Z-TARD Posted May 17, 2004 Share Posted May 17, 2004 I've been searching this subject for the past few days, but so far have yet to see anyone post who has used both the N42 head and the Maxima N47 head to give a comparisson. I'm looking for a new head to eventually put on my newly obtained junkyard queen 78 280z. I'd like to get some opinions from guys who have run both heads as to which one is better suited to use on a fairly stock motor. I'm not looking for 400rwhp, or the ability to run a 10 second 1/4 with the option of acheiving low earth orbit. I just want to raise the compression a little, using a mild cam from either Comp Cams or MSA (270ish duration). Something to make the drive to work a little more interesting, maybe kill a few honda's while I'm at it I can get the heads minus cam from the junkyard for $29, so I may end up getting both and using my Z as a rolling test platform if nothing else. Mike Quote Link to comment Share on other sites More sharing options...
naplesZ Posted May 17, 2004 Share Posted May 17, 2004 I can't offer any help on your head question, but I am in desperate need of a n42 head. Maybe you can help me out and make a little extra money in the process.Let me know. Thanks Quote Link to comment Share on other sites More sharing options...
Mack Posted May 17, 2004 Share Posted May 17, 2004 well, i have been contemplating doing the same thing for about 2 months now. i have a maxima N47 head, its been cleaned up, valves unshrouded, mild valve bowl porting and it has also had the alrger 280ZX intake valves installed. while I havent bolted this thing on to my F54 flat top block yet, I can say that the chamber design is lightyears ahead of the N47/N47 design. also, I have read from a few sources that the N47, with a little port clean up, has an almost perfect for an N/A motor, exhaust to intake flow ratio of around 80%. this was in regards to the Z/ZX N47, buit I could imagine that the maxima head is the same. hpopefully, within the next few weeks, Ill get around to it and let ya know... Mack Quote Link to comment Share on other sites More sharing options...
z-ya Posted May 17, 2004 Share Posted May 17, 2004 I'm running an N47 on a F54 block with flat tops (~10:1CR), and it runs great. Real spunky. It's in a track/autocross car I built with some freinds. We did an autocross yesterday for the first time, and I'm quite happy with it. BTW, it has a stock cam, Megasquirt, and a header/supertrapp exhaust. Pete Quote Link to comment Share on other sites More sharing options...
JMortensen Posted May 17, 2004 Share Posted May 17, 2004 Doesn't the Maxima N47 have the smaller intake valve, due to cylinder bore on the L24? Seems like the Max N47 would be really good with a bigger intake valve installed like people do with the E31 and E88. If you don't want to go to the trouble, then I'd go with the N42. DOH--looks like Mack already mentioned that and I wasn't paying attention. Jon Quote Link to comment Share on other sites More sharing options...
z-ya Posted May 17, 2004 Share Posted May 17, 2004 The N47 that I'm using came out of a 280ZX, so it has the same size valves as other L28 heads. Pete Quote Link to comment Share on other sites More sharing options...
JMortensen Posted May 17, 2004 Share Posted May 17, 2004 z-ya, I'm not real positive on this so forgive me if I talk out of the wrong end here, but I think the Maxima N47 is a whole different animal than the ZX N47. Combustion chamber is smaller, like a peanut chamber 510 head IIRC. Quote Link to comment Share on other sites More sharing options...
evildky Posted May 18, 2004 Share Posted May 18, 2004 The N47 that I'm using came out of a 280ZX' date=' so it has the same size valves as other L28 heads. Pete[/quote'] I am guessing you neant it came from a 280"Z" the ZX na motors all came with the P79 Quote Link to comment Share on other sites More sharing options...
Mack Posted May 18, 2004 Share Posted May 18, 2004 actually, the 79 to 80 280zx's used the same motors as the late 280Z's, complete with N47's and dished pistons. the P79 didnt start until 1981. but, I digress.... the Maxima N47 is a completely different beast than the 280Z/ZX N47. it has a closed, heart shaped compbustion chamber and the high swirl intake ports. much like the P79! but, what it does not have is a bunch of combustion chamber volume. Infact, the combustion chambers are right around 40cc's. as small as the coveted E31, but with a much nicer shape. lots of "squish" here is a pic of my Maxima N47 right next to my 1980 280ZX N47. maxima on the left, ZX on the right. note the extreme diffenence in combustion chamber shape. mack Quote Link to comment Share on other sites More sharing options...
Z-TARD Posted May 18, 2004 Author Share Posted May 18, 2004 Looks like the Maxima head has the large valves as well. Did it come like that, or did you have it fit with larger valves later, as I have heard that the Maxima's came with the small valves. I've seen quite a few of those in the junkyard out here, but very few of the N42 heads. Mike Quote Link to comment Share on other sites More sharing options...
Cable Posted May 19, 2004 Share Posted May 19, 2004 I can't offer any help on your head question' date=' but I am in desperate need of a n42 head. Maybe you can help me out and make a little extra money in the process.Let me know.Thanks[/quote'] What are runnable N42 heads worth? I have a complete motor I may start to part out soon. Quote Link to comment Share on other sites More sharing options...
naplesZ Posted May 19, 2004 Share Posted May 19, 2004 I was going to buy a used one from one of the guys here for $50. I guess that up to the seller.What year is your car? Quote Link to comment Share on other sites More sharing options...
z-ya Posted May 20, 2004 Share Posted May 20, 2004 OK here is the head I put on my F54 flat top motor: I was hoping that the CR would be around 10:1, because it's in a autorcoss/time trial car (not street legal). Is this a fair assumption? The LEngine program says that the N47 head has a 44.6cc chamber volume. Is this correct? I recently finished a motor for my wife's 280Z, and I built it with what looks like a Maxima head, but I used an aftermarket piston with a smaller dish than stock. I also bored it 1mm. I'm hoping the CR on this motor isn't too high for pump gas. The Maxima head looks like a nice alternative if you are looking for a higher CR than stock, but less than 9.5:1. A 1mm overbore, with dished pistons, and the Maxima head give you around 9:1 CR (using 40cc as a chamber volume). Pete Quote Link to comment Share on other sites More sharing options...
Cable Posted May 20, 2004 Share Posted May 20, 2004 I was going to buy a used one from one of the guys here for $50. I guess that up to the seller.What year is your car? I am not even sure the motor is original, but I was told the motor came from a '75. But if the head alone is only worth $50, I might just try and sell the whole complete EFI motor and/or trans as a package deal. It would be great for someone wanting EFI on an older Z. Quote Link to comment Share on other sites More sharing options...
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