Well, I've spent the last couple of days doing the Z31 swap and I finally got everything sorted out today. So far it runs great although there is a very slight miss under light acceleration (maybe 1/8th of the way down on the throttle). I haven't tested out the boost side higher than 5 psi just yet. I wanted to make sure all the fuel lines and stuff didn't leak since I had to swap back to the stock injectors. (I originally had 370's on) I have set the fuel pressure to 32 psi right now. If any of you all are thinking about doing the swap, I highly recommend it. It only requires 3 new pins that need to be inserted into the 280zxt harness (for 82-83, I'm not sure about 81's) and a little bit of splicing and rewiring, not too bad. I think it was 5 wires total on the main harness and then for the afm to maf conversion, basically most of the wires are in the reverse order. Compressor surge is a lot more audible as well. Reminds me of my Nissan Auster back home, or my bro's Silvia.

 

Have you noticed any performance difference? I've heard of this swap before but I don't understand why you would do it. Please explain.

 

The point of the swap is because it has the potential to support more horsepower. The air sensor flows much better and the ecu is far supperior. It uses the turbo type distributor which is also far more reliable than the NA versions.

Again, all this essentially useless on a stock NA motor, but on a modified motor, and those looking to push more RPM's, this mod is an excellent one for the cost.

 

I think the 87-89 300ZX turbo ECU is also partially programable depending on what kind of injectors you are using. The fuel distribution is not so linear like the 280ZX turbo ECU. The Z31 ECU will take advantage of higher boost much better than a 280ZX ECU.

 

I took the Z out last night, and the throttle response has definitely improved in the midrange of the power band (3-4K) I left my inner silencer in so I can't say about the top end power just yet. I'll yank the silencer out today and go for another spin and see what the difference is (my exhaust is loud w/o the silencer though). Maintaining partial boost during cornering is much easier with the Z31 setup, as the old afm would start to make an audible oscillating noise and the boost gauge would flutter a bit and upset the some of the balance.

Bleah is correct that the 87-89 ecu's are adjustable in their programming. They have a 16 bit map vs the older 8 bit. The 16 bits are able to be programmed for anything from 370-440 injectors and even using the 300zxtt maf which is good for ~450-500 hp before the flow gets exceeded. Also, the Z31 ecu has a better fuel map that does not go leaner and leaner once you pass 5000 rpm like the stock 280zxt map. The only downside to the swap is that the maf setup is a bit more sensitive to an externally blowoff valve than the afm setup. It will stumble a bit when coming to a stop if the valve vents, but other than that, this new setup has improved driveability by a lot.

 

Glad to hear its working fine for you. I just purchased the 1987 ECU for my 280Z that has a 1982 L28ET swap in it. I just need to find the time to dig in and get it running again. I'm gonna be using the 440CC Supra injectors(gotta figure out how to manufacture a rail for them), Walbro GSL 392 pump, intercooled, with T04/T03 turbo.

Life, you can get rid of that stumble if you recirculated the vented blow-off air back in front of the turbo. You're loosing some of your calculated air and going rich when it blows off to atmosphere. It'll also help keep the turbo spooled up if its forcing air in the inlet.

 

Yeah, on cars with air flow sensors you really are supposed to recirculate the blow off air. A MAP sensored engine can vent to the atmosphere with no problems though. A lot of stand alone units use a MAP sensor because it's just easier to work with because it's not so touchy.

 

Are you supposed to vent it to enter the system between the AFM and turbo or in front of the AFM and the turbo? I was thinking after the AFM but before the turbo is how I've seen them done.

 

Okay, I took the Z out for some WOT runs to see what would happen, and wow, there is a noticeable difference up top. Boost seems to come in a few hundred rpm sooner, but I think it's just a placebo effect. Up top however, the power does not feel like it fades as much as it did with the stock afm setup. After 3500 revs, it pulls cleanly to redline. It doesn't feel like the power tapers off. I can't say if there's any hp gain, but I'm just happy with a powerband that actually goes close to redline. Anyways, I'm going to experiment with an HKS EIDS unit and see if that will help the stubmbling issue a bit. To answer your question Bleach, the bov gets plumbed after the AFM and before the turbo.

 

Bleach, you're right. After the AFM, if you vent it back to before the AFM, it's like it was just vented to atmoshphere.

 

Hmm ... is this the cheap alternative to a MegaSquirt system? I've got plans - big plans - for my L28 in the near future, and it involves two TD05s from DSMs, a TDI truck intercooler, and some fancy custom work. That is, of course, if I don't follow through with the TD05-fed KA-Z24 hybrid I have planned.

 

Hey Dorifto, thanks for the link man. I'll return the favor.

It's only a cheap alternative to mildly modified turbo car. If you're going twin turbo, you're looking at stand alone bro. These stock ecu's can't be tuned to run on two AFM's. If you go stand alone, and use a map sensor, you can easily run that twin turbo swap.

Are you talking about the KA outta the SX? I've been thinking about that one myself. Still deciding if the weight balance is worth the downsize in engines though. A bigger engine can push more power off pump gas than a smaller one too.

 

I also want to go with the Tornado setup. And see how that works.