260Z Guy Posted February 4, 2008 Share Posted February 4, 2008 I just picked up a 1981 280zx today as a donor car for my 260z! It also has a 5-speed so I am very excited to get the swap done! The engine is not currently running due to inactivity for the last 3 years but I will soon begin the process of getting it up and going again. My plans right now are fairly basic and that is to rebuild it. I am currently trying to find information on what amount of boost (if any) the stock L28 can handle, as well as what would need to be done to get it to put out about 250whp. Idealy my goals are: 1. supercharge the engine, Air/Water intercooled 2. water/alcohol injection 3. 50-75hp shot of nitrous 3. Maintain it's DD status So far I am not sure if a different ECU would be needed, if so mabye Z31 or megasquirt? Also considering using turbo pistons to drop the C/R. Any Info/links/tips are greatly appreciated! Quote Link to comment Share on other sites More sharing options...
cockerstar Posted February 5, 2008 Share Posted February 5, 2008 The internals of the engine in the zx are all forged with the pistons being the weakest point. They are able to handle a surprising amount of boost in their stock form. I believe that 18lbs has been reached on stock l28et internals with supporting mods. Be sure to keep everyhting cool. The internals will most likely be able to handle whatever you are going to supercharge to... What do you have in mind? Quote Link to comment Share on other sites More sharing options...
sweetleaf Posted February 5, 2008 Share Posted February 5, 2008 Search, this has been covered many times. This will probably be in the TOOL SHED in a couple of minutes. Quote Link to comment Share on other sites More sharing options...
260Z Guy Posted February 5, 2008 Author Share Posted February 5, 2008 I'm not quite sure what boost level would be best yet, but I am looking to put down around 225-250whp. I still have somemore research to do, but I do already have a couple of superchargers laying around waiting to be put to use Quote Link to comment Share on other sites More sharing options...
badjuju Posted February 5, 2008 Share Posted February 5, 2008 pistons aren't forged. pretty sure. Quote Link to comment Share on other sites More sharing options...
Comrade_Charlie Posted February 5, 2008 Share Posted February 5, 2008 Yea the comp is 8.3 for na pistons and 7.4 for turbo pistons. My Z31 has 7.8 and ive done as much as 16psi(usually 12-15psi) without any problems for over a year, but thats a z31, so I dont know if L28 pistons are any better or not. the L28 pistons are not forged, rods are. Why supercharger? I like supercharged v8s but not a big fan of superchaged imports. to each his own I guess. Quote Link to comment Share on other sites More sharing options...
cockerstar Posted February 5, 2008 Share Posted February 5, 2008 Sorry, the rods are forged and the pistons are cast. I misquoted 510six If you have a NA L28 your pistons are cast, the L28et has cast pistons as well however they are stronger. The NA pistons should survive a 100 whp shot provided proper safety precautions are taken. http://forums.hybridz.org/showthread.php?t=129409 Quote Link to comment Share on other sites More sharing options...
260Z Guy Posted February 5, 2008 Author Share Posted February 5, 2008 Thanks for the info on the pistons guys! The main thing that I am looking for right now is the low compression ratio. I am hoping that with a properly set up air/water intercooler & water/alcohol injection the charge will stay cool enough as to not knock with street gas, at least with the power levels I am looking for. I'm having the 280zx towed to my house in the next couple of hours, so I should be able to begin the diagnosis soon...I'm guessing at least the gas tank is shot because it has been sitting with gas in it for the past 3 years. We will soon see... Why supercharger? I like supercharged v8s but not a big fan of superchaged imports. to each his own I guess. I have always been a big fan of low-rpm torque and the whine of a supercharger and right now I don't know if I would be able to complete a v8 swap so I figured I'd go with the next best thing IMO. We'll see how it goes as it is a first time for me. Quote Link to comment Share on other sites More sharing options...
260Z Guy Posted March 5, 2008 Author Share Posted March 5, 2008 it's been a while since I started this thread but I finally got her running. The air flow sensor was all messed up so I picked up a newer one and it started just fine! My only problem now is that it is running very roughly. It seems that it is running a bit rich. When I suddenly open the throttle it coughs then catches up. Although if i slowly upen the throttle it seems fine. It will shoot some smoke out the exhaust. I noticed an adjustment screw on the air flow sensor and I am wondering if that needs to be adjusted since the AFM was off another zx. I will be picking up a repair manual for it later today so hopefully that will clear things up. In the mean time does anybody know what the adjustment screw does? Or has anybody dealt with this problem before? Quote Link to comment Share on other sites More sharing options...
Gollum Posted March 5, 2008 Share Posted March 5, 2008 The adjustment screw is for idle air mixture. If you open it up (black plastic cover) you can adjust it to make the computer think there's more or less air than there really is. That's the main "adjustment" an AFM can make that's actually meaningful. Was the engine warm? I'd say let it warm up and see if it responds any differently. It's definately either going rich or lean upon rapid throttle, and until you know it's hard to tell what might cause it. I'd bet it's going rich, but that's just me. Try tightening the spring on the AFM (mark it before you do anything) and then loosten it and see which improves it. If making the spring more loose helps then it was going lean and now the ECU is adding more fuel per air molicule. If tightening it helps then the opposite is true, as more air is getting in without the ECU knowing. Quote Link to comment Share on other sites More sharing options...
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