GreggT

Yep.......that's what I think they did.
The pics showed something stuffed up there....maybe some good rags. Whatever would pull out easily & cleanly when you're done.

johnyg

I would NOT port on the cylinder head ports with them still the car. That is asking for trouble. The least bit of metal shavings left in port will ruin your turbo. Porting is a good thing but when done on the heads themselves I would want the heads off and a pro making sure the end results are flow benched equal to one another. Just my 2 cents.

GreggT

Thanks.......appreciate the concern for the turbos, yep it's a risk.
Can you explain please "flow benched equal to one another".......and the reference to 'Pro'.........Some people have said I'm a good, but I occaisionally have my doubts.

MidnighTT

I define head porting pro as a guy who has had the luxury of evaluating many different contours for the castings of interest on the flow bench and on the engine dyno. IMHO, these are the guys who have made enough mistakes to learn what works and what doesn't. GreggT, for all I know about Porsche head porting (which is nothing!), you may very well be such a pro, so please don't misunderstand my post. It's just my definition of 'pro'.

Jeff

Wachuko

I need to read all the posts... but the initial photos are gone.... any chance of reloading those to the thread?

EDIT:: Nevermind... other pages have several posts with photos...

johnyg

porting the manifold is really not that hard just time consuming. I don'tknow the mechanics of flowbenching but you want the combusiton chambers as close to ecactly the same which is called "cc"ing and you want the runners within the head to flow the same cfm for each port or cylinder. The more equal the better. Also flow or velocity can be better that total volume of air. Hope this helps.

TT Surgeon

Kevin, does this apply to 997tt headers as well,don't see why not.

Kevin

Yes, the 997TT will benefit also.. Same basic manifolds.

Kevin

Pictures start around post 47 plus or minus..

drh

Bump

Slalom996T

Regarding improved spool-up on a 996T: Is there any better header available today (aftermarket or...?) than a modifyed oem header?

Maybe with slightly smaller runners or...?

/Slalom996T

Kevin

You do realize that the 996TT headers are used on the 997TT. The primaries are short. Do you also realize that they are double jacketed. The exhaust energy does not cool as much as a single wall header.

Slalom996T

Thanks for your reply Kevin.

So the 996T oem header is used for both the 997T mk1/3.6L as well as for the 997Mk2/3.8L? As well as being double walled?

Double walled is a very nice issue since, as you say, the more (overall) energy released to the turbo shaft results in less spool time.

I guess the slightly larger engine size of 3.8L also must help in the spool department?

But still, is there any better header available today (aftermarket or...?) than a modifyed oem header?

/Slalom996T

Turboslut

Anyone ever used Extrude Hone to smooth out the manifold in its entirety?

Kevin

The factory welds vary between ports and headers. This requires you to vary the amount of grinding from port to port. Manual hand skills is needed vs the automated slinky putty that is used. Please realize that the interior stainless tubing is smooth (doesn't need polishing)..

Again look at post #47. It give you a good idea of the grinding that is required. Final polishing with porting rolls with make it smooth as glass.