saabin

So I have been reading a little about a small mod that I considered undertaking: porting and polishing the stock 997.1 headers. I have read about some mild performance gains (faster spool of turbos) but mostly was interested in attempting this to see if I could do it, and it also allowed me a project that I could undertake in the man-cave at my leisure. 

I didn’t want my car to be undriveable while I tackled this, so I bought a stock set of lightly used 997TT headers from a friendly RL’er for a fair price.

I used an air powered die grinder and a carbide cutting bit to do the bulk of the work.. I only have a 15Gal compressor, which will work with the die grinder, but it runs out of steam unless you stop every 5-10 seconds. Thankfully my neighbor has a 60 Gal compressor with a 50ft hose, so I borrowed his air so I could have a nice continuous operation of the grinder.

Looking at the stock headers, there’s a fair amount of extra metal around the welds.. I wanted to keep the lip/ridge around the collector but smooth out the bigger humps.

I started with the carbide bit, followed by some 80 grit cloth rolls, followed by 130 grit, followed by some emery paper. The surfaces of the exhaust runners and collector are now super smooth..

I cleaned them up by washing them with my power washer.

I used all new gaskets and the install took about 2 hours.. not bad.

Unfortunately most of my pics of the fully polished product got corrupted by my phone, but I have some of the porting..

A few pics of the before and after:

Stock parts have a fair amount of thick welds..









Gaskets:



Polished exhaust runner:



Ported but not yet polished parts...

CodeRed

Wow, great post...can you do mine next? Seriously, very interested to see what effect it has on performance...seems like a nice bit of fine tuning.

993MAN

Why wouldn't Porsche do this in the factory I wonder?

L_perm

I would imagine cost-to-benefit doesn't make sense for Porsche. Plus, they have to give us some things to mess around with.

Zuppy51

Please clarify, I was under the impression, that in order to realize any gains in air flow, you would also have to port/polish the intake side as well? Otherwise what you are doing would be negligible?!

CincyScott

I've done it on several Porsches, but never as an isolated mod. As such, I've never been able to see how much it does as I was doing other things at the same time. I did it to my current 997, but as I said before I did a whole lot at the same time so I couldn't tell.

I'd be interested to see what real world improvements you see!

saabin

Perhaps thats the case for a NA car, but from what I've read it helps with turbine speed/velocity of the turbos.. faster spool..

Yeah, me too. Did you do it yourself or did someone else do it? It was actually a fun project.

I don't have another dyno appt scheduled yet, but will most likely do one before any more mods. I plan to datalog some more and see what's up.

CincyScott

I did it myself. If you think the 997 ones have a lot of room for improvement, you should see the 993tt's... What a mess.

Kevin

The outlet side of the header flange. When cleaned up really improves the velocity to the turbine hot housing. When you couple that to extensive port matching of the turbocharger turbine hot housing, you really reduce lag > by increasing the port velocity. One can see the blobs of metal welds hanging in the airstream.

This mod is good for 200 to 300 RPM's of throttle response. Throttle tip in will be more NA "feeling"..

911mhawk

How long did you spend doing the port and polish part?
I've been staring at a spare pair on my workbench for a while now.
Thanks-

CincyScott

If you have more than 8 hours total in the whole grinding project, I'd be surprised. Much of it has to do with having sharp carbide bits, that makes the work much faster.

saabin

I probably spent that amount of time spread over 2 different Saturdays.. and yes having the correct carbide bits for the initial knock-down work is key.. and having enough air to keep the die grinder running continuously