Mack Posted December 15, 2003 Share Posted December 15, 2003 well, I have this junk N47 from a 1980 zx and I thought it would be good for some practice. all i have done as now is to trim up the area directly above the valve seat on the exhaust side and remove some casting marks on the intake. here are pics of the exhaust work, let me know what you think. McAdam[/url] Quote Link to comment Share on other sites More sharing options...
JMortensen Posted December 15, 2003 Share Posted December 15, 2003 Are you sure that link works. I only saw 2 pics, and I couldn't tell that you had done anything yet... Jon Quote Link to comment Share on other sites More sharing options...
Mack Posted December 15, 2003 Author Share Posted December 15, 2003 yeah, the link works, but I didn;t take out much. try it again, i photo chopped the pics. painted the areas yellow. works better now. McAdam Quote Link to comment Share on other sites More sharing options...
turbobluestreak Posted December 16, 2003 Share Posted December 16, 2003 You really need to get a N42 or a P90. I want to get a N42 to port out but I don't have that kind of money to just waist when I could put that money to a turbo. Although I did try my hand at porting on my extra P79's intake and I was pleased with it I didn't increase any volume just a lot of shaping. I would except higher flow numbers from that port if I would have it tested but after I talked to Dave at rebello I just figured that they could do a better job at porting my head for my application since they've been working on Nissans for around 20 years. Total cost for a street port and polish would be around $1760. But theres a lot that goes into that besides just porting. tbs Quote Link to comment Share on other sites More sharing options...
Mack Posted December 16, 2003 Author Share Posted December 16, 2003 I am not going for turbo, yet. the car i bought (or rather took) had a blown head gasket. so, I am putting a maxima N47 head on it to get the compression up a bit and I figured I would do a little porting and cleaning up of the head while I have it apart. this is just a motor to get me by until I get my turbo motor built. just to see what I can do with it while still keeping it N/A and not going all out. by the way, check out the main page on the link in my first post for pics of the car I got for FREE, lol McAdam P.S. I have 2 P90's and am selling one, if you are interested. Its a mechanical lifter head out of an automatic 280ZXT Quote Link to comment Share on other sites More sharing options...
JMortensen Posted December 16, 2003 Share Posted December 16, 2003 My E31 has bigger valves, and when the shop installed bigger seats, they ported the area you are working on. Seems to me that they tried to make the area from the seat to the bottom of the bowl as straight as possible with no big lip before the seat. That's about all they did on the head. When I took it off again to fix the stuff they screwed up on (valves were ground WAY too far to use stock springs with my .490 lift cam, valves were all warped, etc), I did a lot of chamber reshaping and polishing and unshrouding of the valves. I also notched the block to match the head, and cleaned up the short side radius. Don't neglect the chambers is what I'm trying to say here. The chambers can be really improved by cutting down all of the sharp edges and unshrouding the valves. Also for a NA motor, take down the ridge between the valves, it looks like the N47 has a ridge. My E31 had a big ridge between the valves, but the E88 in my garage doesn't. CC the chambers while you're at it. Keep posting more pics. Different angles too. You may want to consider the shave the P90 .080 trick too. That seems to work pretty good on a NA motor from what I've heard and supposedly they have the best port shape from the factory. Jon Quote Link to comment Share on other sites More sharing options...
turbobluestreak Posted December 16, 2003 Share Posted December 16, 2003 Mack how much for that p-90? IF you don't want much I'll take it. Also what condition is it in? tbs Quote Link to comment Share on other sites More sharing options...
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