Mack

well, I thought I had pinging issues but it turned out to be bad gas, lol! it also helped out a lot when I changed out my TPS. Plus, it would probably help if I weren't running 15 degrees initial advance. Its running great now that I stopped buy gas from ANY old station. I run chevron premium only now. I dont know how it will do with dish pistons because they wont provide proper quench. I think my car is def. a mid 15 sec car, which isnt bad for a 280zx 2 + 2. I am going to do a compression check on it and make sure the bad gas and pinging didnt mess anything up, but so far so good! Mack

uhm, If your gonna do all that work, just get an L28. go to the local u pull it and get an L28E with a flat top pistons. then, get a 1981 to 1984 nissan maxima head, bolt it all together and you get a nice 11:1 motor. Its just that easy. Mack

Did you plug your pop off valve hole yet? a completely stock motor, just with the boost wicked up should be good for almost 275rwhp-ish on stock everything. also, do you have a Air/fuel ratio graph yet? that'll give us a LOT of instight as to what is going on with your motor.

I think we have a winner! doenst the stock pop off valve start to vent at like, 10 PSI or something? you have to remove it and plug the hole all together. If you do that, I bet it'll help A LOT Mack

Id have to agree with cronic. something doesnt seem right. usually the L28 puts down a LOT more torque than hp, for any HP level. i think JeffP is making 415 rwhp and 473rwtq @ 24psi. thats 100 more RWHP for 3 more PSI. Ive seen dyno charts of completely stock 20 yrl od 280ZXT's that put down 170rwhp at stock boost with JUST a 3 in exhaust. what are your air to fuel ratios like? I dunno man, sorry! hope you get it figured out. Mack btw, a complete stocker picks up about 20rwhp just by going to a 3 in exhaust.

Looky here . Ive spoken to a few people who know their way around the deisel motor, not just the crank, and they say it has replacable liners.... Mack

DrSideWays, get outta my head! lol, the deisel block is exactly what I was thinking about using, seeing as how I bought the whole block for the cranka while back. I was contemplating building a Long Rod stroker motor. I was looking at a 90mm x 90mm motor. it would work out to be about 3.45L. The Diesel block is the only way you could mantain a decent rod/stroke ratio. I figure I could use 4 cyl rods, like Z20S or L20B and I wouldnt be too bad off. the deisel block already has liners, so it would just be a matter of taking the old one out and pressing a new one in. Tony D is always talking about having a ride in L series 3.3 and 3.5 motors, so it got me thinking. I wonder if you could have a stock deisel crank re-worked that far tho.... Mack P.s. on the head part, Ive got a few tricks up my sleeve.... A freind of mines father owns a machine shop, with a flow bench, he has ported a few P90's to flow about 205cfm intake and about 155cfm exhaust @ 25 in of water.

so, who makes nice custom crankshafts? I was looking at scat and they charge about $1100 for a forged crankshaft for chevy smallblocks, so I would imagine L6 would be comparable, yes? I am contemplating a custom stroke cranky.... also, whata bout cylinder liners? who sells em? looking for liners for an LD28 block... evil ideas about in this post.... Mack

grrr, bout the 3rd time Ive answered one of these threads in as many weeks. I am running about 11:1 compression. I have an F54 flat top block with a maxima N47 head and a 260Z "c" stamp camshaft. I am running a felpro headgasket, which is a little thinner than a nissan unit. with the excellent quench characteristics of the head and the slimmer gasket, I CAN run 89 octane, but I usually stick to the 91 stuff. My car is my daily driver, and I deliver pizzas with it. oh yeah, I run about 15 degrees initial and whatever the total would be with an '82 distributor. Mack

HA ha! ya missed that one, you must be getting old!

so, Ive heard good things about these turbo, great HP #'s at low boost, decent response, good top end and what not, but I have not been able to find compressor maps to save my life! here is a link to one I am talking about.... deisel turbo So, can anyone tell me what the max HP would be? this would be going on a VG30DE engine. a nice single set-up, and no, its not in a Z32, no way no how would I ever own one, engine bay is waaaaaaaay to cramped! Mack

here ya go http://www.meggala.com/RB30head.htm probablly just more of the same info, but it never hurts! Mack

