What exactly is the difference between 280zxt ecu and 300z ?

[Guest alex12582]

Tried the search, not what I'm looking for. I know it has MAF instead of AFM. I have a slightly modified 83 turbo engine pushing 195hp. How much gain in HP should I expect? Also, what parts need to be changed? ECU, MAF, how about distributor or ignition coil, injectors are the same,

right? Is this even worth doing?

Thanks.

[Brad-ManQ45]

I doubt you'd gain much in the way of horsepower. Driveability and gas milage would improve.

 

You would need the CAS wheel inside the 300ZX distributor, six resistors, and swap a couple of injector leads.

 

Your knock senszor will no longer work.

[Guest alex12582]

so, would I have to replace the whole distributor with the 300zx unit?

Also, can you please explain the CAS wheel and 6 resistors? Is this something that has to be custom made or is it stock in either cars?

Thanks, help is appreciated.

[240ZinTN]

You would need to use the distributor from an 82-83 280ZXT and swap the CAS wheel with an 84-88 300ZXT CAS wheel. I am not sure about the resistors. Look at the Turbo forum. It has a Sticky post that details the swap very well.

[fl327]

z31 has a different fuel curve that stays a bit more linear than a 81-3 efi setup. also calculates air a little better than the earlier ecus. worth doing since parts are easier to get at the junkyards.

[Guest Gillez260ZT]

What exactly is the difference between the slotted wheels in the Z31 turbo distributors and the 280Zx turbo?

[Bernardd]

What exactly is the difference between the slotted wheels in the Z31 turbo distributors and the 280Zx turbo?

 

The z31 wheel has a #1 cylinder reference. One of the 6 windows for cylinder reference is wider.

 

The z31 ecu will meter air until the maf is maxed out regardless of the rpm. The stock efi afm is wide open by about 3500 to 4000 rpm and fuels the same from that point on.

There are two benefits to using the z31 maf as far as power goes. You'll get better response because the timing map has more advance at lower rpms, and there's no flapper door to open.

 

 

Bernard

[Guest bastaad525]

The stock efi afm is wide open by about 3500 to 4000 rpm and fuels the same from that point on.

 

Actually from what I see on my dyno air/fuel ratio it maxes out more like 5000rpm. At 4000rpm, 10psi, WOT, air/fuel was a nice 12:1, at 5000rpm it very suddenly leans to 13.2:1. However, it does stay level after that up to 5600rpm which is as high as I took it. I have since lowered my boost a bit

 

 

asides from the bugs a lot of guys seem to encounter, the 300zx ecu swap seems to be a really good swap. I think max power WILL improve because, as was said already, the ECU keeps a flatter fuel curve. Problem with the stock 280zxt ECU, is it runs WAY rich from the point of boost onset up to 4000 or so RPM, at about 10:1, and you can see the torque curve dips with the air fuel ratio... not good. And of course the aforementioned lean-ness above 5000rpm, which also causes torque to fall off at that point, hence cutting the power a bit short. My power peaked at 5000rpm and stayed almost level up to 5600 as torque fell off. A stock 280zxt should peak it's power at about 5500... my guess is mine didn't because of the lack of fuel. With more fuel on top you should see a little peak hp increase, I think. And of course, more power under the curve with the leaner midrange.

 

I want to do this swap so badly......

 

 

another advantage that I recently found out; the 300zx MAF inlet and outlet are the exact same diameter as the 280zxt AFM... so no fussing with new hoses or whatever, just 'drop it in'.