100 Octane Petrol in N54

[Kiwi_Mike]

I just got my 35i remapped by a local tuning specialist. No Dyno so I have to take his word for the claimed figures (380HP 520NM) but the car definitely pulls a lot harder and smoother than before and the exhaust sounds great.

He told me I should be using 98 petrol but my local petrol station only has 95 or this 100 plus.

Do you guys think I’ll be OK using 100 instead of 98?



Cheers

 

[Chippie]

I would have thought that 100 would be better than 98 with the remap.

 

[R.E92]

Are those ratings US Octane or European RON? Normally those warnings about additives are only present in race fuel.

380 is quite low for a 35i, the engine isn't being pushed too hard so I wouldn't worry too much if you had to use 95RON fuel.

 

[B21]

It looks like it marketing snake oil for 'normal' high octane automotive petrol.

https://www.npd.co.nz/100plus-high-octane-petrol/

So given it doesn't appear to be race 'hooch' you should be fine to use it, IMHO

If he has set the mapping up on the assumtion of a max of 98 octane then you can use it without limitation.

It won't confer any benefit over 98 octane apart from the witch doctor claims..

Normally people use data logging and/or dyno runs to see how the tune is behaving in the engine.

The N54 engine is pretty much a commodity engine with a well trodden path, so I assume the tuner is using some fairly standard maps copied from somewhere.

My 35is moved from 347 ish to 390 ish with just a re-map so it doesn't sound implausable..

 

[Mister T]

Use the 100 Plus stuff.

With 95 you'll run more of a risk of detonation.

 

[Flyingfifer]

Use the 100 Plus stuff.

With 95 you'll run more of a risk of detonation.

Does the E89 ECU not take account of fuel/knock?
Obviously if the car was mapped on 100 then use 100, if it was mapped on 95 either will do.

 

[R.E92]

Use the 100 Plus stuff.

With 95 you'll run more of a risk of detonation.

Does the E89 ECU not take account of fuel/knock?
Obviously if the car was mapped on 100 then use 100, if it was mapped on 95 either will do.

The car as standard is mapped for low grade fuel. In places like California people only have access to really s**t fuel (ACN) that would be equivalent to 92RON. If a standard 35is can run fine on Californian fuel then I wouldn't be worried about using 95RON on a lightly tuned car.

In my experience you are fine at moderate power levels (370-390bhp on standard turbos) with just standard 95RON. It does depend on how the car was tuned though, you could ask the tuner what the timing curve looks like at high load. If targetting less than 6degrees then you'll be fine.

 

[Marcoose]

California has 87 and 91 octane petrol. At the track, there’s 100 octane. If your vehicle isn’t tuned for 100 octane, it won’t do anything. My track car and bike are not tuned for 100 octane. I’ve never felt fuel was the winning/losing factor. How much sleep and exercise I get the days leading to the race correlate far more with results.

The BMW US owner’s manual says to use 91 octane. I don’t track the 35is. On the streets, the car runs just fine. It outperforms 95% of all vehicles. (I do.) Higher octane would not improve performance. At this point, it’s all with the driver. If you’re using 400 bhp on the streets, you’re doing something wrong.

It’s the first time I hear s**t fuel.

 

[R.E92]

American tuners offer 91 maps and 91 "ACN" maps for Arizona, California and Nevada as their 91 isn't as knock resistant as 91 in the rest of the country so they lower the output.

 

[Mister T]

Use the 100 Plus stuff.

With 95 you'll run more of a risk of detonation.

Does the E89 ECU not take account of fuel/knock?
Obviously if the car was mapped on 100 then use 100, if it was mapped on 95 either will do.

Who knows what safety features have been disabled by the mapper, not worth the risk IMO

 

[Flyingfifer]

Who knows what safety features have been disabled by the mapper, not worth the risk IMO

Kinda boils down to know what is being done to your car

 

[B21]

Who knows what safety features have been disabled by the mapper, not worth the risk IMO

Kinda boils down to know what is being done to your car

AFAIK, most 'commodity level' N54 tunes change the fuelling tables and boost tables and leave much of the rest alone..

