Exhaust Manifold

The turbo manifold turned out to be a huge undertaking. Due to the size of the turbo and the fact that you can’t really buy anything off the shelf to suit an FD motor and 323 build - I decided to make my own. There are various opinions on Stainless but I decided to go for Schedule 40 2” steam pipe. I managed to get a whole bag of bends and tube from the local supplier for under $100. I bought plenty of extras to fix any mistakes I might make on the way.



Two of my key considerations were 1) Keeping the runner lengths as close to the same length as possible and 2) Keeping the split pulse timing to match the turbo. I started off by mounting the base flange to the engine (I bought this - much easier than making your own) and then removing the exhaust housing from the turbo (to make it lighter to handle) and roughly suspending it from the ceiling rafters in the position that I wanted it in the engine bay. I made my own split flange for the turbo mount. Once in position I tack welded two lengths of steel between the engine flange and the turbo flange. I could now fit the runners in between flanges.
The first step was making the collector. This is the bit that joins the two runner tubes to the turbo flange. They merge at about 15 degrees and I welded a separator plate between them to keep the split pulse.



A lot of cutting and fitting took place to make up the runners - the first one is easy. I started with the runner that connected the flanges at their furthest points. All my bends and bits of pipe were mocked and held together with tape to make changes easier. The second runner is harder because to retain the same runner length you have to put an extra bend in. I basically mucked around until I had it about right. All the seams were spot welded before doing the final welds. I also used a mig welder rather than a tig. After talking to a few friends - their suggestions were that tig welds on these heavy manifolds seem to crack after a while.





The next step was making the wastegate runners and collector. Do to space restrictions it was virtually impossible to retain the same runner length for the wastegate. It’s close - and the pipes merge right on the wastegate valve.



After some final fitting and welding I wrapped the entire manifold with heat wrap and painted it with high temp VHT manifold paint. I worked on this for about 4 months to completion (on and off) and for the price it cost me (Around $250 in raw materials, a lot of grinding, cursing, welding burns and at least 100 fitment tests) I’m really happy with the outcome!

Brakes

The standard 323 brakes would never stand up to the increased power and stopping demands that the rest up the car is undergoing. I have a friend who has been through about 4 gts-t Skylines and got the disks and 4-pot calipers for a song (free!) from him. I also had an old Toyota Trueno front end lying around. The hubs on these are very similar to the 323 ones with the exception that the disks are bolt on for the Toyota ones and solid hub and disk for the Mazda ones. You can machine the disk off - but it was easier to just machine the Toyota ones slightly to fit the 323 hub axle.


I then also machined the outside of the hub so that the disks fit over them. They are then just floating disks - secured when the wheel gets fastened.
The next job was mounting the calipers. For this I had to mount the disks, then clamped the calipers in place on the disk and made up a mock mount to get the correct spacing measurements. The mount has been milled out of a sold 20mm thick x 100mm wide bar. They bolt on to the old caliper mount points and then onto the new 4 pots.



The final part to the brakes was upgrading the master cylinder. I went as big as I could find - a 1” bore master cylinder from a Hi-ace van. They’re about as big as you’re going to find. A made up a custom adapter plate to fit the master cylinder to the brake booster. The master cylinder is also mounter upside down (the only way I could get room for the fluid outlets).



The rear brakes are standard R31 disks and calipers.

Building the front struts

I started out with the standard 323 front struts. The shock shaft has been shortened by 100mm and then re-tapped to M14X1.5. The next step was to ditch the old 323 shocks and holders. I removed the old spring cups from the shock body with an angle grinder and then smoothed everything off. You can buy adjustable sleeves and nuts that you can then weld onto the shock - but the local supplier had the customer service of a tree stump and my tolerance for poor service is zero. Also - the bought kit came in at over $300. In the end I was lucky enough to spot some second hand KW coilover shocks on Trademe for $100. There would be some people cringing around now - these retail for over $1200 new. I biffed the shocks and cut up the struts (they’re stainless) to get the stainless thread that I could then weld onto my strut. By fluke the I.D of the KW ones was only marginally smaller than mine. I machined them out on a lathe with a boring tool. You get about 110mm of adjustment but you still need to do a mock install to see how low you want the car to sit. Once I’d found the right height I tig welded them to the strut body.



