# 2 stroke inboard



## PeterSailer (Mar 20, 2010)

I was wondering why there is no or almost no 2-stroke inboard engines??
I know that they burn more gas then diesel engines but they can run even if the boat is heeling 45 degree. I think thats a big + for 2 stroke.

The only thing very bad about 2-Stroke is the risk of explostion caused by the gazoline in your tank...

I was thinking about that because one of my friends ran into bad weather last year, got scared or something and started he's disel...he broke'blew it.


I only saw two 2 stroke inboard, one was in a contessa26 and the other one was in a paceship 25 I think.


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## erps (Aug 2, 2006)

Did the diesel faill because of the angle of heel? I would have figured that there would be enough oil in the sump to handle moderate angles of heel. On one of our previous boats, our motor used to quit in rough weather with high angles of heel, but I think it was because we only had a 20 gallon fuel tank, and the fuel pickup tube was on one side, so we would start sucking air.

Our first boat had a 6 hp Evinrude on it that burned 1 gal/hr. Our current boat is around ten times heavier with a four stroke diesel that burns around 1gal/hr.


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## klem (Oct 16, 2009)

2 stroke gas engines are almost dead because of emissions regulations. Evinrude is really the only company still making them for sale in the US. You can't find them in a sailboat because there isn't the market for them so no one makes one.

While it is true that a flooded sump engine has more problems at very large angles of heel, in my opinion that is an appropriate trade off given all of the other advantages.


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## SlowButSteady (Feb 17, 2010)

PeterSailer said:


> I was wondering why there is no or almost no 2-stroke inboard engines??...


Two-stroke engines are dandy, if you don't mind the the noise, smoke, and fuel inefficiency.


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## PeterSailer (Mar 20, 2010)

> Did the diesel faill because of the angle of heel?


yes i'm pretty sure,he ran in some very nasty stuff...He was trying to sail in the south from New-Brundwick Canada and when he was off Nova-scotia he ran in a storm.( not sure if it was a actual storm but thats how he called it...) I think he was trying to get away from a lee shore so he started the motor to mortor-sail and then he lost he's motor.



> 2 stroke gas engines are almost dead because of emissions regulations.


That make sense, a couple of my buddies were complaining a while ago about some laws that were gonna kill the 2-stroke motocross.


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## Faster (Sep 13, 2005)

OMC and Volvo both produced a 2 stroke saildrive unit... neither proved historically reliable and despite the reduced cost vs diesel never really caught on. Most boats originally so equipped now sport outboards (many of them still have the original drive unit in place)


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## asdf38 (Jul 7, 2010)

One of the advantages of two-stroke is weight. For inboards weight is less of a goal (they're lower and don't get moved by hand). But there have been a number of them. Lots of Contessa's shipped with Vire 7hp 2-stroke gas engines for example.

There have also been some two stroke diesels.


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## miatapaul (Dec 15, 2006)

asdf38 said:


> There have also been some two stroke diesels.


I have read this, but have never seen one. Air cooled yes, but never 2 stroke.


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## Coquina (Dec 27, 2012)

There are TONS and TONS and TONS of 2-stroke diesels around!
GM Diesel - now Detroit Diesel - ring a bell? 6-71 etc.





Model Displacement Engine configuration Horsepower 
1-71 1.2L (71ci) Single-cylinder 10 
2-71 2.3L (142ci) I-2 68 
3-71 3.5L (213ci) I-3 113 
4-71 4.7L (284ci) I-4 160 
6-71 7.0L (426ci) I-6 238 
6V-71 7.0L (426ci) V-6 238 
8V-71 9.3L (568ci) V-8 318 
12V-71 14.0L (852ci) V-12 450 
16V-71 18.6L (1136ci) V-16 635 
24V-71 27.9L (1704ci) V-24 1800


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## Markwesti (Jan 1, 2013)

Back in the mid 80's my dock neighbor built his own inboard 2 stroke out of a out board Evinrude . It was really cool I wanted to do it to my boat (O'Day23) The Admiral freaked out . I had to admit that would have been a big hole in the bottom of the boat .


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## jgeissinger (Feb 25, 2002)

Re 2 stroke diesels: That's why so many dragsters, etc. with Roots style superchargers refer to them as 6-71, 8-71 etc. That's where they originally came from.


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## Foxy (Sep 14, 2013)

I think having an oil/gas mix in the fuel tank for long periods of time might be problematic and face it, fuel tanks on sailboats are not filled often. Aside from the oil turning into varnish, we now have ethinol to deal with in gas. Another reason to choose diesel.


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## chuck53 (Oct 13, 2009)

Coquina said:


> There are TONS and TONS and TONS of 2-stroke diesels around!
> GM Diesel - now Detroit Diesel - ring a bell? 6-71 etc.
> 
> Detroit Diesel Series 71 - Wikipedia, the free encyclopedia
> ...


Don't forget the 92 series. Lots of them out there as well but everything I've ever read, seems the 71's were the better, more reliable engine.


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## Coquina (Dec 27, 2012)

What may fool some people is 2-stroke diesels use oil in the sump just like a 4 stroke and have camshafts and valves as well. They do have a fun feature that if the rings get bad and the engine sucks in the lubricating oil they will run away at full blast or more until the oil is gone.


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## chuck53 (Oct 13, 2009)

Coquina said:


> What may fool some people is 2-stroke diesels use oil in the sump just like a 4 stroke and have camshafts and valves as well. They do have a fun feature that if the rings get bad and the engine sucks in the lubricating oil they will run away at full blast or more until the oil is gone.


At least you don't have to mix oil with the diesel like you do with gas on gas 2 strokes.


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## MichaelAngel442 (Nov 13, 2013)

The early (1970) CAL 27's came with VIRE 7hp and 12hp.


