Tonights Yacht Club bar discussion

[roycharles]

Tonights discussion turned out to be engines and with not one engineer among us and with one or two pints of Adnams ended in confusion.
Everyone understands the power cycle of a four cylinder four stroke engine - one power stroke evrey 1/2 revolution.
But what about a two cylinder four stroke? Presumably the pistons are set 180 deg apart so does that result in two power strokes on one full revolution and then the next revolution with no power strokes?
(this was further complicated by someone who said they once had a twin cylinder BMW motorcycle where both pistons were at the top of the cylinders at the same time).
We then moved on to three cylinder engines. Are the pistons set at 120 deg (360/3) and if so what is the power stroke/ revolution relationship?
I said there is bound to be someone on the forum who could give a simple explanation that even we could understand (don't let me down guys).

Can't wait for next week when we will probably move on to 6 and 8 cylinder engines and even 'V' configurations.
What about 5 cylinders engines?

 

[andy_wilson]

1 cylinder = 1 power stroke / 2 revolutions.
2 cylinder = 1 power stroke / revolution (as the opposing is on induction stroke).
Boxer engines like BMW bikes and Subarus have horizontally opposed pistons, and therefore forces. The firing strokes are staggered however, the horizontalness cancells out the reciprocation.

3 and 5 cylinder engines cancel out well the usual harmonics of a 2/4/6 cylinder engine.

 

[ccscott49]

2 cylinder engines, the pistons are normally at the top together, but on different strokes, ie one on the firing stroke, one on the exhaust start of induction stroke. One power stroke every revolution. Four cylinder two power per rev, six cylinder three per rev. etc. Yes 6 and 3 cyl, 120 deg. 8 at 180 deg. but all this changes with V8, V12 etc. depends on the angle between the cylinders, V8 should be 90deg, but some arent, V12 60 deg, V6 60deg V4 90deg. Then we get onto broad arrow 18cyl, (three banks of 6 cylinders) Next we have to work out firing orders!!!! For flat plane crankshafts in V8's. It's a bloody complicated subject. Lots can now be done with computer ignition systems, in fact most of the newer configurations cab only be done with computer systems, with magnetic flywheel timing pick ups, fun eh?

 

[tangofour]

Used to have a kawasaki 750 triple - in line transverse across the bike. Went like the clappers. Never stripped the motor down so cant comment on the phasing of the crank but 120 degrees would be logical. I seem to remember that the yamaha tripple had a layshaft next to the crankshaft with a counterbalance to smooth up the power delivery.

There are a lot of 3 cylinder engines about, for example the smart cars use a 3 cylinder unit. Quite a few marine engines and outboards.

What about the old radial engines with 9 or 12 cylinders and of course the daddy of aircraft piston engines, the merlin, 12 cylinder, 60° V, 27 litre displacement, try working out the plug leads on that!

BTW. 4 stroke = a power stroke every 2 rotations and 2 stroke a power stroke every rotation.

 

[yindoor2]

Suck - squeeze - bang - blow

 

[Kawasaki]

banjo, I could answer all Your quieres ref number of cylinders, two or four stroke,
Vertical, opposed, together,opposite, horizontal.firing order, smoothness, vibration, induction, production,performance, price, pointers, pistons,swept volume, compression,depression,exhust,inlet, toilets. wastegates,turbos,tremellos,
bhp,bnp,radials,radicals,v4's,v8's,v12's Vd.Kawasakis (goes without saying) Hondas, Yamahas, Suzukis and the odd Norton. Triumphs, (Feel Like Japs now)
J A P's now there was an engine.
P and M panthers (Phelon and Moor) never mind all that stuff.
I have a 4 stringed Banjo that needs tuning.
Can I tune it like a Guitar and play the same shapes/stuff?
Banjo was a gift some time ago.
I like to mess, it,s good fun.
Anyway so's yer know.
Some British(well most really) Motorbikes, the pistons went up and down together.
That's why they could shake themselves to bits!
There was a counter balance shaft (someone mentioned a lay shaft but that is a bit in a gearbox0 that a few Manufacturers tried to develope for twins.
Too tired an emotional now
Tarra
K

 

[ccscott49]

Just so as you know, radial engines are always odd cylinders, if they are like the dakota engine 18, then they are in two rows and staggered, even number radials would lock up.
I used to work on the meteor, v12 tank engines, de tuned merlins, not just the firing order was a problem, it had twin magnetos and 24 plugs!! Try timing those effin magnetos hanging upside down in a tank engine space or through the access hatches at the back of the turret, real fun that! Plus timing the two overhead acmshafts, Oh joy!

 

[William_H]

No no Coscott you have got it wrong for Dakota C47 DC3 they came in 2 engine types the wright R 1820 had 9 cyclinders One bank the other option is the pratt and Whitney R 1830 more common has 2 banks of 7 cyclinders making 14 cylinders.
Of course the big P&W R 4000, the last of the big petrol engines had 4 banks of 7 cyclinder making 28 cylinders or 56 spark plugs. With a dedicated flight engineer who had an osciliscope ignition monitor to keep tabs on the 4 engines (224 spark plugs).......

