Wagz

I'd like to hear from people who have had a P&P job one on their NA 944. Was it worth it?? And how does the car run?? I've gotten mixed results from this question so far. Also, how much hp did u get, if ANY?

My car is street use only for now..but wille ventually autox.

cheers,
Wagz

Brian McCoy

Porting Might gain you a few HP if you have a lot of other changes (custom intake, high-flow intake and exhaust, engine built for more flow) but generally it's a huge waste of money in and of itself. Polishing, on the other hand, will absolutly ruin flow charactristics, cause poor vaporization of the fuel and generally hurt the running across the board. You'd get something polished so people could see (exterior) or for bragging rights (who'd know anyway?) ~ not for performance.

If you feel like letting someone have a go at your head, make sure they are VERY experienced with the 944... higher CFM is NOT the only goal here ~ you have to consider many other things.

Manning

Not sure about porting on these cars, but every fairly current article I have read on the subject as a whole suggests polishing is a big waste of time. Smoothing is good, but polishing adds nothing.

Porting can be really dangerous if you don't know what your doing. You can really screw up how everything flows through the engine if your not careful.

Wagz

That's what i've been hearin, thanks for the info!

Oh, what does it cost to 're-seat' the head, i have 2 bent valves and am rebuilding my head, it must be re-seated as well i've been told..anyone kno a price on that?

Cheers,
Wagz

FSTPRSH

I agree with Manning to an extent on that. The smoother the surface, the less obstruction. Think, the smoother it is, the more like Teflon it is. The extent part is that I'm very **** about details, so if there is a .35 CFM to be gained, I'll do it just to know it's getting all it can. That's just me though, everyone hates it until it comes to their project. But like the others are saying, unless you have done something else, neither porting or polishing will do much for you. You can only get so much air into the cylinder on a stock setup, and "they" did a pretty good job of that from the start. Now, add a cam and make the valves a hair larger, then you'd benefit.

-edit-

Just reread Brian's post. Also a good point. Fuel atomization is important. Despite common belief, a certain amount of turbulence is desired in the intake tract to help the atomizing process. It's a trade off, like everything.

Brian McCoy

Seating the valves is a time consuming, but Very easy process. You'd need to spend about $10 on lapping compound and a valve seat tool (it's basically a dowel rod with suction cups on each end). Put the lapping compound on the valve face, install it in the head (no spring or anything, just with the head upside down slip the stem into place), then take the tool and place it on the bottom and start twisting the valve. You'll be able to pull the valve after a little bit and see a polished 'ring' arround the seating surface. You just want to make sure it's equal and goes all the way arround (the valve is seating completely).

I'm not sure if the Porsche valves are coated or not (motorcycle valves are and you don't lap them because of it), but find out for sure. I forget just what the name of the coating is, sorry....

SoCal Driver

I must have cheated when I laped in my valves. I stuck the valve through the head and clamped my 3/8" drill motor on the stem. Put a bit of lapping compound on the valve face, pulled the valve into the seat and ran the drill motor back and forth!

If the guides are with in spec, not out of round or have been pushed out by the bent valve, then you can lap the new valves back in if the seat is still decent.

Now if you mean reseating as in replacing the seats then you need to send it to an automotive machine shop. A good machine shop!

sharky47

On using the drill, you really need to put a rubber hose that barely fits on the valve stem and then chuck that up in your drill. This lets the valve find it's own seat a little better, we do this all the time on aircraft valves cause there is no head or cylinder, it's all one piece and you can't get to the top of the valve anyway.

I was talking to my dad, who has been an IA for 30 years and has forgotten more about engines than I'll ever know and he had a different take on the polishing thing. Our cars have the injectors right at the valve and do not require any mixing. Whether it's smooth or not, doesn't matter since there isn't enough length of travel between the injector and the inside of the cylinder to mix any better anyway. If it had the injector/carburetor was farther upstream, it would have an effect, but I really don't think it makes a difference on our cars. Correct me if I'm wrong, but that's my story.

SoCal Driver

Best to have a bit of roughness on the surface of the intake mixing or not. Improves flow.

If I were to do anything to the intake it would be to match the intake manifold to the openings in the head.

As to the injectors location: The best thing you can do for the injectors is to keep the same plastic caps on all of them. The ones you want have a conical recess where the injector in sticks out.

Also look at the end of the injector pin. This is flaired. If the flair breaks off then you get a solid stream of fuel. Not good.