Mack

well, Ill chiime in here.... I get about 21~22mpg with 70% in town/30% highway under normal usage. ON the recent trip to Cali for MSA I got about 27mpg, judging on distance, not odometer readings, because my odometer stopped working, HA ha! also, we were doing about 100mph 3/4 of the way, ooooops. this was verified by my freinds MEGASQUIRT tach and tire combination and back calculating and what not. on the way back I only got about 24 to 25mpg doing a little more sane speed. of course on the way back, its all uphill. I have an 83 that would get about 30 on the highway. I know that for a fact because I could drive from fargo, nd to minot, nd and back on one tank of gas (290 miles each way) and still have change left over.

i will be putting a square port 6 into 1 header tomarro. i plan on matching it up to make sure it will not block any of the round exhaust port. ill let you know how it goes!

yeah, the P47 is a nice head. The "evil" exhaust liners are not really all that evil. Stock for stock, a linered head will flow roughly the same as a square port head and you can mildly port the the valve bowls and get them to flow just as much as a decently ported square port head. also, you really cant match the P47 head as far as combustion chamber size or shape. its 38 to 39 cc's stock. it EASILY accepts N42 and N47 larger intake valves and its pretty ping resistant. prettymuch the ultimate bolt on L6 NA head nissan made. McAdam oh yeah, the other nissan head that has round liners is the P79

alright, so this isnt really a megasquirrt question, but I figured this is the most knowledgable forum and I would have the best chance of finding an answer here I have an infiniti M30 injection system ready to go on my L28, problem is L28 injectors = low imp, M30 injectors = high imp. my question is this.... can I just put a 10 ohm inline with the negative (or positive) injector wires? would that effectivly make them a high imp injector? both injectors have the same flow, just the diff impediance. also, I would just use the infiniti, but they are some weird combination of top feed and side feed, or flow thru, whatever it is. thanks in advance! McAdam

all this talk about CC'ing chambers and what not, I just thought Id pitch in that I and 1 fast z CC'ed a maxima N47 that had not been shaved or altered in any way, with a sparkplug in it the number we got was somewhere between 38 and 39 cc's. the reason for the range is because it was leaking mildly thru the valves. needless to say the head is in dire need of a valve job, lol! I know its not an E88, but its an alternative if your E88 doesnt work out.

So, I stumbled across a sparkplug when I was researching another little thing called a hot vapor combustion engine and I started reading on this sparkplug. seems too good to be true and even the inventor is not sure exactly how it does what it does. FireStrom sparkplug he says its good for almost zero emissions without a catalytic converter, smog pump or any other smog crap, not to mention 44% better fuel economy, idles an engine at 250RPM and never has any gap growth. oh yeah, with this you can get more HP and torque running a 24:1 AFR with no ping or misfire. its a long read, but well worth it. dont know whether to beleive it or not, would like to get my hands on a set tho! ****, if people pay $15 to $20 iridium and platinum plugs, whats $10 for one of these? heres a lil pic of it in action... FireStorm on left, regular plug on right. on an interesting side note, this guy says he was partially responsible for the splitfire seeing the light of day and even he admits it was just a gimmick! he seems kind of honest on that note, lol!

Daaaaaaaaaamn! what ignition system is that?!? lol trick set-up! as far as how I got my compression number ..... Maxima N47 = 40cc ombustion chamber.... so, stock L28......43mm x 43mm x 3.14159 x 79mm = 458.9cc's. compression volume... (44mm x 44mm x 3.14159 x .8mm(felpro gasket)) + 40cc = 44.865cc's so, (458.9cc's + 44.865cc's) / 44.865cc's = 11.22:1 compression! damn, higher than I thought, HA ha! is my math off anywhere? I don't think so. The chamber shape really helps with the P79/P90/Maxima N47 its that really nice heart shape. I did not do any chamber massaging, I did do a very mild port job on it tho. If I had a better FI system, Im sure I could get rid of the ping all together. it just sucks that the stock AFM maxes out at 3500RPM. time for a Z31 or MAP based system.

