dougs280z Posted October 15, 2006 Share Posted October 15, 2006 im fairly new here. ive been reading for about 3 weeks straight. i recently bought three z cars. 82 280zx turbo, 81 280zx, and a 77 280z. the 77 is what im keeping. the rest are going to be used as donors. i last buildup was a 95 talon that i converted into a turbo 420a engine. i have been running 9.6:1 CR on the engine with about 16 psi of boost. of course it was intercooled and water injected, but i never had any knock/ping. anyways, to my question. i would like to build up my car with approximately 8-8.5 CR. i would like forged pistons, but im not clear on how much power the turbo pistons have been proven to. i have been reading about the different heads and im also a little confused on which would be the best. i havent dug into the cars to see which one is which, but ive read that the n42 head will give you about 8.5 CR. Is this a good idea on a turbo engine. how is the flow on this head. or better yet, what engine/piston/head combination has been proven. any other input or information will be appreciated. until then, ill continue researching. thanks Quote Link to comment Share on other sites More sharing options...
Alex_V Posted October 16, 2006 Share Posted October 16, 2006 http://www.geocities.com/zgarage2001/z.html Thats got alot of great basic info, I just read it all again last night. Ive been looking at L28ET stuff and it looks like the stock engine is good to about 300WHP no problem at all, and Garret us running 460WHP on the stock restrictive cam, with a built block. Ive also seen 275WHP and 320WTQ on the stock turbo with a front mount IC and 3in exaust and a FPR (again garrets car) so its got some potential stock. 8-8.5 CR seems to be a good turbo and off boost setup. Just make sure its intercooled when you go much above stock boost. ~Alex Quote Link to comment Share on other sites More sharing options...
dougs280z Posted October 16, 2006 Author Share Posted October 16, 2006 im looking about mid 300 range....300whp would be fine with me. i plan on running larger injectors with a custom o-ring fuel rail, fmic, 3in exhaust. i would still like to get forged pistons just to make me feel better. so those cars you explained were all with the stock turbo head? what if i got stock forged pistons (7.4CR) with the N42 head...from what i read, thats about 8.5CR...is that head a lot more restrictive? Another question. I was using a vortech, super fmu on my eclipse. It worked fine, but of course idle was a little lumpy with the big injectors. i think im going to try the megasquirt, but how come i havent read about anybody using the vortech fmu?? i dont see why that setup wouldnt be an alternative to some lower HP setups. Thanks. Doug Quote Link to comment Share on other sites More sharing options...
Alex_V Posted October 16, 2006 Share Posted October 16, 2006 The best F/I heads are the P79 and P90's and then from there you get some 8/8.5/9-1 forged pistons. 7.4:1 kills off boost response and unless your going to run 30+ psi its needless. But ask BRAAAP about heads, he knows all about that and engine setup. Also look into over boring you engine to get some extra displacement. Personally Ill be going with 8.5:1 pistons and some mild port work to my head when I do get around to building my engine next summer. That'll give good off boost driving and not need race gas for mild boost. Ill be looking for ~350WHP. Best thing to do is just look at a bunch of diffrent setups and see what you like. People may be using the vortec FMU as it is a decent one but once you get over the stock turbo its best to get a Z31 turbo ecu setup (which isnt hard to setup) or a megasquirt, neither of which need a FMU. Even with the stock turbo tho its a great idea to get a new ecu setup... ~Alex Quote Link to comment Share on other sites More sharing options...
zeiss150 Posted October 17, 2006 Share Posted October 17, 2006 The N42 isn't a good choice for turbo ... I whish it was, because I have an N42 on my L28 right now. The CR would be right but the design of the chambers don't have the best characteristic to prevent detonation. The P90 head (which is the stock turbo head) is the best head for turbo application. Right now there is a hybridZ member that is making 460 RWHP on the Stock P90 head and cam. Forged pistons is a great idea if you intend to make that kind of power. If you are looking to stay in the 300 WHP range stock pistons should work just fine. If you want that sweet spot CR of 8.5:1 CR then just use the P90 head and the N/A FLAT TOP pistons, that combo will put you right at 8.5:1. If I remember correctly Arazona Z cars sells flat top forged pistons that will give you 8.5:1 and they will also change your pin height so that you have a better stroke raito. The hardest part of building a turbo motor is deciding what you want to do with it. Because the L28 is so versitile you can make whatever L28 turbo your wallet can handle. Good luck and let us know if you have any other questions Quote Link to comment Share on other sites More sharing options...
slownrusty Posted October 17, 2006 Share Posted October 17, 2006 I'll chime in for a bit. The P90 is the best choice for a turbo set-up..its all about flow and the P90 does it the best for all those heads. I WOULD not get caught up with forged pistons. If you want insurance replace the bottom end with all ARP harware. You can easily spend well over $2-3K if you build the bottom end with forged rods, forged pistons and associated machine work. Bottoms ends on the L28ET motors will see disgusting abuse to well past 200,000miles. I am building my set-up right now, and with the right tuning I should see well past 450whp. I spent ALL the $$ on the head and the manifolds and the turbo, I left my bottom end UNTOUCHED. Hope that helps. Yasin Quote Link to comment Share on other sites More sharing options...
