Engine Design & Build

[gbowne1]

Hello All!

I'm going to attempt to design and build my own engine! I'm sort of new at this but hopefully I can get hints from you all to help me. I've played around with building some small single cylinder engines just to get the idea going. Well, First of all my thoughts were to build either a 4 cylinder, a V6 or a V8 engine.

My second thought is that I want to keep the cylinder bore diameter between 2.0000" and 4.0000", but I have no idea about what stroke length to use, and I figured if I used one of the .2500" or .5000" steps between 2" and 4", I would have a nice engine. I also don't know how far apart to keep the cylinders. I also would like the engine to operate nicely and efficently when the car is at around 85 MPH, though normal speeds would be 55-65 MPH.. I would like the RPM Limit to somewhere around 7,000 RPM.

I also figured on this being a fuel injected engine. I will either use a GM or Bosch computer (was thinking about the Jetronic series from a donor vehicle), and whatever injectors will work out fine. For spark plugs, I thought of several common ones I could use. I'll put together a list of the ones I thought of, with specs along with the next post after I get a reply or two.

I figured on having flat lifters, and the 7.8" pushrods. The valves would be 1.9400" and 1.5000" diameter, all 16 of them. A flat bottom lifter 2.0000" long x 0.8410 dia. might work also. As for fueling this engine, I'm not sure what I will use, but mainly gasoline, though I'm not sure what octane rating would be best but I will have a look at whats available in this area. I figured on using a 4 speed manual transmission, similar to a saginaw.

As for belts, I figured on using either a Serpentine Belt or a high strength durable V-Belt, and they would supply power transmission to the various accessories, A/C, Alternator, etc.

That being said, I also see that from the reading and research I have done
so far, that 4 cylinder engines from 2.0L to 3.0L are popular, and V-8 engines from 300 to 400 cu. in. are popular. I have no idea about V6 engines.

Well with that said, are there any suggestions? Any other information I need or missed here?

Greg

[nyleeloise]

[/QUOTE]I built an engine way back when ,, I am going to try to forward a photo of it to you[my computor skills are limited so you may have to email me back] I don,t know how to transfer aphoto from adobe to this email Nyle

[NC Cams]

Many of the factors cited in your engine "wish list" summary are already found in many of the production V-6 and/or V-8 engines that already exist - small block Chevy and Ford's are two that have many of the specs you cite.

I'd strongly encourage you to build something using asmany off the shelf parts as the engineering and machining of MANY of the parts (cams and cranks specifically) for an engine capable of 7000 rpm and with the bores and strokes you suggest are NOT readily doable.

If you want to turn 7000 rpm, whittling a billet cam suitable for attaining that engine speed is NOT easy. It took us years to learn how to do exacly that REALIABLY and we still have issues getting stuff to live. And we have professional quality cam grinding equipment.

Your "project" is QUITE ambitious. It is beyond "extremely ambitious" for the DIY machinist - and, frankly, I know of very few professional engine "builders" who have the where withall to machine all the parts you speak of in-house - they all outsoruce stuff like rods, cranks, valves, springs and definitely cams and pistons and billet head and blocks.

[widgits]

Take a few minutes and follow my lead
Just remember where you heard it first

What would designing and building a standard internal combution engine get you?
Other than being able to say you did it?
Besides it takes years to develop such a thing if it's done right
And by the time your finally done it wouldn't be any better than what is already available

What about looking into other alternatives for building something like this
Obviously there are too many parts inside current designs for engines
Just count the parts in a standard valvetrain
I always wondered why car manufacturers and engine designers have never really pursued designing overhead rotary valve designs for use on standard
engine short blocks
Do you realize how much energy is lost in torque at the crankshaft by compressing all those springs with a lumpy stick (camshaft) just to open the valves and make an engine breath?
Wouldn't simply spinning a ported rotor with a timing belt use less energy?
Couldn't this be sealed by spring loaded carbon wipers on a ceramic rotor surface?
Could the rotor also be sealed from one cylinder to the next by the use of mechanical shaft seals much the same way turbocharger shafts are sealed today?
If a current bottom end is used it already comes lubricated and has cooling jackets already designed into it

