2p Upgrade

[Bramble111s]

Put in the 'expensive' unleaded yesterday, by mistake, started, so carried on just to see if any difference.

It is the high octane variety from Sainsburys, I don't ever normally use supermarket fuel but I had been on refill for a few miles!

 

Now, this could be in my head, but the engine seems to be running really smoothly.

I had assumed I was imagining it, as having driven to the petrol station, it was warm on its return run, but even this morning from cold, it sounded so much smoother, without any stutters or growls and bangs.

 

I don't really know what the difference in the fuel is, hell, I don't even know what Octane is, a gas???

Anyhow, do I now continue with this 2p a litre upgrade?!?

 

Anybody else tried, or swear by 'expensive' unleaded?

[Mark H]

heh, many threads about this already in Technical. General concensus is that it does nothing for the KSeries engine apart from cleans it as the engine doesnt have a knock sensor to adjust the timing based on the higher octane.

[Mark H]

http://www.midlandslotus.co.uk/forum/index...opic=1540&st=0&

[Scott_Mac]

I always run on Optimax... i find the car runs smotther and i get slightly more MPG.

 

For the extra 4p per litre its worth it for the cleaning alone IMO - I also doubt that std fuel is actually 95 ron half the time - at least with Optimax/Super you know its ok.

 

I also get shed loads of PlusPoints from Shell cos you get bonus ones with Optimax

[Bramble111s]

Hmm, thought I had seen this kinda debate previously.

Its obviously just in 'OUR' imagination?!

 

Will switch back to normal next tank and see if I can spot the difference....

[Mark H]

Never really noticed any difference in my old Elise TBH.

[GCCK]

Try half & half, or alternating fills if you want to save a quid.

[simon_prickett]

Made a huge difference in my old Impreza, Optimax easily paid for itself in increased mpg and the car ran smoother... however that had a knock sensor.

 

Given up running the Elise on BP Ultimate, as it's not making a shred of difference... do give it some every 4th tank just to clean it a bit.

 

Simon.

[Bramble111s]

My wifes gonna fill up my car the next few times, then I will have to do the unleaded challenge to see if its all just in my head.

 

It sure sounded smooth this morning.......

 

Although it seems likely its my imagination...

[chorton_1]

Is it possible that there are two potential effects going on, but of which only one is relevent to an Elise?

 

e.g.

1) Optimax has a higher octane rating and can therefore accept higher boost or more ignition advance without detonating or knocking. This is of no benefit to Elises as neither boost (no turbo!) nor ignition advance (no knock sensor) are controlled.

2) Optimax has some characteristic, e.g. the way it atomises/burns and/or has a higher resilience to dropping out the air and coating the engine walls that gives better transient response and or more power. Depending on driving style, this could well equate to better MPG (depending upon whether you thrash the car for the hell of it, or just apply enough throttle to get the desired accel).

 

The above murmurings are merely speculation, not something I am proposing as fact !

[Scott_Mac]

Part 2 i can see, and also part 1, but as you say not relevant to the application.

 

I have done some back to back tests using Optimax and std Shell 95RON, i averaged approx 20 miles more before the REFILL.... i also reckon (could be imagination) that there is a little more keeness to rev in the car.

 

At the end of the day it cost me about £1 extra per tank of fuel, i get Plus Points from Shell (bonus ones for using Optimax) which i currently have about £220 worth of vouchers from and if it cleans my engine - the test in Evo said it did - then thats a good thing too.

[Bramble111s]

sadly I find myself swaying towards Scotts view that it is a good thing....

 

[Scott_Mac]

There is hope for you yet Bramble....

 

[MattyB]

Made crap all difference on my 160 :/

 

Still a pain in the arse to start, still rough, still as great but yeah, I try and put the occasional tank in.

[MattyB]

thinking about it...would their be any advantage to having the ECU adjusted to use 98RON? I assume then using 95 would cause "pinking" ?