dougs280z Posted October 17, 2006 Author Share Posted October 17, 2006 from what i read at arizona z car, you have to use the l24 connecting rods with the forged flat top pistons?? is that correct. i did read about them being longer and therefore making a less drastic piston/rod angle, but do you have to use them with the l24 rods...if so, where can you get them at. i am intrigued to go with the forged flat-top pistons. that would give me the compression i want, and the reliability i want. im a little curious about this z31 setup though. why is this so great and what does it do differently. in my previous setup, i never changed my ecu or any other electrical components. i just simply turbocharged, and had to compensate with extra fuel. thats where i used the warlbro/450cc injectors/SFMU. When you use the z31 setup, does it build extra fuel pressure some how, or just compensate in some other way. i keep looking into the mega-squirt, but am a little intimidated at the tuning. i wouldnt want "test" tuning on this car when im done. anyone in the pittsburgh pa area that can help with that later? thanks! doug Quote Link to comment Share on other sites More sharing options...
BayAreaZT Posted October 17, 2006 Share Posted October 17, 2006 The rods you are looking for are out of a '73 240Z. They're a little bit tricky to find since they were only made for one year (they may have also been in the early 260Zs). I'm looking at buying a '73 parts car this week just to get the rods. About the Z31 setup, there's a sticky in the turbo section that will probably answer alot of your questions. I agree that the L28et bottom ends are really tough. I may go with forged pistons on my next build but it's mainly because I want to raise the compression ratio a little. Quote Link to comment Share on other sites More sharing options...
zeiss150 Posted October 17, 2006 Share Posted October 17, 2006 I forgot about using the 240 rods with the forged pistons. I think they have 8mm ARP rod bolts now, so any year 240 rods should work great with thoes bolts. The reason that you didn't need to change your ECU is because it was late 1990's tech. The ZX turbo ECU is from 1980... think about computer tech in 1980. does the comador 64 ring any bells. So the stock ECU is just not up to the task of a performance turbo engine. The Z31 ECU is only slightly better. I am also intimidated by megasqurit but there is tons of info and people to help. Keep in mind your WHP goals, If you are looking for 300 or less I wouldn't worry about forged bottom end spend your money on a better turbo better ECU better BOV,RRFPR,exaust, down pipe,radiator, IC, Clutch, and suspention. Now if you want Austin kind of WHP ... forged bottom end is a great idea. Matt- Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted October 17, 2006 Share Posted October 17, 2006 What zeiss said. Look at it this way. The top end MAKES the power, the lower end has to TAKE the power. Since a solid, stock, lower end can TAKE 300-350 rwhp. Concentrate on MAKING the power with top end stuff. Quote Link to comment Share on other sites More sharing options...
dougs280z Posted October 17, 2006 Author Share Posted October 17, 2006 well, i say 300 whp...but of course after about a month...ill want more. i would rather go forged for a few hundred extra. from what i read about the z31 ecu is that it could be a direct plug in, as long as you seal the connections. then i have read that the maf sensor needs changed. i think i would want to try the MS system. I have a crap load of questions still. Ive been reading as much as i can, but still have a ton of questions. What is a "Dizzy"...i know its a distributor, but what are the benefits and what is it. Will those flat top forged pistons from Arizona Z car work with 280zx rods? i emailed them and he just told me that the 240z rods will bring the pistons flush with the block. will the 280 rods just be slightly lower compression? In order to put the 280zx engine in a 280z, is the wiring harness the same that i can just plug the ecu's in, or do i need to swap the wiring harness? Finally, i should open a new thread, but to save space, the 280zx turbo i have has a 5spd tranny...its the borg warner one. am i going to encounter problems swapping that into the 77 280 i have? thanks doug Quote Link to comment Share on other sites More sharing options...
zeiss150 Posted October 17, 2006 Share Posted October 17, 2006 I think a forged bottom end is a lot more than a few hundred dollars. I wouldn't use the forged pistons from AZ Car with out the 240 rods... whats the point you would just be lowering the CR and thats the opisit of your goal. I was not trying to talk you out of a stout bottom end, if you have the cash... go for it, but if you're on a budget thats a good place to save money. Dizzy is just slang for distributor (just like you thought) There are basically 3 kinds of Z dizzies: point (240z), reluctor (280z- N/Azx) and the Optical Crank Angle sensor (280ZX turbo) You should use the one that is on your turbo donner car It works with all the computer systems that you might run. The Other Dizzies work best with N/A engines. The T5 Borg warner Tranny will work fine and will fit fine in your 77 280Z. I think the only mods nessary would be the trans tunnel mount and the shifter whole needs to be trimed so that the BW shifter doesn't hit. I belive that the N/A ZX 5 speed is considered the better tranny for a turbo build. If you wanna go crazy you can put a Z32 6 speed tranny in there (it will cost some $ and mods) there is also a 240SX 5 speed tranny swap that is good for up to 350 WHP. Suposedly the BW tranny blows second gear (or one of the other gears) pretty easy, Im just going off memory from previous post, so Im sure that others with more tranny info will chime in. Keep the Questions comming Matt- P.S. tranny is slang for transmition:wink: Quote Link to comment Share on other sites More sharing options...
