Mack

stroke is 79mm, like all L28 motors, P90 combustion chamber CC's should be 53cc's and the dish in the pistons is on the order of 10.3cc's. hope this helps. McAdam

the valves came out of my 1980 stock 280zx motor with the N4 on it. the machine shop said they were a spot on match for the maxima valves, with the exception of being bigger in diameter. they said they were the same length as well, as that was one of my concerns. Ill have to look into the springs on the maxima head. i did no know it was weaker. but, will that really matter with a stock-ish cam? hrmmm, food for thought. stock max cam is what, 240 degrees? 260Z "C" stamp cam is 256, but same lift. will the weaker springs have adverse affects with this cam? good question on the cam and valves, about trying to skirt the cost of 16 new lash pads. I dont see why it wouldnt work? way to think OUTSIDE the box, lol McAdam

to clear up some stuff, i had originally brought in my 280ZX N47 head to a machine shop, because the motor had blown the headgasket. they found out that it was warped .018" and that many of the coolant passages were corroded. they gave me a ridiculious quote to repair it, including shaving top and bottom and welding coolant passages, at which point it ws decided to use this head for parts and purchase a maxima N47 that was in far better shape. After i purchased the N47 max head, I ran across a running 82 parts car for $200. So, naturally I bought that and this is more of a project than a make it run so I can drive it thing. I havent the foggiest on chamber voulme, stock is 40cc, i know they didnt take out THAT much when they unshrouded. Id say its close to 42cc or so, Ill ry and measure it with a graduated cylinder sometime soon. the head was pulled from a 1983 nissan/datsun maxima/810. It had large exhaust valves already and the tops of the bores were nothced to allow this. The machine shop machined the valve seats and installed the 280ZX N47 intake valves for me. I beleive that it would have been more costly to run the shaved head, because I would have had to find cam tower shims and pay for the extreme shaving of the head, as well as measure and purchase new lash pads. All they really had to do to this Maxima head was unshroud and install larger intake valves. it will still run stock lash pads, not require shimming and it still has a smaller chamber volume than the .080" shaved head. McAdam

what are the advantages of 280Z valves over the ZX valves? I thought all N47 headed L28E motors with dished pistons were the same? the machinist was the ones that used my 280ZX N47 valves in the maxima N47 head. he said that they were the same length, diameter stem and everything, just the 280zx ones had a bigger diameter head. hope to have it up and running soooooooon, lol McAdam

Actually, I have gone that far, I just havent bolted it on yet. The head had the larger exhaust valves, but was lacking on the intakes. so, I put my 280ZX N47 intakes in it and had both intake and exhaust unshrouded all the way out to the fire ring (traced on the head from the head gasket) I also cleaned up the bowls above the valves extensively with a trusty dremel. cleaned up some of the bumpy casting marks on the intake runners and I obviously couldnt do much to the exhaust ports. all said and done, I have about $255 into the head. $30 for the head from the J/Y, about $150 for machine shop work. $25 was for the 260Z "C" stamp cam and another $50 for dremel tools and sand paper. I just hope it will still run on pump gas. calculating a compression ratio of about 10.7 ~ 11 to 1. sounds like it should, as norm is running even higher on the crappy N47 280zx head (sorry, couldnt resist) hopefully, I will get to bolt it on this week sometime, as I have had this damn head sitting in my garage since the beginning of summer. Mack

hrmmm, can I throw a monkey wrench into the mix? what about a maxima N47? it has a 40cc combustion chamber and also the quench area shape of the P series heads? what will THAT do on a street motor? epsecially if I put a "C" stamp 256 degree camshaft in it and bolt the sucker onto a flat top block and give it bigger intake valves? McAdam

check the fuel pump!!!! I had this very same problem happen to my 1983 280zx. the fuel pump was so old and worn that after running for a while, it would heat up and without constant air moving around it (i.e. while driving at 20mph+) it woudl lock up. I would have to wait for about 20 mins for it to cool down before it would turn on again, or I could throw some cold water on the fuel pump itself and the car would start right up. odd as it sounds...... I replaced the fuel pump and have had no probs with it whatsoever.... Mack

the VG30ET are not forged from the factory, but they are pretty strong. The old school formula for a stroker in japan used to be an LD28 crank, FJ20 rods and a set of 6 honda XL500R motorcycle pistons! they were forged from teh factory and had the proper bore, as well as the proper pin height to match up with the FJ rod, LD28 crank and L28 block. Its the XL500 or XR500. Im sure someone here will chime in, this is REALLY old school stuff! Mack

well, if you are planning on messing around with rod/stroke ratios and the lot, I would suggest finding an LD28 motor and KEEPING THE BLOCK! It has a higher deck height (L24, 26, and 28 blocks = deck height of L16 and L18, LD28 block = deck height of L20B) then you could get custom pistons (33.5mm comp height and an 87.5mm bore) and use Z22E rods and have a 3.0L motor with a rod/stroke ratio of 1.8XX:1!! Ive already got he block and some rods.... just a thought..... I do like the destroked L series idea. It would work with LD28 rods or FJ20 rods, if you can find them.. (140mm) VG30 pistons and an L24 crank. get the pistons in a +1mm overbore and you should be good to go. Mack

