Update & Corrected Running Costs

[disorderly]

Hi Mindi,

I think it big call to say Andrew Norton does not know his stuff!? He has tested just about every outboard out there, often on a long term basis and he takes indepth full usage figures. He reports them in great detail, and has for years. He also made the comment about the E-Tec 150, whereas you are comparing a Suzy 70 and a E-Tec75!!??

I know nothing about the Suzuki 70 and very little about the E-Tec 75. I agree if you use those two reports then they support your contention, but that is a pretty big bow to draw to then say a DI 2 stroke uses about 20% more fuel than a comparable 4 stroke, based on 2 reports from manufacturers sites on two different boats. If that was true (across the board) do you think they would be selling as many DI 2 strokes as they do!?


I am not looking to defend DI's, let the facts speak for themselves. I suspect on average they do use slightly more than a 4 stroke, but not 20% on the evidence I have seen. It is the trade off for the greater torque and holeshot that you expect from the DI 2 stroke. For example I have seen a thread on another forum which I think you were also involved in where a dealer stated that the E-Tec 75 is actually putting out 82hp. If that is true, then you would definitely expect it to use more fuel than the Suzuki 70, possibly +17% perhaps being 82hp vs 70hp ie +17%, hope you see my point.

As to how you allow for it in the spreadsheet, I have a few thoughts. I will PM you to get a copy and have a look.

Still think this will be a worthwehile exercise if we can get flexibility in the calculations to allow for differing usages etc.

Cheers

Dave

Good points Dave...it makes Mindi's whole comparison invalid from the start as we are talking about motors of a different HP rating under different conditions on different boats tested by different people with different axes to grind....

Mindi....this is about the most unscientific comparison I could imagine

As for using l/h as a guide...I also remain unconvinced, as the motor will run at every rpm between 0 and WOT over the course of my day's travel....

The only meaningful fuel consumption figures for me are how far I have traveled in the day and how many litres of fuel I used ie km/l .

Scott

[Outsider1]

Mindi kindly sent me a copy of his spreadsheet and I have been having a bit of a look and a think about the running costs comparisons.

It is easy to get bogged down in the complexity of different outboard set ups, performance profiles etc, but they are real and do make these types of comparisons very hard.

I have attached a document that highlights these issues. There is an example of the same motor on 3 different but similar hulls. Fuel consumption for the same motor at the same rpms varies by up to 33%!.

My first thought is can we simplify this back to what Mindi was really trying to compare in the first place. Now I have not discussed it with him, but I assume that one of the things he was trying to compare was the 3 year/300hr service cycle of the E-Tec vs the annual/100hr servicing of the average 4 stroke.

If you assume that fuel consumption is basically the same, then it is a comparison of the cost of 2 stroke oil plus 1 service vs the cost of 3 services. This takes any hull or set up variances out if it.

Adjusting the price of XD100 to $55 for 3.78 litres in the formula and equalising consumption the result shows that the E-Tec would be about $340 cheaper in total @ 50hrs pa for 3 years. If you pump the hours up to 100 pa the difference almost disappears i.e. the cost of the XD100 offsets the savings in service costs.

In the 50 hours pa comparison the E-Tec could use up to 9% more fuel and still be cheaper overall to run.

Cheers

Dave

[STUIE63]

When the figures were done for oil usage what ratio were they calculated at because by Daves PDF the etec/opti would approx 65% of the time be useing less than 100:1 this could be another huge variable in the costings
Stuie

[STUIE63]

mate the variables in this equation would be enough to send Albert Einstein round the twist I'm with Noelm here just get the motor that has a good service agent/dealer in your area
Stuie

[Outsider1]

When the figures were done for oil usage what ratio were they calculated at because by Daves PDF the etec/opti would approx 65% of the time be useing less than 100:1 this could be another huge variable in the costings
Stuie

It worked out at an average of just over 100 to 1, 102.2 to be more precise. This was Mindi's original assumption and appeared quite sound to me.

Yes agree, it is an almost impossible equation with all the variables. We have not really talked about the Optimax for example. It has a displacement of 1.526 litres whereas the Suzy is 1.298 and the E-Tec 1.295 litres. So the Opti has over 17.5% more engine displacement. You would therefore expect it to use more fuel, but on the plus side it should be very torquey, understressed and perform very well. How that translates back to running cots is hard to say though, it really depends on the hull and the set up. On some hulls it may be the only motor you might consider for the particular use.


Cheers

Dave

[disorderly]

It worked out at an average of just over 100 to 1, 102.2 to be more precise. This was Mindi's original assumption and appeared quite sound to me.

Yes agree, it is an almost impossible equation with all the variables. We have not really talked about the Optimax for example. It has a displacement of 1.526 litres whereas the Suzy is 1.298 and the E-Tec 1.295 litres. So the Opti has over 17.5% more engine displacement. You would therefore expect it to use more fuel, but on the plus side it should be very torquey, understressed and perform very well. How that translates back to running cots is hard to say though, it really depends on the hull and the set up. On some hulls it may be the only motor you might consider for the particular use.


Cheers

Dave

So many variables alright...
Since fuel went up and I started driving much slower (I also do quite a bit of trolling)..my XD 100 oil ratio has been around 145 to 1.

I have also noticed in some of the Optimax ads that they claim
figures of 3.28 km/l vs 2.85km/l for the E-tec in the 90 hp...almost 20% right there....I think sometimes such figures are just plucked out of thin air and dont reflect real life situations.

The only way to obtain valid data IMO is to run the same boats side by side with the different brand ,similar sized motors properly setup for those hulls...and even then some motors may perform differently on different hulls but at least you would be comparing apples with apples and get some comparable data.

Scott

[Crocodile]

Fuel is all very well but that is only part of it.
What about rego, insurance, maintenance on the trailer and boat.
The really big cost is depreciation or even worse interest on the loan.
If you have a 75hp motor, total rig cost is at least 30K which will be worth 20K (if you are lucky) after three years so add in ar least 3K per year depreciation.
Don't get too bogged down over a few bucks difference in fuel dollars.