[winther1]

ie in a tuned 440i when it comes to performance and engine health? Taking it on a dyno next week as I want to see how it performs before and after BM3 stage 2. Not sure if 98 would make a difference

[seenthelight!]

Based on my experience, yes it does. The car was an Merc amg45, stage 1 tuned. I know it wasn't a BMW, but I believe putting premium fuel in any performance/tuned car is beneficial. On normal 95 octane fuel, the 45 ran a little noisier and 'slightly lumpy'. On premium fuel, it was quieter, smoother and throttle response was slightly better. Also, the exhaust tone seemed slightly better - a bit throatier/raspier. Also, on the Dyno, premium fuel gave about 8 bhp more than the norm fuel - not much on 410bhp anyway, but it all counts. Also, with premium fuel, you have the benefit of the internals being kept cleaner, as the fuel burns more efficiently. I also got a couple of mpg better as well. Btw, in this car, I tried shell and BP premium fuels, but found the best to be Tesco momentum, which is 99 Ron I believe.
Hope this is helpful

[HighlandPete]

For ultimate performance, yes. BMW engines with knock sensors can run on optimum timing settings with 98 RON fuel.

[winther1]

My tank is about 1/3 filled with 95 - can I mix?

[seenthelight!]

Originally Posted by winther1

My tank is about 1/3 filled with 95 - can I mix?

Yes no probs, but you won't feel/see any benefit till after a couple of full tanks of premium fuel. It will take that long for the ecu to fully adapt and the previous fuel to fully get out of the system

[Londoner]

Yes it won't hurt mate. I always use V power - it will give ever so slightly better BHP and MPG than the regular stuff.

[M140_BCS]

Originally Posted by winther1

ie in a tuned 440i when it comes to performance and engine health? Taking it on a dyno next week as I want to see how it performs before and after BM3 stage 2. Not sure if 98 would make a difference

It all depends which BM3 Stage 2 tune you want to run?

There is a 95RON tune, 98RON and 102RON/E30.

Stage 2 95RON will target less boost and ignition advance than the 98RON tune.

If you run 95RON fuel on a 98RON tune the engine will pull ignition timing and knock.

Not good for the engine at all and less power.

The B58 log thread gives lots of info -

https://f30.bimmerpost.com/forums/sh....php?t=1648722

[MY340i]

might throws an EML when run on 95 ron.

[Dang3r]

Its maybe measureable and just for your brains comfort. Wouldnt use it just for 1HP more.

[Skyhigh]

Short answer: Yes, even if you may not feel the difference, it does make one. Usually 98 fuels are also better quality and better for the engine in the long-run.

And besides that - why would you use anything lower than 98 on a performance vehicle!? I use min 98 on my (non-high-performance) Audi as well.... The extra price is at least partially compensated by a lower fuel consumption.

[Goneinsixtyseconds]

Used 95 in my 440i for most of it’s 45,000 miles. Tried a couple of months on 98, couldn’t tell a blind bit of difference, so stopped.

The engines are designed to run on worse quality fuel than ours in other countries. So will be fine.

Proper tests show mixed results on benefits, maybe there is, maybe there isn’t. Pretty certain that 95 won’t do any harm at all, and you may be able to notice a small difference in higher grades, but it won’t be night and day.

[Skyhigh]

98 is a recommendation by BMW for B58 (for a reason). And a REQUIREMENT for MPPSK. Not to mention other tunes.

It's all about the ignition timing.

[Silverlining_m2]

American here, so I'm running the octane versions. I find the difference between the bm3 stage 2 tunes with 91oct and 93oct negligible. I can run a 4.43 sec 0-60 on either. Though on stage 2 93oct I ran a best of 4.4 flat.

When I ran the 93oct tune on 93oct gas (98ron), I had minor timing corrections I could only fix with a gallon of e85.

Now I run stage 2 91oct tune on 93oct gas, have impeccable timing and no need for an "octane boost".

Bm3 seems very dependent on the gas you're putting in, and seems to perform better (in my experience) using gas that's one step higher octane.

[AlwynMike]

Originally Posted by Skyhigh

98 ... a REQUIREMENT for MPPSK.

It's all about the ignition timing.

A requirement??
As in, damage may occur? Or to get the quoted performance increase, 98 should be used??

