve engine has ten times the surface area so frictional power losses skyrocket almost exponentially at higher and higher RPMs. Very cool and innovative design but not a high RPM power maker. High VE at low RPM (Torque), that is what they are good for. At an amazing 1.36hp/cid they where the most efficient engines of WWII. The Merlin and Allison engines made .98hp/cid

http://en.wikipedia.org/wiki/Napier_Sabre

http://www.eagle.ca/~harry/aircraft/tem ... /index.htm

I personally like the P5 design for two valve and the pent roof four valve for over head cam engines. If I could do ANYTHING I wanted,,,,,,,,,, I would have to evaluate the situation and pick the best design to fit the needs of that situation. The engines intended purpose will be the ultimate deciding factor not how many valves or where you put the cams. For ultra high RPM ultimate power, four valve pent roof with dual over head cams with a rocker follower at 1.35 to 1.4 ratio would be the most efficient in my opinion. Pneumatic valve return system mandatory. A 500 cid engine could make about (estimating here based on HP/cid and rpm gain for peak TQ) 1550 to 1600 horsepower at 10800 to 11000rpm with a shift piont of 11500rpm. I can dream cant I? I don't think we could push the piston speeds much higher than that.

[Unkl Ian]

Or maybe I'd figure out how to make a clear cylinderhead,
mount it on a dummy motor,hook up a high speed camera,
to do wet flow experiments,and try different quench areas.

Having the cylinder cycling would give some real world feedback
on how things work inside.

[ACE]

I've never been a believer in the rotary valve design, and was going to blast it pretty hard at the beginning of this thread, but it sure has become an interesting topic. One thing for sure, there needs to be a place to showcase these ideas, in a very high profile and profitable situation. Personally, I would like to see some changes in some racing venues like NHRA Pro Stock and Nascar Cup. I would like to see them eliminate rules requiring pushrods, valve springs, and carbs. Let the guys who have the big bucks to spend on new technology go after it. Anybody who can build a better mousetrap, should have the opportunity with a chance for reward. The sooner it can float down to rest of us, the better. Maybe someday we'll see a 500 cid pro stock engine put out 1700HP with .25 BSFC!

[Windsor377]

powered by pure hydrogen and oxegen derived from an on board water source

Sounds good but what power source will seperate the water in to H and O?

Nuke Power? In that case you could do without the conversion and just steam the water like powerplants do.

A bank of batteries that weighs a couple of hundred lbs and is charged by plugging it in in your garage and using electricity generated by a coal fired powerplant. Hey, it’s zero or at least low emissions as long as I don’t have to see it, right?


Why all the extra steps? If you want electric motors then just run them off of the batteries used for the electrolysis, and save yourself the weight of the water tank, electrolysis equipment, generating equipment… if you want to build a hydrogen powered zeplin then just leave the electrolysis setup at home and save all the weight and multiple energy conversions.

But do us all a favor, unless you run the electrolysis setup at home off of batteries charged by solar cells on your roof don’t try to sell it to us as the eco friendly solution. Oh, and don’t do it in my neighborhood unless you’re going to burry the whole setup in a bomb proof bunker far enough underground not to hit my house with the shrapnel when your setup blows up.

I do believe I answered all that in follow up.

[Windsor377]

Guess somebody's gonna post next that sleeve valves don't work either.......

The Napier Sabre Sleeve Valve engine was a bad ass design in WWII and they do work, but it is limited to a very low rpm range due to the kinetic energies associated with the mass of the cylinder sleeves and the friction power losses associated with the overall surface area of the sleeves themselves. A sleeve valve engine has ten times the surface area so frictional power losses skyrocket almost exponentially at higher and higher RPMs. Very cool and innovative design but not a high RPM power maker. High VE at low RPM (Torque), that is what they are good for. At an amazing 1.36hp/cid they where the most efficient engines of WWII. The Merlin and Allison engines made .98hp/cid

http://en.wikipedia.org/wiki/Napier_Sabre

http://www.eagle.ca/~harry/aircraft/tem ... /index.htm

I personally like the P5 design for two valve and the pent roof four valve for over head cam engines. If I could do ANYTHING I wanted,,,,,,,,,, I would have to evaluate the situation and pick the best design to fit the needs of that situation. The engines intended purpose will be the ultimate deciding factor not how many valves or where you put the cams. For ultra high RPM ultimate power, four valve pent roof with dual over head cams with a rocker follower at 1.35 to 1.4 ratio would be the most efficient in my opinion. Pneumatic valve return system mandatory. A 500 cid engine could make about (estimating here based on HP/cid and rpm gain for peak TQ) 1550 to 1600 horsepower at 10800 to 11000rpm with a shift piont of 11500rpm. I can dream cant I? I don't think we could push the piston speeds much higher than that.

Never say never...

PS, do you mind if I ask what you see in the P5 that you don't see in the Splayed Valve?

Thanks.

[Ron E]

PS, do you mind if I ask what you see in the P5 that you don't see in the Splayed Valve?

Thanks.

I realize it's directed at Darin, but, I'll toss mine in for him to correct or expand on. On the P5, the I-valve to bore relationship has better short-side flow organization potential. The flow in that area degrades at a more gradual rate. (better diffusion properties). This is simply due to the bore location. It eases the expansion rate. (Of course, it ain't automatic, but the valve/bore relationship helps in this goal.)

When viewed from above the engine, the intake runners are straight, if using 2 carbs. Unlike say a single-plane, with the 2 4bbl arrangement and the high port angle, the possibility exists for a lot of fuel to reach the chamber without actually coming in contact with the port-walls. The P5 arrangement removes the curves from that plane, which I think is a plus.

Nothing about the P5 exists that can't be incorporated into the new played casting, it's just the p5 is closer without "moving stuff around." It's amazing how much work the guys (Darin included) did to the early splayed heads to get them to such power levels. My observation is there would have been much less Stop-Leak needed along the way with the P5.

[Ron E]

One more tidbit. The P5's port angle approach to the bore allows less push-rod to port inteference per rocker offset.

[bc]

Where could I get more info on or pics of the P5 heads?