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Getting set to port my P-90


turbobluestreak

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Guys I don't care what any of you say about doing the port work at home I'm stilling going to do it. Having said that I got my P-79 out and exsamined the intake ports to be just about a match to the p-90 if not dead on. I just bought myself a air die grinder today and with the help of my coned carbide cutter I started attacking the port. I did what I believed was best for the port from my research, I redirected the short radius to be a little more gradual drop off to the valve, I removed almost all of the valve guide boss and blended the boss to the large radius, I cut the valve guide down too, smoothed the transsion of port to valve seat, smoothed most of the castings down, also opened the sides of the port just slightly to make the transsion to the radius a little smoother. Well I was just thinking it over with my friend and had a hunney of an idea. In wind tunels if you want to see how wind flows around an object they spray small amounts of dust and watch the wind carry it. I did mostly the same thing using chalk dust and an air gun at 40psi. I noticed two small spots where the chalk build up. This test also showed how the air travels out of the port and into the chamber you can see where the most turbulance is going to be created. I just thought I would share my findings with the rest of you guys. One last thing, my port I did collected less chalk then the unpoted one. I'm not just considering the casting but the areas where there was a lot of build up. From what I can tell Nissan gave us fairly nice intake ports I just wish I could say that for the exhaust.

 

 

 

tbs

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Guest d3finitlymaybe

Nice job on the DYI...just be carefull to not open the seat of the port too much, otherwise you could lose compression...But other than that, it sounds good..How long do think it will take you to finish the complete head?

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