dougs280z Posted October 18, 2006 Author Share Posted October 18, 2006 well i got plenty of questions. Do the ecu plugs match on both the 280z and zx turbo? what about the distributors? im kind of getting to, do i have to swap wiring harness's, or just parts? i dont want to completly destroy the donor turbo car, because my dad might restore it with my z engine/tranny. i really would like to build the bottom end, and i still might pursue it, but has anyone here used water/methanol injection? if i kept the stock pistons, and a lot of boost (intercooled and water injection) is the 350hp still the limit? and when you say 350...is that max...or reliable max.... getting to i dont want to run "100% duty cycle" on my engine and have that constant fear of blowing her. i believe the first gen talon/eclipse were 7.5:1 compression and i dont remember it being toooo bad off boost response, so i might be able to deal with it. one last question for now....does the megasquirt control spark too? if so what is the need for the stock ecu at all? so what kind of 1/4 mile numbers will 300 whp in the 280z put down. oh, one last question...what is the stock injector size? Quote Link to comment Share on other sites More sharing options...
zeiss150 Posted October 18, 2006 Share Posted October 18, 2006 Hey Doug. If your plan is to have RWHP of 250 or so you need to dump the entire 280zx ECU. Even with all kinds of mods It still isn't up to the task or real HP. The Z31 is an "ok" substitute but it still is lacking for the kind of WHP you want. If you use Megasquirt or some other type of aftermarket ECU you will be able to trash the entire stock ECU and wireing, and yes megasquirt can run the distributor (it controlls the timing). I think the size of the Injectors are 11mm or something like that. They were 260cc (or was it 280cc?) for the turbo but most guys upgrade to the toyota supra turbo 440cc injectors. More important than building a forged bottom end is getting a quality FI ECU that can make you the power you want. There is a step by step thread on swaping in a Z31 ecu into a zx harness but why bother. Stock compression on the 280zx turbo is 7.4:1 and off bost it is suposedly a dog... keep in mind this is hearsay I've never driven a stock turbo zx. If you want the car as an everyday driver 300 WHP can be made without pushing the L28 to its limits. I think the limits of the L28 (for most mortals) is 500 WHP or so. But having that much WHP does not make for a daily driver. 1/4 mile times... well that depends on the suspention the wheels the tires the engine, and oh yeah... THE DRIVER. There was a guy that ran high 12's with a non turbo SU (carborated) 240. I think Austin is trying to break the 10 second mark and he's got 460 but i think he has plenty of HP to reach his goal. Oh I forgot to give my general disclamer: I am a retard, and all the info I have given you is subject to correction by much smarter Z'Ophiles than myself. All stated info should be taken as a "possible" fact and further investigation should be done to verify said "facts". Keep the Q's comming and I'll do my best. Matt- Quote Link to comment Share on other sites More sharing options...
dougs280z Posted October 18, 2006 Author Share Posted October 18, 2006 well, i think thats about it for now....i got some parts to start collecting. ill start researching the MS better and look into getting one of them. That way i can get rid of all stock wiring and have complete control of the engine. i havent seen anything about the supra injectors being direct replacement, so i assume there is still mods to be done. i have some stock dsm 450cc injectors, (i need two more), but i plan on getting a fuel rail extrusion and making a custom fuel rail. im still going to keep my eye out for a good set of 8:1 forged pistons, but im going to start with the fuel components first. lets see....anymore questions...i dont think any as of right now.....is there anything else that i should salvage off of the turbo model....rear end (i havent checked to see if they are the same)....etc. thanks for all the answers...ill be back later with more doug Quote Link to comment Share on other sites More sharing options...
slownrusty Posted October 18, 2006 Share Posted October 18, 2006 Stock compression on the 280zx turbo is 7.4:1 and off bost it is suposedly a dog... keep in mind this is hearsay I've never driven a stock turbo zx. Absolutely wrong! Off boost the ZXT is extremely driveable. Quote Link to comment Share on other sites More sharing options...
TimZ Posted October 20, 2006 Share Posted October 20, 2006 Absolutely wrong! Off boost the ZXT is extremely driveable. Thank you - I was going to say the same. Nobody has ever accused my car of being a dog - on or off boost. I think if you do the math, the hp difference in the off-boost rpm range is maybe 3 or 4 hp for a cr change of 7.5 to 8.5. I run an open chamber N42 (albeit modified) head, too... Quote Link to comment Share on other sites More sharing options...
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