Talk Morgan Forums Morgan Sports Cars Classic Morgans (pre-CX) Advice needed (again!) - Fuel

Hi All

During the running in and getting-used-to-it-all stages, I stuck with normal '95' petrol.

Is it now worth moving up the grades please.....?

I used 98 for my first re - fueling and kept on using it. My Volvo S40 - which happens to be 'kaput' again! Does not like 95 and as they are basically the same engine I decided to use the higher grade. Also in France, the Octane Rating for 95 is lower than UK; at least at our Supermarket chain.

Intial 'mpg' figure based on 2200 kms of driving is only 33 mpg, but still early days.

Information always seems so varied on this topic.

For engines in a lower state of tune, the higher octane really seems to make little difference either in bhp or mpg. However, where the benefit has been proven is with high performance engines.

I'm not sure whether I'd notice the benefit on a standard engine - have tried before and even with the Aero V8 with valvetronic, I could feel a benefit

Thanks chaps - these are exactly the kind of comments I was hoping for, and (to my mind, anyway) show the value of the site for gathering information.

Spot on Simon!

In Canada, we live 10 miles from the legendary Circuit (sir-kwee) Tremblant. During the summer season, race track fuel is sold by two stations and I keep my mog tuned for and full of 96 minimum (which translates to 102 Octane in European standards). The car's performance is sharp as a rapier. (Of course, mileage suffers.) When we go mogging, I detune the car to accept 92 Octane (aka 97 European). Noticeable difference.

Always use the highest octane you can find for a tuned car you use for fun. Snowmobiles are the best, you can change the fancier models from low tuning to high with the turn of key. Try that with 182 bhp on a 240 kilo machine!

Lorne

Thanks Lorne.

Just to confuse things a bit more, I found this review on 'Optimax'

http://www.ciao.co.uk/Shell_Optimax_Petrol__Review_5329606

And here's a claim i'll follow up on

"Independent tests have shown the acceleration increase from using BP Ultimate Unleaded is roughly equivalent to upgrading from a 2.0 to 2.3 litre engine "

http://www.bp.com/sectiongenericarticle.do?categoryId=4005565&contentId=7009016

Although on a quick first glance at the 'independent test review', I see that the test was on only two cars (BMW M3s), and although the test was repeated, they don't say if the fuels were swapped over at any point...

Paul,

I tried to find the EVO test for you but couldn't. Perhaps someone else will or maybe you read their fuel test about 12-months back?!

Cheers

Simon

Hi Paul, you may be surprise, but the best fuel is Tesco 99, a couple of Atom owners had tried it, and they confirmed it was noticebly better than shell or bp...

http://www.pistonheads.com/gassing/topic.asp?h=0&t=302977&hw=+%2Btesco+%2B99

I agree with Lorne and Simon, if you wanted to take full advantage of hi octane fuel, you would really need to have your ecu re-mapped....

Thanks again for all the advice.

On reflection, the BP test does not stand up to scrutiny, and was very poorly designed. A 'between groups' test on just two high performance cars, with minimal, limited and vague reporting of variables is not enough to justify their claims. The TMS report is however far more convincing.

BHM advised that the ECU will now detect, and respond accordingly to a change to a higher octane - but I was hoping that the 'premium' fuels have other ingredients as well that will have an affect.

Any re-mapping will have to wait until warranty expires, hence my interest in a quicker 'uplift'.

Think I'll try a switch to Tesco 99 however, out of interest, and see if I notice any difference.

The Tesco 99 fuel... is part Bioethanol...

Now the only benefit the higher Octaine rating is going to give you is the ability to advance the timing without causing "knock" or "pre-detonation" and the ability to run higher compression.

This is also why Turbo engines when "on the turbo" will benefit (they also have nock knock sensors).

Additionally the Bioethanol part of the Tesco mix causes a slight lowering of the intake temperature at the port inlet. For every 1 Degree C you should see something like 2-3% BHP increase (roughly speaking)

The only downside is that Bioethanol has a lower chemical energy content therefore whilst providing some knock protection and reduced intake temperatures it does not necessarily provide as much chemical energy as a 100% unleaded mix such as BP105.

At the end of the day.. even with an adaptive ECU it will still be within a boundary and chances are you'll only see major benefits with a re-map.

On the most part the, car will feel more responsive "chrisper" and the engine will run slightly smoother (Although this can vary significantly between fuels)...

Probably easier to find one fuel that make the car "feel" and run well and stick to that where possible... for performance it's not going to make the biggest difference... especially for the cost of purchasing High Octaine fuel all the time.