I also incorporated keeper springs (the yellow ones). They are a lower spring rate and just help keep everything captive when the car is jacked up. The main springs are rated at 6kg/mm. Pretty stiff - but I’ll see how they feel once everything is back together. I machined the spring hat out of billet aluminium and these have a little lip that go straight into the spherical bearing of the adjustable camber plates. I also machined up and tapped a thread into some round bar - then tig welded a nut on top to bolt the shock shaft to the camber plates.



I was going to make up some camber plates but in the end it was cheaper and more time economical to buy some. I found some on ebay (Mookeeh) with blank mounts (i.e drill and stud them yourself) for $100US).



They seem okay - you can replace the bearing in them so if it’s crap I’ll do that. So once everything is installed then you can dial up the preload to make the ride really stiff or dial it down to ride in the weeds!

Mazda Project Intro

I’ve been working on a car project for a few years now (actually it just rolled over 10 years this year). I’ve always been interested in mechanical things and when I was younger I bought a clapped out old Mazda 323 with great intentions of turning it into a fire breathing monster. As you do when you’re younger - you tend to keep purchases like this secret from your parents. This however made the purchase quite tricky. The best tried and true method was just to get it and surprise them. Better to beg for forgiveness than to ask for permission. I bused my way into town to pick the car up. The engine had run a main bearing but still ran - so I drove it home! The knock from the motor got progressively louder with each kilometer traveled and the temperature gauge was just under the red the entire trip home - but I made it! Surprisingly my parents were okay with the purchase. I suppose they viewed it in a positive light - at least if I was in the garage I was off the street, parties, etc that other teens get up to. Right? Yep - sure.

Well as the weeks turned into months, and the months into years - the project became more complex and involved. As soon as you start working on something - you come up with other ideas and eventually you have a ten year project on your hands.

So the car started out as a 1978 Mazda 323 RWD. I originally wanted to put a naturally aspirated 13B rotary engine in it. I bought one but the engine turned out to be a lemon. Being a student at the time (read: lack of money) - the project was put on hold. Life then catches up with you - I got married and moved to another city - while the poor old Mazda sat in my parents garage. Well eventually after getting a place of my own - I’ve been working away slowly over the last five years. Here is a basic rundown of what I’m doing:
Car: 1978 Mazda 323 RWD
Engine: 1993 13B REW block, large streetport with 12.7mm dowel kit, 9lb aluminium flywheel with Exedy clutch.
Intake and exhaust: GT42 Large frame Garrett on custom steam pipe manifold. Tial 44mm wastegate, Tial 50mm BOV, 600x300x100 front mount intercooler with 3” plumbing. 3 1/2” exhaust. Water injection to come.
Fuel system: 850cc primary and 1680cc secondary injectors. Holley Red lift pump from tank to surge tank, Aeromotive A1000 from surge tank to engine. Aeromotive rising rate fuel reg. 15mm fuel lines.
ECU: Link G4 RX
Gearbox: FD RX7 5 speed
Differential: Borg Warner shortened live axle. 4 Spider shimmed LSD. 28 spline axles. 3.89 ratio. Custom 3 link Chromoly bars with rosejoints.
Brakes: Front - 4 pot Skyline gts-t calipers and disks. Rear R31 skyline calipers and disks. 1” Master cylinder.
Suspension: Front - custom coilovers on shortened shocks, adjustable camber plates. Rear: QA1 coilovers.
Wheels: 16” Mak Fiorano

In a nutshell that describes the running gear. I still have a lot of work and decisions to make on the interior. I’m basically aiming for a fast street car (legal) - that I can have a bit of fun with at drag days. I’m aiming for 500hp at the wheels.