Guest tejas74260 Posted January 20, 2004 Share Posted January 20, 2004 ive been hearing a lot about the different head options that you can put on the z's. my question is, which one would be the best on my 74 260z for a NA motor. im only 16 and dont have enough funds for forced induction, but i do know a guy who does cylinder heads for cheap. i was planning on building up the valvetrain and cam, and possibly buying the 3.1L stroker kit to squeeze out all the power i can. im also planning on running triple weber carbs. so what should i do? seek out a p90 head from a zx turbo or stick with my stock e88 head? thanks a lot. Mark Quote Link to comment Share on other sites More sharing options...
Guest ON3GO Posted January 20, 2004 Share Posted January 20, 2004 well if you cant afford a turbo then wouldnt the stroker kit be alot more? Plus you can build a 3.1 for cheaper then the kit that MSA sells and etc. http://www.geocities.com/row4navy/engine.html but i say N47 but others know more then me. mike Quote Link to comment Share on other sites More sharing options...
Guest NorCalZ Posted January 20, 2004 Share Posted January 20, 2004 FI will be cheaper man. But if you insist go for an p79 or n47 or something. The later the year the more they flow but if you friend can do work it doesn't matter. Just shave your head down and shim up the cam towers and all that shit to bump up compression just high enough to run on pump. Quote Link to comment Share on other sites More sharing options...
texasz Posted January 21, 2004 Share Posted January 21, 2004 If you decide on a P79 I have one off a running engine that I'll sell ya. Just PM me if you want it. Quote Link to comment Share on other sites More sharing options...
turbobluestreak Posted January 21, 2004 Share Posted January 21, 2004 Kid, your 16 I know what it's like trying to get a z going at 16 and 3 years later it's almost there. These things take time and if you’re going to do something to this motor do it right. I'm suggesting using a N42 head. It’s the best selection as it sets stock for a N/A car but a modified P90 will work as well. Personally I can't stand any of the factories L6 heads. Well this is just my 2 cents. tbs Quote Link to comment Share on other sites More sharing options...
preith Posted January 21, 2004 Share Posted January 21, 2004 Why not just stick with the E88 head? Quote Link to comment Share on other sites More sharing options...
Mack Posted January 21, 2004 Share Posted January 21, 2004 cheap option? how bout a Maxima N47? on an L26, it would give you somewhere in the 10:1 range for compression (me thinks) and they are EVERYWHERE in the junkyards. they flow decent and have a great chamber design. check this out here is a pic of a Maxima N47 (on the left) and a 280ZX N47 (on the right) side by side. notice the VAST difference in combustion chamber shape? just food for thought McAdam Quote Link to comment Share on other sites More sharing options...
Guest tejas74260 Posted January 21, 2004 Share Posted January 21, 2004 haha i thought there was gonna be lots of conflicting opinions. i suppose most of the heads are good but have their tradeoffs. the reason i was drawn to the p90 was the stuff about the quench and the efficient combustion chamber design, but i suppose those might work better on forced induction rather than NA. i guess i could just research the other heads a little to get a good knowledge. so i wont ask yall, but if you would, would you let me know of some good sites to look at? thanks Mark Quote Link to comment Share on other sites More sharing options...
Guest tejas74260 Posted January 21, 2004 Share Posted January 21, 2004 wow im glad i have this little tool. im not sure where i found it but its an "L engine builder tool". how does this combination sound? keep the stock l26 rods and block. put on a n42 head with l28 flat top pistons. the results told me that with a .120 overbore (not sure if thats way too much) that i would achieve 2753ccs and a compression ratio of 9.82:1. If i added a HKS 1mm headgasket, it would raise the compression to 10.08:1. what do you guys think? if all the other options work, do you think i could go with the 10.08:1 compression? we're blessed in texas with somewhat better 93 octane, while not as good as 94 ohio or other states, i know it beats the california hippie-controlled 91 octane. so tell me what you think. thanks. Mark Quote Link to comment Share on other sites More sharing options...
JMortensen Posted January 21, 2004 Share Posted January 21, 2004 This is the way to go if you want a P90 on a NA engine, IMO. http://geocities.com/zgarage2001/p90.html Jon Quote Link to comment Share on other sites More sharing options...
Lockjaw Posted January 22, 2004 Share Posted January 22, 2004 120 overbore is to much. Personally I would go with a P90 or 79, and have it milled, it has the best combustion chamber design. The Maxima N47 head is another appealing option if you ask me. I know from talking to Rebello that even on the turbo heads (p90) they port the exhaust side, the intake flows good. So in an NA application it is far more important to get it in there, the engine will get it out. IMO. There is alot of debate on this board between me and a few others, but I have seen a P79 run better on every engine we have ever installed one on, keeping everything else the same. The high swirl design of the combustion chamber aids in detonation resistence, which allows more compression, and hence more power. The E88 is not a good choice unless it has the E31 combustion chamber design, which looks similar to the p79. The fact that most all hipo heads now days are a closed combustion chamber to me speaks volumes about avoiding the E88 and N42 head. So I am sure you will see someone take issue with me, but my friends 240 ran 8.40's in the 1/8th mile on a stock 2.8 liter engine with a milled P79 and bolt ons. And I also believe this, if nissan went to all the trouble to redesign the combustion chamber, there must be a good reason for that. See if you can find DAW and he can fill you in on the Maxima head. I would go there first. Good luck. Quote Link to comment Share on other sites More sharing options...