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## capta (Jun 27, 2011)

chuck53 said:


> At least you don't have to mix oil with the diesel like you do with gas on gas 2 strokes.


Actually, diesel is basically kerosene with 4% oil.
When in Rarotonga I was offered as much free kerosene (jet fuel) as I could put in my tanks, because the drums had been stored wrong and some water had gotten in. Not a big problem for a diesel, but a HUGE problem for a jet engine, I guess. After some research, I found I could safely use it if I added 4 gallons of motor oil for every hundred gallons of diesel; scored 250 gallons of free fuel oil!
Also, I've never heard of a diesel, or a marine gasoline engine failing because of rough water and/or heel. Most "marine" diesels and gas engines have a sufficiently deep sump to handle the heel/roll as no boat stays all the way heeled all the time and the rougher, the more movement. Most engine failures in rough water are caused by fuel filters plugging up from dirty tanks.
Another reason not to adapt a stationary or auto engine to marine w/o knowing what one is doing.


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## christian.hess (Sep 18, 2013)

again good points capta....its not the heel that kills diesel in rough weather, its unmaintained diesel filters and tanks that cause it to fail when everything gets sloshed aroudn to hell, they stall and clog up the injectors which becomes a task to be done only at the dock.

I will point out though that some diesel manufacturers DO state maximum tilt angles and heel for normal use...it might have something to do with lubrication over a long period of time...I know I didnt feel too comfortable when motorsailing on my small h28 with a yanmar 2gmf...

having said that we did use it a couple of times to get out of an iffy situation...mosty thick chop when the wind died and seas were still sloppy and we were close to shore...


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## christian.hess (Sep 18, 2013)

to the op I WOULD love ideas on inboard 2 strokes from days gone by...I wouldnt mind trying to fabricate one since outboards are plentiful here and I am in need of an inboard as I prefer it...


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## christian.hess (Sep 18, 2013)

chuck53 said:


> At least you don't have to mix oil with the diesel like you do with gas on gas 2 strokes.


there are many 2 strokes that use oil injection....

VESPA motorcycle engines do so this way...they have a fuel tank and oil tank...

however those that wanted max performance took the oil injection off and mixed their own batches of oil to fuel ratio...

I have not looked into a marine version of this engine but I think it would be a great solution to old or stale fuel mix combos...


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## chuck53 (Oct 13, 2009)

christian.hess said:


> there are many 2 strokes that use oil injection....
> 
> VESPA motorcycle engines do so this way...they have a fuel tank and oil tank...
> 
> ...


My point wasn't oil injection vs.manually adding oil to gas....my point is oil doesn't have to be added for 2 stroke diesels


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## christian.hess (Sep 18, 2013)

oh sorry thought that it was about 2 stroke engines...


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## chuck53 (Oct 13, 2009)

christian.hess said:


> oh sorry thought that it was about 2 stroke engines...


No, you're still missing my point....2 stroke gas engines have to have oil added to the fuel for combustion either by adding oil to the gas in the tank or having oil injected into the the fuel from a separate tank.

With 2 stroke diesel engines, oil does not have to be added to the fuel for combustion. There's enough lubricity in diesel fuel that additional oil is not needed.


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## christian.hess (Sep 18, 2013)

Im not missing any point...I thought the thread was about 2 stroke GAS inboards...thats why I commented...

I understand about 2 stroke diesels, aircooled etc...

I misunderstood some posts that were previously posted thats all

carry on


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## captain jack (May 5, 2013)

does anyone have any information about converting an outboard for inboard use? the cal27 i just bought used to have a vire 7. it is gone and the previous owner mounted a bracket on the transom for an outboard ( which is also not there, now ). i would rather have inboard power thasn outboard. i personally don't care if it is 2 stroke or not. if there is a 4 stroke option i would rather that. 

i am working on a....restrained budget. so, if i could find a way to convert someone's old outboard to inboard use, that might be just wat the dr ordered. sorry. not trying to hijack the thread or anything.


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## lillia28 (Aug 12, 2011)

Your best bet would be one of the old OMC sail drive units. It basically is a 30 HP outboard turned into a 15 hp sail drive. There was a company adapting Honda outboard engines to sail drives a short time ago, but I haven't looked for a while (Saildrive 280). SAILDRIVE.INFO - Selection Try this site lots of useful info. I have no connection other than a google search. In my experience, it is rarely less expensive to engineer a new system. That is hanging an outboard on a boat that originally came with an inboard is easy. Converting a boat that came with an outboard to an inboard, not so much. Converting an outboard to saildrive, and cutting a 2x3 foot hole in the bottom of your boat to mount it, well it could easily be the long way around. 
Lou


captain jack said:


> does anyone have any information about converting an outboard for inboard use? the cal27 i just bought used to have a vire 7. it is gone and the previous owner mounted a bracket on the transom for an outboard ( which is also not there, now ). i would rather have inboard power thasn outboard. i personally don't care if it is 2 stroke or not. if there is a 4 stroke option i would rather that.
> 
> i am working on a....restrained budget. so, if i could find a way to convert someone's old outboard to inboard use, that might be just wat the dr ordered. sorry. not trying to hijack the thread or anything.


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## captain jack (May 5, 2013)

i may have found a direct replacement motor for that boat. that does seem to me that is a lot more work than simply adapting another inboard motor to fit. when i read about adapting an outboard to fit, i had thought of using the existing shaft, in some way. if you had no original inboard ( no shaft or other elements for the placement of an inboard ) then i think this sail drive might be a good idea. much like an outboard well, just sealed in. i have been considering modifying the lazerate on my holiday 20 into an outboard well, but a sail drive sort of set up might be an idea for that. possibly a future project


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