2-stroke vs 4-stroke

[Sharkbyte]

For me, it would come down to what size engine is required.

 

30hp+ it would be a 2 stroke every time. Usually faster, like for like, miles better hole-shot, they weigh less, servicing at a fraction of the price of comparable 4 strokes, far less to go wrong. Modern 2 strokes don't require any mixing up of fuel /oil. It's injected automatically. They're cheaper to buy.

 

On the downside, the fuel economy of the older generation of 2 strokes isn't great. That said, with the Etecs, Hpdi's and variants around, that's no longer an issue.

 

 

I use a 10hp 4 stroke as an aux and although it's far heavier than an engine of this size should be, it does the job well enough.

Edited June 26, 2007 by Sharkbyte

[Ken Davison South Wales]

I have been looking at packages boat/outboard ranging from 16' to 20' and most of the deals are with 4 stroke.

 

I have turned my head a little to look at 18' to 20' with inboard engines, diesel turbo units and though they are a few quid more I am sorely tempted, one or two good second hand buys around, one sat in Swansea Marina I might pop down to take a closer look at.

[Ian Burrett]

I reckon within 5 years all manufacturers will have gone back to two strokes with fuel injection.

 

The new breed of Evinrude have a better fuel economy than the present four strokes.

 

Many figures are quoted about the advanatages of four stroke fuel economy over two stroke but I found them grossly exaggerated.

 

On a average trip two identical Hulls and pay load and fishing the same marks. The two stroke would use 5 gallon and the four strokes four gallon

 

With the two thousand pound difference in price you would have to do a serious mileage to get your money back on a four stroke.

 

The two stroke gives more acceleration and instant power which is sometimes necessary in rough seas.

 

Three of our boats are now using the Tohatsu 70's and apart from initial teething problems on one of them they are proving very reliable.

 

A 70 HP is only £3600 and i believe is the best value at the moment

[chesters1]

we had a air cooled 4 stroke! fantastic engine and without the hassel of waterways in the engine getting blocked up and lighter than an equivalent 2 stroke and far less thirsty

[captain cojones]

 

im a little bit concered about fuel economy on my latest boat................4x250hp mercs

 

(and then i woke up)

[chesters1]

blimey prime smug drugglers getaway boat

[Newt]

I don't know if it is likely to become an issue in the UK any time soon but emission standards have caused some changes here.

 

California is our toughest state on engine emissions due to their high population of autos and have recently tightened up on the ones for boat motors as well. A standard 2 stroke engine cannot pass and can no longer be sold new in that state. 4 stroke and the hybrids like the Merc Optimax in my link do pass and can be sold. Johnson & Evinrude both offer a similar hybrid engine.

 

One reason I paid a little extra for the Optimax over a standard 2 stroke is the possibility that if I want to sell it at some point, the higher standards will be nationwide and I would be stuck with a 2 stroke I could not sell.

 

As far as I know, all of the larger horsepower 2 stroke and hybrid 2 stroke outboards made today have oil injection so the issues with mixing your fuel and the fact that no single oil/petrol mix can be efficient at both low and high rpm has certainly made owning a 2 stroke less of a bother.

[Elton]

Interesting reading, this.

 

My primary reason for asking is that when I've been out on small boats, fuel consumption has been a major issue.

 

With fuel so expensive in the UK, even a short trip for two people can be more expensive than the relative cost of a charter boat divided by 8 people.

[Fin-S]

I think there are a few more variables to consider. What size of engine, what type of hull, how far are you running, what throttle opening etc. From my experience, I now save 40% on my fuel bill by running 4 strokes vs older 2 strokes. However, this is comparing 2 x 115hp (4s) Suzuki's vs 2 x Yamaha 115 Enduros. My average run is 40NM out, trolling for 4 hours, and then a 40NM run back. The motors are rigged on a planing 24' cat hull and I average 24 knots at 4000rpm. On this rig I now use 160 litres per day in total. Some of our local fleet has switched to the new E-Tecs and are also having good savings and cheaper maintenance costs - however the motors are noisier and I find the 4 strokes allow me to get much closer to a feeding shoal of fish, meaning shorter casts and more fish. Whatever you choose, the new generation of motors are light years ahead of the older ones and are far superior in every respect.

[Ken Davison South Wales]

Interesting reading, this.

 

My primary reason for asking is that when I've been out on small boats, fuel consumption has been a major issue.

 

With fuel so expensive in the UK, even a short trip for two people can be more expensive than the relative cost of a charter boat divided by 8 people.

 

Thats the main reason why I have been looking at inboard engines, it appears you get a far better return for your fuel cost.

 

Am I guessing right that you are looking for an outboard for your boat?