Porting Progress... 2g head.

EclipseGST · 02-24-2006

Well I've heard people say the 2g head can be very decent if you port the hell out of it. Well I was bored the other night and started working on the one I have. Basically all I started doing is gasket matching the ports, then I will go back through and smooth them out and sand them down with 80 grit.

I ended up taking out 3/8" of metal out of the ports. Just started on the first cylinder then decided to take pictures and show the difference. Here they are:

EclipseGST · 02-24-2006

Some more... Any thoughts/opinions??? So far I have about 10 mins into this project. The bits I have for my die grinder work extremely well!

Super Bleeder!! · 02-24-2006

i THINK you are suppossed to leave a bit betwixt the head and the gasket. meaning, don't port match the head to the EXACT dimensions of the gasket, leave a little bit of material. it'll form a step that'll help eliminate reversion back into the cyl.

the effects on a street car are probably quite negligable, but i thought i'd say something anyway

oh, and don't touch the intake ports. seriously.

**Kracka** · 02-24-2006

Like Floppy said, leave a step on the exhaust ports.

EclipseGST · 02-25-2006

I wasnt planning on doing a lot to the exhaust ports what so ever... The intake ports is what I took the pictures of. I'm not looking to make gobs of power on this head, just a learning experiance and see if it helps at all.

Thanks for the input guys.

thomyd · 02-26-2006

[QUOTE=notnormal]i THINK you are suppossed to leave a bit betwixt the head and the gasket. meaning, don't port match the head to the EXACT dimensions of the gasket, leave a little bit of material. it'll form a step that'll help eliminate reversion back into the cyl. QUOTE]

what is reversion?

**Shane@DBPerformance** · 02-26-2006

Reversion is when the exhaust the an exhaust manifold or header starts going backwards/the wrong way. So people try to make the runners in the header bigger, which causes there to be a step up at the exhaust port in the head. The step is to try to slow down the exhaust gas from getting back into the combustion chamber. On a turbo car though, you have extreme amounts of pressure in the exhaust manifold under boost(usually 1 to 2 times the amount of boost/pressure in the intake manifold), so a little step might not do all that much. The extreme pressure on the exhaust side is also why they make "turbo cams" with much less overlap and duration. You aren't worried about the boost on the intake side going into the combustion chamber and right back out the exhaust port during overlap, but actually the exhaust coming in and filling the cylinder.

rst95eclipse · 02-26-2006

Quote:

Originally Posted by ecoli

Reversion is when the exhaust the an exhaust manifold or header starts going backwards/the wrong way. So people try to make the runners in the header bigger, which causes there to be a step up at the exhaust port in the head. The step is to try to slow down the exhaust gas from getting back into the combustion chamber. On a turbo car though, you have extreme amounts of pressure in the exhaust manifold under boost(usually 1 to 2 times the amount of boost/pressure in the intake manifold), so a little step might not do all that much. The extreme pressure on the exhaust side is also why they make "turbo cams" with much less overlap and duration. You aren't worried about the boost on the intake side going into the combustion chamber and right back out the exhaust port during overlap, but actually the exhaust coming in and filling the cylinder.

I understand what you're saying about the step. However, are you saying not to port the intake side of the head (so it will flow better)?

**Shane@DBPerformance** · 02-26-2006

I was only talking about the exhaust side.

Just remember, bigger isn't always better. Higher numbers on a flow bench also doesn't always mean more HP. The intake ports on the 4G63 heads have gotten smaller and smaller over the years. The Evo has even smaller ports and it is probably a better head than the 1G and 2G. Usually you want as straight of a path from the start of the intake port into the combustion chamber. This often requires raising the intake port floor and getting the ceiling up higher in the casting. The idea is to keep the air velocity up as high as possible throughout the entire intake stroke to get max cylinder filling for the RPM range that you run the motor in. Huge intake ports can often hurt low and midrange power.

EclipseGST · 02-27-2006

That is very true... I only am porting the beginning of the intake port so there isnt a huge step between the intake manifold and head. The intake manifold runners are the same size as the 1g intake gasket shown so there for I want to gasket match it so the air flows smooth as possible. What is shown is all I am going to be porting. Wont touch anything past the first 1.5" into the port.

thomyd · 02-27-2006

so who does the best p&p job on heads? buschur, sbr ?

x-pride · 02-27-2006

Quote:

Originally Posted by thomyd

so who does the best p&p job on heads? buschur, sbr ?

LSE baby

.

**Shane@DBPerformance** · 02-27-2006

Jakey · 02-27-2006

Quote:

Originally Posted by thomyd

so who does the best p&p job on heads? buschur, sbr ?

Polk Performance
http://www.polkperformance.com/

Shep runs a Polk head. Also, back in '02 Don Polk posted a nice list of flow bench test results:
http://www.dsmtuners.com/forums/showthread.php?t=16920