Z4-forum.com

warmasice wrote: ↑Fri Nov 13, 2020 1:18 am

buzyg wrote: ↑Thu Nov 12, 2020 12:47 pm

Chris_D wrote: ↑Thu Nov 12, 2020 12:34 pm No benefits to be gained whatsoever with anything higher than 95RON, especially if you don’t have a high compression engine.

Indeed, do the E89 engines improve their performance on higher Octane petrol? I have know idea just asking..

Certainly the S54 needs it in the E85 M's but what other Z4 engines are designed specifically to run better on the higher Octane fuels?

With a remapped N20, I can confirm higher octane fuel (I use She'll V Power) makes a noticeable difference to performance. 100%.

Can you share those *kof* 100% performance increase figures perhaps? That 3/10ths of a second quicker to the next set of lights time?


I don’t get it tbh, not just you but everyone who claims their car goes faster on super/98RON. It must be such a marginal gain for owners willing to spend the extra on premium fuel, what with all the speed cameras on UK roads preventing owners from exploiting all that ‘extra’ performance and most owners not racing or tracking to be tricked by the brand marketeers into a real placebo.
No offence, I’m all for and believe in the power of placebo speaking from first-hand experience, it works! But that’s the single biggest factor that the brands utilise and would have you fall prey to. Unless you’re running an engine specifically designed to run on higher octane fuel, with the appropriate cmpression there’s really no point otherwise.

I cite in other threads like these the case of our mechanic Dave tuning our Atom for 100RON racing fuel usually Sunoco FR as I recall,l and it making not a blind bit of difference to our ‘ring laptimes, apart from our thinning wallets that is.
Yes we may have been faster in some places, in certain gears at certain parts of the rev range but overall, no real or significant increase in performance due to downforce and gear ratios on the straights and that’s from driving a car at 10/10ths.....all the time!

Carry on spending on super though, if it makes you feel the car has more zing, why not?

I always thought that the 98 RON fuels keep your engine 'cleaner' so it runs sweeter for longer. Am I wrong with that thought?

I've tried several fuels on my 23i. I now just stick to good quality unleaded. Local Shell for convenience.
Weather conditions seem to have the most effect, i'm sure we have all felt the performance gain on those cold misty mornings.

Apparently higher octane fuels burn slower so some goes down the exhaust. Mine certainly pops more on the super unleaded.
Any power gain quickly becomes unnoticeable, if any, just don't use cheap Asda unleaded.

john-e89 wrote: ↑Thu Nov 12, 2020 9:52 pm

R.E92 wrote: ↑Thu Nov 12, 2020 5:37 pm It's nice to have another option aside from just VPower and Momentum but the price makes it useful only as a last resort.

There's no benefit in using higher octane fuel unless tuned though. Both the N20 and N54 engines in their standard state will operate at maximum output on any standard petrol. There's no method by which the engine can produce more power with the increase octane, it can only reduce output when the fuel quality is bad.

Point taken. So what in your opinion or professional opinion is the point of higher octane fuel...? Genuine question, not a sarcastic post as it may seem to be given it’s through a keyboard and not face to face.

Not an expert, just an anorak

I can only talk with certainty about the N54 and it's sensitivity to octane. Premium fuels often claim superior cleaning due to additive packages as far as I know they all put additives in and I've not seen any evidence to show any variable performance of cleaning agents, this just tends to be all about marketing.

With the octane rating there's actually a measurable difference that the engine will notice. With the N54 there's two modes by which the engine can reduce power in relation to fuel (and none to increase power). There's an instantaneous reading from the knock sensors where the engine computer can detect knock and as a result will retard ignition timing in that cylinder for a couple of seconds. Then there's a long-term adaptation value which is constantly calculated as a result of the noise in the cylinder. This long-term value is used to proportionally reduce the engines targeted load (essentially boost). If the car has ignition problems as picked up by the knock sensors then it will gradually reduce the boost. This is a gradual process that takes place across hours rather than seconds and is probably intended to protect the engine in countries where real bad fuel exists and not western Europe. California for example has terrible standard fuel as a result of its war on ICE vehicles so people there either have to run ethanol fuels or stay away from tuning.

Bad fuel isn't the only reason for knock though. It could be a problem with spark plugs, injectors, fuel pressure, coils, battery/ground or air supply issues such as intake valve coking.

Bad fuel doesn't exist in the UK as far as I'm concerned. Any perceived differences when filling up are psychological, likely a manifestation of years of clever advertising from fuel companies. It's possible that an engine may have ignition issues as a result of any previously mentioned factors and that a slight increase in octane rating is the difference between a smooth idle and a rough idle but that would be quite the coincidence.

