Tuning tips: Petrol, octane and additive tips

[obi_waynne]

There is an ever increasing array of fuel on offer. With the addition of a whole plethora of additives the motorist can be left wondering what is the best for his car. Which octane is best and should you use additives? Are all brands of fuel the same? The quick answer is that all fuels [...]
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What do you think of this tip then, read the article and post your comments in here.

 

[HDi fun]

"An engine contains a knock sensor and if it detects that knock is occurring it reduces the fuel sent to the engine thereby decreasing power."

No it doesn't. It retards the ignition timing for the offending cylinder(s). Reducing fueling, ie. running on a weak mixture, will exacerbate the knocking.

 

[stamford]

What he said ^^

My MG was remapped using standard 95RON pump fuel, purely because at that time it was my daily driver. However it is going to be remapped using the 97/98RON as this will benefit from it.

What I will say is, I did run my MG on the Ultimate or optimax, as it was then, and found very little in it. Probably placebo in some instances, however when running my V6 Calibra I did notice a marked difference in that the engine ran sweeter and idled cleanly. The MG on the other hand had an ECU that could learn small changes and adapt, but had certain limitations. When remapped it is able to make the most of the higher octane fuel as it is tweaked 'on the fly' so to speak. So any changes can be monitored and AFR checked.

As for additives, never used them and if they were that good why are they not added as standard?

 

[one in a million]

on my clio 182, when i open the petrol cap, theres a little green sticker with "97", does it mean i should run it on optimun 97, i did run it on 95 for a month, and for the last 2 months now since i have owned it its run on optimun. what do you suggest

 

[obi_waynne]

Thanks for the feedback HDI - much appreciated and well spotted. A lot of these articles are quite old an clearly need revising and proofing!

OIAM -
You can potentially do harm to an engine using high RPM loads on too low an octane fuel so be careful.

In reality there is not a lot of difference between a 95 and 97 but if your maker specified 100Ron (many jap cars) then 95 is a bit low.

 

[HDi fun]

@Stamford - additives are added as standard, that's the differrence between supermarket fuels and premium forecourt fuels - the additive package in the forecourt fuels is of much higher quality.

Some additives are beneficial, especially with diesel cars but I'm not going to pollute this thread because it is specifically about petrol engine.

Most cars will self adapt to different research octane number fuels. My BMW is supposed to have 98RON ideally according to the handbook but it also says that 95 is fine as well. The timing adapts itself imperceptibly. It's not a high performance car anyway and the differences are miniscule.

 

[stamford]

I know the mainstream fuel makers use additives in their own fuels as they use this as part of their marketing blurb. What I should have referred to was the aftermarket ones as seen on the shelves at your local high street bicycle store or Walmart. I'm not one for supermarket fuels unless I have no option. But then again, is this just hearsay, selling poorer grade fuels with no or little additives?

 

[HDi fun]

I know the mainstream fuel makers use additives in their own fuels as they use this as part of their marketing blurb. What I should have referred to was the aftermarket ones as seen on the shelves at your local high street bicycle store or Walmart. I'm not one for supermarket fuels unless I have no option. But then again, is this just hearsay, selling poorer grade fuels with no or little additives?

I have used the occasional bottle of Forte or Millers Diesel additives to great effect but they're not essential. Petrol injector cleaning compounds are little more than kerosene or white spirit with some red dye added. Wonder which product it is to which I am referring?

One that is meant to be worth a look is BG44K or BG244 for diesel.