Question: Number scheme for BMW Model's

I know that in *most* cases this is how the numbering scheme works on BMW's:
First number indicates the series of the car: 3,5,7.. etc.. the next two numbers *normally* indicate the liter of the engine.. 25=2.5,
28=2.8, 40=4.0 ...etc.. then the letters indicate the package of the car..
My question is on the 1998, 1999 and 2000 3 series they have a 323 model listed if you look at the engines in those models though they are infact 2.5 liter's not 2.3. Also the 1997 BMW 318 = 1.9-liter I-4... My question is, What was the reasoning behind this? Does anyone know why they seemed to have "mismarked" these model's?
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Branden Nelsen
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The 323i had a detuned 2.5 which made about 25bhp less than the engine it replaced. This was done to improve mid-range torque amongst other things. It was called a 323i mainly as an historical reference to the E21 and E30 323i.
The 1.9s just kept the same name. They did the same thing with the 320i when it got the M54 2.2 engine.
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Then there was the 740 with a 4.4l engine etc. etc.
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Ah, ok, A co-worker and I were sitting here scratching our heads wondering why this was, and we couldn't come up with anything so I knew you guys would know :)
Thanks

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John Burns wrote:

The worst "rip-off" is the 318 TDS: that one actually has a 1.67 liter engine. Talk about "over-badging" your car.
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Not so, the E23 745i was a 3.2 and later a 3.3 :-) Except in South Africa where it had the //M1's 3.5 engine. BMW multiplied by 1.4 as this formula was used in the rules of certain racing series for turbo equipped cars. (Jings, I know some serious trivia.......)
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John Burns wrote:

I'm assuming you knew this off the top of your head? :-)
Hats off to you, sir!
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I badly need to get a life..... ;-)
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John Burns wrote:

Who needs that when you've got UNIX?! :-D
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The engine is, in effect, de-tuned on the lower number cars. The motor is the same, but the pistons and/or connecting rods are changed to reduce the displacement (this is the case with the M52 motors), or the computer profile is changed, or some combination of these things, to reduce the power.
The M52 motors ('96 thru '98) are available in both the 323 and 328 configurations. The 328 is a 2.8L engine, but the 323 is a 2.5L engine. The 328 has a compression ratio of 10.2:1 while the 323 compresses to 10.5:1. One way to affect a change like this, lower displacement and increase compression ratio would be to change the connecting rods and/or the pistons. If the pistons went up further, but didn't go down so far, then you would effectively increase the compression ratio and reduce the displacement. Why did they do this? I don't know, but I'd guess that emissions rules played a role. The 328 makes more HP than the 323, by about 22, so upping the compession ratio by itself does not make for more HP. Well, upping the compression can make more HP if nothing else is changed, but obviously something else changed because the HP dropped when the compression was raised.
The M52 motor is used in the E36 cars, I'm not sure of the designation of the motor used in the E46.

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"Branden Nelsen" wrote

Add to this the latest 325i which has a 3 liter engine. :)
Cheers,
Pete
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engine, i.e. 2.5 litre, yet it still develops 3bhp more and exactly the same torque as the US 325i 3 litre! Why the difference?
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zerouali wrote:

US gallons vs UK gallons.
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Or more displacement to drive on the "right" side of the road?
Tom
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What have gallons got to do with it? Cubic capacity is in inches or litres, which are the same on both sides of the pond.
Is this due to the US emissions requirements to try and protect it's home manufacturers?

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"zerouali" wrote

I think he was referring to the power output measurements.
Pete
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zerouali wrote:

But it's simple
3.0 liters are +/-0.66 UK gallons. 2.5 liters are +/-0.66 US gallons.
There you have it.
:-)

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We've answered this question time after time after time. Please pay attention: The US uses a slightly different method of measuring HP. Additionally, US environmental regulations require a different placement of the catalytic converter that robs a couple HP.
FloydR
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