Why do people buy high octane petrol?

[Admetos]

Err....

Look at this graph lifted from a Thorney Motorsport pdf.

You can clearly see that the super unleaded fuels are making more torque than the regular 95 RON regardless of rpm. Here on super unleaded fuel, engine is making the same torque at circa 1800rpm as the 95 RON does at circa 2200rpm.

I'm saying that having more power allows the driver to choose a higher gear sooner then he normally would, thus increasing mpg. Mechanical sympathy also if like.

My post was in response to another poster implying super unleaded only helps when your driving very fast.

 

[Gaygle]

In North Midlands area all fuel is supplied by Shell Stanlow refinery, I believe the only exception is the Tesco 99 as that contains 5% biofuel additive.

IIRC, it was legislated under the Renewable Transport Fuel Obligation that all fuels England must have at least 5% bioethanol (yes even V-Power).

And, i have lost all faith in Thorney Motorsport fuel comparisons, ever since seeing their absolutely LOLworthy figures using Tesco's Momentum99.

 

[Gaygle]

I've used normal RON 95 in my 335i in the past couple of weeks and it definitely feels like it has less power than on 99 RON. With 95 RON i should think it takes it from about 320bhp to around 290-300bhp.

On my old 330i, the only difference i ever noticed between 95 and 99 was that it felt like it had slightly more torque in the mid range. But that was it.

 

[J1nxy]

In North Midlands area all fuel is supplied by Shell Stanlow refinery, I believe the only exception is the Tesco 99 as that contains 5% biofuel additive.

I do recall a couple of years ago some Sainsbury's fuel was imported on a boat tanker, and the tank had not been cleaned prior causing contamination and damage of catalitic converters, this was London / South area however.

I live in Crewe and have used either Sainsburys 97 RON and Tesco 99 RON for many years with without issues. Ran a Integra Type R the last 4 years. I have used v power but in Crewe price is not justified over Tesco 99.

Here is another Thorney Motorsport rolling road comparison done in 2006 between Tesco 99, then Shell Optimax, BP 97 and normal 95.

http://www.thorneymotorsport.co.uk/content/site/downloads/press-release-full-290806.pdf

There are also the Northampton and area contamination from the Tescos stores which wrecked the MAF sensors due to silicon or simliar being in the fuel.

 

[[TW]Fox]

I'd be amazed if it makes that much difference. 30bhp on fuel type? Behave. It's comments like that which add ammo to the 'It isnt worth it' crowd.

 

[dave_beast]

215bhp out of a 1.6 turbo running 2.2bar of boost, I notice the difference between 97 and 99 octane (BP/Shell~Tesco) as on the lower octane stuff the throttle response is not as crisp, probably the torque curve being less peaky

 

[Gaygle]

I'd be amazed if it makes that much difference. 30bhp on fuel type? Behave. It's comments like that which add ammo to the 'It isnt worth it' crowd.

It could easily be that much IMO.

In that 5th Gear test they had an Impreza that went from 235bhp on 95 RON, to 250bhp on 98RON (Shell Optimax). Or around a 6% difference. 6% difference on my car = ~20bhp. So from 320bhp -> 300bhp.

Now factor in that Shell V-Power is 99RON (as opposed to Shell Optimax being 98RON) and my car is a larger capacity engine, quite a bit more powerful, and has twin turbos - it could easily fall from 320bhp on 99 to 290-300bhp on 95.

You don't think that's plausible?

 

[mrk]

My car doesn't even have a performance engine yet I notice the throttle response is snappier running on Vpower and economy is also improved, a whole tank gains up to 50 extra miles depending on driving style employed for that tank.

High rev acceleration is also improved as is smoothness in high rev gear changes between 4-5500rpm.

 

[[TW]Fox]

My car doesn't even have a performance engine yet I notice the throttle response is snappier running on Vpower and economy is also improved, a whole tank gains up to 50 extra miles depending on driving style employed for that tank.

It really is this sort of comment that makes people so sceptical. Come on guys lets bin the snake oil exageration. You don't get 50 miles more when running VPower in a 318i - I don't in any of the cars I've driven!

Infact to be honest I notice very little difference at all - I don't use higher octane fuel because I can literally feel the difference, I do it because thats the manufacturers recommended spec and I trust the judgement of the manufacturer.

I really do think most of the people who claim to really notice the difference are suffering from placebo effect.

 

[Gaygle]

Infact to be honest I notice very little difference at all - I don't use higher octane fuel because I can literally feel the difference, I do it because thats the manufacturers recommended spec and I trust the judgement of the manufacturer.

Neither did i when i had my M54. As said, i only thought there was a slightly better pickup in the mid range, but nothing spectacular at all and almost exclusively used 95 RON fuel. I am, by default, a high octane fuel sceptic, but i from seeing large increases in power on other turbo charged cars, and applying those figures to my own car, i came to my conclusions above, which i believe are perfectly valid.

I really do think most of the people who claim to really notice the difference are suffering from placebo effect.

Why do you think the points in my post was exaggerated/suffering from placebo effect?

FWIW - i also think ridiculous claims of 50 more miles per tank on a 318i are counter productive, however if mrk can show any evidence that can back this up (which i doubt he can), i would be more than happy to reconsider my opinion.

 

[Kenai]

It could easily be that much IMO.

