2 stroke or 4 stroke (owner)

[kyjake39]

Originally Posted by MartyGras

If by ethanol you mean E85, there is no savings to be had by using E85 fuel. Yes it costs less but because there is less energy in a gallon of E85 it would need to be $1.00 or more below the cost of regular gas just to reach the break even point on cost per mile

Don't mean e 85 which is a very bad thought for me and hope it never comes to past widespread.

[Macgregorsailor51]

Sorry its an 86(?) Evinrude 8 hp Twin..

Originally Posted by HarborRat

Tohatsu makes Mercury and Nissan small outboards....most parts are interchangeable and Tohatsu's are cheaper by a few hundred $. I had an 8hp 4stroke Tohatsu and it was great. Have a 50hp 4 stroke fuel injected bigfoot Merc now and it is great....the early to mid 2000's 4 stroke Mercs and Yams were a joint venture, so they are called Yamamercs.

For the original question, go with a 4 stroke. Much better mileage and much quieter. Will probably be a little heavier but it's worth it.

Mac, if your 8hp 2 stroke is a Yami I will buy it from you. I have a friend looking for one (if he still is). PM me if it's a yami.

[fisher419]

If you are going to be using ethanol gasoline, stay with a 4 stroke. 2 strokes do not tolerate lean mixture conditions as well as 4 strokes which is what ethanol fuels cause if it site for more than 30 days (can be less in humid conditions). 2 Stroke generate a lot more heat in the combustion chamber which can lead to severe detonation when used with deteriorated fuel. This destroys pistons and rings within minutes. Ethanol soaks up moisture and lowers the effective octane rating. Also, if doing a 4 stroke try to stay away from carburetor engines. Ethanol destroys the rubber seals in the accelerator pumps. Rebuild kits are available to solve it.

If you are going to be using 100% non-ethanol fuel, you can't beat a 2 stroke for power to weight ratio. Also, if you are going to be running the boat regularly that ethanol should be ok but make sure to use the 93 octane.

I have a racing business up north and have seen what this crap fuel can do. As for E85, it makes great race fuel but terrible street fuel. Average mpg will drop by about 40%. Standard air to fuel ratio for gasoline is 14.7:1. E85 is 9.8:1. Never even think of this stuff for marine use unless the engine is specifically built and tuned for it.

[wpc691]

Originally Posted by kyjake39

Thanks for the replies.I would use the boat for fishing the harbor and some canal fishing at times.Would be using the ramps at Spring lake,El Jobean and beach park.Have found some good deals on boats with Tohatsu motors and other brands made by them.Have owned boats for over fifty years,all 2 stroke.Think in the future 2 stroke outboards will not be allowed on the water.Later model 4 stroke advertise or recommend that they can be used with ethanol which would be more economical
and less trouble than using rec fuel and mixing.

The performance argument most often made for 2-strokes is superior hole shot performance when attempting to get on plane in shallow water (you can go on The Hull Truth and debate the subject forever if that interests you). If that's of no concern, 4 strokes are quieter, almost smoke free, get better mileage and eliminate mixing. If 2 strokes are ever regulated away, those in service will certainly be grandfathered.

[Macgregorsailor51]

HummmI and anyone else who has owned 2 stroke outboards has been using 10% Pump gas for what 20+ Years? I am all in for 4 strokes love them, and as wpc mentioned you can argue till the cows come home on the Hull Truth Board about 4's versus the New 2's..
Honestly fisher I have never had any of the problems your talking about.. I do have a water separator , how much that really helps me, is unknown.. I have NEVER in my life paid for 96 Octane Gas for any boat I have ever owned... I ran 10% ethanol in my 1996 90HP Merc Tower of Power and I ..... never had an issue.. The difference between Fisher and the rest of us is!!! We are running 10% and getting maybe 85hp out of our 90's.. Fisher Demands 96 HP out of his 90.... OR MORE and he knows what he needs to do... to get it and IT MAKES a Difference to him..
I am STUCK with my Old Generation 2 stroke.. I could maybe increase my speed a few mph and increase my mpg close to double? What would it cost me? Around $22,000 that aint gunna happen.. I can buy a lot of $3 a gallon off road fuel for $22,000.00/ even $11,000.00

[HarborRat]

Originally Posted by Macgregorsailor51

...... I do have a water separator , how much that really helps me, is unknown.......

In my post above I recommend not switching back and forth between ethanol and rec, the water separator is one of the main reasons.

Ethanol absorbs a small amount of water (from condensation in the tank or otherwise) and it will burn through the engine harmlessly diluted in the fuel. If it ever absorbs too much water it will phase separate....which is bad! As long as rain doesn't get in the tank and the boat is used often this should not be a problem. The water separator should never have water in it when using ethanol, and neither should your tank.

