Boring out an M44?
 

As i just bought another ti, i am faced with the issue that plagues the car. a lack of power. Im only looking to get a moderate power gain out of the engine, say 20-25hp, just to make it a little bit quicker. I figured id chip the engine, get an intake and a cat-back exhaust to start out with, but i would imagine that this would only be good for around 10hp. Then i got thinking would it be reasonable to bore the engine out to say 2.0 or 2.1 L. I know an engine swap is the most efficient way to gain power but I'm weird and would like to keep the M44 engine with the car. So back to my issue, would it be reasonable to bore the engine out a little? And if so what kind of power gains should i expect? Then what else on the car would i need to change to accommodate the new bore? Would i just need new pistons or is there more than that? Ive really got limited experience with the engine itself so I'm just kind of spit-balling here. Any and al ideas, responses or tips are greatly appreciated. thanks

Boring a AL block is a cubic $$ proposition and the M42/M44 block has little room for an overbore.

The only cost effective displacement increase is a stoker crank from a diesel..
(Search on M47 I believe...)

Dave

alright, ill look into that, i just figured that increasing the displacement by 100-200cc and having new pistons might give me an extra 10ish hp. I've got a friend who works on a lot of euro cars and has 2 318is's, both with the M42 but he could bore the engine out for me free of charge so i figured i might as well look into it

why dont just go turbo and have more power with a stock motor, ur gonna end up spending about the same money to stroke/bore the engine than just getting the stock motor turboed or DASH

I've just heard horror stories about turbos killing the engine, although my same friend did turbo his M42. I'm really not looking for that much of a power gain, up to 175 max

It costs over 1500 to bore an aluminum block , the cylinders have to be recoated after the bore is done and that's where the big $$ come in. There are only a handful of after market companies inthe world that can do it right, otherwise you have ot install sleeves in the bore, about 200 per hole to do right.

Turbos especially if you rebuilld the engine correctly are stone reliable when done reasonably conservative... IE not running 25 lbs of boost... on 10:1 pistons...

Basically the BMW M4* series engines were engineered to be light, reliable and make as much mileage and HP as they can. Its a ring of comprimises.

Way cheaper to just go to a 6 cyl if power is what youneed.

Dave

ok so realistically boring out the engine is not the best idea. so if i got for a low boost turbo, say 8psi? then i imagine id make the hp increase I'm looking for, but what else would i need to do to the engine to accommodate the turbo?

Even though the M44 has an alum block there are iron sleeves in the cylinders. You would just have to find out how thick the sleeve is and how much could safely be taken out of it. Here is another thread on the subject. http://forums.bimmerforums.com/forum...?t-311269.html

It might be better to consider some of the other suggestions as building an engine from scratch requires some knowledge or you will just end up spending a lot of time and money for nothing. However, if you are willing to take the time to find out the answers and do it right it can be very rewarding.

thanks ill definitely look into that, ideally id like to stay NA and not FI and I'm only looking for the hp to get up around 160-275 so i suppose the most cost effective way of doing this with the M44 is what ill most likely go with

There are several good threads on here about builds, John Boy having a couple of the bigger ones... My bad I could have swore the M44 was Nicasil not sleeved.

AS far as normally aspirated it will limit your ability to exploit the engine and if you drive it on the street it will be technically illegal at least with the EFI you might pass a smog check if you had to with the right tune, with carbs it wont happen.

Look up Metric Motors , youll get an idea of the cost of high performance work on a BMW.... :)

Dave

haha if you're referring to metric mechanics engines I'm quite familiar with their prices on BMW engine builds, granted that would be awesome to have one of their engines in a ti. and I'm not really an engine person so I've got no real idea of whats possible to get out of them, I'm much better with suspensions haha. anyways overall would it be more advisable to do a small turbo over boring out the engine?

Even if you don't buy a motor from MM, like PDXmotorhead said just look at some of their build specs for their NA motors. This will give you some idea of what it takes to build a more powerful motor. It takes expensive parts and precise machining to build fast engines and if you stay NA more power is usually a trade off in drivability. Thats why a lot of people like forced induction FI because you can have drivability and more power. I like NA motors myself, just because I like simplicity, but like has been stated on the site many times that M44 is pretty well maxed out from the factory. So to make it better you would have to spend some time and money on it. There is nothing like the sound of a nastyNA high performance motor though if you can get it right.

for sure, those metric mechanics engines sound AMAZING revving up to the stratosphere.i guess thats why i really like NA, because you can rev them so much, but if a turbo is gonna be easier to do and have more drivability i suppose thats the ideal route to go with, especially since I'm only looking for a relatively low hp gain IMO

I always liked this guy's build
http://forums.bimmerforums.com/forum...d.php?t=433471

It's an M42 but still pretty awesome and some of the stuff can apply to the M44.

wow, thats hugely impressive.