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Speed Freak :-)

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Re: Speed Freak :-)

Postby Martin » Wed Jul 05, 2017 9:58 pm

DouglasW wrote:Martin>
"A higher octane fuel will require a higher compression/temp before ignition to give a complete burn."


Hi Martin I would not get too hung up on theory, open your mind and get yourself a tank or two of premium petrol and try it for yourself. :)

Douglas


Hi Douglas, I can assure you there are no hang ups this end.. :D
I have - and do run nothing but quality fuels having taken advice from the lab techs at Shell and BP. I deliver the additives to the refineries and take fuel to the test facilities around the UK.

If you read back through the post you will see i was advising Pete to read his manual and to do what that says, If you say the manual only states nothing lower than 90 RON then so be it, you would assume that 95 Ron is more than acceptable.
However, Increasing the fuel to a higher octane rating without adjusting the motor running temp, timing and such could easily cause an adverse effect, being that the octane rating delays the ignition of the fuel you could find that the detonation is far too late and the piston will get a gentle push down on the latter end of the stroke rather than the boom and wallop of the ignition explosion at the correct time degree of ignition that the outboard was designed on.

The other thing people are mixing up is additives and terminology for fuel.
Supermarket fuel is straight refined fuel by the refinery producing it.... ie, NO extra Additives, just the usual run of the mill additives that all fuels get.

Fuel going to the dedicated stations of the refinery will use the extra additives button, This magic button dispenses the selected additives for the branded fuel, ie.. BP, Shell, Texco etc.
Tesco, Morrisons, Asda etc all buy there fuel from refineries that produce for other brands, Years ago when i frequented Shell Stanlow regularly you would see numerous different companies, all loading from the same pipes, in same refinery... But it is not the same quality of fuel....

Shell Nitro & BP Ultimate are similar, Top quality fuels tested and produced to give the best they can for the vehicles required and designed to use those fuels. Loaded with additives to burn clean, keep the egr/valves/injectors as sprightly as possible.
Tesco99, 'I'm led to believe' is supermarket blend 95 with higher content of ethanol and poorer quality/less detergents that are needed for modern engines...

Given the advice from various engine test facilities, I only run my vehicles on Shell fuels which has proven to be invaluable in my line of business over the last 15yrs :thumbsup
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Re: Speed Freak :-)

Postby DouglasW » Thu Jul 06, 2017 8:54 am

Time for some more experiments!

Last night HW was about 21:50 and it was completely windless. The sea was a like a millpond so ideal treat conditions.

I have two fuel tanks one was filled with Shell regular and the other with Shell V power. I took along my Garmin GPSMap 64S with battery saver off and WAAS/EGNOS switched on to give most accurate results. This part of the test is of my Yamaha F15C only as I was on my own and I can't get it on and off the transom when my boat is on its trolley without assistance.To avoid upsetting the locals I bimbled round the coast to my chosen test location starting with the regular fuel. Straight away I can tell you that this motor really does not like warming up on regular petrol it is like it is only running on one cylinder! But 4 minutes later it was smooth as silk!

My plan was 12 standing starts and run it to max speed for each fuel i.e. 24 runs in all. I would then analyse the GPS tracks to calculate acceleration times 0-25km/hr and to confirm max speed.

As I had indicated in my post above
With the 15HP Yamaha 4 stroke I do not notice any difference in ability to rev getting out the hole with premium fuel.
the acceleration times were all within 3% of each other, the mean regular acceleration time was exactly the same as the mean V power time.

The maximum speeds were much more variable with a difference of 7% between the slowest and the fastest. The mean regular top speed was 41.2km/hr and the mean V power top speed was 41.5km/hr but these were not statistically significant using a t-test at 0.05 confidence limits.

I am not sure why the top speed varied so much as each fuel type was tested the same number of times in each direction and I kept everything else the same. The only thing I can think of is that with all the rain we had over the previous two days there is a great deal of variation in salinity near the Solway coast, sometimes I was in near fresh water and sometimes in salt. Anyway you expect variation in results of experiments and that is why you need to analyse the results with a statistical test.