Better yet, Throw the whole damn thing over your shoulder and start with a blank sheet of paper

Obviously the fewer moving and wear parts there are the better
Ok, you need one part for the block, better yet how about just a single cylinder, one tube thats it and it doesn't move.
Could you put sealed endcaps on it like an electric motor with a rotor shaft sticking out the ends, now you have an output shaft that force can be generated upon, Like an armature in an electric motor

Now you need someway to get compression and expansion from burning gases and turn it into rotary motion
OK hows this

Take 2 rotors from a vacuum pump booster (like a supercharger only they have straight lobes not spiraled)
Cut a slot into the center of each one halfway down their length
(yes this would remove one of the endshafts from each rotor)
This would allow the rotor to fork into each other
The best way I can explain the shape is for you to make the Star Trek Vulcan hand sign of live long and prosper on each hand by spreading your 4 fingers into a VEE shape
Now put the Vee shape on each hand together and interlock them 90 degrees apart, now your fingers on each side would be shaped and placed just like 2 straight lobed rotors forked into each other
Now twist your hands in opposite directions
See how the space between 2 sets of your fingers closes together as the others open
Another way to see this action is to take a standard pair of scissors and open them till the handles and blades are equally spaced 90 degrees apart
Now open and close the scissors all the way, see how the area closes off in one space and opens in another?
The interlocked straight lobed rotors would do the same action
The volume is achieved thru the length

Wouldn't this give a change in volume that your looking for?

Now seal the tips or the rotors with the tube (main housing or cylinder)
Possibly using something like the rotor apex seals from a Mazda wankle rotary engine
Could porting holes be put into the side of the cylinder for air/fuel and exhaust ports, or placed into the encaps to give a cross thru flow design
Air/fuel on one endcap and exhaust on the other

Now you would have to time the rotor scissor action to time it with the porting in the tube or endcaps for suck, squeeze, bang, blow
Could you use reed valves like a 2 stroke engine , or would they even be necessary?
HMMMMM
I wonder if some type of profiled slot could be cut into the endcaps or the wall of the housing tube itself and by using a cam follower be able to contract and expand the rotors in correct timing?
Being these are fixed surfaces in relationship to the porting I would think this is a logical place to start
Letting the rotation of the rotors themselves give the correct timing by opening and closing the scissor action between them
There you go, call it a scissor engine

But you still have the problems of lubrication and cooling to overcome
Couple thoughts on cooling
Could coolant be pumped thru the center of the rotor shafts themselves
keeping the rotors cool
A center shaft is required and recommended to hold the rotors in true center alignment and permit this coolant passage
Could this whole unit be finned for incresed surface area and placed inside another larger tube and sealed off creating a jacket around the whole thing for circulating coolant?

How do they lubricate a Wankel to keep the apex seals from burning up
And how is the rotor shaft sealed
Isn't this already proven technology whose patent ran out years ago?

Internally It wouldn't have too many parts thats for sure
Just 2 main moving parts!!!
Thats about as few as you can get

Sure would be cool to 3D model something like this in a cad program that has an animation package like Solidworks or Inventor
Utilizing parametric designs and constraints on the objects to hold them together as you made the design

Then by rotating the output shaft you could see all the parts interact with each other and also calculate the volumetric compression ratio also

Some software packages also have the ability to calculate thermal expansion rates of the various materials telling you if this thing will lockup at a certain temperature

We have the technology with fuel injection and electronic ignition to give the fuel and spark and time both of these

Just some ideas for you to consider
If you couldn't tell I like to push the mechanical design envelope as far as I can. Using common sense and a back door to solve problems all the way

If it works I get 10% , HA HA
I dont mind being a prostitute with my ideas and labor
Just not a cheap one at that

Maybe I'm in the wrong trade!!!

Widgits

[NC Cams]

The "Achilles heel" of rotary valve engines (not rotary ported 2 cycles but true rotary valved 2 or 4 cycles, non-piston ported in any way, the are directly subected to the comustion chamber temps and pressures) is sealing. Period, Paragraph

The challenges of/for that minor technical difficulty was already explained, in detail, in the "F1 motogp experimental single cylinder" thread that is readily findable on the 'Zone.

