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4 stroke / 2 stroke
andrewturner - 7/11/07 at 11:24 AM

What is the difference between a 4 stroke and a 2 stroke engine and what is the "stroke"?


Benzine - 7/11/07 at 11:28 AM

2 stroke vid

This vid explains the 2 stroke pretty well. I want a saab 96 2 stroke

With a 2 stroke you get good power to weight so you can have a pretty small engine with good power. Need to mix oil in with the fuel aswell.

[Edited on 7/11/07 by Benzine]


designer - 7/11/07 at 11:29 AM

4 strokes have cam shafts and valves, 2 strokes do not.

They are much simpler, but don't bother with anything 2 stroke as the EEC are banning them very soon.


Guinness - 7/11/07 at 11:31 AM

Wikipedia is your friend.

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



4 Stroke Engine.

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



2 Stroke Engine

HTH

Mike


nick205 - 7/11/07 at 12:00 PM

And the Wankel engine...


[img][/img]


mookaloid - 7/11/07 at 12:06 PM

quote:
Originally posted by nick205
And the Wankel engine...


Image deleted by owner


And how many strokes is that then?


Werner Van Loock - 7/11/07 at 12:19 PM

quote:
Originally posted by designer
4 strokes have cam shafts and valves, 2 strokes do not.

They are much simpler, but don't bother with anything 2 stroke as the EEC are banning them very soon.


That's not entirely true, most of the 2 strokes don't have camshafts and valves, but there are with valves.

http://www.dieselduck.ca/machinery_page/diesel_engine/diesel_engine.01.htm


britishtrident - 7/11/07 at 01:03 PM

quote:
Originally posted by Werner Van Loock
quote:
Originally posted by designer
4 strokes have cam shafts and valves, 2 strokes do not.

They are much simpler, but don't bother with anything 2 stroke as the EEC are banning them very soon.


That's not entirely true, most of the 2 strokes don't have camshafts and valves, but there are with valves.

http://www.dieselduck.ca/machinery_page/diesel_engine/diesel_engine.01.htm


B&W marine slow speed diesel 2 strokes had truly enormous exhaust valves Image from dieselduck.ca
http://www.dieselduck.ca/machinery_page/diesel_engine/diesel_engine.01.htm Rescued attachment modified.ani.sulzer.gif
Rescued attachment modified.ani.sulzer.gif


britishtrident - 7/11/07 at 01:05 PM

In cylinder video

http://video.google.com/videoplay?docid=-5815350492893860613&hl=en


coozer - 7/11/07 at 01:09 PM

2 strokes go 'ring ting ting' and stink.

4 strokes go 'brum brum' and sound crap against a 2 stroke with a 'spanny on

3 moving parts in a 2 stroke, thousands in a 4 stroke.

Mourn the death of 500cc V4 GP bikes


speedyxjs - 7/11/07 at 01:37 PM

quote:
Originally posted by nick205
And the Wankel engine...



Dont you just love the word Wankel


MikeRJ - 7/11/07 at 04:13 PM

quote:
Originally posted by designer
They are much simpler, but don't bother with anything 2 stroke as the EEC are banning them very soon.


Going to be a lot of unhappy ship owners then! IIRC the two stroke diesel is the most efficient internal combustion piston engine available.

[Edited on 7/11/07 by MikeRJ]


nasty-bob - 7/11/07 at 06:06 PM

quote:


They are much simpler, but don't bother with anything 2 stroke as the EEC are banning them very soon.


Not so sure about that. A few companies, Aprillia for one, are lauching their range of direct injection turbocharged 2 strokes. Beautiful idea. Think about it- the problems with 2 strokes are lubrication, volumetric efficiency and emissions (due to port timing overlap).

With DI and turbo you can have an oil filled crankcase as per 4 strokes, over 100% volumetric efficiency and as the fuel can be injected after the scavenging period is complete emissions are up to 4 stroke standards.

So you get all the best bits of a 2 stroke without the bad. Although I will miss the smell......


Coose - 7/11/07 at 11:01 PM

You can't beat a good two-stroke (I've had sooooooo many! ).

Did you know, the last of the Honda NSR500 grand prix bikes had been known to put out over 200bhp! They never raced them though as the wouldn't last a full race....

Yes, that's 500cc, normally aspirated, 200bhp!!!


thomas4age - 8/11/07 at 03:38 PM

In mc racing if they have a combined field with 2 and 4 stroke engines, almost always the 4 strokes may have about twice the dicplacement against the 2 stroke.

remember that a 2 stroke makes twice the powerpulses per revolution compared to a 4 stroke.

dragracing also used 2 stroke engines with rotating-disk intake and superchargers, those thing made power beyond believe per displacement.