So the result of this albeit small test is clear, there is no difference in acceleration or max speed between regular and V power petrol when using a newly run in 4 stroke 15hp on an F-RIB 330 which is the maximum rated power for the boat. I will repeat the experiment with my 6hp Yamaha. This ignores any long term benefits that using fuel with extra additives may have on the fuel components or cylinder internals.

One thing I have discovered is that these small Yamahas are not as primitive as I thought. Their compression ratios are much higher than the Evinrude and Johnson outboards I had in the 70's and 80's. The F6C is 8.9:1 and the F15C is 9.3:1. Both have electronic timing advance and retard but neither have knock sensors.

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Re: Speed Freak :-)

Postby Martin » Thu Jul 06, 2017 9:28 am

A great write up Douglas, thanks for the testing and the results. :IANW

Being 100% honest, I'm not suprised in the outcome as the shell standard fuel is remarkable anyway.
I'd be very interested in the same test between a standard supermarket fuel and the standard shell fuel.

I'm not sure what the octane rating/make up is on the v-power, Do they increase the octane over the 95/98 or is it some other lab wizardry :LMT
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Re: Speed Freak :-)

Postby chris moody » Thu Jul 06, 2017 4:07 pm

I would also like to see a test between supermarket standard fuel and premium brand standard fuel. Often wondered if you are paying extra for brand snobbery, or better performing fuel.
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Re: Speed Freak :-)

Postby Martin » Thu Jul 06, 2017 4:27 pm

chris moody wrote:I would also like to see a test between supermarket standard fuel and premium brand standard fuel. Often wondered if you are paying extra for brand snobbery, or better performing fuel.

I can deffinately vouch for the shell standard diesel over the cheaper standard diesel, doing approx £1000 a week in fuel alone I have to save wherever possible. It's false economy for me to run the cheap stuff.
0.5mpg is early gained with shell over the week, the benefits also include no problematic injectors, no night heater issues and generally one fuel filter & gauze clean per year. My emissions at test time are rock bottom low !!!!
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Re: Speed Freak :-)

Postby DouglasW » Fri Jul 07, 2017 11:01 pm

IMG_3919.JPG

It was another flat calm day on the Solway. Time for EXPERIMENT TWO!

I wanted to test my F-RIB 330 and Yamaha F6C in marginal planing conditions with the equivalent of two people aboard. The object of the test was to see if Shell V Power could coax the boat onto the plane in marginal conditions. I already know that the F6C will happily drive a 90kg helm + usual fuel/gear onto the plane at 26-27km/hr at 5,400RPM with the 7.25" x 8.25" standard prop. However, with two people (150kg) on board it will not plane and stick in the hole at 8.5km/hr and even at WOT it will not rev beyond 2,400 so the engine never reaches full power. So I bought a smaller prop 7.25" x 6.5".

With a passenger load of 150kg and the small prop, the F6C will climb out of the hole and start planing at 9km/hr and then go on a top speed of 12km/hr at 5,300RPM. However with a passenger load of 180kg the F6C and small prop at WOT won't rev beyond 2,600 and sticks in the hole at 8.5km/hr.

On to the experiment, I needed some flat stones for a building project so I headed out to a beach on one of the islands with the F6C and a tank of Shell regular and started loading stones into the boat. After every few stones I checked that the boat would still plane. I kept doing this until the boat would no longer plane. Amazingly the final rock that stopped it planing was just a few grams less than 9kg! The boat again stuck at 8.5km/hr and the revs stuck at 2,600. I then switched to the V Power tank and did a few circles to clear the regular fuel from the carb. Then I opened it up. It climbed out of the hole at 9km/hr then the revs rose to 5,200 and it was planing at 11.6km/hr. I did this 10 times and it planed every time. I switched back to regular fuel and the engine would not go above 2,600RPM and stayed stuck in the hole at 8.5km/hr at WOT. In fact if I backed off the throttle to just under half it still ran at 2,600RPM at 8.5km/hr.

