4 stroke V 2 Stroke outboard engines?

Lakesailor said:
Why does an SUV do more harm than an ordinary car?
My last two Grand Viatras did 36 mpg and my Jeep does 31 mpg. Plenty of cars are worse than that.
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It's generally thought that barn door aerodynamics combined with the extra friction of 4WD adversely affect fuel consumption. We'd need to know more details such as engine type in order to pick an equivalent car for comparison.
 
Irrelevant. If I choose to drive a Jeep at 31 mpg or a Jaguar at 28 mpg I am using less fuel to get me around in a Jeep.
If I choose a Fiat 500 I will use less than the Jeep.
If I choose a Bugatti I will use a lot more fuel than any of them.

It's not a matter of this vehicle or that vehicle. It is a matter of how much fuel I use to move myself about.
Many high performance vehicles use way more fuel than my car. If you use the performance. But why buy it if you want to drive slowly?

I was questioning the default position that SUVs use more fuel than other vehicles.
 
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You were challenging the assertion that SUVs, as a class, were thirstier than regular cars. In order to debate this you need to take, as far as is possible, one or more SUVs and compare their consumption with comparable cars ..e.g same fuel, same performance .. ideally same engine and carrying capacity. Of course there are some cars that are thirstier than some SUVs but that that doesn't disprove the assertion ... you need to compare like with like. If you're not convinced then I can look through an old car mag. and look for comparable pairs of vehicles but right now I must walk the dog.
 
reeac said:
You were challenging the assertion that SUVs, as a class, were thirstier than regular cars. In order to debate this you need to take, as far as is possible, one or more SUVs and compare their consumption with comparable cars ..e.g same fuel, same performance .. ideally same engine and carrying capacity. Of course there are some cars that are thirstier than some SUVs but that that doesn't disprove the assertion ... you need to compare like with like. If you're not convinced then I can look through an old car mag. and look for comparable pairs of vehicles but right now I must walk the dog.
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i'm not convinced.But please don't bother on my behalf.
SUVs have been stereotyped such that I have been accused of raping the planet by people who run vehicles worse than mine. I, however, don't suggest that vans or luxury cars are worse polluters per se.
 
Great advice, thanks. I will try running the engine with the fuel switched off and draining the fuel at the end of the season. Interestingly I have a 2.8m HonWave and it definitely does not plane with this engine.
 
Seven Spades said:
Great advice, thanks. I will try running the engine with the fuel switched off and draining the fuel at the end of the season. Interestingly I have a 2.8m HonWave and it definitely does not plane with this engine.
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May be worth having the engine uprated to 5hp which iirc just costs a few pounds. This is what the original purchaser did with my 4hp and maybe, just maybe it may improve the starting as mine starts much more more easily than yours. A couple of other thoughts, what floor do you have in the Honwave as my Avon Rover (also 2.8) does not plane easily unless i get the inflatable floor pumped up fully ? It cannot be your weight (;)) as mine will plane easily with my wife & I on board and I doubt you weigh more than both of us !

Definitely worth trying, as doing longish trips in the dinghy on the plane really save saves so much time and is great fun :) As it has 4hp marked on the cowling I can imagine it must puzzle onlookers when they see me whizzing along at high speed in the mornings when I go out to lift the lobster pot.
 
Seven Spades said:
Are 4-strokes less prone to problems with fuel clogging the carburetor than 2-strokes? I am at my wits end because I use my outboard so infrequently I really don't want to have to drain the tank after each use. As I say I never had this problem with my old engine. I am not sure if it is the new engine at fault because it might just be a coincidence I believe we now have a proportion of ethanol in our fuel and this is the main cause of the problem.
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The 5%Ethanol added to petrol today is the Pitts.

E5 petrol is supplied in most regular petrols today and gives poorer starting and slightly lower power, along with leaning the mixture strength, due to the higher oxygen content. Particularly noticeable with small engines run at full power, which of course covers many outboards. Use BP ultimate premium 97 ron which at the moment has no alcohol. Restored better running and power to our 2002 yamaha 8.

I believe the west country has a greater preponderance of alcohol laced fuels due to the supplying refinery.
 
david_bagshaw said:
The 5%Ethanol added to petrol today is the Pitts.
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Elder, Younger, or perhaps both?

david_bagshaw said:
E5 petrol is supplied in most regular petrols today and gives poorer starting and slightly lower power, along with leaning the mixture strength, due to the higher oxygen content.
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I'd be very interested in your source for that information. So far as I know the only IC fuels which "lean mixture...due to higher oxygen content" are nitromethane and nitrous oxide (although the latter isn't strictly a fuel).

P.S. I'd add that any fuel available at a petrol station which endows oxygen available for combustion would be welcomed with open arms by the motor racing fraternity. Getting oxygen into an engine by normal means is quite difficult (indeed it's the limiting factor to power); getting fuel in is, by comparison, a doddle.
 
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macd said:
Elder, Younger, or perhaps both?



I'd be very interested in your source for that information. So far as I know the only IC fuels which "lean mixture...due to higher oxygen content" are nitromethane and nitrous oxide (although the latter isn't strictly a fuel).

P.S. I'd add that any fuel available at a petrol station which endows oxygen available for combustion would be welcomed with open arms by the motor racing fraternity. Getting oxygen into an engine by normal means is quite difficult (indeed it's the limiting factor to power); getting fuel in is, by comparison, a doddle.
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3.13 on page 11

http://assets.dft.gov.uk/publicatio...f-carburettor-icing/bioethanolstudyreport.pdf

If an engine is run on alcohol instead of petrol jet size is increased due to I believe lower calorific value, so putting alcohol in petrol without up jetting will lean the mixture, never mind the item above.
 
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david_bagshaw said:
3.13 on page 11

http://assets.dft.gov.uk/publicatio...f-carburettor-icing/bioethanolstudyreport.pdf

If an engine is run on alcohol instead of petrol jet size is increased due to I believe lower calorific value, so putting alcohol in petrol without up jetting will lean the mixture, never mind the item above.
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Thanks, David. It's a long paper, which I'll read with interest when I have time. Regarding 3.1.3, "Ethanol contains about 35 % oxygen"...that may be so, but it's not free oxygen, so I'd be surprised if it has a bearing on mixture strength (unlike nitro and nitrous, which I mentioned before, both of which liberate huge amounts of free 02. Indeed with engines run on nitro, you often throw away the main jet altogether: too restrictive).

P.S. Forgot to say that you are quite right that there are many other issues with ethanol fuels, one of the results of which is to leave the field open for dodgy theories and "remedial" potions.
 
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