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Thread: 325 vs 330 engine tech

  1. #1
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    325 vs 330 engine tech

    I would like to know if anybody has any info on the diffs b/t the 325 and 330 engine specifications i.e. valve size, cam profile, intake/exhaust manifolds, head design, compression ratio, ecu mapping. I know they are the same 3.0L, but how does BMW get more power from the same three liters.

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    ancient chinese secret

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    that's what I'm talkin about. Seems you might be able to mod the 325i a bit and get it running with 330i's, or more ?

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    Quote Originally Posted by builder
    that's what I'm talkin about. Seems you might be able to mod the 325i a bit and get it running with 330i's, or more ?
    Definitely. You need to get started on that right away. Make sure you don't tell BMW though. They might figure out a way to make the 325i as fast as the 330i too. Oh wait, they already did, it's called the 330i. Maybe you could make the 325 as fast as an M3. That would be a nice trick.

    In fact, I had a Jetta GLX with a 2.8L motor. Do you think I could bore it out to 3.0L and make it as fast as my 330i, or even a little faster?

    In all seriousness, the answer to both these questions is yes, but the question really is, how much will it cost? Spend away my friend. Spend away.

    Oh, and then search the archives. There are about 20 threads to this effect. The only real differences are:

    1. The entire intake system (the valves and heads are likely the same)
    2. The clutch diameter
    3. The brakes
    Last edited by CC 330i; 07-12-2005 at 05:30 PM.

  5. #5
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    Quote Originally Posted by CC 330i
    Definitely. You need to get started on that right away. Make sure you don't tell BMW though. They might figure out a way to make the 325i as fast as the 330i too. Oh wait, they already did, it's called the 330i. Maybe you could make the 325 as fast as an M3. That would be a nice trick.

    In fact, I had a Jetta GLX with a 2.8L motor. Do you think I could bore it out to 3.0L and make it as fast as my 330i, or even a little faster?

    In all seriousness, the answer to both these questions is yes, but the question really is, how much will it cost? Spend away my friend. Spend away.

    Oh, and then search the archives. There are about 20 threads to this effect. The only real differences are:

    1. The entire intake system (the valves and heads are likely the same)
    2. The clutch diameter
    3. The brakes

    and the stronger tranny too. I am all for mods but if you want a 330 you should have just bought one.

    stack

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    alright no need to be rude we're just throwing ideas out there.

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    I know, I'm sorry.

    It's just that since BMW decided to put the same displacement in the 325 as the 330, everyone thinks it would be easy, and a great idea to modify their 325i and make it "as fast as a 330i".

    I will say what I always say:

    1. You will end up spending more and getting less than if you just bought a 330i to begin with. Even if you get more than 255 hp, you are still not getting as much "stuff" as you would for your money.
    2. You will end up voiding your engine warranty.
    3. There is a reason that the 330i has bigger brakes and stronger tranny with the added power.

    I shudder to think what a new engine would cost. If it's not covered under warranty, just about any engine component failure will cost you more than the difference you would have spent on a 330i.

    You could have bought an Acura TL for less than your 325i and it has 270 hp.

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    Cool

    No prob and I do appreciate the info, alot of good points!

    Yeah, a 330i would be the way to go. I actually haven't bought anything yet but will soon enough. I had contemplated the TL as an option but I think I'd still prefer a 325i over it.

    I will probably end up getting a 325i with a few nice options (leather, paint, HID's, heated seats, sport package) and leaving it at that. I doubt I will mod it much, especially the engine since I'd rather not void the warranty like you stated, and the last thing I need is another ticket

  9. #9
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    Yes, and the 325 is a great car anyway. I am all for minor mods, including a mild intake and cat-back exhaust. You could even go for aftermarket downpipes and a full exhaust if you wanted. It's just hard to make the 325 into a 330i for less than what it would have costed from BMW, and pretty risky too.

    Doesn't mean you can't make it better than every other 325 out there by adding some performance and other mods. And you can make it cooler than a regulare old 330i by personalizing it to your taste. You can probably even gain some performance that way too, but 40 hp is a big leap.

