Twilight Zone

[Fire99]

Hi All,

This is not the most serious of posts but when driving home last night i was very low on fuel so, without taking the risk of believing the Chim's fuel guage below a 1/4 (i ain't that crazy ) i stopped at the first available petrol station.

Well they had no Super so had to put Normal Esso 95 in.
Now i expected her to run a little rough or even pink a little when on full welly but guess what.. She seemed to run better than on the previous tank of Esso Super.
I did a few miles to check and she runs great. The book and the sticker by the fuel cap all say 97 or 98. but on 95.. Perfect.

Do i have the only Twighlight Zone Chim??

[jasandjules]

Could be that the timing has been retarted so it is happier on 95... I think.

[Tafford]

No, you haven't got the only one. After running mine for ages on Optimax etc I've now decided it runs a lot smoother on normal unleaded. I put it down to the fuel being fresher - I don't see a lot of people using high octane petrol so maybe it goes stale?

[leadfootlydon]

My Chim 500 has run on 95 since before I bought it last year.

The previous owner had it modified and tuned (to 297BHP) and specificaly had it set to run on 95.

I have never tried 98. It would be interesting to find out if I can detect a difference. My MPG is all over the place anyway, from 13 to 26 depending on what I am up to.

[Fire99]

Bizarre really.. (Not that i'm complaining!!)
The previous owner always ran the Chim on Super but hey, if she is happy with a cheaper drink who am i to complain?

[redeye]

run my 4L chim on only 95 Ron runs a dream ,use the higher grade stuff and she splutters and spits run real bad ,95 only for me

[2 sMoKiN bArReLs]

Reckon it must depend on the car & the set up. I've always run mine on 98. When in Italy (where 98 is scarce) I had to run 95, and they were pinking all over the shop. Pretty much had to run one gear lower.

[chezgilo]

This is a very interesting topic. I have been running mine on 98 - mostly Shell Optimax, because that's what the previous owner ran it on (and told me to run it on), and that's what the petrol filler cap sticker says. My TVR has been faultless since I bought it about 8 weeks ago but there is a bit of muffled burbling on the overun.

I think I might try 95Ron and see if it makes a difference (like make it even faster!). If is makes no difference then am I right in saying that it won't damage any mechanical parts in the engine? If not then I will certainly save a few pennies.

[BatleyBoy]

I reckon it's all propaganda from the petrol companies. I read another post from somebody who works for one of the major oil comapnies and he said as much.
I reckon there must be loads running on standard driving fuel without any difference in performance. 50/50 95 vs 98 I bet.

[p400pls]

I read an interesting article in an old copy of Sprint at the weekend written by someone who worked within the fuel refinery business. I can't remember the technical detail but the conclusion I took from it was that the higher octane fuels may not always aid performance but the ones with cleaning chemicals in them will keep injectors etc clean over a period of time, which helps long term efficiency.

I have always run mine on the standard fuel and its been faultless, however I will probably change to the optimax / ultimate based on the argument of longer term cleanliness of engine components rather than increased speed / acceleration.

It will be interesting to see if I notice any difference going the other way.

[shorty123]

Well, i usually run standard unleaded and its great, whenever i fill with optimax or super plus i get uneven running, thought it was a coincidence at first. I guess you have to suck it and see, some cars run better on different octanes.

[Fire99]

Some cars (mostly Turbocharged) can adapt to the higher octane and improve performance a little. Others are tuned especially for 97 & 98 Ron fuel and will 'Pink' or retard the timing if run on lower octane.

I think the RV8 Fuel / Electronics is not adaptive being faily old fashioned and the engine is either tuned for 97/98 or 95.

I think the bottom line is not to assume that just cause the fuel is dearer and may have rave reviews, doesn't mean it will always make your car run better.

Took mine for a good run last night and she was definitely running and pulling better with 95 than with Esso Supreme 97.

It's saved me a few pennies..