T-tops and turbo time.


Coast to Coast

So a few years ago I traded a t500 for this 87 z31.
It was originally a 2+2 factory turbo automatic.
Swapped in a manual transmission and drove it for a year but decided it needs a little more boost than the factory snail can provide. Basically, full EFI system replacement, bigger turbo, engine rebuild, hopefully double the stock power for a fun summer daily.


Coast to Coast

Engine out and about.

Exhaust studs need a bit off help

Heads rebuilt, cleaned and decked
Block hot tanked and decked as well

Crank clearances check out


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Coast to Coast

Stock t3 on the left
Holset he351cw on the right.


Megasquirt ms3x ecu to replace the 33 year old factory ECU


Coast to Coast

Engine together

Mitsubishi 3000gt fuel rails bolt up with some mount fabrication.
1g DSM blue top injectors, 420cc top feed vs the stock 270cc side feed injectors

irk miller

You've been mostly-dead all day.
Oh yes. I drove a red 89 Z31 ZX in college. The non-turbo. That was such a fun car.


Coast to Coast
Oh yes. I drove a red 89 Z31 ZX in college. The non-turbo. That was such a fun car.

They’re honestly pretty underrated, and relatively cheap for an older sports car.
Haven’t driven the non-turbo version myself, but heard they respond pretty well to a good set of cams and headers.

I picked up a second one this summer to drive around, guy was basically giving it away because he though the head-gasket was toast.
One intake gasket later and she runs mint, shiro #63 of 1076.



Coast to Coast
Going to need a better clutch kit. The z31 had two flywheels, the 84-86 turbo as well as the 84-89 N/A had a 240mm version, the later 87-89 turbo had a 250mm to go with the beefier 30a transmission.

They are interchangeable but must be used with corresponding clutch kits.


This fidanza wheel is about 1/2 the weight and can fit both styles of clutch.
The surface is also perfectly flat and will let me use z33 (350z) pressure plates and clutch disks for a cheap clutch upgrade.


Coast to Coast

Intake plenum, original intake has these snaking passages down each side. Pretty restrictive when trying to bump up the airflow. Top was cut off of this spare intake and a 1/8th plate was welded to the top.

I still need to drill it out and weld in some bungs so that i can fit the bolts down through the plate and plug the top after.


Wires are all soldered to the ecu connectors.
The ms3x can run full sequential injection and ignition. All lines to the ecu are switched grounds or sensor lines. Need to add a fuse box and 2-3 relays to keep everything independent of the factory harnesses and then run the power lines to the injectors and ls coils.


Coast to Coast

Now the digital dash cluster that was available in these is pretty nifty. Thankfully the gauges should all work without the factory EFI harness because the gauges all have separate sensors from the ecu.
The only issue is the tach takes its signal from the coil voltage spike so if i discard the factory distributor and use 6 ls coils it would read at 1/6th the correct rpm.
Now the MS3 expansion card has a tach output on it but it’s only a 12v square wave signal. I need to convert this somehow to run the original tach.


Coast to Coast
Been pretty busy so slow going
Bought some fuel rail stock and some injector drill bits to make up a few sets to sell. The cost of getting some of these up to canada is about 250 USD. total cost for tools was about 180, and material is like 40$/set with some -6an fittings so it’s a no brainer.

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Coast to Coast

Got them sat up on there to test fit, had to trim some down as the original length was about 1/2” to long. The stupid coolant filler neck still interferes a wee bit. Was hoping to avoid putting a 90° right into the rail.


Coast to Coast
Got my NPT tap in the mail today, but still waiting on the -6 fittings. Got half the rails tapped and threw some of the -8 fittings in for a test.


Coast to Coast
Been awhile, farm livin’

So most older nissans use an optical sensor & LED to send the crank & cam signals to the ecu. In this case they are located in the distributor.
The original wheel has 360 slots for the crank signal and 6 slots (one larger) for the cam signal.
This wheel doesn’t play nice with aftermarket ECU as the resolution isn’t there for sequential ignition & injection. I replaced the factory wheel with one that simulates a 12-1 crank wheel with a single tooth cam wheel.


Also received my new injectors, i realized that they’re probably the dumbest place to try and save a few bucks on this project, especially if i need to pay someone to tune it.

They may be nearly double the price of other equivalent size injectors, but the extra characterization data from ID apparently makes worlds of difference.


Coast to Coast
It ain’t much, but finally got the rail mounts made up and the injectors mounted in an acceptable fashion.
1/8 galvanized angles i had kicking around from the farms feed system did the trick. Nice and solid.

Finally got her twin out for the first rip of the season as well.


Coast to Coast
Working on the wiring harness, breaking it down into several subharness’ so it’s easier to work on in the futur. Concentric twists for flexibility and tight fit.


After seeing the turbo piping mocked up, decided to order some sch40 stainless weld els and pipe to top mount the turbo. Will also be able to use an external wastegate to control boost better.


Staff member
Impressive - I've never paid any attention to twisted wires in a harness till now.


Coast to Coast
Thanks guys!

After seeing some professional concentric twist harness’s mine looks like a 5 year old did it by comparison.
Unfortunately I’ve gone way over budget elsewhere and can’t really afford to spend over 1000$ on the harness so this will have to do.

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Coast to Coast


New wastegate arrived, 44mm
Absolutely massive compared to the internal gate on the he351.
Sch40 pipe got here too so just waiting on the flanges to start welding up the turbo pipes.

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