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100 Octane Petrol in N54

Specific discussion about the E89 2009 Z4 (sDrive35is, sDrive35i, sDrive30i, sDrive23i)
Kiwi_Mike
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100 Octane Petrol in N54

Post by Kiwi_Mike » Thu Oct 14, 2021 9:49 am

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?
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100 Octane Petrol in N54

Post by Chippie » Thu Oct 14, 2021 9:58 am

I would have thought that 100 would be better than 98 with the remap.
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R.E92
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100 Octane Petrol in N54

Post by R.E92 » Thu Oct 14, 2021 10:07 am

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.

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100 Octane Petrol in N54

Post by B21 » Thu Oct 14, 2021 11:24 am

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..
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Yellow Peril 1: 1977 Fiat 126 (1977-1980)
Yellow Peril 2: 1989 Yamaha FZR1000 EXUP (1989-1995)
Yellow Peril 3: 2012 BMW Z4 20i MSport Auto (2017-)
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100 Octane Petrol in N54

Post by Mister T » Thu Oct 14, 2021 11:33 am

Use the 100 Plus stuff.

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

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100 Octane Petrol in N54

Post by Flyingfifer » Thu Oct 14, 2021 12:12 pm

Mister T wrote: Thu Oct 14, 2021 11:33 am 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.
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100 Octane Petrol in N54

Post by R.E92 » Thu Oct 14, 2021 1:06 pm

Flyingfifer wrote: Thu Oct 14, 2021 12:12 pm
Mister T wrote: Thu Oct 14, 2021 11:33 am 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.

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100 Octane Petrol in N54

Post by Marcoose » Thu Oct 14, 2021 1:56 pm

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.
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R.E92
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100 Octane Petrol in N54

Post by R.E92 » Thu Oct 14, 2021 2:25 pm

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.

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100 Octane Petrol in N54

Post by Mister T » Thu Oct 14, 2021 3:01 pm

Flyingfifer wrote: Thu Oct 14, 2021 12:12 pm
Mister T wrote: Thu Oct 14, 2021 11:33 am 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

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100 Octane Petrol in N54

Post by Flyingfifer » Thu Oct 14, 2021 3:02 pm

Mister T wrote: Thu Oct 14, 2021 3:01 pm 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 :thumbsup:
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100 Octane Petrol in N54

Post by B21 » Thu Oct 14, 2021 3:13 pm

Flyingfifer wrote: Thu Oct 14, 2021 3:02 pm
Mister T wrote: Thu Oct 14, 2021 3:01 pm 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 :thumbsup:
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
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100 Octane Petrol in N54

Post by Marcoose » Thu Oct 14, 2021 3:15 pm

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:
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100 Octane Petrol in N54

Post by Flyingfifer » Thu Oct 14, 2021 3:32 pm

Marcoose wrote: Thu Oct 14, 2021 3:15 pm 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)
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100 Octane Petrol in N54

Post by B21 » Thu Oct 14, 2021 3:53 pm

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? :rofl:
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