  10. #10
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    Quote Originally Posted by J667
    I would like to know if anybody has any info on the diffs b/t the 325 and 330 engine specifications i.e. valve size, cam profile, intake/exhaust manifolds, head design, compression ratio, ecu mapping. I know they are the same 3.0L, but how does BMW get more power from the same three liters.
    Does anybody know the compression ratio, valve size, cam profile of each of these motors or can somebody direct me to a place where I can get technical information.

  11. #11
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    Quote Originally Posted by J667
    Does anybody know the compression ratio, valve size, cam profile of each of these motors or can somebody direct me to a place where I can get technical information.
    I am interested to find this info out as well

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    I guess out of the 400+/- people that have visited this thread nobody can answer this question. I am very disappointed. I hoped I had found a great forum; I guess not. Can somebody please prove me wrong.

  13. #13
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    Here's a discussion of the 325 v 330 including a chart comparing the differences in parts between the two. Dunno if that helps.

    http://www.e90post.com/forums/showthread.php?t=1596

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    Thumbs down

    Quote Originally Posted by CC 330i
    I know, I'm sorry.

    It's just that since BMW decided to put the same displacement in the 325 as the 330, everyone thinks it would be easy, and a great idea to modify their 325i and make it "as fast as a 330i".

    I will say what I always say:

    1. You will end up spending more and getting less than if you just bought a 330i to begin with. Even if you get more than 255 hp, you are still not getting as much "stuff" as you would for your money.
    2. You will end up voiding your engine warranty.
    3. There is a reason that the 330i has bigger brakes and stronger tranny with the added power.

    I shudder to think what a new engine would cost. If it's not covered under warranty, just about any engine component failure will cost you more than the difference you would have spent on a 330i.

    You could have bought an Acura TL for less than your 325i and it has 270 hp.


    The ACURA TL is a piece of junk ... there are two dimes a dozen. Just as common as a Honda Accord or Toyota Camry.






    Execution
    Execution - The Executive: E90 on ASA AR-1's front 19 x 8.5; rear 19 x 9.5

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    Quote Originally Posted by Execution

    The ACURA TL is a piece of junk ... there are two dimes a dozen. Just as common as a Honda Accord or Toyota Camry.


    Execution
    Um, yeah, that was my point. And it's "A dime a dozen". Two dimes a dozen is 20 cents.

  16. #16
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    I finally got some type of info from European Car Magazine if any one cares

    "If it were that easy to turn an E90 325i into a 330i, everyone would be doing it. There's more to it than ECU mapping, but the actual final word is not available yet, and probably won't be until someone takes a 325i and a 330i and starts removing parts side-by-each. We spoke with a BMW master technician regarding this question, and he did not have the full story, either. What we do know is the ECU mapping is different, the camshafts are different, the intake system has no DISA valves in the 325i -- just plugs where they are on the 330i, and there is a heat exchanger in the front of a 330i. I suspect there are other differences, too, which will be revealed in time. Obviously, BMW is not forthcoming with the exact differences -- this car is a marketing wet dream, and if it becomes easy to change a 325i to a 330i, it will be like someone switching on the lights in the middle of that dream."

    Best regards,
    Mike Miller

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    Exclamation Review of the Two E90s

    Here is a review that is a subjective comparison of the 325i vs. 330i, if anyone is interested & hasn't already read it.

    This: "I had no problems with the 330i, but went off course twice with the 330i." is obviously a typo.

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    Actually...I disagreed. The Acura TL is a very nice car....a peace of mind for someone who wants a quality car fully-loaded for $35,000. The ride is smooth and quiet, dvd sound system kickass, and the navigation is the easiest by far to use......I can't imagine getting a 330i fully-loaded with everything the TL has to offer......for under $52,000.

    In the end...I settle for a 330i...because it was a BMW.
    Last edited by NaTuReB0Y; 08-11-2005 at 03:21 AM.

  19. #19
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    It's now 2018. Is there anything recent that can be safely done to the 325i to get a little more power and fuel economy out of it? 19.2 mpg is the brst I can get out of my 2006 E90 325i. I figure that more HP will equal better fuel economy depending on my right foot. Any updated information?
    Thanks in advance,
    TampaNative

  20. #20
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    I'm curious to have the same question as the guy above me. Not worried about fuel economy though

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