1. I run on 92 octane and only get ping when my EFI system decides the AFM is maxed out and goes on its little preset curve thingy. I can tune it out by plumbing a pot inline with the coolant temp sensor and making the engine run richer. 2. I use whatever NAPA is selling, I think it was a 170* 3. Ive got a stock 260Z cam. same lift as all the rest, but 256 degrees duration on both intake and exhaust. 4. I have my advance set to factory specs. 5. Im running factory 280ZX ignition. 6. I run factory EFI, unless Im racing or otherwise, then I can always put the POT in. 7. Are you kidding? I deliver pizzas with my car! it runs JUST fine! and I used the felpro gasket and I have never had any problems with it. Ive probably put about 10K on my car. I really need megasquirt, that would help a lot the "ping" problems. the stock EFI REALLY sucks.

11:1 is fine. Ive been running it on my daily driver for about 9 months now. Its a stock short block with flat tops and Ive got a Maxima N47 on it, by my calculations its good for about 11:1. It has 40cc combustion chambers and a felpro gasket. I run premium gas on it and have no problems, except with the stock injection system. I get ping ONLY after the AFM maxes out at 3.5K RPM, otherwise, I couls stick it in 5th at 20mph, floor it and not get ping. It makes for a lively motor!

preith... I read that article as well, it was a nice write up. It would be a nice period peice! GREAT for historic racing! I did read that the cams they used were something on the order of 296 for the street and 306 for race!! thats INSANE! Lots of L series heads rarely go above 300, even for race! just tons of lift. IF you were looking for a DOHC for a 4 cylinder, the KA24DE will actually fit on an L series 4 cylinder. there was a guy a while back running a KA24DE head on a KA24E block (11.7:1 compression KA24E = flat tops, KA24DE = 10.5cc dish) and the KA24E headgasket is a spot on match for a Z20/22/24i headgasket, and we all know about interchangeability between L and Z series engines. I think a KA24DE head without the 96mm stroke could be made to scream. HS30-H forgive me on the quote, it has been a while since I read the "How to Modify" book as my ex roomy stole it! lol I should know better that to trust that book anyway. A LOT of his piston specs have been found to be innacurate. Have you ever seen an O.S. giken head running on a car? Im sure it would be a sight to be seen! I plan on using KA pistons for a KA head! lol. Actually, i was looking at some custom pistons to be able to use the LD28 rods, unless you know where I could get a set of FJ20 rods or perhaps L20A (139mm, correct?) rods? Im going for improving the rod/.stroke ratio for some high RPM's. was even contemplating an L24 crank/89mm bore/LD28 rod. R/S of 1.9. ultra tough, but man, those LD rods are H-E-A-V-Y. yes, it would be optimal to run a domed piston on a pent roof head! I was looking at these wave roller pistons. It looks as though this place has a good idea of whats going on, as opposed to just being a marketing tool.

as far as the "figures", I was just going off of what others here have said as well as what has been stated in the "how to hotrod and modify" book. also, when I said stock for stock, what I meant was just bolting an OS giken head onto an L28 engine that was already running tripples and a header. basically, doing nothing to the bottom end, specail cranks, pistons and rods be damned! lol The head I am building will work. I have condfidence in my mechanical abilities, as well as my engineering abilities. Perhaps we should have waited until we had a finished product, but we figured the Nissan community would respond favourably to it, which most have. as far as designing everything from scratch and what not, thats the beauty of the frankenstein head. Nissan did most of the engineering and it is a proven design. Shims on buckets, cant go wrong. The head flows phenominally (well, when compared to L series stuff, lol) and we know it supports high HP applications. ( I know of a few 500+rwhp KA24DE-T's) Ill compare the project to the OS giken head all I want because unless you have an OS giken head, it may as well be our head. The fact of the matter is that I am 99.999999% sure that NO ONE on this board has ever owned or worked on an O.S. giken head, so its all speculation anyway. Do you have access to some Dyno charts for the head? Do you know where I could find some? I would LOVE to see them! Im not trying to be a smartass, I really would love to see them! Im not trying to belittle the O.S. peice, god knows I would LOVE one, if for nothign more than an "era correct" conversation peice. But the fact of the matter is, no one will ever touch one for under $20K, even if they did reproduce them. Adjusting for inflation, how much would those 15,000 1980 dollars come out to be? Im guessing AT LEAST 30K. And how much does a used one fetch, if and when the owner decides to sell it? It just comes down to what people are dreaming about and what people could have. Im a helluva lot closer to my frankenstein head running than I, or anyone else I know, will ever be to even owning a TC24B1 head let alone having one in their daily driver. And that, unfortunately or fortunately, is a fact. McAdam

