6 replies to this topic

[mingy]

We were out in the mini last weekend and i decided to fill up as the fuel level was very low, i decided to try some Shell V power unleaded and promptly filled the tank to it,s max.

Well, normally the engine would run on after i switched it off so i would put it into 2nd gear and stall it.

After filling up with V power and doing 100 miles or so the engine performance has increased but better still it stops properly after turning it off, why has this happened ?.

[RooBoonix]

Carb or Injection?

[mingy]

The engine is a 1380 fuelled by the usual HIF44 ( with some Vizard modifications ).

[PandO]

Shell V power is at least 98 octane I believe - regular stuff is 95 and supermarket premium/super is about 97 (Tesco's has good reviews though and could be higher than this). It's the octane rating that has probably helped. You have probably had some pinking (pre ignition) which leads to overheating which causes run-on. Also the branded super has cleansing additives which after a 100 miles may have removed deposits which can glow after the ignition is switched off. I've heard the best stuff is BP ultimate at around 100 octane - my nearest garages for this are miles from home so I'm using Shell. If you're engine has been modded and your timing is set correctly and plugs are not too hot - either a skimmed head and/or HC pistons fitted you will have problems with cheap fuel. Try another quantity of regular and if/when the problem returns fill up with Shell in future. Good luck.

[markyB]

In basic terms, it's a better quality fuel. It has a higher octane and more / better quality additives. This all adds up to the fuel burning better, creating a hotter cleaner bang when the fuel is ignited and therefore burning away carbon deposits

We have so many customers with problems when running their vehicles on supermarket 'city fuel' (especially using diesel) We advise them to use a better quality fuel ie shell/bp

[Steve220]

Higher octane = slower burn. Personally i'd be looking at why you were getting pre-det in the first place rather than putting a plaster over a broken leg.

[carbon]

Normal petrol = 95 octane

 

Shell V-Power = 99 octane

 

Running on is typical symptom for having fuel of too low octane for the engine. MG Metros used to have this problem, solved by fitting an anti run-on valve.

 

If you have a compression tester run a check, if it comes back over 200psi with warm engine then you really need to use 99 octane fuel all the time. With Shell V-Power it's still good at 225psi.