Dan Baldwin Posted January 22, 2004 Share Posted January 22, 2004 Not this again... You can make VERY good power with a 280Z N42 head. Some are more concerned with what the chamber looks like, though;) I've seen ZERO evidence that the P90/P79 cc design offers *any* performance advantage. Where are the 255rwhp or 12.8x sec @ 107.x mph P90-headed, pump-fuelled, NA cars?! Back to original question: I don't know if I'd let a guy who does cylinder heads for cheap cut any metal on MY cylinder head. As has been said, you can make your own stroker kit with an early 80s Maxima diesel crank, 240 rods, and KA24E pistons. BUT, as has also been said, you shouldn't bore the 260 motor out .120. Only the 2.8 motors can be bored that much. But you should be able to find a L28 block for cheap. Your stock E88 head gives the 2.6 liter pretty low compression unshaved, and it has smaller intake valves than the 2.8 liter heads. On a 3.1 liter bottom end, with your E88 you'd be making ~9.6:1 CR, which ain't too bad, really. N42 would have you at just over 10:1. Or you could shave a P90 (or P79) .080", shim the cam towers, and use the longer N42/N47 valves to get about the same CR. Whatever you do, to get it done *right*, it's gonna cost MONEY. Quote Link to comment Share on other sites More sharing options...
Guest tejas74260 Posted January 23, 2004 Share Posted January 23, 2004 well, i dont want to have to buy a new block, i just thought i could make some good compression (and displacement) with those l28 flat-top pistons. i did find some flat-top ones for the l24 and l26 engines from zcarparts.com, but im not sure what type of compression exactly would be made, since its not in my handy-dandy "Lengine builder". anyone have any idea about this? i read that the stock L26 pistons have a 7.01cc dish, so i suppose i might be able to get about 9:1 compression with the n42 head and some headgasket work. how could i get the compression increased a little more if possible? oh and by the way about the guy who does my heads, he's only cheap because i know him and he cuts me deals since he done the heads on my friends 86 grand national, my other friends 03 svt cobra, and my friends ls6 block (oh boy ) camaro. Quote Link to comment Share on other sites More sharing options...
technicalninja Posted January 23, 2004 Share Posted January 23, 2004 Cheapest bang for the buck is to find a usuable 81-83 NA 280ZX engine. Don't take it apart. Any time you break into a motor it cost mony and time. As many on this site will attest it will consume alot more money and time than you ever expected!. I believe you will have more fun with a running car for the first couple years and you will gain experience and knowledge which will be priceless when you do "build up" a killer engine. The stock 81-83 ZX motor has 9.0 to 1 compression ratio 2753 cc and other improvements over the L26. Keep the orginal block in a bag in your garage if you worry about having an original drive train but enjoy the dime a dozen flat top L28 in your car. The 5 speed which came in 81-83 ZX has many improvements as well. Do not pay much for these parts as entire cars are commonly available in the 200-500 dollar range. If you purchase the car (and it is a 5 spd) you will also gain a 3.9 ratio R200 for the back. I believe if a person were careful they could install a complete 81-83 drivetrain for less than it would cost in parts and machine work to bore the L26 top 280z bore (.120 inch) and reassemble the engine. The flat top (pistons) 280ZX block is the best starting point for a serious engine and will provide excellent performance as it is stock. Do not use 74 carbs as they will make you go insane. They can work but it takes a master who has many years of experience to get them adjusted properly. Use either the earlier round top SU clones of of 70-72 240ZS or the fuel injection from the ZX. The F/I will be much more difficult to swap over but may be worth it in long run. You can use the ZX exhaust maniflod but a round port header (to match the p79 head) will make the job easier. Swapping drivetrain 1-2 weekends using 72 carbs. Swapping F/I probably 1 month ( get real NISSAN! manuel if you are going to do this for the correct year 280ZX It will be expensive 70/80 bucks but worth it!) Swapping a engine/drivetrain is an excellent first project. Trying to modify an engine internally is far more complex and many "first time project cars" with fully dissembled engines are sold by disgruntled young owners for pennys on the dollars. Choose your battles wisely as it is more fun to drive a Z than work on it. Quote Link to comment Share on other sites More sharing options...
