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Originally Posted by CC 330i

I agree, to each his/her own, but for me the 330i was just too compelling.

First of all, there are the bigger brakes, the extra power (on my car right now, from the factory, fully covered under warranty), Logic 7 sound system standard, bigger wheels standard with sport package, resale value... etc.

There is no question in my mind that you could get the 325i up to 255 hp with aftermarket mods, but that begs the question: how much horsepower could you get from a 330i with aftermarket mods? I'll bet Dinan will sell plenty of performance parts for 330i's too. And I don't care how good the aftermarket engineering is, it will never be as good as factory engineering for durability and overall driveability. And just because the 325i has the same displacement as the 330i, it doesn't mean that the rest of the engine internals will be the same. There could be more than just intake differences. (lighter pistons and valves, for example).

Remember, BMW makes Formula 1 engines too, but they don't last for 100,000 miles. They only last a few races at best. Heavily modded engines don't last as long as ones designed by the factory to last for 100,000+ miles either. Bottom line is, speed costs money, and sometimes that money will be spent in the form of a blown engine. Modding out that 325i will likely void your powertrain warranty, and any problems that do arise will become your fault, even if it turns out that your engine problems are happening to everyone else and we all get new engines under warranty.

The engine internals are the same. Search and you will see that the only differences are the intake manifold, software, and exhaust (I am pretty sure).

Also, Dinan's website admits that the CAI/software update for the E46 330i doesn't do much more than raise the rev and speed limits. That engine was pretty much tuned to it's maximum from the factory. This is not so for the 2.5 and 2.8 liter engines.

From this you could conclude that the 330i's 3.0 is maxed out (excl. forced induction), while the 325i's 3.0 is not.

I want to doubt it also, but I need a better argument. The best argument that I have come up with so far, is that since BMW and Dinan are in cahoots together BMW will limit what it allows Dinan to offer for the 325i.

Of course, they have no control over Jim Conforti.

[shipo]

As an E90 is most likely in my future, the issue of "Breathed on 325i vs. Stock 330i" is of course very much on my mind. As such, I've come up with two questions that, for me at least, make the decision fairly simple.

Givens: E90, 6-Speed Manual, Xenons, Logic 7, PP and SP
Price Difference: $3,300
Weight Difference: 132 lbs.

Questions:
1) Short of adding a blower of some sort, is it really possible to economically bump the 215 hp engine to 255 (and gain the torque increases as well)?
2) Assuming (for the sake of argument) that question #1 is ultimately answered in the affirmative, "Does it actually make economic sense to take the $3,300 savings from the 325i and invest it in aftermarket modifications?"

Regarding question #1:

What we know: The 325i has a single path intake manifold; the 330i has a variable three track intake system.
What we think we know: The firmware in the ECU is different between the two.
Other potential differences: Cams? Crank (cast vs. forged)?

I have seen many opine that since the E46 3.0 liter mill is capable of more power than the E90 325i engine of the same displacement, it should be a relatively easy thing to change the ECU and regain that lost power. Personally I think that is a gross oversimplification. The E46 engines have what is referred to by BMW's web site as a "Fully Variable Intake Manifold", which is clearly much more advanced than the single path system in the E90 325i. How much could a new manifold cost? Plenty. Last time I checked, aftermarket intake manifolds for late model BMW were well over $1,000, and even then they were only single track units that were tuned for higher RPMs. I'm betting that a decent aftermarket multi length intake system would be well over $2,000, plus installation and the new ECU software necessary to go along with it. In the end, my bet is that IF (and that's a pretty big if from my perspective) bumping the 325i so that it yields as much power as the 330i is doable for less than the difference in the cost between the two, it won't be much less.

Regarding question #2:

What we know: The 330i has larger and more capable brakes, larger and more capable wheels and tires, a larger and more robust clutch disc, and a heavier and more robust 6-Speed manual transmission (Getrag Type "H").

I'm thinking, "Do I really want a car with the power of a 330i with the tiny little 11.8" disk brakes?" Not really. I'm convinced that the larger and more capable brakes on my E39 530i (as opposed to the brakes that were on the E39 525i and 528i) have already saved one life, and possibly two others (long story). Then I find myself wondering, "What would happen to that lightweight Getrag Type "I" transmission, that is standard in the 325i, if I start pumping 255 hp through it?" Probably nothing good.

Summary:

In the end, buying a 330i for say $40,000 will yield better performance and more resale dollars than buying a 325i for $36,700 and then adding $3,300 in aftermarket modifications. As such, it is my firm belief that if you want your 325i to beat a 330i around a track, your best investment will be driving/racing schools. Dollar for dollar, the 330i is simply more bang for the buck. So, for me at least, the answer is easy, 330i all of the way.

That's my story, and I'm sticking to it.

Best Regards,
Shipo

[Tierfreund]

@shipo

Excellent analysis.

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Originally Posted by shipo

As an E90 is most likely in my future, the issue of "Breathed on 325i vs. Stock 330i" is of course very much on my mind. As such, I've come up with two questions that, for me at least, make the decision fairly simple.

Givens: E90, 6-Speed Manual, Xenons, Logic 7, PP and SP
Price Difference: $3,300
Weight Difference: 132 lbs.
Shipo

Agreed that is a good argument/analysis.

Let me retort that the price difference between my choice of a 325i with metallic paint, cold weather, sport, xenon, and sat prep comes to $34,945. A comparable 330i is $40,145.

Price difference - $5200.

Also, let's look at how much faster an E90 330i is than an E46 330i -- not THAT much. Also look at the torque difference -- not that much. Now WE all know that BMW horses are bigger, but the average joe does not. With 330-fighters upping the horsepower wars by leaps and bounds, you must admit that some of those 255 horses are MARKETING horses!

Do I need my 325i to make all 255? I don't care what the number is, I just want it to be 330-fast.

An E90 325i does 0-60 in 6.7 seconds.
Stock, that is what my E46 328i does as well.

Would a chip/cai upgrade lose a half second on that acceleration time? It is definately within the realm of possibilities. Would I be able to get that upgrade for about $1000 -- also not too outrageous of a thought.

Would I have near 330 performance for $4000 less?

Well, it seriously boils down to maybe!! The real tell will be in six months when there is a Shark Injector for the E90. It is all conjecture, so we have to leave it up to the engineers.

Great discussion though. I will shut up now.