lammbn Posted June 1, 2007 Share Posted June 1, 2007 I was at my local Z performance shop earlier today; they deal only with Z's and have a few hundred Z's lying around, both inside and outside. It’s great resource to have nearby. Anyways I was speaking with the owner there about the possibilities of my engine with an N47 head and flattop pistons and he then proceeded to show me all the N47 heads that he had pulled recently, all of them cracked on the #3 chamber underneath the exhaust port, effectively talking me out of any notion of this route. He showed me at least 10 of them, and had many more to show me. Then he showed me a recent head he pulled off an engine. It was marked N47, looked like all the other N47’s but the chambers where a smaller volume. I believe he said that they were something like 38cc vs. the normal 44.6cc that would put my compression in the range of 11:1. He said that it must have been ordered from Japan when someone had done a rebuild, but that it was no longer available. He is holding it for me currently and I am going to go pick it up on Monday. I am going to take a closer look at it before I take it home. I was just wondering if anybody had heard of this obviously rare head? I can’t find any information on it after hours of searching. I am definitely purchasing it if it turns out to be authentic. Any help or ideas on this would be great. Quote Link to comment Share on other sites More sharing options...
OlderThanMe Posted June 1, 2007 Share Posted June 1, 2007 Search for the "MN47". I have one that I stripped the valves and stuff from. Don't pay more than $100 for it... Let me explain: You want a head that is fresh off a car... that works and you know how many miles are on it. You don't really get that with a head sitting on a shelf... It came from the L24e in the 80-84 Gas Maxima. "Ordered from Japan"...LOL It is a really good head! I can usually get them for a really good price at the local yard... They are a little hard to find but easier to find than an E31 head. This is what it should look like. It should also have steel exhaust liners. It has a 39 to 39.5 CC combustion chamber. You would not believe that this head has 210,000 miles on it. Even after this quickie cleanup. Quote Link to comment Share on other sites More sharing options...
Administrators BRAAP Posted June 1, 2007 Administrators Share Posted June 1, 2007 Sounds like you are referring to the Maxima N-47 head. Not really a rare head. They were installed here in the states on the late L-6 powered Nissan Maximas, up to ’84 on the L-24E. We have custom built them for a few customers and run them on our own L-28’s. "1fastZ" is quite fluent in this head as well. FWIW, an L-28 with OE Flat top pistons, MN-47 head, yields between 11.4-12:1 comp ratio. Just do a search on this forum for “Maxima N-47†or “MN-47â€, as it is affectionately refereed to around here. I’m sure that I have written at least 2 or 3 novels on those heads here on Hybrid over the past 6 years or so and "1fastz" has posted quite bit if not more on those heads as well. Quote Link to comment Share on other sites More sharing options...
Challenger Posted June 1, 2007 Share Posted June 1, 2007 Im guessing you talked to Kim? I love Idaho Z Car, great place. Does this head other then higher compression provide any benefit. From what I read on the "p90 porting realization" when he cut a p90 to show a cross section the ports werent very smooth. Is the cross section similar and like the p90 have some pretty bad port designs? Or is it better? Quote Link to comment Share on other sites More sharing options...
OlderThanMe Posted June 1, 2007 Share Posted June 1, 2007 I think the bad port design of the P90 is due to the raised ceiling and shorter vaves. The MN47 uses the same valves as an E88 head like the one I have. Thus the ports should be more gradual than the P90 ones because of the lower ceiling and longer valves. Just seems logical. Remember that the MN47 still has port liners on the exhaust. They suposedly still flow well for a street motor. Quote Link to comment Share on other sites More sharing options...
HizAndHerz Posted June 1, 2007 Share Posted June 1, 2007 As OTM and BRAAP say, there's plenty of info in the archives. To sum up what you'll find: Smaller chambers (around 39.5cc) yielding higher compression Good quench characteristics Smaller intake valves and lower intake valve lift favoring the low RPM range and fuel economy (afterall, the engine came in a 4-door sedan) IMHO, to make it worth it, it is best to exchange the cam with the later N47 280zx head, as well as replace the intake valves. I'm not sure, but the intake valve springs may be weaker and might need to be replaced. A more agressive cam than the regular N47 would be even better. Some chamber work might be necessary after putting in the larger valves. I've got four of those heads, so I would hardly classify them as rare or NLA. I like them alot on a NA engine, especially for "in-town" driving, but you'll need to invest time/money to get a significant performance boost. I should the the disclaimer that I'm mostly spewing what I've read here and elsewhere. I'm just starting the process of getting one of my MN-47 heads rebuilt with a reground cam and larger intake valves. Quote Link to comment Share on other sites More sharing options...
