Explain the Difference in M30 Heads

[speedhop]

Can someone further explain the differences between the heads put on the m30? I know they are notoriously known for bad flow...but why? What makes the b35 head better flowing than the b34? If I were to purchase a b34 head and have it ported...would it then be just as good if not better flowing than the b35? Furthermore...if I'm building up an m30 for turbo and the head will bottleneck on me, making it great flowing is of necessity. So I'd port head, larger valves, dv retainers...etc? What would one do if building for turbo? Please excuse my ridiculous ignorance...never worked with an m30. Thanks for the help

[Mike325]

I believe the main dierence in the two heads is the size of the valves, the b35 having the larger.

For turboing the m30, most o the time you will not need to do anything. If you want to get fancy, you can change the HG to a larger thickness to lower the CR and add some strong HB, forget the company name, metric blue maybe? That is only if you run lots of boost though.

[speedhop]

Well I'm thinking of putting down at least 500hp and leaving some room to play...boost levels will probably be at 1 bar+

and then there is drive train issues...ahhh :)

[Belteshazzar]

uhhhhhhmmmmm.
you wanna motor to "put down" 500hp at 1 bar. That basically means, in rough terms, it needs to be able to put down 250hp N/A.
If it where me, i'd start by completing the m30 swap. Then I'd do a turbo that simply worked at all. Lastly I'd build up to the power levels you're talking. Going straight for the throat like you're talking is how people end up selling half finished projects.

[speedhop]

^^ very true...I figured if I have the motor out and ready to build, might as well slap it all together there. Patience is a virtue as they say, but what about killing two birds with one stone? :)

i said 1 bar+ to give leeway...any more input?

[Mike325]

I agree with taking it slow. What you can do to prep the motor out of the car for turbo is to do the head gasket and bolts for the head. No problem with doing that. Then the turbo install would be just to change the manifolds for a turbo one, run some oil to turbo lines and do exhaust. You can run an m30 turbo without an intercooler and no software. Talk to Frank (m3fan4eva). He makes about 300 whp iirc.

So for now, if you do the swap, I would hold off on the turbo. Unless you have a lot of money, you can get a turbo kit from TCD, Turbo Charging Dynamics.

[speedhop]

well obviously I'm made of money...just like everyone else on r3v :drink:

You are both very right...taking it slow is better at this stage. Build up instead of blow it up...thanks for slapping me out of that

I'm still going to get the motor in and turbo at the same time...I'll just wait to go crazy with the head.

What turbo ism3fan4eva running? No software either? What injectors?

[bmw335isturbo]

Head

here is just something to look at one idea. http://www.cardomain.com/ride/629515

[euroshark]

You don't need tons of fancy head work to get 500hp on a turbo M30... Just pump more boost!!

Ok, just kidding. But really, they aren't notorious for bad flow, they are actually fairly efficient and beautifully running motors. If you need flow, but a B35 head on a B34 block. You will get lower compression for more boost, as well as revised ports and 1mm larger valves.

[speedhop]

the b34 block with b35 head will result in lower compression ratio instead of complete b35? How is this possible?

[speedhop]

here is just something to look at one idea. http://www.cardomain.com/ride/629515

sweet setup!! Have you upped the boost since? Why did you choose air/water intercooler?

That thing must be a beast :-D

[Belteshazzar]

something else to do while the motor's out, the oil return fitting on the pan. Make one, then plug it 'till later.

[speedhop]

I've heard that the oil pan is good but not as strong as tapping the block.

Any thoughts on this??

[CarsSuck]

Not that I have any experience, but lots of people tap the pan for their turbo motors. M20s and M30s alike. Since the motor will be out, just take the pan off and weld on a bung. That'll be plenty strong.

But its not like an oil line is under any appreciable mechanical stress...

[Funkmasta]

No need to build and rebuild M30s unless you are looking to sustain SERIOUS power. If you want medium power, there is no need to do any building of an M30. So you blew it up? that sucks. Time to get another $300-$1000 long block.