The argument I guess since so many people have tweaked this engine, and relatively speaking so few have blown them up that its a pretty tough engine and runs out of steam before it can blow up, unless you start adding bigger turbos and meths /ethanol etc..

I went with the N54 and then MHD Flasher precisely because so many people had been down that route.

That was one of the issues with the N20..there was precious little UK experience of tweaking it and in the US people had blown a few motors asking it to do too much.

Those guys doing the really silly tunes and they have now taken the N54 past 1000bhp are into a world of expensive adds ons or very careful monitoing.

That's why some folks use tools like JB4 (a piggy back device) AND an ECU flash as the JB4 can save the engine from a major issue if something goes wrong..whilst a pure flash will keep going till it goes bang.

So yes it can go wrong, but if the guy says 380 bjp on stock parts then it doesn't set the alarm bell ringing (directly)..IMHO

 

[Marcoose]

I’m yet to meet to one driver/biker that I look up to who complains of 91 octane petrol in their street cars/motorbikes. The ones who complain also spend a lot of time talking about launch mode. :roll:

 

[Flyingfifer]

I’m yet to meet to one driver/biker that I look up to who complains of 91 octane petrol in their street cars/motorbikes. The ones who complain also spend a lot of time talking about launch mode. :roll:

91 Octane is basically our 95RON which is your basic bitch fuel, I would not however run 95RON in my turbo cars though admittedly they were mapped to run on 99RON and didnt run well at all on 95RON (there is a noticeable difference in performance as well when map accounts for fuel quality)

 

[B21]

From MHD N54 spec

Stage 1+ (up to 390HP/600NM) - 91oct/95ron, 93oct/98ron, 95oct/102ron, FMIC recommended.

So US 91 is our 95!

Unusally for a nation so keen on bigging it up why is their gallon less than ours and their octane rating?

 

[R.E92]

Who knows what safety features have been disabled by the mapper, not worth the risk IMO

Kinda boils down to know what is being done to your car

AFAIK, most 'commodity level' N54 tunes change the fuelling tables and boost tables and leave much of the rest alone..

The argument I guess since so many people have tweaked this engine, and relatively speaking so few have blown them up that its a pretty tough engine and runs out of steam before it can blow up, unless you start adding bigger turbos and meths /ethanol etc..

I went with the N54 and then MHD Flasher precisely because so many people had been down that route.

That was one of the issues with the N20..there was precious little UK experience of tweaking it and in the US people had blown a few motors asking it to do too much.

Those guys doing the really silly tunes and they have now taken the N54 past 1000bhp are into a world of expensive adds ons or very careful monitoing.

That's why some folks use tools like JB4 (a piggy back device) AND an ECU flash as the JB4 can save the engine from a major issue if something goes wrong..whilst a pure flash will keep going till it goes bang.

So yes it can go wrong, but if the guy says 380 bjp on stock parts then it doesn't set the alarm bell ringing (directly)..IMHO

The JB4 is more likely to cause your engine to blow than save it. I saw a person recently who blew their low mileage engine using just a JB4. They were fortunate enough to be logging the car at the time and the logs showed the engine detecting an issue and trying to reduce boost pressure but the JB4 overrides the engines requested boost and keeps targetting the full amount. Because of the way the JB4 lies about the actual engine load the engine thought the boost had been lowered therefore started to target a really lean afr which caused the engine to blow.

I know they use the JB4 safety features as a selling point but realistically it's marketing BS. One thing that struck me about the JB4 forums was the number of people on their second or third engine, it was almost like a rite of passage.

 

[B21]

Kinda boils down to know what is being done to your car

AFAIK, most 'commodity level' N54 tunes change the fuelling tables and boost tables and leave much of the rest alone..

