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Cynthetiq · 05-06-2008, 11:18 AM

Quote:

Originally Posted by willravel

Gas in the US is different than in the UK and Europe. The 330i in the US gets about 20/30 (city/highway).

umm no, gasoline is not different.

Diesel is different.

The only difference is the miles are imperial miles as are the gallons.

Bob, The Auto Answer Man

Quote:

Dear Bob,
I have a project I have to do for school on Octane. I need to know how the octane rating of gasoline is determined and which octane ratings are available today? I've searched the internet and can't get any straight answers, so if you could help, that would be great. Thanks!
Howard

Howard,
Your answer will vary greatly depending on where you live (region and country). For a definitive discussion on octane ratings, look up the procedures in the SAE (Society of Automotive Engineers) publications (major public libraries may carry it).

The octane rating is basically an anti-knock rating. Engine "knock" is also sometimes referred to as "ping". It is basically pre-detonation of the fuel before the piston is in the correct position (either near top of it's stroke or on its way down on the power stroke). Ping occurs while the piston is on the upstroke. Essentially, it is the elevated combustion cylinder temperature mixed with the now elevated cylinder pressure (compression) that will cause fuel it ignite without the spark.

In the United States, pump octane is an average of 2 ratings, research octane (RON) and motor octane (MON). If you look at any gas pump in the United States, you will see a yellow sticker that says "octane by R + M / 2" That is the basic formula for an average. These 2 numbers mean different things. You could make an analogy to that of a blood pressure reading (systolic and diastolic). Research Octane number is always higher than Motor Octane number.

In Europe, they only report the RON. You may hear people discussing that in Europe, the octane is higher. Well, that is not exactly true. You see, in Europe, you might find 96 octane at a local gas station. (wow 96, highest we have here is 94). Well, that 96 is equivalent to 92 here in the States.

The octane value of a fuel can be varied by several different processes. It can be refined to that value (usually more costly) or enhanced with different additives. Different people will argue which method is better. I hope that gives you a good basis for study!
Good Luck!
Drive Safely!
Bob, The Auto Answer Man

The tuning and peformance of the vehicle is different.

Chip tuning - hype or the real thing?

Quote:

Is it true that it is possible to gain more power from your engine, simply by replacing the main engine management chip? Most of us have heard both sides of this story, but if this is the real deal, then it's a very cheap way to gain more horse power. I decided to give it a go...

I am not sure yet about the use of K&N filters (going to check that next), but if you are installing one of these anyway, I believe a tuning chip will make a great addition. One of the larger K&N suppliers in Europe are YB Filters. Visit their site or eBay store for a great price.

First of all, let me start by thanking James and Jayson for supplying the chips. They made this review possible.

Secondly, please note that my car is the European version, not the US. Even though they appear to be the same, they aren't. Part of the Motronic engine management apparently differs, so if you drive a US version, you can not expect the below result with the Euro chips. The US chips which are not performing well on my car, should run perfectly good on US spec cars, whereas the European chips most likely will trigger a 'Check Engine' fault and performance should be down, compared to my results. Always go for the chip designed for your specific market if you want maximum performance.

There was a time, when doing a go-fast chip was for the major tuning companies only. But now quite a few hardcore BMW fanatics, with access to the right equipment, are making their own chips. AND making them available to the public too at a much lower price, of course. But just how big is the difference between the chips currently available?

As always, I must remind you that the info supplied here is as unofficial as it gets. I am not a BMW tech and I don't have any testing equipment. Instead I have a passion for BMW and the will to make it go faster! So when I test these chips, the result is strictly my own opinion...

All tests are done on my stock 525iA, 1989, M20. For the technically inclined, the DME is a 0 261 200 173 and the original chip is a 1 267 355 794...

It's a good idea to plan ahead for this, since your new chip will only run on premium gas. The standard chip on my M20 is designed for RON 91, but the new chips all require at least RON 95 or higher. Why? Because the tuning chips advance the ignition timing and that calls for a higher octane, or self detonation will be the result. On newer engines with knock sensors, the DME will readjust the timing to save the engine, but this will also take away most benefits of the new chip. Older engines may be subject to unreasonable wear, so take your precautions: with the old chip still in place, you should run the car until the tank is almost empty and the fill up with premium gas. Or maybe just fill it 50%, to save weight on your first test run :-)

A few words about octane... 91 octane is not just 91 octane, because Europe and the US uses different standards. Don't know about the rest of the world... In Europe, the Research Octane Number (RON) standard is used, whereas the US uses an average of MON and RON, the Anti-Knock Index (AKI). In comparison, AKI 91 octane in the US is the equivalent of RON 95 octane in Europe.

In other words: chip tuning requires you to use higher quality gasoline. If you are in the US, you should go no lower than 91. Europeans need 95 or higher...