I remember this one time I took a maxima N47 (40cc combustion chambers) head and put it on my L28 flat top block..... it was pretty sweet. actually, it is pretty sweet. it runs great and I can even run 89 octane on it if need be. this is a daily driver. I deliver pizzas with it. I had the valves slightly unshrouded and installed larger 280ZX N47 intake valves. I am using a fel-pro gasket that is supposed to have a compressed height of .8mm, so that helps attain proper quench, this is the only reason I can come up with as to why it survives day to day on somewhere around 11:1 compression and 15 degrees initial advance, all stock electronics. If you go this route, dont be dumb like me, I screwed up and used the maxima valve springs, they are much weaker and I get REALLY bad float at 5500RPM. Mack

I thought some of the Z31 cars DID come with the VG30DET? I may be mistaken tho. I recall reading a site that stated the non turbo 89 Z31 had more HP than the previous year turbo and that the singlew turbo version had 250ps. oh well. on a side note, the blocks may LOOK the same from the outside, but the SOHC heads have 5 headbolts a peice holding them to the block in a 5 pointed star pattern, the DOHC block has the more standard 4 square headbolt arrangement. not even close to fitting. What can anyone in this thread tell me about transmission interchange-ability between the DOHC and SOHC blocks? I want to use the SOHC transmission on a DOHC block. starter placement being the obvious problem, anything elses? will it bolt up? I know a guy that is using DE cranks, rods and flywheels in VG33E blocks. has to have the flywheel machined to accept a Z31 starter ring gear, but other than that, it works fine. that brings up another option for people looking at a Z31 engine swap. pathfinder/xterra/fronteir VG33E. just bolt all your turbo stuff on and go. 10% bump in HP just from displacement. also, rumor has it the heads flow better than VG30 heads. McAdam

well, I caught myself in a half turth. after beating on my car all weekend, I have come to the conclusion that the maxima intake valvesprings get airborne at around 5500rpm's under hard acceleration. When I said it revved nicely past 6K, it did! sitting in the driveway, lol! anything past about half throttle and over 5500rpm's and the engine feels and sounds like it cuts out on most if not all of its cylinders. so, within the next few weeks I will be ordering a reground cam and rockers at which time I will also install 280zx valve springs. I have heard that the maxima small valves tend to cause an L28 to fall flat on its face at anything much over 4750rpm's. when my valves do start to float, its still pulling HARD and it feels like someone slams on the brakes. this is with 280zx intake valves, which are bigger and have more mass than maxima valves, which only exacerbates teh problem caused by the weak springs. McAdam EDIT: GREAT thread with a TON of Maxima N47 info on it, including info on port and runner sizes! http://www.zcar.com/forums/read.php?f=1&i=501641&t=501546#reply_501641

Ill have to check on this. This was a concern of mine while I had my head in the machine shop, that a bigger valve would really do nothing and that the seat had to be bigger as well. I recall the machine shop saying that it was the same size seat or some such thing.... at any rate, I have my old N47 and I will be pulling a P47 for someone else soon and I will compare the valve seat opening diameter on both heads and see whats what. I dont think they got too agressive in unshrouding the valves. I noticed minimal change in the shape and appearence after the unshrouding of the valves. although they did take out some material. I woudl think that if they had to take out a lot of material, they would have charged me a lot more than they did, lol! Thats still $120 just in cam tower shims. plus however much they charge to shave a head .080" also, the P47 is MUCH easier to come by than the coveted P90's. I cannot argue with you on this, all I can say is that the P47 has a lower initial cost, as they are more plentiful. and also, even tho it sounds like more work (install bigger valves, unshroud valves) it is cheaper and all you have to do is droip it of at the machine shop and they will do it all at once. this is true. on a street motor this is an excellent weekend project! for an all out racer, maybe a P90 is the way to go. some other things to consider, The E31's used to be the head of choice for HI performance, all of the ports were designed for small valves, yet people still used them. at least the exhaust port on the P47 is designed with the bigger valve in mind. I think the intake might be as well, I will have to check. I know the beginning of the port where the intake manifold attaches was the same size diameter as my N47. this is good info and food for thought! keep it coming guys! and, as soon as my local car club http://www.az240sx.org has another dyno day, I will get it checked out for sure! of course, by then I hope to be running my M30 ECU/wiring harness with a colt cams 260 degree FI grind. McAdam

