like PPI said, its gasket matched... why go wider than your gasket allows ? keep in mind also, that is the exhaust side showing... the intake is a little bigger. He also picked up almost 25% in flow on both the intake and exhaust side... with the intake being higher.

 

Buschur recommends to not touch the intake ports? Anyone know why. Friend talked to them and didn't give any detail. I just polished them.

 

not sure since jam definitely touches them lol

 

Now I feel like an idiot. The ports match up perfect to the gasket. I could have swore I could have taken a little off.

 

The intake ports do not need polished because the velocity of the air creates a static wall on the intake port walls. So the air will not be any smoother through the intake track, now if you inlarge the ports that is different, or change some of the radius's.

 

Well, first we must understand that when you flow a head, your not making sure the head is the same "in and out". It only tests one side at a time, and it blows out the exhaust port or pulls air in the intake port, depending on which side we are testing...




I would be lying if I said we tested every port, on every head, in my opinon only a novice would have to do such a thing. If you know how big the port should be, and the shape is there, the valvejob is done correctly, the head will flow within a couple of percent.

 

looks like alot of it becomes experiance needed. nice stuff. and thanks for the info

 

Any pics of the exhaust ports?

 

'Ideal' flow balance between the intake and exhaust ports doesn't mean they would flow equally on a flow bench.

 

Yah, I understand that part, but in looking at the pictures, it looks as though the exhaust side wasn't even touched, and as confimed in a later post. It seems as though you could do a few simple steps to the exhaust side to make it better than "stock", such as kinfe edging the divider for slightly better flow merging, and lightly sanding the port walls to simply knock all of the casting off, creating a smooth wall (Only for the exhaust side though). I am going to polish mine (Exhaust side only) to try and help the carbon buildup (Or lack there-of) situation, as they do with combustion chambers. (Although the combustion chambers is done to eliminate hot spots as well.)

Once I get around to popping the head off, I guess we will see how this goes.

 

maybe the pics i took were terrible then... they are definitely smooth. Not knife edged, but smooth and very wide .... you can see the whole damn valve when you look into the port lol. The chart showed a 25% gain, so whatever they did worked. We will have her together and on the dyno soon, so subydudesti will have some numbers in his sig when im done tuning

 

I have seen a 300gt vr-4 head done by head games and it looked beautiful!
definitely a good shop!

but for all you do it yourself at home guys, there is alot more to porting than making everything bigger and adding a sharp edge where it was once round. It is really easy to kill the ports by making them too big,,, usually people lose velocity in the runner, or crate a shraper bend where there was once a nice gentle radius. the end result is a head worse than stock..

Also be very wary when people quote gains on a flow bench. The Static flow of a flow bench is wildly different from what happens on a car. ALso it is very rare that people test on a flow bench with the valves installed. and the area around the valve is the biggest choke point in any cylinder head... so huge gains on a flow bench are meaningless if the head can't flow that much with the valves installed...

quite often the ports in the head are fairly well optimized and most gains come from changing valves, skinny valve stems are great, (undercut valve stems are NOT) deshrounding the valve in the combustion chamber, ( but be careful not to ruin the quench areas....) and a good 4 or 5 angle valve job on the seats....

If anyone is felling adventureous,,, endyn, a shop from Larry widmer has some excellent articles on this... the website may still be some thing like "theoldone" .com .... this guy really knows his stuff,,, 364cfm from a honda k20! freaking amazing!!!!

oopppss... i just quoted flowbench numbers..... always take them with a grain of salt!

 

By Headgames

Although, we don't knife edge them anymore..here's all I have.

 

Thank you for the compliment...but I must correct you, most people flow a head with valve, I would venture to say few flow the head without a valve, as if you did you would have no way of measuring the different lift points..and it would really just be useless info without a valve. You can get some cfm out of the valve, but your biggest gain will be from the valvejob. We have a race valvejob that pics up almost 30cfm on any head we put it on! That's what some pick up on porting the whole head..

 

yes.. maybe "most people" was not too correct, but I have seen people do it... that or put the valve at lifts that it would never see with the cam they are using...and then try to claim that as a huge gain...

either way.. it's no good...

and when i said area around valve, i meant not only deshrouding valves in the combustion chamber, but certainly the valve seats too...

just out of curiousity, what is your thoughts on the undercut valve stem debate? do you guys like them?

( for others, by undercut valve i mean when the shaft portion of the valve has a reduced diameter for a short length before the "large splayed" portion on the valve.)