Engine porting
12-23-2002, 11:09 PM
#111
Member
Join Date: Oct 2002
Posts: 47
Originally Posted by pengaru' date='Dec 23 2002, 08:09 PM
is there a reason you didnt mask the sides?
12-24-2002, 12:26 AM
#112
Senior Member
Thread Starter
Join Date: Jun 2002
Location: La Plata, Maryland
Posts: 9,725
Originally Posted by l8t apex' date='Dec 23 2002, 08:33 PM
[quote name='Fd3BOOST' date='Dec 21 2002, 02:39 PM']You need to take more out on the end plates. Also se the shape you have is wrong.
Make a cup with your hand. That is the shape you want all the wall. Kinda like a skateboard ramp. you want the arch right.
I dont know that would open the exhaust ports up that much either. The bottom looks like it is to much. Im sure you can still make it work.
Make a cup with your hand. That is the shape you want all the wall. Kinda like a skateboard ramp. you want the arch right.
I dont know that would open the exhaust ports up that much either. The bottom looks like it is to much. Im sure you can still make it work.
Also I will say from experience that I had too large of exhaust port on my first motor.
It would out do a normal port but in the second drag (hard run after brake in) the seals
broke and locked up my ****! I had the port so wide that the apex seal couldn't hold under a load. I tried to copy just from those photos in the how to modify you rx7.
lost the whole motor.Never chase a straight line when porting to the limit.It'll get away from you.
(Other post) He doesnt need to mask the housing from painting....just a little brake cleaner cleans those faces up nice. [/quote]
I mean the actual inside arch, not the outside shape that you see when looking at it. But the path that the intake charge will actually take.
12-24-2002, 12:28 AM
#113
Senior Member
Thread Starter
Join Date: Jun 2002
Location: La Plata, Maryland
Posts: 9,725
Originally Posted by spoolin' date='Dec 23 2002, 09:09 PM
because it was a whole lot easier to rub on the surface with a rag and carb cleaner right after i painted. plus, those little scrotch bright pads and green finger attachments work wonders on a right angle die-grinder
01-09-2003, 05:32 PM
#114
Senior Member
Join Date: Jan 2002
Location: NJ USA
Posts: 1,915
Originally Posted by l8t apex' date='Jan 8 2003, 01:29 AM
Well I did it! I was thinking instead of watching and let the bottom of a front side housing port get away.Its been ten years for me and I regret giving up the bits. But hey, Judge Ito has bailed me out for reasonable fee.
Now to get it straight...I mean corrected.
Now to get it straight...I mean corrected.
01-10-2003, 05:43 PM
#115
Senior Member
Join Date: Oct 2002
Location: Tallahassee FL
Posts: 345
thanks guys, that helps out a lot. wow 30 percent power increase that's tempting.. wouldn't you lose some torque with that gain of horsepower? other than sound (i don't mind loudness, in fact i prefer it) what do you sacrifice the larger you port?
01-22-2003, 11:54 AM
#117
Senior Member
Join Date: Sep 2002
Posts: 525
Ok, here's my first port job (as will probably be aparent). This is my friend Brad's (rotary speedster's) engine. I used a racing beat template. The ports weren't finished in the pics, but our computer guy was walking by with a digicam, and I had him click a few. The last one is of the front side housing. I hadn't had a chance to practice on a secondary port (where I had on a primary) and there wasn't much light in the shop when I started. On the bright side, I now know where the water jacket is on the secondaries, and know where not to port.
Sorry for the links, but until vosko get's his pic server up, I have nowhere else to host them.
Primary
primary
The other side of the int. housing
primary2
The rear housing
secondary
And here is the front secondary. You can just barely see the 2mm x 1mm slit into the water jacket. I'm putting this up here to show my stupidity, and to show others the general position of the jacket.
oops
Sorry for the links, but until vosko get's his pic server up, I have nowhere else to host them.
Primary
primary
The other side of the int. housing
primary2
The rear housing
secondary
And here is the front secondary. You can just barely see the 2mm x 1mm slit into the water jacket. I'm putting this up here to show my stupidity, and to show others the general position of the jacket.
oops
01-22-2003, 02:57 PM
#118
Junior Member
Join Date: Dec 2002
Posts: 8
I am not a fluid dynamics expert, just a hobbiest. I think this idea has merit. I finally found the information I knew I had read a while ago on porting:
From: http://www.babcox.com/editorial/ar/eb120121.htm
"On late-model Chevy Vortec heads, you don’t want to change the shape of the port much. The best advice here is to clean up and equalize the ports so they have the same height and width. On small-block heads, there’s a large pocket right below the rocker arm stud in the roof of the port. This should be filled in with epoxy to improve airflow. Doing that will give you an extra 15 cfm."
Is the pocket in the port on the long side radius? If so it could help quite a bit. Remember an engine is a pulsed system so the air is stopping and starting in addition to the wave pulses reflecting through the intake tract so a flow bench may not show an accurate picture. I would think a change like this would show more improvement than the flow bench would indicate. I would love to see more experimetation like this. Let us know how it turns out.
From: http://www.babcox.com/editorial/ar/eb120121.htm
"On late-model Chevy Vortec heads, you don’t want to change the shape of the port much. The best advice here is to clean up and equalize the ports so they have the same height and width. On small-block heads, there’s a large pocket right below the rocker arm stud in the roof of the port. This should be filled in with epoxy to improve airflow. Doing that will give you an extra 15 cfm."
Is the pocket in the port on the long side radius? If so it could help quite a bit. Remember an engine is a pulsed system so the air is stopping and starting in addition to the wave pulses reflecting through the intake tract so a flow bench may not show an accurate picture. I would think a change like this would show more improvement than the flow bench would indicate. I would love to see more experimetation like this. Let us know how it turns out.
01-23-2003, 06:46 AM
#120
Senior Member
Join Date: Jan 2002
Location: NJ USA
Posts: 1,915
The primary ports need a bit more laying down towards the closing part of the port(Upper edge) primary ports looking good. Secondary ports need to have a nice even metal porting from one side to the other, If you notice is not even across the upper edge like your primary ports are. Take time and make a nice flowing port from inside the runners to the actual closing of the port. Use the porting bit with the belly on it. That will allow you to create a nice even flow. Ask me some more and ill try to help..