beaulauber
Novice Class
Green Blood
Posts: 51
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posted July 02, 2002 09:33 AM
P&P the 12's head...????
Is it worth it? I am thinking of pulling the head this winter and having it P&P. I will still be on the stock motor (no big bore). I was wondering if anyone else has had the head profesionally ported with a flowbench.
thanks,
beau
  
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swft
Needs a life
Full throttle!
Posts: One MEEEEEELLION
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posted July 02, 2002 01:45 PM
A long time ago, someone posted flow numbers for a zx12r head. Can't remember who, tho. Would be interesting to see before / after numbers! I think the stock head is pretty good. After all, it costs as much as the rest of the motor put together! 
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Y2KZX12R
Needs a job
CompetitionCNC.com
Posts: 3762
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posted July 02, 2002 02:08 PM
 Edited By: Y2KZX12R on 2 Jul 2002 15:44
Beau, There is VERY small gains to be had with "porting" the head. Its really more of a clean-up.
You can reduce the boundry layer with polishing, but dont expect big gains.
Theres two places I found significant airflow increases.
The first place is at the top of the intake valve seat area.
The factory cutter leaves a cutter ring or lip around that area. This has an effect at low valve lift numbers (.100") or less. This may not sound important but the sooner you get the flow moving and the longer it squeezes past the valve the better. Also remember the valve is at that lift twice as often as it is at say .300"
The second area is in the combustion chamber where the factory cutter again leaves a large lip. This lip is huge in relation the the first one. Forming a radius out of the lip is the biggest gain in total airflow you will find without replacing the valves with bigger ones. Doing this increases the higher lift flows. Say above .150"
The intake ports in general are big enough to feed the engine so hoging them out wont be any bennifit unless the engine needs it. At close to 123 cfm of air flow at 10" of water (about 248 CFM @ 28" water) the velocity is quite low in the port. You could never run a 46mm carb on this engine/head combo and have any driveability down low on the street. The signal to the carbs would be just to weak.
Fuel injection alows you to get away with things you just cant with the same sized carbs.
So if you happen to have the head off and you want to mess with it thats one thing. But to tear the engine/head down to "port" it isnt going to give you much bang for the buck.
The first picture is the stock chamber. You can compare the first two pictures.
Notice the difference in the chamber from the exhaust and the intake, close to the valve.
Also note the carbon patterns. They are a road map to airflow. They tell a tremendus amount of info. This carbon pattern is far different from the stock pattern. I wish I still had pictures of the pattern the first time I took the head off after several thousand miles. You could compare it then.
(I lost alot of stuff in a windows crash a few years back.)
Notice the dark spots on the chamber on the short turn side of the valve. Its about 3 mm over from where this spot was from the factory.
A better view...
Now look at the piston carbon.
Notice the washed spots. This is from high velocity contact with the airflow. Notice the ones on the side near the cylinder wall. These were non existant with the factory chamber.
This combustion chamber reminds me of, and has many of the same "problems" as,(believe it or not) a pontiac Ram Air 3 and 4 head. Some of you guys may remember those old RamAir 400's.
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jimp
Expert Class
Posts: 291
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posted July 04, 2002 05:33 AM
Ron Carpenter does a good clean up job on the 12 head, he has it down to a science. Ron uses a CNC for the clean up.
http://www.carpenterracing.com/
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Y2KZX12R
Needs a job
CompetitionCNC.com
Posts: 3762
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posted July 04, 2002 07:19 AM
Does anyone have any pics of the finished product?
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ninja12
Needs a job
Posts: 3310
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posted August 12, 2003 02:30 PM
y2k how about a couple arrows, to show THEM newbies what you are saying?
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Y2KZX12R
Needs a job
CompetitionCNC.com
Posts: 3762
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posted August 15, 2003 07:08 AM
Look at the piston picture. Notice the clean spots around the intake valve reliefs. Notice the clean spots IN the valve reliefs. Thats where the increase in flow is.
To obtain it look at the closeup of the chamber picture.
Notice how the sharp edge from the cutter is removed and the wall is laid back.
I dont reccomend anyone doing this sort of stuff unless you are familiar with the disassembly of the valves and are confortable with it and have the tools needed.
I use an "airbench" that floats the head on a cushion of air and you can move it and position it with 1 finger. You dont want to score the walls of the head were the bucket rides. I wouldnt take the head apart with a c-clamp style automotive valve spring removal tool. Everything is too small.
Your best bet is to send the head out. I just posted this info because at the time I got many emails with questions about it.
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Y2KZX12R
CompetitionCNC.com
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