The best big Four stroke

[jwalker]

Isn't the current move to 4 stroke engines by some manufacturers an attempt to adhere to future emission legislation which they fear they are not going to manage to do with 2 stroke motors?

[rama]

Originally Posted by Rogue Wave

Finally who makes who's engines!

[Roy Smith]

Great point. They even make a honda Four stroke garden strimer re the emissions thing.

[Brambles]

Originally Posted by jwalker

Isn't the current move to 4 stroke engines by some manufacturers an attempt to adhere to future emission legislation which they fear they are not going to manage to do with 2 stroke motors?

JW,

That's what I always thought as well. I have done a quick Google & can't find a clear explanation of the future legislation.

What I do know however is that the 'rude Etec 2 stroke engines were the first ever designed to meet 2006 EPA, European Union (EU) and 2008 California Air Resources Board three star ultra-low emissions standards. If 2 stroke efficiency continues to improve then surely they will meet future legislation?

As for Roy's comment about Honda strimmers - well, they would say that wouldn't they? After all, Honda committed themselves to 4 strokes many years ago and perhaps feels the need to justify their stance. They used to claim that their 4 stroke outboards were 50% more fuel efficient that the equivalent 2 stroke. Having had experience of a BF225 & 250 Etec on the same boat I can confirm that this is complete bollox...

Just my thoughts.

Regards

Ian

[hard1]

Originally Posted by Brambles

JW,


What I do know however is that the 'rude Etec 2 stroke engines were the first ever designed to meet 2006 EPA, European Union (EU) and 2008 California Air Resources Board three star ultra-low emissions standards. If 2 stroke efficiency continues to improve then surely they will meet future legislation?


Just my thoughts.

Regards

Ian

Codprawn will no doubt find the right page for you and post it - I can hear him panting from here. As for meeting future legislation, I think you're probably right but they will continue to move the goal posts on emissions making it hard if not impossible for any 2 stroke to meet the constantly evolving requirements. However, if they can find a way to avoid any oil being burnt with fuel whilst keeping the essence of 2 stroke ICE then yippeee! The fat lady may stop singing....

Without wishing to stir anything up, I wonder how far in the future it will be before they come down hard on leisure boating anyway as regards emissions. Politicians will no doubt be trying to score cheap points in the global warming feeding frenzy and they may shy away from Chesea tractors in favour of soft targets, but not to worry, we'll all have our lead booted inclined car engines on the back by then.

[Brambles]

Originally Posted by hard1

I think you're probably right but they will continue to move the goal posts on emissions making it hard if not impossible for any 2 stroke to meet the constantly evolving requirements. However, if they can find a way to avoid any oil being burnt with fuel whilst keeping the essence of 2 stroke ICE then yippeee! The fat lady may stop singing....

The manufacturers of 2 strokes are trying to, and may well have succeeded, in moving the goal posts in their favour for the time being. The way they see it is that the past calculations were not a true reflection of the "whole of life" emissions of 4 stroke engines. As you mention, 2 strokes burn oil into the atmosphere whereas 4 strokes (usually) don't. As far as I understand the EPA now include an "environmental cost" for disposing of the sump oil from a 4 stroke when the make a comparison.

Seems fair enough to me

[DJL]

Looking at engine specs over the last few months I’ve found it quite hard to make sense of it all on paper.

The weight difference is so minimal its almost non existent, and in some cases 4-strokes are lighter. Take the Yamaha F150 and HPDI 150 - they weigh the same and a 140 Suzuki weighs less than an opti 135. The weight difference is more manufacturer dependant than whether the engine is 2 or 4 stroke

The price difference isn't that great these days either. Again taking Yamaha as an example there is only about £300 between F and HPDI.

So what about fuel economy - most of the test reports I have seen generally put 4-strokes slightly ahead, but not by much. Performance wise there’s not much difference either, although 2 strokes do seem to have a slight advantage here. Interestingly though several sources seem to indicate higher top speeds are achieved with 4 strokes – which is exactly what happened when I changed from a 60 2/ to 4/.

So what am I going to put on my next boat? A Yamaha four stroke. Why? They're quiet, they don't smell of burning oil, I like lots of mid range torque, don’t need to worry about oil, I like the colour and they have nice digital instrumentation.

[hard1]

Yeah but the smell of an Opti on a summer morn....phew...even Rovert Duval would have got off on that.

It's gonna be sorely missed - ask any Opti owner.