Evening all ,
so don’t know how I ended up where I did ( dodgy internet search maybe lol )
but I never knew the real difference between lower octane and higher octane fuel. I just presumed it was more powerful / more fierce , bigger explosion etc but it’s actually harder to ignite and is better under compression. Is this the reason some of us use it due to the whole (det) scenario ? I did always wonder. Anyway that’s it I was just a bit shocked when I read this. Did you all know this already and I’m just being dull ! Lol

 

Its harder to ignite under compression and you get a cleaner more even burn so you can advance timing is what I thought.
Happy to get to the truth tho

 

Adding to that Tesco 99 is the highest octane and the best to use , shell is a max of 99 , where as Tesco’s can be higher so greater at knock protection and more power , getting knock is a good way to kill any engine especially a scooby one

 

That’s handy as I only have Tesco near me. Nearest shell is an hour away ! , always carry some Nf just incase.

 

I'd like to know if esso 99 is 99 or upto 99 like shell

 

It will very likely be the same sort of spec as shell , I’ve not had an issue with either , Tesco say to a refinery this is the spec fuel we want and then it’s blended / mixed , and the tesco octane rating is likely to be higher than 99 and at least a minimum of 99 octane , which helps reduce knock and should produce more power

 

I had an issue getting Vpower during the fuel shortages a few yrs back and was advised to use Tesco 99 and as an alternative and been using it ever since with no issues, lot easier also as Tesco is right on me doorstep whereas nearest Esso is like 7 miles away, saying that also stick Tesco 99 in me 03 Golf GTI as don't rate that new unleaded fuel we now have to use.

 

I e been advised by 4 mappers and two engine builders to use Tesco 99 over shell vnpower. They say it’s better and gives better results like for like. Going back to your comment on the e10 fuel your correct , I use daily Strimmers / chainsaws / mowers and if the fuel is left in the tank for a period of time it eats away the pipes and seal’s especially between tank and carb ! They have all been drained for winter now and next year we have a couple of mowers coming and the manufacturers still can’t gaurantee against the pipes perishing so they will all be run on Tesco 99.
I wonder if I can get the mower mapped ?? Lol

 

I drain all my lawn/garden tools after every use back into a sealed can. As if left longer than two weeks they become an **** to start. As the tanks aren't a tight seal the lighter more volatile aromatics (the stuff that ignited easily) evaporates. And don't start me on the Ethanol damage. I sold my Kawasaki H1 becayse I was fed up of cleaning the verdigris blocking the idle jets and jamming the float needles.

For that reason I used Esso Supreme which despite labelled as E5 was ethanol free (still gasses off though). Jag also ran superb on it (best it ever has for years since Optimax was replaced with Vpower). Unfortunately Esso started adding Ethanol last month.

One thing high octane does is test your ignition system more...any weakness will be worse with higher octane. Back in the day I had kit that could measure the spark voltages and you could tune (old school tune not mapping) engines based on that; weaker fuel mix would have a higher spark voltage IIRC.

 

It's always good to learn something new, and the details of fuel octane ratings can be quite fascinating. Many folks use higher-octane fuel for better engine performance, and it's not something everyone knows until they dig a bit deeper!