port and polish question for NISTECH
port and polish question for NISTECH
Hey NISTECH, i work with 2 master techs at the local firestone and i am rebilding the top end after blowing my head gasket on my 90 240SX. I am porting and polishing the head myself, but have a question for you. I know i can port AND polish the exhaust side, but what about the intake side? One master tech says just to port it but leave it rough, the roughness will help atomize the incoming fuel and make a better charge. The other master tech says that because the intake ports are small, i can polish them to gain more incoming velocity of the air/fuel mixture. Which is best? Will there be any difference between the two? Of course, one master tech is speaking from his experience with his own 70 Mach 1 Mustang, so i doubt either really understand the KA24E like you would. Any help would be awesome! Thanks!
Ok, but what about polishing the intake side of the head? I understand about the lip on the manifold, and im not enlargening the intake ports (gasket matching) on the head, i am just removing material from inside the ports to make them larger and less restrictive. But should i polish the intake runners or leave them rough? I know if i still have a lip on the manifold i would still get the tumble/swirl effect, but would it be better to have a smooth intake on the head or a rough one? I am only speaking of the head itself, i am doing nothing to the intake manifold (not even removing the butterflys). I have all of the valves out of the head and am finished removing material from the intake side and just need to know if i would be better leaving that side rough or polishing it up.
s13sr20chris wrote:
"leave a very small lip on the manifold so that the port in the head is bigger(very slightly) than the intake manifold. this fights reversion and promotes tumble/swirl. if you do this and also remove the little butterflies from the intake ports you will have less idle problems from removing the butterflies"
i think thats it ?
"leave a very small lip on the manifold so that the port in the head is bigger(very slightly) than the intake manifold. this fights reversion and promotes tumble/swirl. if you do this and also remove the little butterflies from the intake ports you will have less idle problems from removing the butterflies"
i think thats it ?
I think the keyword i am using is the word "POLISH". Should i take a polishing tool and POLISH the intake runners on the HEAD to smooth them out or should i leave them rough? I completely understand about the LIP, or the difference in size of the INTAKE MANIFOLD and the HEAD, but i am asking about POLISHING the HEAD on the INTAKE SIDE. I have already PORTED it, but i need to know if POLISHING is better or if leaving that side rough is better. Again, i have done and am doing nothing with the INTAKE MANIFOLD itself, i am just talking about the intake half of the CYLINDER HEAD. I am not talking about port matching the intake manifold to the cylinder head, like s13srchris was talking about.
Polishing can go either way I think its more on prefference then anything, if its smooth there no where for carbon deposits to collect, on the other hand having a slightly textured surface can help very very slightly in the atomization of the fuel when passing through. I would go for the polished method to prevent carbon build up[personal preffrence]