Port and polish?

Concerning the 944S convertion, after asking a lot of questions about it, many people have suggested that I should just port and polish the head...it would be cheaper and all that stuff about the easiest way to have a 944S is to sell the 944 and buy 944S. So what exactly is porting and polishing do? What does it do and what kind of performance gain can I expect from that? (and, of course, how much does it cost, and where can i get it done)

Most respectable shops can do the port and polish for about $250.

Porting and polishing opens and smooths the air passage going into the combustion chamber. Usually in mass production the head is simply cast into a rough shape and the time and $$ involved in machining the passages isn't cost efficient in building engines. So the smoother the air the air can get in and out, the more efficient the engine runs.

PS: bring your intake runners so they can be match ported as well.

Is there a good amount of gain? It seems like it would help just as much as exhaust/intake...all it is is letting gasses flow more easily...right? That doesn't seem like all that much to me...but then again, i don't know anything about anything...he he he

You apparently know about slave cylinder rebuilds.

I've read claims ranging from 7-25 HP increase. I guess it would depend on who you ask.

Think about this though, the head is the most restricting part of the engine. If you port the head and remove it's restriction, the exhaust becomes the most restricting. One dent in your life savings later and the intake becomes the restriction. So on, so forth.

I was looking around and came across this webiste: http://www.sa-motorsports.com/diyport.htm Its instructions for a Do-it-yourself Port and polish kit...I dont want to buy the kit, but the instructions seem pretty comprehensive...I own a Dremel...and I'm pretty good with it, but is this something that I can really do, or is it just not recomended for a Porsche?

It's doable. I used a kit on a friends Honda 400EX ATV. You'll need a flex shaft to do things right. It takes an awful long time too. Like I said though, it's doable.

Think of your engine as an air compressor-the more air you can get in-the more air you can get out-the more power you can make. dremel tool is ok but to speed the process up buy a cheap die grinder(Home Depot-$25 bucks) and a goodson port and polish kit( $50.00 for the kit which includes carbide cutter, flapper wheels of sand paper and scotch brite on a wheel) and go for it. If done proffesionally the runners are put on a "flow bench" and perfectly matched with each other. But even if you smooth out the casting marks and polish the runners you will gain HP

I do fortunately have a diegrinder and some peices for it, and the compressor (obviously), so I dont have to worry about that, I just wasn't sure if these people were messing with cars that could really run if you threw a wrench into the crank case...I'm sure that a Porsche is a bit more picky than a Ford, but now I feel better about it. Also, how much is a three angle vavle job and timing adjustment...or can I do the timing thing myself?

There is no way to adjust timing on a 944 unless you buy the adjustable timing gear which goes on the cam shaft

But when I tear down the head, wont I need to re-tune everything? And how much will all that stuff cost (from my previous post)?

Other than idle, the engine pretty much tunes itself. If the engine senses too much air, it adds fuel, etc... The AFM and O2 sensor usually keep things in balance.

This could also lead you to upgrade to larger fuel injectors if the standard ones can't cope.

no, wait, im not talking about adjusting the timing to gain power (like advanced timing or anything), just timing so that the engine runs correctly...If i do a head tear down, when i put it back together, i dont want my valves open at TDC...Will it show me how in the Hanes Manual?

As stated earlier the timing can not be adjusted. Your options Are an adjustable timing gear or some chips advance the timing curve slightly.

As stated earlier the timing can not be adjusted. Your options Are an adjustable timing gear or some chips advance the timing curve slightly.


So what you are saying is that I can just put the cams in any ol' way and it'll run fine...All I am asking is how do I put it back together so the valves open and close when they need to. Like I stated earlier, I am not interested in advancing my timing, I just want to know whether I can do that myself, or if I need to take it to a pro. Sorry for my inclarity. Also, how much is a 3 angle valve job, Im sure after porting it I will need one...

yeah, throw it in any ol way you want, the camshaft will lock up till the timing belt jumps to the correct position when you first start the car. NOT!! Please don't do this!! Someone took me seriously once, and I helped him pay for the headwork cause it kinda was my fault.

www.clarks-garage.com
left hand side has topics
goto Garage Shop Manual
Look under camshaft and read till your eyes bleed!!

www.clarks-garage.com

You can put the cam in any old way you'd like, as long as you make sure the timing mark on the camshaft drive gear is lined up when you put the head on the engine. You can turn it over by hand to get it into the right position, but I would not recommend this, as there would only be assembly lube to prevent damage to the lifters and camshaft.

I don't know what the 944 has, but my 924 has a small extrusion cast into the valve cover head, that is used to line up the camshaft timing mark.

The rule of thumb is, pull the head when the engine is at 0 degrees, when the #1 piston is at top dead centre, and using a scribe or a paint stick, make a mark on the camshaft timing gear, and on the cylinder head, so that the two marks line up and you can tell the exact position of the camshaft prior to disassembly. Then when you reassemble, just line up the marks and it'll be in exactly the same position.

Now, assuming all is well with your camshaft, and someone has not advanced or retarded the camshaft timing previously, when the crankshaft is at top dead centre, the original timing mark on the camshaft gear, which is usually a small bump cast into the gear, should line up with whatever the 944 uses to line it up with, one of you 944 guys should be able to tell him what it lines up with. :biggrin:

You'll want to find TDC before you disassemble the engine. A manual will explain but the marks are clear and easy to see. Are you going to do the "s" head conversion? Cause if your not you only have 1 cam to worry about.

QUOTE] Someone took me seriously once, and I helped him pay for the headwork cause it kinda was my fault.
[/QUOTE] Are you serious? Dang 83-944, your a really nice guy. Um, no, Im not going to do the "s" conversion, well, not in the near future. Everybody has been telling me to just port and polish, so I figure I will just do that for now. It will give the perfomance gain I'm looking for, for now anyways. Maybe when I get the "I need more" feeling I will (but hopefully I will be able to hold out for a while...) Thanks a ton guys, you all are awsome