well, if your power goals are 600rwhp, I don think the OS giken peice is for you. Stock for stock, they offered a marginal 5% gain over stock. They were a trick looking part, but they didnt flow very well and had very thin walled port castings, allowing for very littel porting. Mind you, this is what I have read of them and I have never seen one in person. As far as finding one in a junkyard?!? HA! thats all I have to say on that. As far as reproducing them? fat chance on getting the company to reporduce them, its been attempted many times over the years, and no such luck. Not to mention they cost $15,000 in 1980's dollars, god only knows what they would cost now. People scoffed at the idea of a $5000 bolt on DOHC head that flows 250CFM STOCK, and you think anyone would shell out 15K? DO some reading on some of the work being done by myself and 1 fast Z. we are actually making a DOHC head for the L series. McAdam

the heads will have dowel pins pressfit inbetween the halves (thirds?) that wil be drilled using a template that is made to keep the cam bores aligned. that will keep it from twisting. The head will be put on the block with more locating dowels than stock, Im thinking 4 to 6 total. The bolts are more to keep the head together while it is off the block. There will be a gasket made of expanded PTFE inbetween the halves. its temp range is -50 to +500. its only sealing water, and the radiator cap blows at 14psi anyway. Oil passages will be sealed with hollow dowels, seeing as how they see more PSI. I think the combination of dowel pins, head bolts and little bolts will keep the head wherever it needs to be. Its not going anywhere once the head is clamped into place with 14 headbolts and 70 lbs/ft of torque. McAdam

hey guys, Im looking for some STOCK RB26DETT cams, if anyone has some, shoot me a PM on price and such. I know there are a few poeple out there that have upgraded (stony for sure).... I know this isnt classifieds and what not, but seeing as how this is RB specific.... also a quick question to make it a technical post! lol DO the solid RB cams have a different base cirlce than the hydraulic ones? I knwo the profile and ramps will be a little different, just wondering if anything else is! thanks in advance.....

I would say that if you put a maxima N47 head on a de-stroked L28, with a decent cam, then had your SU's tuned, you'd be set. I think the legendary Norm the 12 sec dual SU dude was pulling 13.5's out of his old L24 before he went to the L28/L29 set up. The power is def. there. If you found a tripple weber or solex or mikuni set up, you'd definately be set. I recently had mine tuned on a car Im trying to sell and I must say, the thing is DAMN fast. Its a real weapon. Its got the characteristic bog when you stab it but, it only stumbles for about 1/2 a sec, then it launches like a rocket. You can pick up sets for under $600 if you keep a vigilant eye on ebay. Mack

well, because I like to argue and stoke the fire around here, and because *I* like the idea, I will just say this, to get CLOSE to the potential, you would need the RB26. and then this thing would still have .5L (30 cu in) on it. If it was on a 3.1L stroker. and with the RB26, you need a LOT of custom stuff. this would sit on stock motor mounts, stock transmission, stock oil pans... all that crap. Granted this would need custom manifolds, but when you're getting into the HP this thing WOULD be capable of, if he can get it to work, you'd be needing custom stuff for the RB anyway, and parts availability is another thing...... this *would* use KA24DE head parts (all available at prettymuch anywhere here stateside) and stock or readily available L series bottom end stuff. its a win win....... Mack

Good Point, Jmortensen! I do not know the rules for SCCA racing, and Im sure once you get into the upper eschelons of it, they change dramatically. If one were interested in doing some racing, what would be the rules considering an aftermarket head? its still the same block and what not, just a different head. I wonder what the SBC camaros with dart heads get classed as? I personally think it would be good for more than just 50hp. Especially when you start turbocharging. I mean going on the fact that there is a 80rwhp difference between a 2.4L and a 2.8L, just by doing the displacement math you would get 618rwp,. with a 2.8L vs a 2.4L. Thats 168rwhp difference! and thats not even accounting for the higher red line of the L6 vs. the KA, KA made that power without going over 6.75K, me thinks. 96mm stroke, go figure. I just think its funny that all these people say "Oh, If O.S. Giken made the TC24B1, Id buy one today for 10K!" where are they now? lol

yeah, the stock datsun head design is absolute garbage. no offense to the engineers, Im sure it was awesome and cost effective 30 years go, but we have better things now. Also, something to consider... I know of a certain KA24DE that has a big friggen turbo on it and about 29lbs of boost thats making 530rwhp. from a 2.4L 4 banger. Now, look at L motors, 2.8L I6, only person I know of running that much boost is JeffP, and hes putting out what, 450rwhp? More displacement and more cylinders, less hp. Yup, that stock non crossflow head is really awesome. as far as the cost thing... maybe 5K may SEEM steep, but think about it. The poeple that are probably going to buy this probably already have a BUILT 3.1L motor, and if they could just bolt on this head? they could keep thier forged rods, they could keep their forged pistons, prepped cranks, everything. From THAT point of view, I can see its worth the money, they wouldn't have to start with a clean slate, you know>? Its piqued my curiosity.