I would have thought that if 98 was mandatory, BMW would put a sticker on the fuel flap to that effect when MPPSK has been fitted - along with the other stickers in the pack.

I understand that higher octane is advantageous for higher performance in a high compression engine, and that the management will retard the ignition timing if it detects knock, with the resultant decrease in performance.

Mine has only rarely had in 98, even pre-MPPSK. I run it on Tesco 99 unless I'm in dire need. Its never had normal unleaded in it.

[M140_BCS]

Originally Posted by f32spaceship

American here, so I'm running the octane versions. I find the difference between the bm3 stage 2 tunes with 91oct and 93oct negligible. I can run a 4.43 sec 0-60 on either. Though on stage 2 93oct I ran a best of 4.4 flat.

When I ran the 93oct tune on 93oct gas (98ron), I had minor timing corrections I could only fix with a gallon of e85.

Now I run stage 2 91oct tune on 93oct gas, have impeccable timing and no need for an "octane boost".

Bm3 seems very dependent on the gas you're putting in, and seems to perform better (in my experience) using gas that's one step higher octane.

I also run 93 octane fuel on MHD Stage 2 91 map and the ignition timing is clean throughout.

93 fuel on 93 map = timing pull mostly in mid range but minimal up top.

[Silverlining_m2]

Originally Posted by M140_BCS

I also run 93 octane fuel on MHD Stage 2 91 map and the ignition timing is clean throughout.

93 fuel on 93 map = timing pull mostly in mid range but minimal up top.

Very similar results here. Started clean, some corrections, back to clean up top. I definitely subscribe to running a slightly higher quality gas than your tune is designed for.

[Skyhigh]

Originally Posted by AlwynMike

A requirement??
As in, damage may occur? Or to get the quoted performance increase, 98 should be used??

As in if you want to get the advantages of the product you paid for.

From the official BMW MPPSK Workshop Manual:
"In combination with the M Performance Power and Sound Kit, the use of
RON 98 fuel (AKI 93) is recommended."

[HighlandPete]

Originally Posted by Skyhigh

As in if you want to get the advantages of the product you paid for.

From the official BMW MPPSK Workshop Manual:
"In combination with the M Performance Power and Sound Kit, the use of
RON 98 fuel (AKI 93) is recommended."

Also says the same on the Workshop Installation Certificate.

Putting RON 95 in the MPPSK, is like milk drinkers having semi-skimmed, when you can have full fat milk.

Even my humble 'standard tune' N55 wakes up on RON 98/99.

[Wills2]

My MPG was always much better on the good stuff I found engine felt sharper as well.

[chris-c]

I used to get lots of timing corrections running lower than I should but since I've started pushing it harder I can't even run it on 99 (Momentum) anymore without timing corrections so normally add a few litres of ethanol to pep it up a bit.

When you have MPPSK they give you a certificate of installation and it says to run 99 fuel.

The BM3 site goes into enough detail about running lower fuel than you're mapped for and you're just asking for problems running lower grade fuel on a higher map. Just swap it to the 91 map instead of 93 and you'll be fine.

Adding the fuel now doesn't mean you car needs to adapt over a few tanks the timing corrections happen instantly. The moment your higher octane fuel mixes and gets fed to the engine you will see the benefits.

[HighlandPete]

Originally Posted by chris-c

Adding the fuel now doesn't mean you car needs to adapt over a few tanks the timing corrections happen instantly. The moment your higher octane fuel mixes and gets fed to the engine you will see the benefits.

Yes, you notice the difference within a couple of miles. Noticed this with V-Power and Momentum.

For me, one subtle, but obvious change is the gearbox behaviour. Extra mid range torque means the gearbox down changes more readily, when using similar throttle inputs, compared to running RON 95 fuel.

[Skyhigh]

Originally Posted by HighlandPete

Putting RON 95 in the MPPSK, is like milk drinkers having semi-skimmed, when you can have full fat milk.

Never understood those people.... you either drink milk or you don't! Skimmed milk is not milk - it's muddy water!

Performance engines (especially tuned!) benefit from the highest octane fuel one can find on a gas station. With the additional benefit of the additives in higher quality fuels.
If I only had regular access to 102 Octane... Unfortunately 98 is the highest I can get around.