I put that final 9kg rock back on the shore and the boat just managed to plane again on regular Shell.

So there is absolutely no doubt that if you have a small engine that is heavily loaded at about half revs, just under planing speed then using V power will help the engine rev higher and get you out of the hole. Note that I am not saying V Power petrol will produce more power than regular petrol near maximum revs where peak power is produced. I don't know what additive is making this difference but something in V Power is helping a heavily loaded engine rev higher at WOT.

I was chatting these results over with the local Yamaha service centre. They told me that unlike cars (which are tweaked to run best on the fuel in the country they are sold in) outboards are the same in all world markets and are designed to run on a wide variety of fuels including fuel with a high bioethanol content. I had joked to Martin that I could always add meths to reduce Shell Regular 95RON down to Yamaha's recommendation of using a MINIMUM 90RON. However, I was wrong, increasing alcohol actually raises the octane of fuel. So these motors can handle fuel with a higher octane due to a higher ethanol content. Martin was concerned that the slower burn of high octane fuel would be wasted as the piston would already be travelling too far down the cylinder at peak burn and the engine would not develop peak power. However, my experiments with the F15C on a lightly loaded F-RIB showed that the engine developed peak revs and identical top speed using both regular and V Power fuel so this fear is not realised in practice.

Interesting stuff. I am hanging on to My F6C for when I want to transport my boat somewhere in the car so I will continue to use V Power in it for its performance benefits. I will also use V power in the F15C for its additives that are designed to keep the engine clean.

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Re: Speed Freak :-)

Postby rogerblack » Fri Jul 07, 2017 11:38 pm

:wavey

Great stuff Douglas, good to have this proved empirically rather than just relying on the theory. :thumbsup

Now, would you mind doing me a favour and repeating the experiments, only this time using BP Ultimate petrol
as that's what I'd use so as to get the Nectar points . . . :whistle

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Re: Speed Freak :-)

Postby Paul » Sat Jul 08, 2017 12:24 am

rogerblack wrote::wavey

Great stuff Douglas, good to have this proved empirically rather than just relying on the theory. :thumbsup

Now, would you mind doing me a favour and repeating the experiments, only this time using BP Ultimate petrol
as that's what I'd use so as to get the Nectar points . . . :whistle

:cheers


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Re: Speed Freak :-)

Postby daveh » Sat Sep 02, 2017 4:48 pm

Great thread, very interesting Douglas..Cheers
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Re: Speed Freak :-)

Postby DouglasW » Sat Sep 02, 2017 6:10 pm

Thanks Dave,

Since I did the above experiments, I have read the Yamaha F15C owner's manual properly!!! On page 13 it says that if you have any problems with running use "premium unleaded fuel".

I use premium primarily for its additives to keep the engine and fuel system clean.

Although I initially thought that premium fuel made no difference to the performance of my F15C, now that it been fully run in, I am getting more revs and top speed at WOT out of it with the standard prop than when I did the above experiments. Obviously a lot of that is due to the running in but I do have a spare fuel tank with regular grade petrol all ready for another test. However, it has been a windy summer here on the Solway and you need flat calm for such tests. At the moment it is averaging 16 knots gusting 21 knots and the kite surfers are out so no testing tonight!.

In the meantime, I continue to use premium petrol. My friend Angus uses regular in his new this season Suzuki 9.9A 4 stroke. I had to rescue him today after it would not start and he was blown offshore in in a 10-13 knot wind. He had pulled the starter cord so many times and so vigorously that somehow the cable that activates the in gear lock for the starter mechanism had become bent and the end had come out the locking cam on the starter mechanism leaving the starter locked. I am not saying premium petrol would have made starting easier...but....

Douglas :)
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