CSL exhaust valves and gas flowed head

[J2LTB]

Out of interest why does a std m3 and Csl share the same inlet valves - 11347830889
But they don't share exhaust valves ?

Csl 11347833676

m3 11347830888

They both list the same sizes. Is it CSL tax ?

Inlet 35.0/5.95mm

exhaust 35,0/5.95mm

Any ideas ? Sodium filled ???

Cylinder heads list same part no. But mine is heavily gas flowed on the inlet side and throttle bodies matched the same. Looks to be CNC machined. Exhaust ports are un touched.

Can anyone else tell me if they know of any other gas flowed csl's ?

[NZ_M3]

This is a post from m3forums ... might shed some light into the fact that it isn't a CSL tax.

Originally Posted by Alex@DPE

BMW Motorsport P54B32 and OE CSL Exhaust Valves
It's been known for quite some time that the OE CSL Exhaust Valves are different than standard. Many assumed it was solely a difference in size from standard S54B32. Being one of the first on the forum to actually order these, Chris found out that the shape is totally different! Please note the conical shape of the face of the valve compared to the standard exhaust valve. Out of more curiosity, he also ordered a P54B32 exhaust valve to see how it's different than OE CSL. Low and behold, the shape and point of the conical valve is even more different than OE CSL! The OE CSL and P54B32 valves also appear to be made of two different metals. Compare the delineation of the two with the standard valve.

[J2LTB]

That's interesting. So there is a difference. It's funny how the inlets are std but ported and the exhaust's are modified with std ports.

[uncle benz]

Are you sure about the porting? Standard M3 S54 engine has porting work on the inlet side. I'll get a picture in the morning if I remember...

[J2LTB]

I'm sure the ports on my head are matched the the ported throttle bodies. I wasn't aware that a std M3 has this as std. I'll put some pics up

[J2LTB]

Ported and matched throttle body



Machined inlet port knife edged



Top end rebuild in progress



Rebuilt Vanos unit

[uncle benz]

Standard M3

[J2LTB]

Cheers Benz. Are the throttle bodies opened up as well on a std m3 ?

[uncle benz]

Yup

[J2LTB]

I see. Thought mine had something special done