Bmw cly walls are close together. Especially on the M54, N52, and S54. Even if you could it wouldnt be smart. Besides, the difference between 528i and 530i is intake, ecu and exhaust. The engine itself is identical. Boring out is cost prohibitive especially on a 6cyl thats 15 years old. It would be cheaper to buy a new motor.

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It seems to me that you can't get larger displacement by just changing the 3 items you mentioned, you have to either change the bore and or the stroke to go from 2.5 to 3.0....

 

I believe the difference between the 2.8L and the 3.0L was the stroke. As stated above it would be more expensive to do the engine work then buy a used 3.0l with all the correct accessories and ECU.

If your 528i is running and you're not thinking about doing this because of some engine issue it would probably be cheaper still to sell your car and just buy a 530i.

Tim

 

Check out video #8 (boring a BMW engine block) in this group of videos that tim330i posted back in April of 2011

http://www.bimmerfest.com/forums/showthread.php?t=534596

All of the videos are very good.

Ps. Check out the cost for a (BMW E60/E63 M5/M6 (2006-2010) bored 5.2 liter version of BMW's V-10 engine.)

http://dinancars.com/product/d850-1030-dinan-performance-52-liter-v-10-engine-2/?series=M-series&mid=1066/

 

I've just never heard of it. Oddly enough I'm happy with my 528i it fits my needs well. It just seems like old school tuning has died and I was sort of wondering why. It always sounded like such a fun process really.

 

It always sounded like such a fun process really.

Did you miss my Ps. in my first reply? Fun but expensive nowadays.

 

I see.

 

It is possible to buy oversized pistons for BMWs n52 motor so I believe it is possible to overbore the motor, by about 1mm. The 2.5l is 82mm bore by 78.8 mm stroke. The 3l is 85x88mm. So you won't turn a 2.5l into a 3l by boring it. But the other complication is the fact that some "325" cars really have a 3l motor and some have a 2.5l. You have to look it up. If you have a 3l and your car says 325 it has a low rated 3.0l and can have it's output increased without overboring. There are also several ratings for the 2.5l motor so depending on which you have, some increase in power may also be possible.

Overboring is normally done not to increase displacement but, rather, to deal with a badly worn engine.

 

Years ago I worked for Bekkers Import as a sales manager but also built many of the high performance blocks that were sold. As I recall we had Weisco custom make the pistons for us, I think they will do this for most anyone or they used to. Try contacting them to see what they have to offer these days.

Good luck.


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Another option for more hp is to deck the head to increase compression. I did it on my personal M52 back in the day and was pleased with the gain. I did most of the work myself so cost wasn't much of a factor.


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