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For the higher grade fuel doubters



It's a common misconception amongst car enthusiasts that higher octane = more power. This is simply not true. The myth arose because of sportier vehicles requiring higher octane fuels. Without understanding why, a certain section of the car subculture decided that this was because higher octane petrol meant higher power.
The reality of the situation is a little different. Power is limited by the maximum amount of fuel-air mixture that can be jammed into the combustion chamber. Because high performance engines operate with high compression ratios they are more likely to suffer from detonation and so to compensate, they need a higher octane fuel to control the burn. So yes, sports cars do need high octane fuel, but it's not because the octane rating is somehow giving more power. It's because it's required because the engine develops more power because of its design.
There is a direct correlation between the compression ratio of an engine and its fuel octane requirements.

http://www.carbibles.com/fuel_engine_bible_pg2.html
 
  fiesta 1.25
So are you saying that if the engine requires or prefers a higher octane fuel then it will have maximum power with that?
 
  Jagggg...missing the 182!
as an rs clio says on the fuel flap 98 octane, whats the compression ratio on them?
 
  Clio Sport 172 Mk2 Ph2
well i know i get higher MPG and smoother power curve with Vpower wouldnt say its faster thought.
 
tank of V power will see me an extra 50 odd miles in my 1.2. But the cost is greater . . . swings and round abouts.
 
  Clio Sport 172 Mk2 Ph2
performance dont change but i do get more MPG and further miles its also better for engine as it burns cleaner. and tbh my car dont need excuses to break on me.
 
  Nissan 350z
I always use Total Excellium which i think is 97ron? Just makes the car better to drive before it warms up but for the sake of a couple of quid i think its worth it.
 
  Albi Blue RS 200
Not sure about power but I do get more MPG for sure with Super. Enough to make it worth the extra cost
 

Tav

  Clio 197
Someone needs to look at the out puts of the knock sensor and the cars ignition timing and see the differences there.
 

ForceIndia

ClioSport Club Member
  Gentlemans spec 200
Performance diff will be negligible. I use vpower for every other fill up, mainly because of the cleaning properties, which cheaper fuels miss out on.
 
  clio trophy
the only difference you notice is in yer wallet...!! :rasp:

And tesco's fuel is the worst in the world....AWFUL..!! robbin F***ers...!!
 
  clio trophy
Used to use their denzel in the work van, swithched to esso to see the difference and got bout 120 mls more to a tank. was driving roughly the same roads, same speed, same load. decided to try the same on the trophy out of interest and found that get on average 50 miles more( half a wks petrol)...and didnt notice any difference in the performance/idle at all..!! Car runs exactly how it used to on 99 or 98

So i dont go to Tesco's at all and use 95 as long its from Shell or Esso....Thats just my opinion

OH aye and also sum c**k dented ma bunnet :mad::mad: when was in shoppin 4wks after buying the car so maybe it's a grudge thing i'm never gona get over...!!
 
  Ph1
Big 4 page spread in one of the race car mags which backed up the vid. They did all the rolling road tests etc etc and found there was differences between the higher grades let alone comparing against unleaded.
 
  Clio Sport 172 Mk2 Ph2
tesco fuel as a general rule has alot of ethernol in it. was told that by tesco tanker driver. its y it doesnt go as far.
 
  HyperAlloy Combat Chassis
"For the higher grade fuel doubters".....but the video shows that 99% of road cars don't benefit one jot? Of course there are engines that do benefit, like big power turbos, but I don't think anyone said otherwise?

As for the "cleaning benefits", I would take all that with a pinch of salt. The uncombusted fuel touches hardly any of the engine. If you want a cleaner engine, service it properly and use decent oil. Oil is what removes contaminants from the engine.

I used to use Sainsbury's 97 octane, as it's supplied by BP and is often the same price, or cheaper, than "regular" from the likes of Shell etc. MPG was no different from V-Power after careful testing.
 
  182
I've never had a problem with the tesco 99 stuff. It does seem to get slightly more miles out of a tank with it or vpower. I'd use vpower but the robbing b******s at the station near me charge 11p a litre more than standard.
 
  WR1 impreza
Ive got no problem with Tesco 99 ron tbh. Infact its the only fuel that gives me over 300 miles to a tank, and I get me clubcard points too ;-p
 
  Evo 6, E92 320d
I have been using 95 lately as i cba to drive to tesco, but usually i find local 95 is more expensive than tesco 99, also the idle is smoother with 99 but thats it.
 


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