xonix_digital Posted November 5, 2010 Share Posted November 5, 2010 Hey guys, I recently picked up an L28E to swap into my 73 240z. I picked it up on Craigslist for $200 with all the EFI gear and a 4 speed transmission. The motor came out of a 1975 280z so it shipped with the N42/N42 block/head combo. The guy mentioned that he thought the previous owner might have replaced the head on it at some point because it was considerably cleaner than the rest of the motor. After checking the stamp I noticed it was an N47. After I got it home I started looking into the N47 head and the N42 block and began to read a whole lot about how neither of these are the most desirable members of the L28 lineage. Needless to say my hopes were't very high for the condition of the components either because the guy I bought it from was not a Z guy by any means and didn't know anything about the motor. And I paid $200. haha After finally reading through all of the posts in the L6 heads thread (That I had previously skimmed). I noticed something funny about my N47. I'll be damned if those aren't a dirty little set of quench pads. Did I happen to score an MN47 by accident? If this really is an MN47 head, with the previous owner's configuration of stock N42 dished pistons, rods, crank, and the 1mm Felpro head gasket this little guy was seeing a 9.2:1 compression ratio in the MN47's 38.5cc chamber! That's a touch better than the 8.26:1 that it would have had the the Z car N47 and a stock Nissan gasket! Please tell me if Im an idiot or if I really scored. haha thanks! Quote Link to comment Share on other sites More sharing options...
jc052685 Posted November 5, 2010 Share Posted November 5, 2010 What does the casting say? show us the ports also. Quote Link to comment Share on other sites More sharing options...
xonix_digital Posted November 5, 2010 Author Share Posted November 5, 2010 The head casting says "N47" as stated above. Here are the best pics I have of it right now. Ports (sorry about the gasket): Plug side: Whaddaya think? Quote Link to comment Share on other sites More sharing options...
Tony D Posted November 5, 2010 Share Posted November 5, 2010 N47 with q-pads is from a Maxima L24E. N47 with that same area slightly domed is from an L28 for the required combustion chamber volume to keep CR lower. "MN47" is an internet fabrication, there are no castings that say that, they are all merely "N47" Same as non-us spec N42's with no injector port cutouts and carb-only bolt flanges on the intake side, and some N42's with chambers that look just like your N47 there (but with square exhaust ports!) There is stuff out there... Quote Link to comment Share on other sites More sharing options...
xonix_digital Posted November 5, 2010 Author Share Posted November 5, 2010 Woo! Now I really can't wait to get this thing up and running! Might even spend the extra money to do this head up right with a valve job etc. I've never seen one of these for sale. Are they worth anything? Quote Link to comment Share on other sites More sharing options...
NewZed Posted November 6, 2010 Share Posted November 6, 2010 Not to be a buzz-killer but don't the quench pads only "quench" on flat top pistons? With dished pistons you'll just get a higher compression ratio but without the benefits of a quenched chamber. Slow burn with possibility of detonation. Just testing out my understanding of what I've learned since getting in to Z world. I might be totally off-base. Quote Link to comment Share on other sites More sharing options...
Tony D Posted November 6, 2010 Share Posted November 6, 2010 Yep, quench pad only really works with flat-tops. All this does is raise the CR and give you the same detonation prone chamber as an N42 that has been shaved to get 9.XX C.R. Quote Link to comment Share on other sites More sharing options...
xonix_digital Posted November 6, 2010 Author Share Posted November 6, 2010 Nothing wrong with that! Running flats would put me in the High 10.x:1. Won't be doing that on this motor. I'm just glad I'll be able to get a touch more power out of it. Quote Link to comment Share on other sites More sharing options...
rejracer Posted November 7, 2010 Share Posted November 7, 2010 You have the Maxima N47. With flatops that's a great street n/a motor, if you get the quench and tune right. The non maxima N47's do not have the head temp sensor boss between port 5 and 6 on the plug side. a couple of good threads, (in the sticky's) that's worth a read: http://forums.hybridz.org/index.php/topic/39134-big-and-nasty-headwork/ http://forums.hybridz.org/index.php/topic/62691-l6-heads-pics-and-descriptions/ Quote Link to comment Share on other sites More sharing options...
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