started porting and polishing the 924 head

Obin Robinson · 06-13-2001, 07:26 PM

well, i've taken the advice of a few motorsports guys (and a few friends, and their mechanics) and i've started porting the exhaust ports.

this isn't as hard as i thought it would be, it's an exercise in restraint. i am just going to clean up the intake side, but not shine it up. i know that the rough edges is nexessary for turbulence, and a good mix of fuel and air.

i did the first part of porting the #3 and #4 cylinders. it was not as hard as i thought it would be. the biggest worry is hitting a water jacket, but from what i could see, that's a very remote possibility with the 924 head. the only part i'm actually cutting into is around the exhaust gasket.

i'll post all the pictures up, and i'm documenting all of the stages. my budget so far? about $20

after the port and polish, i'll be working on the TGIF (Totally Ghetto Improvised Flowbench) that i saw in Hot Rod magazine. us 924 guys have to be resourceful... especially when you live in farm country about 2 billion miles from a Porsche dealership, or a machine shop. my final goal will be to show everyone that you can free up some horses for cheap in your 924. these cars are really easy to work on and things don't HAVE to be expensive. no, i can't duplicate the work of a master engine builder, but i can at least learn from what 3 dozen different racing mechanics have told me so far

... and all of them said that i could do this myself and save the cash

obin

Obin Robinson · 06-14-2001, 05:06 AM

here's some HIGH RES pics of my progress so far:

http://209.150.235.158:8585/cylinder_head/port_polish/

as you can see, i'm going 2 cylinders at a time, and putting together the TGIF project in the meantime. i will start the polishing part later tonight.

enjoy!

obin

Dave951M · 06-14-2001, 04:16 PM

Lookin' good Obin! I think you'll be pleasantly surprised with the results. Are you going to cc the chambers while it's off? Not hard to do and you already have everything except a piece of plexi and a graduated pipette.

Dave951M

Obin Robinson · 06-14-2001, 04:28 PM

Quote:

Originally posted by Dave951M:
Lookin' good Obin! I think you'll be pleasantly surprised with the results. Are you going to cc the chambers while it's off? Not hard to do and you already have everything except a piece of plexi and a graduated pipette.

Dave951M

yes! I have the plexiglas, and the graduated cylinder. my biggest worry is hitting a water jacket, but i don't think i have that much to worry about, hey, if i mess it up, then learn from my mistakes

obin

Cake944 · 06-14-2001, 05:34 PM

What is the purpose of the stopwatch ?

Obin Robinson · 06-14-2001, 06:31 PM

Quote:

Originally posted by Cake944:
What is the purpose of the stopwatch ?

i am using a stopwatch at the beginning and end of each stage so that you can get an idea of how long it took to do this particular job. cool idea huh

that way, if you want to see how long it will take you do duplicate what i did, you will be able to know if you did it faster or slower than i did.

tonight i polished up the #3 exhaust port. i spent an hour just doing the 150 and 220 grit sandpaper polishing (very delicate job). i am going to get a few polishing wheels for my high speed cutting tool. the exhaust ports will be finished to a mirror shine when i'm done.

stay tuned

obin

mike944 · 06-16-2001, 02:59 PM

Obin,

make sure you gat those heads re-surfaced before you put them back on the car. I see quite a bit of corrosion around where the fire-ring part of the head gasket sits. It's a common problem with 924/944 heads.

on this picture espically (i hope i did this right)

http://209.150.235.158:8585/cylinder_head/port_polish/flatter_angle_of_three_and_four.JPG