Carburator or Injector?

[mish]

Today we make a run of 65 km long with my Yamaha F100 (1999). I just bought the engine. The Atol 5.10 meter console boat was powered with a Yamaha F40 (2003, also carburator). The trip cost us about 6,5 hours. The average speed was 10 km at hour. On a canal nearby Amsterdam we run 1/2 hour 30 km/h (3500 rpm).

The gasoline is in Holland very! expensief. On this moment about 1,57 euro for 1 liter. About 7 dollar for 1 gallon..

But, the consumption of the engine was low. About 25 liter for the day. For 1 hour about 4 liter (about 1 gallon). Isn't that nice?? Is the injector engine from Yamaha less thirsty ?

Greetings from Holland.8)

Mish

 

[phatmanmike]

Re: Carburator or Injector?

yes, injector engines use less fuel than carbs

 

[05GlastronSX]

Re: Carburator or Injector?

to add onto mike, direct injected outboards are much more efficent than carbed ones because they send a precise amount of the gas/oil mixture(2 stroke) into the cylinders. This mixture is Just enough for combustion to occur unlike carbs where the flow is not nearly as precise hence the reason why you get unburnt gas entering the water from an older carbed 2 stroke. over the years, carbed 2 strokes has become more efficent and cleaner through better firing systems (more complete burn) and better oil, but they still dont come close to DI 2 strokes or 4 strokes when it comes to burning clean.

 

[mish]

Re: Carburator or Injector?

Allright, thanks for the respons.

The F100 4-stroke (carb) take 1 gallon each hour. The F100 with injector shut take 0.8 gallon or less?
Example: can we tell the injector version is 20%? efficienter than the carburator version of the 4-stroke Yamaha?

Thanks,
Msh

 

[DJ]

Re: Carburator or Injector?

Any carbed engine has a "sweet spot". That is where the fuel/air mixture meets "stoichiometry" or 14.7 to 1 ratio.

EFI engines can get closer to that ratio throughout the RPM/load range.

 

[BoatBuoy]

Re: Carburator or Injector?

Stoichiometry? Very good, DJ.

 

[rickdb1boat]

Re: Carburator or Injector?

Stoichiometry (sometimes called reaction stoichiometry to distinguish it from composition stoichiometry) is the calculation of quantitative (measurable) relationships of the reactants and products in chemical reactions (chemical equations).

Wow! I have no idea what the he** that means, but I like it.....8) Good one, DJ!!!!!!!!!!!!!

 

[Silvertip]

Re: Carburator or Injector?

Just for the record, four stroke injected engines are only more economical than their carbureted equivalents at anything less than full throttle. Go to Yamaha's web site and check performance reports for any engine (two or four stroke). a 90 4-stroke burns 8.2 gal/hr @ 5900 RPM at 38.8 MPH. A 90 2-stroke burns 9.3 gal/hr @ 5500 RPM at 44.3 MPH. Yes, there is a slight difference at WOT. Fact is, it takes so much fuel to make 90 HP. In this example there is about a 10% difference.

 

[Pitusa]

Re: Carburator or Injector?

Hi,

Here in Venezuela, we prefer carburated engines, because 1 litre of gas is cheaper than 1 litre of water, about 0.04cts/US$...So, 40 litre of gas for my vehicle is full tank ..I pay only 2 US$...
I use 1000 litres of gas for my boat, I have twin 2.5L 200HP Merc...So, I use this Qty for 1 months...every weekend ride...
Also, repair carburated engines is cheaper than injected...
Muchos saludos
Carlos

 

[JB]

Re: Carburator or Injector?

Stoichiometry for outboards, simply put, is the ideal ratio of air to fuel. Max power, minimum waste. In internal combustion gasoline engines it is about 14:1.

Computer controlled fuel injection does it very well compared to carburetors. Direct fuel injection (currently only available in selected 2 strokes) does it even better than that because it can stratify the charge, facilitating good ignition and complete burning of a mix that averages leaner than pure stoichiometry.

DFI will appear in 4 stroke outboards soon. It is currently being introduced in a few automobiles.

 

[Texasmark]

Re: Carburator or Injector?

Say pit, hows come?

Mark

 

[dajohnson53]

Re: Carburator or Injector?

.... a 90 4-stroke burns 8.2 gal/hr @ 5900 RPM at 38.8 MPH. A 90 2-stroke burns 9.3 gal/hr @ 5500 RPM at 44.3 MPH. Yes, there is a slight difference at WOT. Fact is, it takes so much fuel to make 90 HP. In this example there is about a 10% difference.

Actually, there is actually no difference at these WOT RPMs in the measurement of efficiency that really matters to me - miles per gallon (4.8 vs 4.7). This is why I prefer to look at MPG instead of GPH. To me, efficiency is measured by how far you can go with a gallon. When I'm going long distances on plane, I'm looking for the MPG sweet spot. It would be interesting to see how these two engines compare at, say, 60%-80% WOT, in terms of MPH and GPH.

Thanks for posting this.

 

[cobra 3.0]

Re: Carburator or Injector?

Very interesting! My experience from actual usage 20 or so years ago between a carbed 2 stroke Merc and new at the time, carbed 4 stroke 9.9 hp Honda engine was staggering! The Honda literally used about 1/3 the fuel...if that.

Mind you this was not a scientific study by no means...just two tinnys of similar size gone fishing for a long weekend. We did quite a bit of trolling for pike (in spring) with the occasional burst to and from different destinations in a very large complex reservoir.

I still remember laughing at the small 3 gallon tank on the Honda (compared to the 5 gallon tank on the Merc). It looked so "punny" and thought "these guys are going to get stranded somewhere up the reservoir with that little amount of fuel". Of course, we ended up not even finishing the tank in 2 1/2 days of fishing!

However, I attribute the large difference in fuel use to the amount of trolling we did in comparison to actual WOT use.

These same fuel savings are my present experience with two quads I have (a 2 stroke Polaris and a four stroke Honda). The Polaris uses on average 2-3 times more fuel. Again, we're not using these machines at WOT everywhere or I suspect it would be closer.

I'd love to hear from some boaters what their actual savings have been from going to a modern four stroke or DI engine compared to their old carbed 2 stokes.