Lockjaw Posted January 23, 2004 Share Posted January 23, 2004 Not this again... I've seen ZERO evidence that the P90/P79 cc design offers *any* performance advantage. Where are the 255rwhp or 12.8x sec @ 107.x mph P90-headed' date=' pump-fuelled, NA cars?! [/quote'] We figured out it was cheaper and faster to go turbo. I mean my 3200 pound car is still 3 tenths and 7 mph faster, and it is only going to get worse the further we go. And it is only a 2.8, with a stock head, and that was on pump fuel, of the 93 octane variety. Stock cam too. Somebody donate me a rolling 240 chasis, and I will make a P-series NA car to be reckoned with, and send all you N42 guys packing. And I won't need one of Sunbelts one off new funky do cams to do it. The combustion chamber does make a difference too. Can you run 87 octane on a 10 to 1 motor with an N42 head and timing advanced beyond the stock setting without getting detonation? I did. Every day, in ALABAMA, where it gets hot. Quote Link to comment Share on other sites More sharing options...
gramercyjam Posted January 23, 2004 Share Posted January 23, 2004 What they said. No point in boring out an L26 block. You should be able to find an L28 block cheap or even free and turbos are cheap compared to strokers. But what shape is the rest of the car in? Personally, I wouldn't start flushing money on the motor until you got the rest of the car to where it needs to be. Quote Link to comment Share on other sites More sharing options...
Dan Baldwin Posted January 23, 2004 Share Posted January 23, 2004 technicalninja offers the most useful response. But I think the stock CR is closer to 8.5:1, not 9:1. But of course it can be bumped up... Lockjaw, you still haven't presented any evidence whatsoever. I'm running 11:1 on pump fuel now, at 34 degrees total advance, with N42 chambers that are essentially unmodified. I ran the motor for years with the stock cam and ~10.4:1 CR, in Georgia and Alabama (quite a few hot days at Little Talledega), with way too much advance, well over 40 degrees, and no perceptible detonation (I was even dumber then than I am now, and set the stock dist to 15-20 deg. initial advance). At the dyno I have found max power with between ~34 and ~38 degrees, so I keep it set it to 34. Again, I'm not saying the N42 is better, but according to MY experience and others, it does a fair enough job. Somebody donate me a rolling 240 chasis' date=' and I will make a P-series NA car to be reckoned with, and send all you N42 guys packing. And I won't need one of Sunbelts one off new funky do cams to do it. The combustion chamber does make a difference too. Can you run 87 octane on a 10 to 1 motor with an N42 head and timing advanced beyond the stock setting without getting detonation? I did. Every day, in ALABAMA, where it gets hot. [/quote'] Quote Link to comment Share on other sites More sharing options...
Guest 240zxt Posted January 25, 2004 Share Posted January 25, 2004 I have an N47 I'd like to sell. Let me know if you are interested. Quote Link to comment Share on other sites More sharing options...
DAW Posted January 25, 2004 Share Posted January 25, 2004 Back to the original question by the 16yr old '74 260Z owner, I think the budget and experience level are key here. The bang-for-the-buck quotia is the most important thing here. I see two options as the most practical here: swap the L26 E88 head for an E31 or early E88 (E31 type chambers) and transfer the L26 exhaust valves (larger) into the earlier heads (L26 83mm bore has factory-cut reliefs at the top of the bore for the larger exhaust valves that the L24s don't have, although L24Es do). Non-leaded seats should be installed too, which adds expense and the early heads can't easily accommodate f.i. Next option is to go to the JY and get a Maxima L24E head, which already has hardened valve seats and provision for f.i., and the larger (L28 sized) exhaust valves. For performance, it needs the cam and intake valve springs replaced and this can be accomplished at the same time that a mild cam & spring kit is installed (use late L28E spec cam so it has lobe oiling not spray bar for use on N47 style head). Larger L28 intake valves & seats could be installed but on a 2.6 liter na street engine the money could be better spent. I would recommend the second option, plus buying the head with the f.i. intake and exhaust manifold on it as a unit and getting all of the matching f.i. components (harness, AFM, fuel pump & relay, etc) to set aside for a later stage. It might be more economical to buy a smashed Maxima with a five-speed and scavenge all useful parts. Use the twin SUs (get some early round tops) initially to simplify (tune needles for c.r. & cam); or just go ahead with f.i. using 280Z fuel supply lines, etc. and tune it for the higher compression, cam, etc. One thing to keep in perspective is the displacement re head choices. We're talking about only 2600cc here (with no practical way to increase it); not 2800-3100cc. The combustion chamber size choice is limited so P79 & P90 stock or cut 0.080" isn't useful, nor is the L28E N42/N47 uncut useful to increase c.r. As an aside, and off the topic, is that one overlooked performance option for an F54 L28E is to retain a P79/P90 head and instead of cutting it 0.080" & shimming, etc., substitute euro-spec raised-top pistons for the flat-tops to increase compression. DAW Quote Link to comment Share on other sites More sharing options...
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