945 Turbo+ light restoration and upgrades

Hello! Here's my 945:

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My dad bought it new in 1998 and drove it for five years, then my mom got it and drove it for 10 years (and nearly into the ground, she could NEVER find any time in her calendar to have it serviced) and when it finally passed to me it was almost ready for the wrecker. The fuel consumption was through the roof, there was a boost leak, brakes were shot, and there were enough minor defects to drive the resale value to nothingness. Even after obtaining the car it felt like fixing one thing made two more break down. However, the engine was still healthy (despite ECU problems) and the chassis was remarkably sound. Brake issues got fixed with a full overhaul (new rotors, calipers, and new e-brake parts all around), engine problems rooted from rotten hoses and bad sensors. A lesson learned, always test if the sensor is OK before installing. I had a bucketload of problems with a dud ECT sensor.

Limits and scope of the modifications
Obviously, the priority is to make everything work properly before venturing into any great modification projects. The to-do list is however getting short and issues on it superficial, so it should be good time to start thinking about upgrades. My goal is to achieve a premium OEM -like feel to the car. Power goal is not crazy high, 300hp would be plenty for a touring car. B230FT with air conditioning and M90 transmission should provide a nice starting point for modifications and upgrades, but there are few legal barriers in modding a car of this age, limiting the options quite a bit:
-Engine swaps involve dealing with MOT approvals and expensive emission tests on a rolling road.
-Head swaps count as engine swaps if the valve train changes, so no DOHC 16 valve heads for this car
-Swapping the turbo counts too, but an inconspicuous change would go unnoticed so TD04HL-20T (with a -13C data plate transplant for good measure) is worth a try, a Holset or a Garrett not so much.
Also, since the car is my daily, no mod should take more than one weekend to install.

Fuel & ignition Chip, intake, turbo and exhaust
I installed a flexfuel kit earlier, RE85 is pretty cheap around here and having 110 octane fuel is a welcome boon for a turbo. Fuel consumption after having the ECU problems fixed on ethanol is decent, around 12.4-13l/100km (19-18 MPG), which isn't bad considering. However with a T+ chip stock injectors already run at alarmingly high duty cycle, so I've planned on getting Viking chips, and modify a 3" MAF into 3.4" to accommodate 600cc injectors for E85 overhead. I purchased a cheap 012-clone from AliExpress, and boy was there a horror show waiting inside the electronics box.
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The wires are hanging on for dear life, the solder joints are unspeakable blobs and the pcb was only held in place with a bit of silicone RTV. Proper multistrand wire, tender care with a soldering iron, heat shrink sleeves, and thermal adhesive should give the thing a bit more life. If it refuses to behave, I will modify the stock MAF. Improving fuel delivery is the first thing on my priority list with the engine.

Turbo will probably be the last step on the engine upgrade path, as I want to see everything working correctly before adding boost. At the moment, a TD04HL-19T or -20T looks like it. Going from stock TD04H-13C to -20T isn't a crazy high step, so I don't feel like staging that transition. Exhaust is probably 3" downpipe and 2.5" catback. I'm fond of idea using several straight-through mufflers, ending with a transverse dual output muffler and dual exhausts, if it can be made to look like factory installation. We'll see.

E85 makes the car more stubborn to start on colder days, so any improvement is welcome. Right now I've only installed iridium plugs, but I'm building a wasted spark setup to eliminate the distributor and improve the spark energy. My car doesn't have an EGR system (to my utter surprise), so I may use the existing connector pins for cleaner installation. Ignition system modifications are much less regulated than fuel/air induction systems, so it's more of an aesthetic thing. This is one I hope is in immediate future.

Head & Cam
I managed to source a 531 head, and also bought an IPD Turbo cam for it. By some accounts they give plenty of top end, but the injector size really is a big concern at the moment. I'm, not going to install those before the new injectors are in.

Drivetrain, brakes, and suspension
M90 should do fine with the goals I had in mind. It occasionally tends to jump out of third gear so that's something I should look into. The diff is G80 locker, which works alright now. Upgrading it with a Dana 30 ATB diff might be an option in the future. I might go for a lowering kit with 20-30mm of ride height reduction, but that too is not an immediate concern. Strut rod bushings are original and *very* crumbly looking. I've ordered a poly bushing set from IPD, I've head great things about it and it would be high time to replace those bushings anyway.

So, that's about it. I'm not rushing into modifying the car, so this won't be a rapidly progressing thread. Hope you found it interesting.

The past year has been mostly about fixing a properly broken down Mazda, so the 940 got even less love than I anticipated. Pure vanities I had time for was window tint to rear doors, wind deflectors and 960 style handle covers.