I won't bore you with a re-recitation of the challenges which have yet to be satisfactorily solved after DECADES of trying by numerous tinkerers, developers and/or inventors.

If you can, however, fix/solve the problems associated with sealing rotary valved combustion chambered engines (both short and long term while also cleaning up the lousy combustion chamber that they typically create as well), perhaps you will have found a new and rewarding occupation.

[jones]

There is a company that is building a rotary valve head which can be attached to most standard engines. It uses spherical rotary valves.

Have a look:
http://www.coatesengine.com/

[NC Cams]

Pertinent comments on the challenge that Coates and other rotary valve engine developers face in making the concept work are discussed in detail within the MotoGP single cylinder research engine thread.

Sealing and durability remains the pre-eminent challenges that all rotary valve engine developers face. I won't bore the members with a re-recitation of these ongoing challenges.

[nyleeloise]

If you are interested in building a 'four banger' visit the SOS webb site their is a group of guys who do nothing but come up with new and wierd ideas to make old four bangers run better. Also you might enter Charlie Yapp as he is the editor of the great mag, secrets of speed Nyle Reed

[Skin]

Originally Posted by widgits ...What would designing and building a standard internal combution engine get you? Other than being able to say you did it? ...Widgits

My name is James... I race bikes with a friend. 3 years ago now we decided for a bit of a laugh to design our own 4-stroke enigine to run alongside the 2-strokes we race with. Seemed a bit like fun and how hard could it be?

Please, any one reading this take this chaps advice.

Two months into the project we had our own running prototype winning races. Flushed with our success, we thought this engine designing lark was easy.

Three years later, we know a lot more about engines, and now we're learnign we don't know much about Bridgeport Interact 412 mills that don't work either LOL

Originally Posted by widgits ...What about looking into other alternatives for building something like this Obviously there are too many parts inside current designs for engines ...Widgits

Good point I'm thinking about flower arranging as an alternative

Any one want to buy a single cylinder motorcycle racing engine that can rev freely past 18,000, probably more if YOU can find damn springs that will take it?

Sincerely

James

[dynosor]

Originally Posted by gbowne1 I want to keep the cylinder bore diameter between 2.0000" and 4.0000", but I have no idea about what stroke length to use... I would like the RPM Limit to somewhere around 7,000 RPM. The valves would be 1.9400" and 1.5000" diameter

The valves have to fit in the cylinder head. Two 1.5" diameter valves are going to make for a tricky combustion chamber shape and volume if you used a 2" bore. 1.9400" valve diameter may be expecting too much... A valve head diameter 1/3 of the bore would package much easier, but for a 4 valve per cylinder design you may have to reduce that further.

Stoke length and RPM limit are closely connected by factoring in peak piston speed...

If you can package the engine so that all the parts fit in that would be a good start. This might make an engine that runs, but may not have spectacular performance.

Things like bore spacing are driven by bore diameter and the widths of crank webs, main & big-end bearings.

[dynosor]

I have started an inline 6 cylinder engine of my own design. It is based on the bore and stroke (.767" & .648") of an OS-30 single cylinder 4-stroke model engine in case I want to use OS pistons and liners (my brother's idea).

The crank in the picture took about 30 hours of machine time on a manual mill, but contains errors that make it a paper weight. The next crank will keep the same stroke length, but will have larger diameter main and crank pin bearings to be closer to scale, based on a BMW 330i crank.

The bore spacing is one inch and the dimensions were based on using a 1/4" endmill for removing the bulk of the crank material (4140 Leaded).

The block is 6061 and the idea is to cut the main bearing directly into the block.

Good luck with your project, Greg.

[balsaman]

Originally Posted by dynosor The valves have to fit in the cylinder head. Two 1.5" diameter valves are going to make for a tricky combustion chamber shape and volume if you used a 2" bore. 1.9400" valve diameter may be expecting too much... A valve head diameter 1/3 of the bore would package much easier, but for a 4 valve per cylinder design you may have to reduce that further.

Uhm, he is not going to actually build it. He just started the thread and now is laughing.

Very nice 6 cyl tho. Nice looking crank. Hope your next crank is a keeper.

Eric