TWO Vs FOUR STROKE ENGINES

[Manos]

Dear All,

I have been talking to many sea people about the benefits of a 2-stroke engine Vs a 4-stroke motor.
However, many (and I mean MANY) are keen to purchase a 4-stroke, which is heavier, slower and MUCH MORE expenssive than a 2-stroke motor.
Do you think that it may worth our while to have a debate on this subject??
or it has already been discussed??

Is just a thought.

[Julian]

Manos

Morning. I think we have been through this topic recently. My own opinion is that a 4stroke engine is better than 2 stroke engine especially with the huge savings on Fuel and Oil. I know the engine is heavy but extra weight on a Rib is not allways a bad thing as long as its balanced out.

Julian

[Keith Hart]

Depends on the size (take note Matt). If, like me you have a small one (engine, engine you fools), and have to carry it, then a 2s is far better because they are about 40% lighter. Anyway my little one is so economical that the cost of fuel is not an issue.

BTW there is an interesting article in the Oct RI magazine comparing diesels and four stroke engines. So go out and but RI and read it. (He's managed to get another ruddy plug in for that damned magazine again)

Keith (I can lift mine up, can you) Hart

[Manos]

As I said I wasn't sure whethere this topic was discussed in detail or not so. MY APPOLOGIES !!
However just to say a few words on your comments if I may.
I am of the opinion that that extra weight on the back is not necessarily as advantageous as if you say had extra weight in the middle of the boat?? (balancing etc)
I have also heard that 4-stroke engines (agree with you that they are more economical than 2-stroke) are a pain to service.
Say, you cannot do an oil change by your self but you need to take it to a dealer.
In some instances the engine has to come off the transom to change the oil.
Also they are not time tested for reliabailit enough.

Any way if this subject has been dioscuused better drop it then unless any one else wants to contribute.

[Manos]

Nice one.
Well (you started it fisrt) if yours is so small ..... I bet it doesn't need any help to get up (must be permanenetly standing) and also should consume less. Don't worry though Keith from what I heard lately size doesn't matter

FYI mine however, is toooooo big and needs some assistance and support and it also consuuumes toooo much (fuel I mean)

Seriously though for small engines , as you said, 2-stroke should be the engine type (I think).
However, from what I know in Switzerland for example in the lakes they do not allow 2-stroke engines any more (big or small). Is it the same in the UK?? or the law hasn't arrived here yet for implementation??

[Alex Brown]

The newer 4-stroke engines now are getting lighter it seems.....

Take the Suzuki 4-stroke 140hp engine for example (which I have just ordered), that engine is I think 180kg, whilst an Optimax 150 is in excess of 200kg.

It is only going to be a matter of time before the lower hp 4 strokes become matched for weight (almost) as the 2's.

There are still arguments for the hpdi (and equiv) 2 stroke engines too, and everyone has a different opinion on what's best

-Alex

[Andy]

Should you not also be looking at 2 stroke HPDI engines and comparing those to 4-stroke. These give 2-stroke performance and weight savings but are far more efficient on fuel, nearing if not matching that of a 4-stroke. They are also quiet ....

If this is true about HPDI engines (I have not bought mine yet so I have no practical experience) then why bother with a 4-stoke at all ....?

Anybody able to clarify.

[narked]

Ta for that Keith,
Even though I have next to no knowledge about outboards, I had gathered that a 2 stroke would be a better option for when I get my SIB, mainly due to the weight issue.

Matt

[Richard B]

Also for SIBs it's a good idea to have a 2-stroke as they will survive being turned upside down, where a 4-stroke needs to be kept the right way up so the sump doesn't loose all the oil through the crank-case breather. Fuel consumption's not an issue for little engines as there's only so much a 250cc engine can get through!

[Simon Guest]

On larger 4 stroke versus modern 2 stroke (Optimax, Ficht RAM, HPDI), this has indeed been discussed before, for instance here
http://rib.net/forum/showthread.php?...ol+consumption

... but I didn't see any conclusion to the discussions.

(Like: how do the running costs compare? How do the noise levels compare?)

cheers,
Simon