M3 Cams in an M50?

[e30foolio]

Sup guys,

Ive been looking to do an upgrade to the cams in my 93 325is

damn cams get way too expensive, over 1200 for the set (just intake,not including exhaust cams!)

Would M3 cams fit in an M50 engine? or would that be a waste of time? (have found used 95 M3 cams intake/exhaust for @ $450) or would they even be compadiable?

thanks for the replys, hope you had a safe and happy Halloween! (only had 2 grouos come to the door, Halloween has lost its flair since I was a kid )

-Ben

 

[BigEarl325is]

You betcha. S50 cams fit like a glove in M50 motors. Just be sure you know what the hell you're doing when you replace them. Also, you'll need to buy the chip to support them. It's here...

http://www.turnermotorsport.com/html/index.asp

 

[andreyiv]

I can't help you with the M3 cams but I do remember someone saying that new exhaust cams give you more power when compared to intake cams because you can't force more mixture into an NA engine than it can hold and making it easier for the gasses to escape brings more power. Also if you do change the cams, get a new chip because then you'll be able to take full advantage of the change.

 

[BigEarl325is]

Yeah andreyiv, that would be me that said that. Thank you for remembering but I also said "don't quote me on this but..." haha, no big deal, it's just what I've been taught.

 

[e30foolio]

Thanks for the replies!

Thats good the S50 cams fit so well, I will try to get intake and exhausts cams.

I have the ACS Chip and ACS intake along with an ACS catback, trying to find some affordable upgrades that may complement them, considering headers, but those are out of my price range for now ,


Thanks again for the replies!


-Ben

 

[andreyiv]

Sorry for not remembering it was you , but I should have guessed, you know so much about bimmers.

 

[BigEarl325is]

haha, thanks andreyiv but I'm just a parrot from what my friends tell me. They work in a shop they deals almost strictly with BMW's ///M division. They've taught me almost everything I know, except for the basics. Anyway, e30foolio, you're going to have to buy a new chip that supports the M3 cams. I also forgot to mention you'll need new injectors. Those get pricey, typically 70-90 dollars a piece. I've wanted to do that mod for a while but I've always been hit with some bill before I can afford the injectors along with everything else.

 

[m50POWER]

I have to disagree with the statement of exhaust cam having the most influence on an engine in terms of power production. The amount of air-fuel mixture entering the combustion chamber is more relevant to power production than it's extracation (not that extracation does not plays a factor) . This is typified by examining head designs of most cars -- most have larger intake valves than exhaust valves. In fact, take the 1.8 turbo Audi engine with 5 valves per cylinder, three of the five valve is dedicated to intake (Toyota even had a N/A 1.6L DOHC 5 valves engine back in 1989). Our m50's vanos applies to the intake cam. Hondas VTEC (albeit not all) lobes mostly influence intake cam mechanics. Nissan had the VCT similar to vanos which influenced intake cam as well. You get the picture now.

But I do hear s50 cams work very well on our m50s'.

 

[BigEarl325is]

Yes but our VANOS units (V-TEC and whatever else anybody calls their system) is there for changing the TIMING. Not so much the amount of air coming or going. The reason I mentioned the oversized exhaust cam as being more valuable is because most of us on here have after market exhausts. In conjunction with this system the bigger cam lobes open the valves much wider and enable the exhaust to escape much more freely without the piston having to put too much pressure on itself to push the exhaust gases out. With the pistons doing less work it allows the power stroke to become more efficient of any other cylinder because it won't have to push all the exhaust gas just as hard. As far as the air coming in, like I said VANOS and V-Tec all change the timing. They don't change the amount of air or fuel in. You can only pack 2.5L of fuel-air mixture into an M50 engine. No more, no less. That's where a lot of people get confused about the intake stroke with larger cams. You're not actually getting more fuel-air you're just getting it easier. In other words, since the valves are open further and longer the air will flow in easier. Only thing is, it already flows very easily the way the stock setup is laid out. So like I said, modifying the intake cam will give you a little bit of power, but compared to the exhaust cam, it won't help quite as much. If this is confusing I'll spend more time explaining it, I'm just kinda in a rush right now. Hope this helps to explain myself.

 

[m50POWER]

Thank you for your reply, BigEarl325is. I am in agreement that changes in cam dynamics can be benifical in power production. Generally, both intake and exhaust lobes are altered (together) to produce this end. Also, you are correct in vanos changing the timing of the cam only. However, Hondas VTEC is a little more complex than that -- they actually have extra lobes that changes both LIFT and DURATION of the cam dynamics. Also, take the examples in my eariler post, that most head designs encorporate larger intake valves and the exhaust valve remains smaller. If exhaust extracation is were more important in power production the intake valves would be smaller valve ( I have yet to see a cylinder head built in that manner). Just as free-flow exhaust may help in power production, many on this board adds a free-flow intake to add more power. Assuming that BMW has a very bad cam profile on the exhaust cam and that their head design is extremely restrictive on exhaust ports -- then I can agree with you on exhaust cam change helping more. But I dont see that to be the case.

 

[BigEarl325is]

You're right. Cylinder heads have ALWAYS had larger intake valves than exhaust valves. And yes I know V-Tec is much more advanced than just changing the timing, however, in my last post I had completely forgotton about that, so thank you for reminding me. In the past I've been told that exhaust cams generally work better, for the reasons I stated earlier. However, your point makes absolutely sense. I'll try to look into it more to see why exactly I was confused. It's very possible that I may have mis-read something in the past and drew that conclusion from what I read. What you said m50POWER makes perfect sense and I agree with you. Thank you for clearing that up for all of us.