4 Valve DOHC 2-Stroke

[jeep97tj]

So air must be sucked into the crankcase, and then through the "transfer" ports into the cylinder.

This is how all 2 strokes work. U have your air filter, then your carb, then the reed valves then the crank case. Piston goes up on the compression stroke which also sucks air through the carb, and through the reed valves and into the crank case. U then have ingition. Piston comes down compressing the cases in the crank case that cant go any where because of the reed valves. Piston goes down till it uncovers the inlet and exhaust ports either side of the cylinder, inlet gases flow in and the exhaust gases are forced out.

I dont understand what u are saying bush65

[ISUZUROVER]

So air must be sucked into the crankcase, and then through the "transfer" ports into the cylinder.

This is how all 2 strokes work. U have your air filter, then your carb, then the reed valves then the crank case. Piston goes up on the compression stroke which also sucks air through the carb, and through the reed valves and into the crank case. U then have ingition. Piston comes down compressing the cases in the crank case that cant go any where because of the reed valves. Piston goes down till it uncovers the inlet and exhaust ports either side of the cylinder, inlet gases flow in and the exhaust gases are forced out.

I dont understand what u are saying bush65

I think he was just being pedantic about the terminology "intake port", and calling it a "transfer port". I still consider it an intake port as it is how the fuel and air gets into the cylinder.

[jeep97tj]

arrr, theirs one in every crowd

Must be about 3 or 4 in the arvo over there hay? Did u watch any TV while u were in Italy? when i was there I was watching some game show or something, didn’t understand anything but it was only about 730pm and some chick comes out topless don’t know what was going on but she come out said something everyone laughed and she left again strange

[ISUZUROVER]

No time for watching TV this trip. But I saw programs like that when I was staying in Rome. Germany is not much different, but they start later.

And here is the last one of my pics from the workshops. There was also a triumph and a jag in there, along with heaps of italian race engines in various states of assembly.

[itchyvet]

Hmmmmmm, Ho Hum, whilst I do not wish to disparage the discussion here, the idea of two stroke and valves for exhaust is not relegated to such small engines, nor is it just Petrol engines.

GM USA make locomotive engines, 16 cylinders and even more, these engines are TWO STROKE DIESELS very similar as the one in discussion here.
With the exception of FORCED air into ports via a mechanical blower device refered to as a scavenge blower, these are COMBINED with Turbo chargers as well to acheive the horse power rating of......... 3,500 a peice.
The 500 horse are used up primarily just to run the systems of the engine and electrical switch gear as well as the compressor/s and traction motor blower fans leaving the 3,000 horse for pure traction effort.

Ah boy, was it a turn on to drive one of these things, especially when there were TWO hooked up in unison, imagine.... 7,000 horse at yer finger tips, full throttle at 0230 in the morning on a cool night, you could hear the things for miles.
Yeah, I know sometimes I'm sorry I don't work anymore.

[droopypete]

Hmmmmmm, Ho Hum.

A good way to endear yourself to fellow forum members
Peter.

[itchyvet]

Peter,
are you saying the people on this forum are unable to deal with such a comment ?

IF, that is the case, they certainly have incredibly thin skins, AND I must wonder, why such comments are interpreted as Personal ?

Fact is, I've been involved with mechanical contraptions of one persuasion or another all my life, and it would appear from many comments made on boards such as this, the majority of members do NOT have similar back grounds, thus when they discover something, they feel it's "NEW" when in fact it's old as buggery and been around for a very long time.

If people get annoyed or upset at this being pointed out to them, I would suggest the problem is NOT mine.

My comments were not made to disparge or upset anyone, it was simply a means of expressing my feelings of boredom on a subject that has been around for in excess of 100 years nearly.

People will read such comments and infer them to mean whatever they wish, I have no control over such issues.

[droopypete]

Peter,
are you saying the people on this forum are unable to deal with such a comment ?