well, being one of the only people on here to actually RUN a maxima N47, Ill chip in my 2 cents worth here. NOTE: Maxima N47 will be referred to as P47 through out the post. THe P47 and N47 have the same valve stem heights, so, when I had my P47 in the shop, they were able to machine the seats and install my old N47 big intake valves with no problems. The whole reason I went with the P47 was because my N47 (1980 280zx) was in neeed of $300 worth of welding to repair corroded water passages. and it was warped .018". then the bottom end ended up being crap too, so I bought an 82 parts car. So, I had this flat top P79 motor, and this summer I installed a P47 head, with a FELPRO gasket (.8mm compressed height) With the felpro, I am getting the benefits of "quench", being there is less than .040" between the piston and the non combustion chamber parts of the head. I also used a 260Z "C" cam and blended the area above the exhaust valve into the liner, as well as took out some sharp ridges just above the intake valve. I also intalled a 60mm TB, 2.5" cat back mandrel bent exhaust and removed the "bumps" for the injector hold down screws in the intake manifold. I am also running a 3" press bent intake witha cone style filter on it. with all this work done, I must say the car pulls MUCH harder than ever before, in all gears and it pulls HARD past 6000. I have yet to take it to the track, but rest assured I will when I get the chance. With the P47, on a flat top with the .8mm felpro gasket, I calculate my compression ratio to be about 11.2:1 (assuming a 40cc combustion chamber). I used MIDGRADE gas, no ping, timing set to 15* initial (go quench area!, lol) total machine shop bill for unshrouding valves, installing larger valves, cleaning 2 heads (dead N47 and P47) and resurfacing the P47 was $250. try doing that with a hsaved P90/P79. plsu, I didn't need to mess around with cam tower shims, thicker lash pads or any of that other extreme head shaving related crap. McAdam p.s. sorry for the long winded post, and yes, the P47 has all the bolt holes for BOTH carb and FI intake manifolds.

on this PAGE I have a pic of a maxima N47 next to a Z/ZX N47. the maxima is on the left, Z/ZX on the right. This is an excellent choice for a head! I am running one RIGHT NOW on my 280ZX with flattops. NICE power over stock. on a flat top, it bumps the compression over 10.5:1. still able to run on street gas too! McAdam[/url]

Holy GOD! wow, If this is what bolt ons can do for this motor, I am impressed, especially for a 25 yr old car! just a short recap.. Maxima N47 with 280ZX N47 intake valves, minor port cleanup, blended exhaust bowl into liner. 260Z "C" stamp camshaft (same lift as P79 cam, but 256 degrees of duration. cone filter intake. 60MM 240sx TB, intake hogged out to match, injector hold down "bumps" removed from intake as well as port matched. intake an exhaust manifold off of a 1980 280zx, with no EGR fittings, not even from the factory! set valve lash, set initial timing at 15 degrees BTDC, set idle using throttle stop on 240sx TB. re routed valve cover breather into manifold, using custom AFM to TB boot. anyways, this car is a 1980 280ZX 2 + 2, with a 5spd. motor was a '82 F54/P79. kept stock bottom end and cleaned carbon off piston tops, FelPro head gasket. (o.k., so that was a not-so-short recap, lol! ) This car hauls ass! Its downright dangerous to drive on these rain soaked, leaf covered roads. I mashed the throttle at 1500rpms, rolling in 1st, INSTANT sideways, same with 2nd! and its wasn't even warmed up yet! Its got a lot more low end, and a lot more highend. probably has something to do with the 10.7:1 compression. and the cam! and I am getting my NEW 2.5in madrel bent exhaust installed later today, then it'll really fly!