found THIS on zcar.com. Looks like someone is actually making one. kind of pisses me off (in a good way), cause it looks like he stole my idea, lol! They appear to be KA24DE heads. I don't know where he pulled the cams from though! Wish he would give a little more info. It also makes me wish I had sent the KA24DE heads I had off to TBS to get them cut up and milled. Oh well, if it works, then maybe Ill get a little more serious about it! HA ha Mack

I really dont mean to threadjack, but If you can get parts for RB motors, how much are aftermarket cams? is there a difference between RB20 and 25 and 26 stuff? Ive got something brewing.......

dont quote me on this, but Ive heard from several swap shops in my area as well as people who have RB25DET's in 240sx's that VG30DE stuff is the same. Its a starting point at least. that stuff should be available prettymuch anywhere.

well, Ive heard that the stock turbos on a VG30DETT are good for about 500 flywheel hp. thats not bad for a set of T22's. you can get some full on T25's and make better power levels and still retain decent spool up, or seeing as how its going in a first gen Z and there will be lots of room up front, get a custom exhaust manifold set made for a big single and go with a T3/T04E hybrid turbo. I would stick with the VG, just because of parts availability. plus, it'll make more torque... and if you wanted to go Auto, you can just get a 300ZXTT auto, they are pretty bulletproof from what Ive read. The RB is a sick motor, but the parts availibilty would kill me in the long run. oh, and I dont think you have to do that much cutting nad hacking. there has been a few VG30DETT's swapped into first gen cars. there was a white 280Z runnign around with a VG in it a few years ago, made a few magazines and ran I think in the high 11's on all stock stuff. McAdam

well, heres what I did..... I have a flat top block with a maxima N47 head that had larger Z/ZX valves installed, a mild port/valve bowl cleanup job and I had the machine shoop unshroud the valves. My block is an F54 flat top with about 150K on it. My intake is a P82 with no EGR, has the "bumps" removed from the injector mounts and a 60mm TB installed. I have a cone aftermarket air filter. stock injection system and what not. 2.5" catback mandrel bent exhaust. oh yeah, almost forgot a 260Z "C" stamp camshaft 256/256 and stock lift. With all this I managed 141rwhp@4500RPM. that may not seem like a lot, but at the time, I had a faulty IC unit that acted as a rev-limiter that stepped in at around 4.5K to 5K, depending on air temp, lol! Also, I only got in 1 run on the dyno before the software took a crap and we had to end the dyno night. I think with a turbo AFM, some bigger injectors and a header, I could probably hit about 175 to 180RWHP. then, If I threw in a cam, well, who knows. If I were you, Id go the maxima N47 head route instead of the N42. the maxima head has better quench! (this outta ruffle a few feathers) I run about 10 degrees initial on pump gas (91) without ping. I had to dial it back a few after I got my new IC unit. McAdam

Id ditch the 2.5in exhaust, that is more than likely the culprit now, since you've taken the pop off valve out of the equation. that being said, switching out the stock exhaust on a stock 280ZXT to a 3in unit saw a gain of 20rwhp on the dyno. no other mods needed. You are correct in assuming that these engines need backpressure to creat torque, on an NA car that is. On a turbo car, the turbo creates all the back pressure it needs and then some! so, you want the exhaust to flow as freely as possible once it gets past the turbo. It has been said time and time again, The best exhaust on a turbo car is no exhaust! Id say drop the exhaust system off from the downpipe and do a run like that, brings some earplugs tho! Im predicting a night and day difference. Mack

actually, you;lll have to use a different rod if your planning on using the LD28 block and a VG piston. the LD rod is 140mm center to center, the piston has something like a 44mm compression height. best combo Ive run acroos would be KA24E pistons on a Z22E( I think ) rod and an LD28 block/crank. the LD28 block has a deck height of 227.5mm vs the L28E blocks beck height of 207.9mm. McAdam