What I am saying is that when you see mr smiley ( ) it means that someone is typing with a smile on their face and a tounge in their cheek,


Let me demonstrate the positive and the negative effect of emoticons.

itchyvet wrote:
Hmmmmmm, Ho Hum.

option 1.
A good way to endear yourself to fellow forum members
Peter.
(please note the use of mr smiley to indicate freindlyness)

option 2.
A good way to endear yourself to fellow forum members DICKHEAD!!
(please note the use of mr bad words to sugest agression and mr eyes roll for acid sarcasm, plus extra nasty points for throwing in some abuse in capitals )

Just to clarify, option 1 would be right at home around a camp fire or a poker table with your freinds and everyone would laugh and no one would be offended or indeed, mean to offend.

option 2 usualy only occurs on the internet or at soccer games after half time.

Peter.

[jeep97tj]

detroit diesels have been around for ever, Iv worked on alot of drill rigs that use them, they were super charged only. We had an oshkosh service truck that had the supercharged detroit plus twin turbos, and that think flew. Never have i heard of a 2 stroke petrol with overhead valves though, so its news to me

[itchyvet]

detroit diesels have been around for ever, Iv worked on alot of drill rigs that use them, they were super charged only. We had an oshkosh service truck that had the supercharged detroit plus twin turbos, and that think flew. Never have i heard of a 2 stroke petrol with overhead valves though, so its news to me

jeep97tj, I have in my possession a two stroke with............. wait fer it.....
...... a ROTATING CYLINDER LINER which drives the crankshaft,(or what is commonly refered to as a crankshaft)in this case, there is no crankshaft as we used to know it.
It also has NO VALVES as we know it, but a hollow cylinder which also spins and positions ports cut into it to allow egress/ingress of gasses.

The engine it'self, is built for model aircraft and in the 10 cc capacity, though there is no reaosn whatever, could not be scaled up into larger versions.

I also have four stroke engines which run on TWO STROKE FUEL, that is the engine has cam shaft, pushrods,valves ect but runs on a mix of synthetic oil and methanol,(two stroke mix) these engines rely on the oil content of the fuel for lubrication, AND are specifically designed with PISTON BLOWBY.
A level of blowby that if it was present in your car, you'd junk it pretty quick. However, it seems to work admirably well in these engines.
They are available from 2.5 cc's right up to four cylinder 50 cc's and even more, like a radial five cylinder or seven of 100 cc's.

Now, the crux comes with these engines that are all designed to run on methanol which is expensive (last I checked, in excess of $30 20 litres)
many are converting these engines to standard petrol two stroke mix just as you run in your conventional lawn mower to cut operating costs, increase power and run cleaner.
Modifications required are inserion of spark plug, high tension coil/battery pack to operate same and a pressure operated carby, all avaialble after market.

Thus, at the end of the day, we have an engine with two valves,pushrods,camshaft,followers running on two stroke fuel mix.

We also have simple two stroke engines with port transfer or reed valves, running on the same methanol mix also converted to petrol by adding spark plug and ignition pack/carby thus basic two stroke engine.
Capacities ar anything from 2.5 right up 150 cc and more, with radial configurations, flat fours and flat 6's even fours and 6's twins in line.

And last but not the least, recently turbines have made a big impact into the scene, these turbines are simply a Garret turbo compressor fixed to a shaft with a turbine wheel attached at the opposite end, inbetween is a combustion chamber which has fuel and compressed air injected into it, ignited via a spark, once alight, it's self perpetuating and increases speed with increase of fuel, if allowed to, it will speed up until self destruction occurs.
Many people have built their own and been very successful, in my case, I bought a commercially produced one made in Perth W.A. which I still have.

If it wasn't such a muck around, I'd post some pics for all to see what we're talkin about, but I can't be bothered with the drawn out process.
Instead I'll direct you to some sites where you can see for yourselves what I'm talking of.

http://bennettbuilt.com/index.html

http://www.gtba.co.uk/index.htm

http://www.gasturbine.pwp.blueyonder.co.uk/newpage.htm

http://www.rc-airplane-world.com/model-jet-engine.html

http://www.justengines.unseen.org/mvvs.htm

http://www.webra-austria.at/index1.php?lang=EN

https://www.nelsonhobby.com/prospark.html

http://www.aero-sports.com/airhobbies/twineng.html

http://www.tjt.bz/

This is just a scratch of what's available, a little research will soon illuminate literally hundreds od such manufacturers throughout the World.
Anyone who is mechanicaly inclined and simply loves such devices wil certainly enjoy the lot. Enjoy.