Wynns petrol treatment

[garynortheast]

Got half a bottle of the above stuff sitting in the garage. Loathe to lob it out, tempted to feed the curvy with it. Anyone got any thoughts on the use of this stuff - is it likely to result in a cleaner fuel system?

I use a little fuel additive[injector cleaner] every two or three tanks when at home without any problems both in the bike and car.
You may have the performance enhancer,JUST READ WHAT IT SAYS ON THE BOTTLE

[garynortheast]

It's just the fuel additive for cleaning carbs and fuel system. I lobbed it in the tank this afternoon before going out for a spin to Y Bermo and back. Interestingly the exhaust note got a little more shrill/raucous as the stuff was going through with the half tank of fuel I had. Refilled the tank on the way home and the exhaust note resumed it's pleasingly fruity note (courtesy of a Free Flow end can).

Then again I may just not have had my ear plugs in as tightly to start with......

modern fuel seems to be more cleaner anyway doesnt it? Ive started using tesco super unleaded (99ron) as my sv was suffering carb icing in the colder weather and just carried on using it.

Bike seems to run a little better for it.

Lee

I appreciate that a curvy is carbed,therefor can be fettled for a higher octane fuel but unless this has been done I was under the impression that the SV standard set-up was for 95ron.I don't know if 99ron has less moisture content than 95ron as say aviation fuel does, but I would have thought the any major carb icing problems would have gone by this time of the year.
Then again I run an F.I.bike which isn't susceptible to icing and I have never found any great increase in amounts that are noticeable, while riding ,to either performance or m.p.g. for the additional cost, that I would consider beneficial


P.S.The additive/cleaner I use was a 5lt freebee otherwise I probably would not bother

could it be possible the 99ron fuel could damage the sv in any way then?

[daveyrach]

Originally Posted by leebex

could it be possible the 99ron fuel could damage the sv in any way then?

Highly doubtful, just gives more of a bang as it has a higher octane rating. I used to use it in my Kwak till you needed a mortgage to fill up

Higher octane fuel gives no more bang then normal fuel, octane just allows the fuel to be compressed more before it will ignite with out a spark, which allows he pistons to get closer to TDC thus producing more power,

If you use higher octane fuel on carbs or a basic fuel injection system, there will be zero difference, as the fuel will just ignite at the same time as lower octane fuel.

The extra power comes when a fuel injection system is able to adapt and delay the ignition.

99ron fuel will cause no damage to your engine

[Sid Squid]

OP: It won't do any harm - but if your bike was running OK it won't do any good either.

So, in all, it won't do anything.

Modern fuels are full of groovy addatives which make fuel system cleaners largely unnecessary, the obvious exception to that would be if a vehicle were laid up for a while and the carbs got a bit manky, if the engine could be started but didn't run well, then a cleaner might be a simpler alternative to removing the carbs and physically cleaning them.

The differing octane ratings describe the detonation* resistance of the fuel, which, very simply put means the fuel's resistance to compression and/or heat ignition. It does not refer to the fuel's energy level, a higher octane fuel doesn't burn more strongly or give more power**

*Variously referred to as knock, pinking, pinging etc etc, all of whch mean improper and/or incomplete combustion.
**Very modern engines often have the ability to adjust themselves electronically to suit differing octane fuels, the fuel itself does not give more power, but may allow the settings to be changed so as to give ever-so-slightly better power or economy.

[embee]

Just a couple of notes to add regards octane rating etc.

What's been said above sums it up in principle. Octane rating is a measure of the resistance to knock (aka etc, as per SS post).

A note on knock
petrol/gasoline as we know it needs an ionisation source to burn, the spark starts it off then the flame front continues the process, flame speed across a combustion chamber varies engine to engine and is highly dependent on load/speed and dilution with EGR etc, but is typically of the order of a few tens of m/sec, say 30-40m/sec is the order of magnitude. The burn process is progressive not an "explosion", the 10-90% mass burn taking typically 30-45deg crank angle (which is why ignition timing is advanced before TDC, the 0-10% burn is slow to get going, as is the 90-100% as the flame approaches the walls).

However when exposed to high temperatures and pressures for long enough, certain petrol ingredients can mutate into unstable compounds which will auto react without the need for the ionisation source. Depending on the make-up of the fuel, the engine speed and the load, you can get to the point where these reactions take place in the "end gas" regions before the flame front arrives and the subsequent spontaneous bulk reaction (rather than progressive burn) results in a very sharp pressure rise, hence the knocking noise.

Normal burn peak pressures might be 70-90Bar, knock produces sharp spikes of a few more tens of Bar. Knock usually gives a "ringing" pressure effect in the cylinder, the primary noise frequency is typically around 6kHz and gives it that characteristic sound. Knock sensors are tuned to this particular frequency in order to pick it out from the rest of the engine noise, and usually it looks at a small angle window just around/after TDC which is when it usually happens.

The tendency of a particular fuel to do this is it's Octane Rating, and is determined in a specific test engine under specific conditions. Now, different fuels behave differently under different conditions, so there are different test conditions used which give different numbers. In the UK/Europe you'll see "RON" quoted (Research Octane Number), the other commonly used one is "MON" (Motor Octane Number, at higher load and with pre-heating) and in the USA the average of these is often quoted ((RON+MON)/2 , sometimes called Pump or Road Octane Number). MON is usually around 7-9 numbers less than RON, so 95RON will be around 91 (R+M)/2. There is also Front Octane Number which relates to transient behaviour.

The number actually compares the real fuel to how a mix of 2 specific hydrocarbons would behave, iso-octane (branched molecule, trimethyl pentane C8H18) which is resistant to knock, and n-heptane (straight chain C7H16) which isn't, so 95RON is like a mix of 95% iso-octane and 5% n-heptane. Cyclic hydrocarbons (benzene/toluene etc) and branched chains (isoparaffins) are generally more resistant to knock, they don't break up as easily as straight chains (n-paraffins). Toluene is a useful additive if you want to raise the Octane value of a commercial fuel (but it's nasty stuff generally).

Higher RON fuels often have very slightly higher calorific values and density than lower RON, but it is a minor effect, a couple of percent, so you don't notice any significant improvements in power or economy in most engines if they can't adapt to take advantage of the higher RON.

You do sometimes find higher RON fuel will feel a bit different, maybe improved response, but that is engine and conditions specific.