OlderThanMe Posted June 1, 2007 Share Posted June 1, 2007 I am driving around with an E88 head and the MN47 cam makes for a nice drive around cam but I lost some of the butt-dyno over my 260Z "C" cam which may have had a slight regrind. I lost top end power by a little bit. You definitely want a cam bigger than the MN47 cam. I just used it because I needed a cam and that is all I had. Good luck!! ~Dan~ Quote Link to comment Share on other sites More sharing options...
nbesheer Posted June 1, 2007 Share Posted June 1, 2007 not to sound stupid but. so it raises the CR which does what ? increase HP ? torque gas consumption ? what lol Quote Link to comment Share on other sites More sharing options...
HizAndHerz Posted June 1, 2007 Share Posted June 1, 2007 As a rule of thumb, an increase of a full-point in compression ratio generally results in a 5% increase in horsepower and torque. Quote Link to comment Share on other sites More sharing options...
lammbn Posted June 1, 2007 Author Share Posted June 1, 2007 Wow that was quick. Thanks guys. I knew something sounded fishy with all this. So are there any markings to look for on this head to prove it is off a maxima? I feel kinda dumb now. I have always heard about the MN47 but never really looked into it because I figured that my head would work for what I wanted to do, that was before I found out that nearly all N47's crack. But the guy wants $250.00 for it, and that’s only after he takes off the valve cover and removes the whole valve train, I think I am getting screwed here. Now that I see that they aren’t so rare I feel like I’m being taken advantage of. I am very well versed about cars in general but not so much in the Z scene and all the little tricks just for the Z. He knows a lot about Z's and I’m sure he could see that I don't. I don't mean to accuse him of trying to trick me because I would like to trust him until he gives me reason not to. I am definitely going to be careful about my next conversation with him. I really want the performance of the MN47 and it would be perfect for my plans with my Z, plus now I realize that there is a lot of info and discussions available for this head. any other advice on this would be greatly appreciated. I need to know what to do. Thanks again for the quick response guys. Quote Link to comment Share on other sites More sharing options...
OlderThanMe Posted June 1, 2007 Share Posted June 1, 2007 The one difference is that inbetween the #5 and #6 cylinder on the passenger side there is a threaded hole for some type of fuel injection sensor. You are being taken advantage of as far as price. PM me and I can get you one for a MUCH better price. I could go even this morning and pick one up... I sent you a PM... ~Dan~ Quote Link to comment Share on other sites More sharing options...
Guest mikes280 Posted June 12, 2007 Share Posted June 12, 2007 So my question is if you have the MN47, what's the best way to build it? (i.e.) What kind of cam and valve train would work the best if you have a F54 block? Quote Link to comment Share on other sites More sharing options...
bernie lomax Posted November 30, 2008 Share Posted November 30, 2008 Hi, interested in purchasing a useable MN47 head at a fair price & I saw this thread & figured that someone may be able to help...appreciate your time...my email address is david.drake@sympatico.ca...thx Quote Link to comment Share on other sites More sharing options...
2eighTZ4me Posted December 1, 2008 Share Posted December 1, 2008 The one difference is that inbetween the #5 and #6 cylinder on the passenger side there is a threaded hole for some type of fuel injection sensor. You are being taken advantage of as far as price. PM me and I can get you one for a MUCH better price. I could go even this morning and pick one up... I sent you a PM... ~Dan~ Au contraire. The later N47 Z head (1980 on) also had the head temp sensor that you speak of. 1 fast Z pointed this out in a prior thread. He stated there is a specific marking on the head that would denote an N47 or a MN47, but the head temp sensor was NOT the way to identify. He was rather vague about the particular marking in his post, but nonetheless, I have been corrected on this misinformation myself, which is why I bring it up. Quote Link to comment Share on other sites More sharing options...
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