That said, there were a number of operations out of pure necessities. The upper water hose on the radiator broke on an especially cold day (the engine block heater had failed, the coolant was slush, and yet the car started with E85 with little problems at first, until it burst the radiator), but unfortunately I had to settle with a stock replacement as neither budget nor schedule allowed a full aluminium radiator. At least it's new and not blocked. Right around the 500 000km mark the head gasket failed (which likely started with the previously mentioned frozen-but-overheating incident), so the new cam and head are going in right now. The injector cycle wasn't maxed out as I had feared. Turbo was absolutely on it's last legs (rattly and loose CHRA, cracked turbine housing, compressor wheel rubbing on the housing, rust everywhere), so the new TD04HL-20T went in much sooner than I had thought (or wished.) It's not right at the surge limit but still a bit close for comfort. Big valves and 86mm crank would definitely reduce some anxiety there. The old compressor housing was machined to fit the new wheel, so outwardly it appears just an overhauled factory part, which is a definite plus with the occasional overzealous and eagle-eyed MOT inspector, and also helps in not having to faff around with a new wastegate mount. Still, I would've preferred to install it at a much later stage.


I bought a snow cap to prevent snow from blocking the air intake in winter, and added the honeycomb mesh to make it less of a pine needle trap in the summer. You'd think those things are made of gold by the asking prices on eBay, and yet local wreckers seem to disregard them entirely.


Lower ball joints were worn out, brake shields were completely gone, ABS rings were encrusted in thick rust, and wheel bearings felt a bit notchy, so all those got replaced. Rubber bushings were extra crunchy so the front end rides on urethane now. Suspension arms were sandblasted and painted with POR-15, so the front end overhaul was quite substantial. Brake hoses and caliper brackets were close, but not so close as to go off in a year and got to stay on for a little bit longer.

Here's a fun little memory, by November 2020 the alternator brushes were completely worn out and while replacement was easy, apparently the slip ring had been eroded by arcing. In August 2021 the new brushes were once again gone, and this time it was time to swap the entire alternator on the shoulder in rain with a single 1/4" socket drive set. Fun times.


Also, while I was undoing a shop "repair" of the air filter housing (self-drilling screws to hold the top in place) and replaced the broken clips with metal clips, I did the usual thing and opened the fender intake in the airbox. I cannot understand the deal at all, why did they bother with an assembly part on a non-functional feature? Anyway the fender intake is now operational, as it should.

One thing I tried with the looks, I'm not a great fan of wood paneling and fake wood paneling feels especially cheesy, so I tried wrapping the dash panels in brushed aluminum look vinyl:

I think the results were okay, but I didn't have adhesion promoter and I had stretched the vinyl a bit too much, so after a while it started to come off. I'll try piano black wrap next.

I meant to do a light refreshes on the rear end this summer. Just brush off the rust, put on some new paint, install poly bushes and be done in a week...



Not promising



The panhard rod and the sway bar were in a very bad shape. They will do for now, but they're not looking great even after a coat of POR-15; unfortunately no photos as I had to hurry to get the car done. Trailing arms were in a good shape, thank goodness. At least I can justify the purchase of a new adjustable panhard rod and heavy duty swaybars much easier to myself now.



Diff housing looked absolutely terrible...


and not without a reason. I only could do a quick patch job with Chemical Metal, and I'm desperately trying to figure out how to fix the rear axle problem properly.


All the bushings were replaced with yellow Strongflex (Sh. A 90) bushes. Getting the reaction arm bushings in was quite an adventure. With poly bushings all around the ride is noticeably noisier, but also more firm. Everything that fit the blasting cabinet got sandblasted and the rest cleaned however possible, and coated with POR-15.
The fuel lines were a story of their own.


The fuel lines at the rear were completely rotten.


Fuel filter was pretty bad, but had no leaks; thick skin!


Fuel filter outlet banjo on the other hand was properly destroyed. It had holes everywhere.


The pulsation dampener hose had a nick and trickled fuel.

Obviously none of that was good, and major repairs were needed. On a side note; 940 went to a single pump configuration after 1995 in Europe.


New hard lines were made from 8mm copper tubing; anodized aluminium alloy would've been better but I couldn't obtain any within schedule.


All the fuel hoses were replaced with teflon core AN6 hardware, except for a short length of rubber hose and PA tubing at the fuel tank, to make the lines fit the existing connectors.

Great progress.

Sorry you have to deal with all that rust...yuck

Thanks man. The work on the engine and suspension has really made a big difference, almost as if a decade or two has been taken off the car.

I made an interesting test in the summer of 2022, I had bought a LiFePO4 battery set (4S, 30Ah) and tested how it works as a starter battery. Turns out it works really well, the starter felt even livelier than with the lead cube.

https://youtu.be/YHdsaQgwv3o

The underhood environment is far too hostile for the battery to stay, but I think it's a worthwhile effort to test actual driving with the new battery in the lower fender pocket on the left of trunk. It's a nice cool place with no real use and ventilated too. I'll include full BMS even though LiFePO4 chemistry is far more robust than Li-poly and would manage without too.