2-Cycle engines to be phased out?

[Blue99]

The EPA Phase 2 emissions regulations for small engines continue to generate new 4 cycle engine designs for hand held equipment to replace 2 cycle engines.

The Stihl 4-Mix engine is a 31 cc, 10,500 rpm 4 cycle engine that runs on pre-mix oil.

Honda has what is termed a “360-degree-inclinable 4-Stroke Engine” that has an onboard oil sump & relies on a splash/slinger system to keep the cam & valves lubricated.

Honda has both 25cc & 35cc models of this engine with 7000 rpm engine speeds.

No doubt other engine designs are still in the R & D phase, but, regardless, we will see major changes in hand held equipment engines for the outdoor power equipment industry.

See the links to view info on these engines.
Stihl 4-Mix

Honda GX35

 

[blano]

Two Cycles are not being Phased out per se. Redmax, Shin, echo, husky and the others all have compliant 2 cycle OPE. Judging by the present patent activity of of husky and Stil I dont think you will see them going away anythime soon. The snowmobile industry is bustling with new clean two strokes that are in some cases cleaner than four strokes. Ski doo has a sytems called SDI and Polaris is realeasing in the next few weeks a 900 cc sled that uses a sytem designed by AVL inc called cleanfire injection. Four strokes are great, but they will never make the power per $ of a two stroke. Four strokes are much more expensive to produce, and design than a simular two stroke.
BTW the new emmission standards will be a on a credit sytem IE CAFE where a mMFG will be able to build traditional two strokes along with emmsions compliant ones.

 

[Blue99]

Blano,

Yes, I agree, some of the currently available 2 stroke engines using traditional technology emit less hydrocarbons & will pass the EPA benchmarks.

In addition to snowmobiles, the marine industry is also under the gun & new designs are being announced on a regular basis.

In my opinion, the toughest application is the hand held market(chainsaws, blowers, trimmers)where light weight and the multi-angle position of operation are the chief design obstacles.

I think the hand held equipment designs will see the greatest changes over the next 5 years.

 

[Cujet]

While the Honda engine looks like a new and fresh design, I have serious doubts about the product. I purchased 3 Honda GX31 engines (similar in concept and size 4 stroke). All 3 engines vibrated so badly at rated speed that the crankcases cracked. The first one actually fell apart!

One thing to consider is that single cylinder 4 stroke engines do not share the smoothness of a 2 stroke at rated speed. Consider that single cylinder 4 stroke dirt bikes all have counterbalancers to match the smoothness of a comprable 2 stroke. Those counterbalancers add weight, so in small engine applications they are not used. However the need is still there.

Chris

 

[cryptokid]

every small engine i have ever opend up, down to a 2.11cc r/c car engine had counter weights.

anyways, newer 2strokes are not really that much different than older ones, if you take for example, homelite brand engines, spesfically the 25cc size, the new ones are identical in every way shape and form, except for a smaller carb, leaner jetting, less oil requirment (probably from smaller carb means less hp per cc and that means less heat so less oil is used) and the addition of EGR. yes, they have egr.
if you look at the combustion pattern of deposits on the cylinder head of a new 25cc with egr vs an older 25cc without egr, you can really notice the change, around half the cylinder stays clean inside. the egr is injected right into the cylinder head via a small port.

to get a new stile homelite engine to perform as good as the old model, you simply tap the egr hole in the cylinder and install a threadded bolt or plug , and install the old stile carb which has a bigger diameter. everything else about the engines, like the piston, rod, the cylinder intake transfer and exhaust port size and timing are the same.

 

[n8wvi]

Not sure if it's in anything production wise, but I saw a 2 stroke engine designe that didn't have 'piston' per-se, but a 'wedge' that pivoted. The oil-in-the-mix requirements were vastly reduced, thus reducing emissions greatly. It was on display at the OshKosh air show this past August.

Dave

 

[Cujet]

I am sorry I was not clear.

I was speaking about counter-rotating balance shafts, used to reduce the vibration problems of high revving single cylinder 4 stroke engines. Not the crankshaft counter weights.

2 stroke engines have far less vibration, partially due to the even firing pattern.

Chris

 

[GT Mike]

quote:

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Originally posted by n8wvi:
Not sure if it's in anything production wise, but I saw a 2 stroke engine designe that didn't have 'piston' per-se, but a 'wedge' that pivoted. The oil-in-the-mix requirements were vastly reduced, thus reducing emissions greatly. It was on display at the OshKosh air show this past August.

Dave

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I remember seeing that. I go every year. My dad gets free tix thru work.
Not like I have to go there to see the air show, though...I can see it from my front yard!

 

[Stooge]

I hope not!! I have an older Echo SRM 3000 weed/brush cutter that is over 15 years old, and I have used it for probably thousands of hours wacking and clearing brush on the property for years. Same goes for my Echo chain saw and blower. I could not imagine any four stroke motor making the power and having the life of these motors and still be "featherweights." These little two-stroke motors are really amazing considering their weight and size!!