You can't actually convert from one octane number to the other unless you can test the fuel. You can approximate the other octane number though, and 6-7 points is a reasonable estimate of the difference.

Euro rating is based on the Research Octane Number (RON).
Another standard is the Motor Octane Number. This uses a different test protocol than the RON method. One focuses on higher engine speeds, the other on lower engine speeds, as I recall. Edit: I looked it up, and the RON test is run at 600 rpm, while the MON test is run at 900 rpm. Since we don't spend much time with our road vehicles at those engine speeds, it shows the theoretical nature of the octane ratings.
North American Antiknock Index (AKI) is calculated as (R+M)/2, so it is the average of the two tests. However, two fuels with the same RON rating may have different MON numbers, and so have resulting different AKI numbers.

All that said, 98 RON is pretty close to 93 AKI in the real world.

You are touching on why the Sprintbooster causes controversy and gets tags like 'snake oil' on this and other forums.

For my part, I understand completely that it changes the throttle pedal mapping, and can thus change the feel of the throttle. That is perfectly logical, and in that sense it is not snake oil.

However, the Sprintbooster is often claimed to increase horsepower. That is when many of us snort in derision, and use phrases like snake oil, because the throttle pedal doesn't control how much horsepower an engine makes. If it did, we wouldn't need turbochargers, we could just install larger gas pedals to improve 0-60 times. It may feel like the vehicle has more power, but logically, it can't.

Your quote above may leave some readers believing that for older BMWs, the Sprintbooser may be an option to increase horsepower and torque.

Good post though, interesting to read. Thanks for putting it up.

JCL,

I said "....If you have an older BMW, I suggest looking at a different option to increase the torque/HP instead." and you responded that "Your quote above may leave some readers believing that for older BMWs, the Sprintbooser may be an option to increase horsepower and torque."

I've made it clear and I'm pretty sure that you'd find that most resellers are NOT claiming horsepower or torque increases. I agree that lots of uninformed people may have got that impression -- but not from what I posted. They'd have to be pretty slow to think that HP or torque gains are possible from the SB.

I probably could have just changed it slightly to say "....If you have an older BMW, I suggest looking at an option that will your increase the torque/HP instead of SB (which only increases the throttle response)."

BTW, As much as people like to malign the SB, it's still nothing like the "BMW X5 performance chips" on eBay that make claims like this $25 product:

MUCH DIFFERENT! Huge difference!

Brian - I just realized you bought version 2. I have the old version, which doesn't have a switch to change between race and sport. On my M5, I just have the M version, which doesn't have a switch either. It's just designed more around the power band of the M models.

Sorry to hear it didn't work out. I absolutely LOVE the Sprint Booster and have had them in many of my BMW's over the years.

Let me also state that the Sprint Booster DOES NOT increase HP or TQ. It just removes throttle lag. For those familiar with throttle lag and how annoying it can be at times, this is your solution. If you have an ECU remap, that too, removes throttle lag, but I will tell you that the Sprint Booster essentially makes it non-existent. I have and had ECU tunes on my BMW's and tested the cars with and without the SB. The SB still made a huge difference. I'll never not own one.

Ah, no!