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ive been reading about porting and polishing the inlet manifold, when i did the carbon clean on mine i did a bit of porting etc but left the surface rough, to create turbulence and mix the fuel and air.

however we have the fuel injected straight piston so no mixing in the inlet at all,

so what im getting at is to polish smooth the whole inside of the inlet shiney smooth?

i saw a thread on 246.de where a guy had done this to make the airflow get into the chamber quicker,

any thoughts on this?

Personally,

I would say you still want an element of roughness to begin the "tumbling" process as its the way the air swirls in the cylinder that equates to a proper burn and eliminates hot spots or issues with the flame front and potential detonation. Obviously thats much less of an issue as we're N/A and relatively low C/R but its still a relevant point just to ensure safety and power.

A totally smooth inlet, mirror polished, would most likely lose power purely from incorrect mixing and possibly evacuating the cylinder quicker than expected - perhaps a mapper could make adjustments for this but that is probably beyond my level of experience and knowledge - at least publicly - obviously its possible to get more air into the cylinder controllably under pressure but purely on velocity and whether this is efficiently useable I dont know.

Good thread though.

J.

yeah i agree about the tumbling process,

im going to carbon clean mine again this year to 1 have a look at the buildup with the mileage and 2 to do some more machining

here is the thread

http://translate.googleusercontent.com/ ... VMpA2Mn5ew

Check this info out in PDF that silverRS4 created a while back.

http://www.jlosee.com/images/RS4/PDF/si ... orting.pdf

Some more info here too:
http://www.mrctuning.com/index.php?opti ... &Itemid=18