#1 "Can you stroke and bore an engine?" yes. "If so can you bore a L28et to 3.1L and then stroke it?" you cannot bore an L28ET to a 3.1. To get the 3.1L of displacement you have to bore AND stroke the L28, not JUST bore or stroke it. "Would stroking only require longer rods or a new crankshaft as well?" rod length has nothing to do with stroking a motor, other than the fact that if you use the same pistons, you will need shorter rods to make sure the pistons dont stick up above the deck of the block. Stroking a motor involves making the throw (stroke) of the crankshaft longer. Stock L28ET crankshaft have a stroke of 79mm, where as LD28 crankshafts (the deisel crankshaft) has a stroke of 83mm. #2 "If you bored and stroked the motor, and ran twin T03/T04 turbos would you get good horsepower? (with intercooling,adjustable wastegates,electronic boost control, and dual blow-off valves both recirculated through the intake)" yes, you would ge tgood horsepower, if everything were set up right. You'd probably want to consider running a standalone fuel management system with some big injectors tho. also, porting the P90 head and a custom intake manifold would be almost REQUIRD at that point. as well as a custom turbo exhaust header. "Would there be a lot of lag?" Yes, I would think t03/t04's would be a little much, perhaps just go with some BIG T28's. they should provide ample HP and not have as much lag. #3 "If all of the above was done along with head work on a P90 along with uprgraded internals, what kind of horsepower would be possible roughly? Could it be run on pump gas (91 premium octane)? Street Legal?If I could do this someday I think it would make for an awesome daily driver." it all depends. the electramotive team that racced a 280zx during the 1980's was running about 600rwhp out of a 2.8L motor. no one has been able to duplicate those results, however, there is a guy that is running about 475rwhp with a single turbo on a 280zx (JeffP) with a lot of money, the sky is the limit. would it be street legal? depends on how you set it up, it could be, and it could not be. Run on 91 octane? if you had a low boost setting, but making 600rwhp on an L series motor with 91 octane would be a feat to acomplish, for sure! McAdam

good to hear from ya, TBS! I was wondering if you got my email with the pics of the RB cams next to the KA head! I was surprised how well it all lined up as well! I have shyed away from the 2 KA24DE heads for now, as I picked up a complete RB25DET long block, that broke a timing belt and bent a few valves, for $150. I have compared headgaskets between the RB and my L28, pretty damn close! well, none too many of the coolant/oil passages line up, BUT! the bores are spot on as well as the headbolts. I am thinking of welding up all coolant/oil passages on the head and drilling/tapping AN fittings and run external lines. why would I go thru all this trouble instead of just fixing the RB25DET and using it? because, when was the last time you saw an RB31DET? L31 stroker + DOHC = smile inducer! I think retro fitting an RB head to an L series block is the best way to go. Mack

yeah, I Id have to agree with those out there that dont like the VG engine cause its soooo fircken hard to work on! lol!!!! but, they are built, like any other nissan engine. and they can pound out the ponies. large, tractable torque bands as well. as far as the head-flow problem, simple solution to that would be to get a set of VG30DET heads from a mid to late 90's Cima. I saw a pic of a VG30DET head next to a VG30DETT head, and I must say the DET head looked like it flowed A LOT more on the intake side than the DETT head. It woudl be interesting to see more built VG's. Ive heard rumors of the VG30ET's putting down in excess of 800rwhp. there is a guy in puerto rico or something with a 1st gen 300zx doing crazy things in the 7's I think. anyway, enough rambling, Im out! lol

I beleive there was a tuning house in Aus somewhere that built an RB30 with a 25 head, Meggala has a link to it on his webpage, it made 457rwhp at a paultry 15psi of boost. try doing that with an RB26. plus, there is a lot of torque to be made with a motor like that. basically, it would be a nissan 2jzgette. McAdam

I think the N47 head came on the N42 block, stock. well, thats if we are talking about a 280z/zx N47, as I am not sure what block the maxima N47 wass on. hope this helps.... Mack

wow! I have never seen anything like that on an Lseries head, and I have a head that blew a headgasket violently.... There was some small erosion around some of the waterjackets, but nothing like that. what brand of headgasket did you use? perhaps it was built with a metallurgically incompatible metal or something to that effect?? Mack