Argyll Andy wrote: ↑Thu Nov 12, 2020 11:49 pm

chasBMW wrote: ↑Thu Nov 12, 2020 11:00 pm

Busterboo wrote: ↑Thu Nov 12, 2020 11:57 am BMW and I recommend 95 RON.

do they ? pretty sure my 35iS had a 98 ron sticker on it

Just nipped out to check mine after your post because I run on 95 RON

Ok I sort of mis-remembered in that it does show 95 as being ok but it does also say that 98 is useable and to my mind it makes sense to use the highest permitted

I use whatever unleaded is cheapest at the supermarket. I cannot discern any tangible improvement by sticking in these premium fuels nor does the knock change. I used to only ever put in V-power but I think it is a placebo effect and a marketing gimmick appealing to enthusiasts that will pay more. 90% of the time it is Morrison's unleaded I use and the car runs perfectly.

The proper parts and good oil, absolutely.

Danglesberries wrote: ↑Fri Nov 13, 2020 12:49 am What page number in your book does it tell you to run a 330i, N52 engine on 98RON?
My book says it CAN be run on 98 RON although 95 RON is standard and PERFECTLY ACCEPTABLE.
91 RON is the absolute minimum you can use and ONLY IN AN EMERGENCY when nothing else is available.

Here's a copy of the 2005 manual for all petrol E90s - it's on pages 108 & 109 and says to fill up with 98 whenever possible.

Mr Tidy wrote: ↑Fri Nov 13, 2020 7:46 pm Here's a copy of the 2005 manual for all petrol E90s - it's on pages 108 & 109 and says to fill up with 98 whenever possible.

Busterboo wrote: ↑Sat Nov 14, 2020 12:17 am Mr Tidy wrote: ↑Fri Nov 13, 2020 7:46 pm
Here's a copy of the 2005 manual for all petrol E90s - it's on pages 108 & 109 and says to fill up with 98 whenever possible.

Fair enough, you obviously know better than the manufacturer!

Mr Tidy wrote: ↑Sat Nov 14, 2020 12:30 am

Busterboo wrote: ↑Sat Nov 14, 2020 12:17 am Mr Tidy wrote: ↑Fri Nov 13, 2020 7:46 pm
Here's a copy of the 2005 manual for all petrol E90s - it's on pages 108 & 109 and says to fill up with 98 whenever possible.

Fair enough, you obviously know better than the manufacturer!

No, I just drive an E89.

https://www.autocar.co.uk/car-news/tech ... eaded-fuel

Worth a read for those who are unsure of the differences and undecided if super is worth using in a particular application

27P A LITRE - I wouldnt pay that for a tank of leopards fanny batter....

I drove a 911 for 5 years/40k miles on Super Duper + Fairy Liquid and have been happier with the 35iS for 4 years/50k miles on RON's 95 not least because it's easier to find. Running low on fuel in the Porker was always a pain in the arse.

Chris_D wrote: ↑Fri Nov 13, 2020 10:27 am

warmasice wrote: ↑Fri Nov 13, 2020 1:18 am

buzyg wrote: ↑Thu Nov 12, 2020 12:47 pm

Indeed, do the E89 engines improve their performance on higher Octane petrol? I have know idea just asking..

Certainly the S54 needs it in the E85 M's but what other Z4 engines are designed specifically to run better on the higher Octane fuels?

With a remapped N20, I can confirm higher octane fuel (I use She'll V Power) makes a noticeable difference to performance. 100%.

Can you share those *kof* 100% performance increase figures perhaps? That 3/10ths of a second quicker to the next set of lights time?


I don’t get it tbh, not just you but everyone who claims their car goes faster on super/98RON. It must be such a marginal gain for owners willing to spend the extra on premium fuel, what with all the speed cameras on UK roads preventing owners from exploiting all that ‘extra’ performance and most owners not racing or tracking to be tricked by the brand marketeers into a real placebo.
No offence, I’m all for and believe in the power of placebo speaking from first-hand experience, it works! But that’s the single biggest factor that the brands utilise and would have you fall prey to. Unless you’re running an engine specifically designed to run on higher octane fuel, with the appropriate cmpression there’s really no point otherwise.

I cite in other threads like these the case of our mechanic Dave tuning our Atom for 100RON racing fuel usually Sunoco FR as I recall,l and it making not a blind bit of difference to our ‘ring laptimes, apart from our thinning wallets that is.
Yes we may have been faster in some places, in certain gears at certain parts of the rev range but overall, no real or significant increase in performance due to downforce and gear ratios on the straights and that’s from driving a car at 10/10ths.....all the time!

Carry on spending on super though, if it makes you feel the car has more zing, why not?

And keep the profits of the petroleum giants going strong by contributing an extra 20% every time you buy their 'super' fuel