They were the heydays.... incidentally American engines were always labelled by the cubic inch capacity so R 4000 is 4000 cubic inch or about 80 litre engine. Fill er up with pertol mate.....not likely
All this if I remember correctly..
olewill

 

[ccscott49]

I'm sure your right, I couldnt remember the number of cylinders for the two row engine, I should I worked on radials in beavers! I knew they had a 9 cyl, thought they just went two rows of 9 = 18, But knew it wasnt an even number in each row.

 

[rudolph_hart]

At the risk of being accused of thread drift .....

When I were nubbut a lad, in the school hols I had a job at a local garage, and I was intrigued by the engine of their Commer breakdown tow truck.

The top of the engine seemed a very long way down in the chassis, and I was told it was:

* Flat 3-cylinder, but with TWO pistons per cylinder, which 'TDC'd simultanoeuosly.
* TWO-Stroke Diesel
* Shaft-driven supercharger

It may also have been air-cooled (can't remember).

I was told the advantages were very light weight for the bhp and low profile. Downside was that the engine was apparently very temperamental.

It could be the 'boss' was simply bullsh*tting a callow youth. If he wasn't, could it be that, by applying modern engineering tolerances and recent developments in diesel technology, such a configuration could have merit?

 

[Dave_Seager]

I used to run an Albin 25 with an Albin AD021 diesel engine. This was a 4-stroke engine and had two cyclinders in-line. The cranks were set at 180 degrees so that the pistons went up and down alternately. As a result, we had two power strokes on one revolution and nothing on the next. This gave it a delightfully synchopated exhaust beat.
A flat twin will also usually have the cranks set at 180 degrees so that the vibration caused by the reciprocating cranks and pistons is largely cancelled out. However, this configuration allows the power strokes to occur evenly, with one for every revolution

 

[Heckler]

hey Col how old are you, tank with petrol engines?
Stu

 

[Heckler]

2 stroke diesels are quite common, supercharged to get the compression reqd, (dont forget the transfer ports are half way up the cylinder) and to get more power the bigger ones are turbo charged as well, think Detroit Diesel. Foden used to make them as well. Commer one i vaguely remember and there was something strange about them but I cant remember all the details, I know it was flat and 2 stroke but thats all.
Stu

 

[ccscott49]

Old enough!
Centurions and conquerer both had petrol engines. V12 meteors, but the conquerer had fuel injection and water methanol boost, the centurion huge effin carbs!
The supercharger on a opposed piston diesel engine, as fitted to early chieftain tanks (Leyland L60, rolls designed) is there not to raise compressin ratio, it's there because they are two stroke diesels and as such do not "suck" air into the cylinders, as a four stroke does, it has to be blown in, or as in a lot of two stroke motor cycle petrol engines, sucked into the crankcase and through transfer ports, blown into the cylinders.
You cannot have a four stroke opposed piston engine, nowhere for the valves!!!
All two stroke diesels whether GM v8-12-16 are supercharged, some of the military GM v8's as fitted to the M107, 109, 110 are also turbo charged.

 

[ccscott49]

He wasnt pulling your plonker, the commer two stroke diesel is famous or was, fast trucks, but no slogging power, due to the fact it was two stroke (low torque)

 

[Wunja]

[ QUOTE ]

* Flat 3-cylinder, but with TWO pistons per cylinder, which 'TDC'd simultanoeuosly.
* TWO-Stroke Diesel
* Shaft-driven supercharger


[/ QUOTE ]
I was intregued by this and a quick google found this site.
Hillman Car Club of Australia

 

[Mudplugger]

Regular run up/ down from London Glasgow back in early 60's, start of motorway's & before barbra Castle screwed everything up with 70 limits. Well over the ton.... exhaust stack belching flames 3 foot long, on the old commer two stoke, but took a while to stop!!! Used to be some outfit in Leeds, that hauled liquid Latex (hot) with much modded scammel type wagons... powered by RR Merlins! Midland Red Coaches couldn't keep up, and really used to get p###ed off when passed by a grubby artic @ about the 120 mark! Tanks solidified after 3hours. Those were the Day's!

 

[ccscott49]

You have big marine deisels working like that as well, similar set up, upright, but with long connecting rods and a the crankshft below the lower set of pistons and inline with the cylinders. The L60 had two crankshafts geared together.

 

[rudolph_hart]

Great link. It's reminded me that it definitely was a TS3.

From some of the other forumites' replies, it sounds as if the broken down Hillmans that it towed were going faster than when under their own steam!

 

[ccscott49]

I do believe the scammels or thornycrofts were powered by a V8 meteor engine, 8 cylinders of the merlin, but still effin fast! We used this engine in Antars, for tank transporters in the army.
But may well be wrong about the Leeds outfit, but thats how I remember them.

I bet those commers slowed down a bit when they got to Shap!! No M6 that far then.