tomorrow! is the day that I bolt the maxima N47 head on my car!! muahahahhahahaa! I just finished the porting on the intake manifold. 60mm's of ported goodness! also took out the bumps in end of the intake runners, near the head. you know, the ones for the injector screws? funny, I took them all the way down and made them non existant, but I never broke through. gasket matched all the ports, blended the valve bowl into the exhaust liner, smoothed the transition on the intake ports.... and am installing the infamous 260Z "C" stamp cam with its 256 degrees of sweet duration! thanks Norm for the guide on resurfacing the rocker arms!!! also, I ground down and smoothed over the little nissan insignias on the valve faces. detonation is not welcome in this combustion chamber! I hope to run low low low 15's, possibly break into the 14's! think Ill pull it off? oh yeah, I have a generic cone filter, with a 3" crush bent intake pipe, and I am getting a 2.5" mandrel bent exhaust with a nice hi flow muffler and hi flow resonator. party on! McAdam

I think the porblem lies not within the block, but in the head. The cylinder walls, even when bored out to 89mm for a 3.1L are still thicker than a stock VG30DETT's cylinder walls. also, the L series is a deep skirt design, which lends itsself well to having the bearing caps stay put on high HP applications. I think the weak link, once you get past the head, will end up being everything else, lol! for ultra high HP, you'll need forged pistons, forged H-Beam rods, and probably a custom crank. with full counterweights. adn if you wanna get crazy, have a girdle made for the bearing caps, but the supra boys run without one and they also have a deep skirt design block. McAdam p.s. TBS... any progress on that head?> do you stilll have the 3 halves? I may be interested, have a line on an awesome heli-arc welder in AZ. EDIT: Don devandorf and electramotive raced a 280ZX twin turbo back in '82 that developed almost 600rwhp. here is the link to some info on the car.[/url]

the short answer to all of yoru questions regarding heads is no. nissan never made better heads that will fit, that you should ever be concerned about purchasing. that being said, you can try and track down an LY head. that was a better head that will bolt on to an L series block. there were roughly about 500 of these made and when they change hands, they go for about $20,000 or so, for a head. RB heads will bolt on, but then you have to run seperate oil lines and coolant lines, as well as figure out how to go from a chain drive to a belt drive. The guy that was making a head has not really made any progress from what I gather. This all stemmed from an Idea I had like, 3 yrs ago, because you can put a KA series head on an L series 4 cylinder, and an L6 is basically an L4 with 2 more cylinders added onto it. I do have 2 KA24DE heads and 2 KA24E heads and may pick up the project again, next time someone dumps $1000 into my lap, lol! A company called BC gerolomay (sp?) that did a lot of work with L series heads was able to get 250cfm out of the sideflow head by COMPLETELY reworking the ports. this would probably cost you close to $3000 for a port job of that magnitude, but it would probably be worth it. use that as a starting base, then add a nice T66 turbo and yor getting close to over 500rwhp. McAdam

well, with this whole quench thing flying around, thought Id toss in my 2 cents.... again. so, that would put me at about 120834234 cents now. may as well go maxima N47 now. on a side note, someone noted that you dont see full benefits of quench unless you have less than .040" of clearance between the flat top piston and the quench chamber, so with that being said, If I have a flat top block and a FelPro head gasket (.8mm compressed height) I should reap the rewards, correct? seeing as how that puts me at .034" between teh top of the pistons and the head. hrmmm.... Mack

economy is one big thing that Im going for. Also, I do beleive that this system will give me a bit of a power bump over the flap style AFM system that was fitted as standard on the L28E's. Also, I was lead to beleive that the MAF system is a bit more flexible when it comes to engine modifications. Mack

o.k. so i am this freaking close to putting this M30 VG30E fully sequential system on my 280ZX, my only question is how do I time the injectors? the L28E has a firing order of 1-5-3-6-2-4 and the VG30E is 1-2-3-4-5-6. now, if I want to see the full benefits of a sequential system, the injectors must fire in the proper order, so this means that I would have to put the VG #1 inj wire on the L28 inj #1, VG2 on L5, VG3 on L3, VG4 on L6, VG5 on L2 and VG6 on L4, am I right, or am I right? lol any input? thanks! Mack