Rec fuel does not absorb water and the water separator needs to trap any large amounts of water that will sink to the bottom of your tank. That is not a problem until you try and pass ethanol through it. The ethanol will pick up too much of that water from the tank, and in the separator, and send it to the engine...sometimes after phase separation.

A little water absorption is a good thing IMHO, it keeps your tanks free of water buildup. Fisher, the water absorption actually raises the effective octane, not lower. Remember water injection back in the muscle car days? It was used to reduce detonation.

I think the above is why many people who switch to ethanol for the first time have problems. If you are going to make the switch, run your tank almost dry and empty your water separator first and you won't have a problem.

[Macgregorsailor51]

Thanks HR...... I am getting ready to drain out all the old 10% from my fuel tank.
(( I am told the County will accept it at the facility over not far from HD in PC?? I better call first! ))
I am then switching over to 100% - Rec off road fuel ONLY.. I figure, I will replace my water filter and fuel filters and maybe even all the fuel lines.. some have been, others have not and the boat is a 98.. I have about 2 weeks work for an old guy and I am getting a full knee replacement in Feb.. so now is the time to get some stuff done If I can stand the pain ..

Originally Posted by HarborRat

In my post above I recommend not switching back and forth between ethanol and rec, the water separator is one of the main reasons.

Ethanol absorbs a small amount of water (from condensation in the tank or otherwise) and it will burn through the engine harmlessly diluted in the fuel. If it ever absorbs too much water it will phase separate....which is bad! As long as rain doesn't get in the tank and the boat is used often this should not be a problem. The water separator should never have water in it when using ethanol, and neither should your tank.

Rec fuel does not absorb water and the water separator needs to trap any large amounts of water that will sink to the bottom of your tank. That is not a problem until you try and pass ethanol through it. The ethanol will pick up too much of that water from the tank, and in the separator, and send it to the engine...sometimes after phase separation.

A little water absorption is a good thing IMHO, it keeps your tanks free of water buildup. Fisher, the water absorption actually raises the effective octane, not lower. Remember water injection back in the muscle car days? It was used to reduce detonation.

I think the above is why many people who switch to ethanol for the first time have problems. If you are going to make the switch, run your tank almost dry and empty your water separator first and you won't have a problem.

[fisher419]

Originally Posted by HarborRat

Fisher, the water absorption actually raises the effective octane, not lower. Remember water injection back in the muscle car days? It was used to reduce detonation.

Sorry this is incorrect. I could write a whole dissertation on this as I have 35 years of building 1000+ hp racing engines. Water injection WAS used to lower combustion temperatures but never to raise octane. It is no longer used because of the problems it caused with cylinder wash.

Motor octane ratings are based on the rate at which a fuel burns. The higher the octane, the slower the fuel actually burns. The way we make the most power is to actually use the lowest octane possible and still maintain stable combustion cycles. This makes the most heat and as you know, heat is energy. The more heat that can be generated in the combustion chamber the more power you will make to a point.

The issue with ethanol is not the ethanol itself but it's tendency to absorb water over time. More time, more water. It lowers the octane and the ability of the fueling system to provide adequate fueling. More water means more fuel is needed to get the same air/fuel ratio. Modern fuel injection systems handle varying octane ratings well as they can adjust fuel and ignition timing based on oxygen sensor and knock sensor feedback. Older carb'd engines with fixed fueling and ignition timing are at risk because they cannot adjust (add more fuel) if the octane drops.

Even worse are boats (like my old Stingray) that for years used regular gas. If you remember that regular gas when left sit would generate a "varnish" that would stick to the walls of your tank and your fuel system. When switching to ethanol based fuels, the varnish slowly got cleaned out by the alcohol in the system and would clog the carbs with a jelly like substance.

Up north, this is big business rebuilding older boat carbs that sit for six months. Once we get these tanks clean we use an additive called Star Brite. It's the only additive that I've seen work.

[HarborRat]

Fisher, I agree with everything you said except I will stand by my statement that normal water absorption by ethanol increases "effective" octane. It slows the burn rate and reduces detonation.....up to a point! When I say "normal water absorption" I am talking about everyday condensation up until phase separation occurs. IIRC this is somewhere around 1% (?).

After phase separation the water logged ethanol will fall to the bottom of the tank leaving just gasoline at the top. Since ethanol is an octane booster, but it is no longer in that gas, the gas left has lost a few points of octane. This ONLY occurs after phase separation, and the whole tank should be discarded. Many people try to siphon off the "good" gas at the top of the tank...big no-no as it WILL have reduced octane.

With normal use and normal absorption this is never a problem, and octane is not decreased. If phase separation occurs, and since fuel is drawn from the bottom of the tank, the engine probably won't even run....and you will probably see water droplets on your spark plugs.

[kyjake39]

Was leaning toward a 4 stroke when I ask the question and have not seen much negative about them except things about not being able to lay some models down will refine my choice to the 4 cycles and use 93 Obtain gasoline.
Thanks