The argument I guess since so many people have tweaked this engine, and relatively speaking so few have blown them up that its a pretty tough engine and runs out of steam before it can blow up, unless you start adding bigger turbos and meths /ethanol etc..

I went with the N54 and then MHD Flasher precisely because so many people had been down that route.

That was one of the issues with the N20..there was precious little UK experience of tweaking it and in the US people had blown a few motors asking it to do too much.

Those guys doing the really silly tunes and they have now taken the N54 past 1000bhp are into a world of expensive adds ons or very careful monitoing.

That's why some folks use tools like JB4 (a piggy back device) AND an ECU flash as the JB4 can save the engine from a major issue if something goes wrong..whilst a pure flash will keep going till it goes bang.

So yes it can go wrong, but if the guy says 380 bjp on stock parts then it doesn't set the alarm bell ringing (directly)..IMHO

The JB4 is more likely to cause your engine to blow than save it. I saw a person recently who blew their low mileage engine using just a JB4. They were fortunate enough to be logging the car at the time and the logs showed the engine detecting an issue and trying to reduce boost pressure but the JB4 overrides the engines requested boost and keeps targetting the full amount. Because of the way the JB4 lies about the actual engine load the engine thought the boost had been lowered therefore started to target a really lean afr which caused the engine to blow.

I know they use the JB4 safety features as a selling point but realistically it's marketing BS. One thing that struck me about the JB4 forums was the number of people on their second or third engine, it was almost like a rite of passage.

Well R.E92, I bow to your accumulated knowledge and experience..good to know..that's another goody struck of the list!

I was re-circulating what appears to be garbage from the BMW tuning web site..

https://bmwtuning.co/n54-tuning-guide-beginners/

Some guys on spoolstreet had also contradicted some aspects of their posts..

 

[R.E92]

That site is a good reference for some things but it's little more than a distillation of forum topics, better to get the info directly.

 

[Marcoose]

91 Octane is basically our 95RON which is your basic bitch fuel, I would not however run 95RON in my turbo cars though admittedly they were mapped to run on 99RON and didnt run well at all on 95RON (there is a noticeable difference in performance as well when map accounts for fuel quality)

But bitch fuel is better than no fuel, right mate? Just sayin'.

As Richard said, vehicles in American are tuned to meet California 'bitch/s**t' fuel regulations. Given there are millions of high-end street cars in America running on 91 daily and nobody is complaining, it's far to assume it isn't a problem. I had taken the old E85 to other states with different fuel ratings. (Other vehicles too.) As far as street driving goes, even spirited, there was no noticeable difference in performance.

So US 91 is our 95!

Unusally for a nation so keen on bigging it up why is their gallon less than ours and their octane rating?

Yeah, I had to and still am getting used to American 'exceptionalism'. Even after more than half of my life here and now a bone fide gringo, I still say aluminium and potahto.

 

[Flyingfifer]

But bitch fuel is better than no fuel, right mate? Just sayin'.

As Richard said, vehicles in American are tuned to meet California 'bitch/s**t' fuel regulations. Given there are millions of high-end street cars in America running on 91 daily and nobody is complaining, it's far to assume it isn't a problem. I had taken the old E85 to other states with different fuel ratings. (Other vehicles too.) As far as street driving goes, even spirited, there was no noticeable difference in performance.

You seem to have mistaken my comment for some sort of slight, I was simply pointing out that 91OCT is the same as our 95RON and is the basic level of fuel quality.
The reason millions of "high end street cars" run 91 is that most cars are mapped for 91 though I would point out that not all of them will, when you start getting into GTR/Ferrari territory unless again they are mapped to take the lesser fuel. The same is the case with the Z4 I run my coupe on 95RON (91OCT) most of the time as it is a NA car that is mapped to take 95RON, my Evo and Glanza however were mapped for 99RON and would be a bag of bolts on 95 with a noticeable dip in performance.