In that 5th Gear test they had an Impreza that went from 235bhp on 95 RON, to 250bhp on 98RON (Shell Optimax). Or around a 6% difference. 6% difference on my car = ~20bhp. So from 320bhp -> 300bhp.

Now factor in that Shell V-Power is 99RON (as opposed to Shell Optimax being 98RON) and my car is a larger capacity engine, quite a bit more powerful, and has twin turbos - it could easily fall from 320bhp on 99 to 290-300bhp on 95.

You don't think that's plausible?

I think it's more plausible that they ran an Impreza mapped for 98 and it did crap on 95 and that your 335i will not see the same sort of differences.

 

[[TW]Fox]

Why do you think the points in my post was exaggerated/suffering from placebo effect?

Because BMW hardly put an aggresive map on it as you'd expect from the Impreza, and I never noticed anything like that in mine (I ran it on Super exclusively though it had half a tank of what I was told was just standard unleaded in it when I collected it).

 

[Dogbreath]

Look at this graph lifted from a Thorney Motorsport pdf.

That's your problem right there. Had this test been carried out by a competent, independent lab rather than someone who blows up engines for a living then it would carry slightly more credibility.

 

[Gaygle]

I think it's more plausible that they ran an Impreza mapped for 98 and it did crap on 95 and that your 335i will not see the same sort of differences.

Because BMW hardly put an aggresive map on it as you'd expect from the Impreza, and I never noticed anything like that in mine (I ran it on Super exclusively though it had half a tank of what I was told was just standard unleaded in it when I collected it).

Just done a quick Google and found this (which would have helped before!) and it seems to almost whole heartedly support my conclusion.

http://www.e90post.com/forums//showthread.php?t=348050

Opinions?

 

[mrk]

What> You want what kind of evidence exactly?

I said up to 50 extra miles based on what I've observed over 3 and a half years of driving this car. 318Ci or not, the difference is there. I don't give a rat's ass if you or anyone else doesn't believe me unless I print something out then scan it and post it on here - I will only post my experience and if you don't trust that experience then more loser to you.

Sorry if that sounds quite aggressive but the usual Fox and entourage followups about "oh it's only a 318, it can't benefit from xyz" mantra is tiring now.

No, my car is not a race car but it does have a fairly complex and modern engine that the manufacturer recommends using high octane fuel on to get the best out of it and they did advertise it as a high revving engine and I do explore the reaches of the engine regularly and guess what, it is the car I drive for several hours daily and have done for those 3.5 years so noticing a difference, however small, isn't exactly difficult.

 

[Kenai]

What does 50 miles extra to a tank work out as in percentage terms?

 

[Gaygle]

What> You want what kind of evidence exactly?

I said up to 50 extra miles based on what I've observed over 3 and a half years of driving this car. 318Ci or not, the difference is there. I don't give a rat's ass if you or anyone else doesn't believe me unless I print something out then scan it and post it on here - I will only post my experience and if you don't trust that experience then more loser to you.

No, my car is not a race car but it does have a fairly complex and modern engine that the manufacturer recommends using high octane fuel on to get the best out of it and they did advertise it as a high revving engine and I do explore the reaches of the engine regularly and guess what, it is the car I drive for several hours daily and have done for those 3.5 years so noticing a difference, however small, isn't exactly difficult.

Wow, alright mrk, calm down.

We're just having a friendly/nerdy debate about cars, no need to get so defensive.

 

[Gaygle]

What does 50 miles extra to a tank work out as in percentage terms?

About 15% i should think. Which is a huge amount just from fuel, which is why i doubted it.

 

[[TW]Fox]

What> You want what kind of evidence exactly?

I said up to 50 extra miles based on what I've observed over 3 and a half years of driving this car. 318Ci or not, the difference is there. I don't give a rat's ass if you or anyone else doesn't believe me unless I print something out then scan it and post it on here - I will only post my experience and if you don't trust that experience then more loser to you.

Sorry if that sounds quite aggressive but the usual Fox and entourage followups about "oh it's only a 318, it can't benefit from xyz" mantra is tiring now.

No, my car is not a race car but it does have a fairly complex and modern engine that the manufacturer recommends using high octane fuel on to get the best out of it and they did advertise it as a high revving engine and I do explore the reaches of the engine regularly and guess what, it is the car I drive for several hours daily and have done for those 3.5 years so noticing a difference, however small, isn't exactly difficult.

Nice little OMG rant, but you've missed the point. The reason why I highlighted the fact it was a 318 is not because 'lol its so teh slow, of course you are wrong' but because I cannot for the life of me understand why a 318i would get 50 miles from a tankful more with SUL when my experience has shown that a Z4 3.0i, 530i and a 335i don't get anything like 50 more miles per tank from super unleaded! These are more powerful cars from the same generation (and newer even) which *are* designed to take advantage of higher RON fuel and even they don't deliver the differences you seem to find with yours?

If I was able to gain even more MPG to annoy MarkDavis with don't you think I'd have jumped at it?

I make a regular identical 370 mile Motorway trip and I've done it on 95, 97 and 99 RON fuel and have had no appreciable difference in tank range beyond a very marginal increase over using 95.

 

[MikeHiow]

I usually stick with 95 in the Clio, despite Renault recommending 98. However today, I did just fill up with SUL to see if I can really notice any difference in performance or economy.

My last two cars were turbo and I ran them on SUL because I feel there is a greater risk of DET with a FI engine. The VXR explicitly said 98 RON and the ST was mapped for it.