If you were looking to do this, I think the proper way to go would be a KA24DE, the DOHC KA. I dont think those lifters bleed down, and there is a solid lifter conversion kit available for the SOHC KA. I know the KA's can handle abuse, as I knwo quite a few people in a local 240sx car club that drift the shit out of them. I think the way to go would be either a KA-T, there was someone who pulled 404rwhp on a STOCK motor at 18psi, not bad, OR an L/KA hybrid. Ive been toying with this for a while. Use an L20B, bore it out for KA pistons, then put a DOHC KA head on it. the KA crank is NOT fully counterweighted, but the L20B is. It is possible, the only problem would be the timing gears on it, youd have to have a custom crank gear made or modify an old toyota 22R to fit on the L series crank snout. Mack

Cryogenics here is a decent webpage, but of course they have a service to sell so wthey will make it look as good as they can, but some of it makes sense. My machinist in fargo said he had some stuff cryotreated (races at the dragstrip and circle track on the weekends) and he sent in a bic disposable razor just for fun.... he got 4 shaves out of it, he normally gets one. thats real world experience! lol!! but seriously... I have heard that brake rotors last 3 to 4 times as long once they are cryo treated. it looks like there is science to it and its not just "snake oil" It might even hlp with the ringlands. it re-crystalizes the metals crystalline structure... who knows. I may have a set of stock pistons done and see what it does. Mack

according to the "How To Hotrod and Race your Datsun Nissan" book, the stockers are forged and if you shotpeen and polish them, they are supposedly good for up to 600RWHP in road race form, not just drag racing. I would not worry about the rods, now the pistons..... as far as cryogenically treating pistons, it helps a LOT in the face of detonation and lean conditions and anything to do with rapid heat expansion. when a piston expands due to heat, it does not expand uniformly around its circumference, some spots expand faster than others, and when that one bit that expands faster, it snags the bore wall. there was one place that took 2, 2 stroke bike motors, one got a cryo treated stock piston, one got a stock piston. they ran them at some RPM's while constantly leaning out the mixture. the non treated one overheated and seized up, the treated one eventually stopped because the mixture got too lean to run. they took it apart, teh barrel wasn't even scored. food for thought.... Mack

that is a nice torque palteau! lol! I would agree with drax. a 3 inch exhaust system would probably help you out a bit. i know a guy named JeffP on here sells them. there were dyno charts posted on zcar.com a while ago. on a completely stock 280zxt, just by bolting on jeffs 3 in exhaust system the car picked up 20rwhp. yes, 20 rwhp. went from 149ish to 169ish. pretty crazy. Mack

well, Tony D sent me a pic, and I photo chopped it down to size and made it a bit easier on the eyes! so, if anyone has any info on this head, please, come forth!! lol edit: go to my homepage, its a crappy cardomain site, but you can see a larger pic of it there, on the 4th page.

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

well, i went to a bar-b-que this weekend at an engine importers shop, they had a couple of KA's laying around as well as a couple of RB's ( includign a "parts" RB26, those sick bastards) anyway, they had a set of RB cams out and I pulled the valve cover off of the KA head. wouldnt ya know it, it fits, besides being 2 cylinders too long. the spacing is there, the cam bearings are the correct size (KA bearing cap fits perfectly on an RB cam) so, I think I found some cams for this head. I'll try and get a pic up, but its probably a crappy one, taken with my GF's camera phone, lol! McAdam

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

Also, keep in mind that we dont really know what lurks over in japan. there could be and probably is a few 1000hp+ L31 ETT or god only knows what hiding in some japanese garages. I seem to recall that a 3.5L L has been spotted. sleeved cylinder liners and a custom crankshaft. remember, the L series was the small block of japan before all of this newfangled DOHC stuff came out. it had a good run up into the late 80's/early 90's. It would be very interesting if we could go over to japan and see some of the crazy Z cars over there. interesting note, if the RB26 has larger headbolts, but the same spacing, it sounds like an LD28 block. but then again, the LD28 block is also taller, requiring longer connecting rods. with the larger headbolts(not near as prone to stretching) and a set of longer, more robust rods(better rod/stroke ratio) and a set of decent pistons, I wonder what the limits of the LD28 block are? McAdam

WOW! I want one! anyone know where I can get one? of course, its gonna cost an arm and a leg, but, DAMN! thats like, what? about 290 cu in? hrmmm, RB26DETT who? 2JZGTTE who? lol! nice find, binsayer McAdam