Quite a bit happened since I last updated this thread. Did another track day at brands indy which was great fun, and a lot more engaging since the updated suspension and wheels. Less track orientated tyres made things quite a bit more interesting. Though there were a few things that stood out. Day started wet and got drier so interesting to have both, but the diff wasn't working properly and didn't seem to be locking reliably or even at all in some cases. Otherwise cooling was ok, but possibly a bit hot on oil.
Following this I noticed the engine started burning a bit of oil which given I'd relatively recently rebuilt the head I decided was likely to have been down to piston rings which I'd previously not changed despite changing out the rods etc. Probably a bit of a missed opportunity, but decided it was a good time to rethink the bottom end anyway especially as not long after i'd noticed a small amount of metal in the head. I pulled the filter off and saw some further small flakes. Enough to decide to investigate further and pull the motor. After doing so the thrust bearing had absolutely had it and was machining the crank down to the point where had I left it it would have likely not lasted very long at all. The bottom end was scrap so decided to double down and go fully forged on a new bottom end, upping the displacement slightly with a set of 85mm Wossner 12:1 pistons.
Whilst the engine was out I decided to take a look at the front chassis rails as they were pretty clearly done for. I'd thought they were ok when I bought the car, but on closer inspection with the engine out it was apparent someone had patched over them to hide the rust rather than replacing them, so that was the next task. While front subframe was off I managed to pick up a galvanised one for little money so decided to replace that as well as refreshing the engine bay which was a bit of a half job and then all suspension arms and polybushing.
That led to doing the same on the rear subframe and adding new anti roll bars all round.
While the diff was out I'd sourced a 4.7 crown wheel and pinion from a Kia sportage along with a new MSport locking unit to replace the Blackline which I sold as a whole. The 4.7 will mate with the 5 speed and should meaninggully imrpove acceleration, obviously cutting down on top speed. No photos of this at the moment as it's off being built up by a local classic car gearbox rebuilder.
So all in essentially refreshed the entire running gear, brakes aside. I also added a new GCFab roll bar, as running on track without one always felt pretty sketchy which allowed me to move to full harness for the tillet seat.
Engine was in build for a long time as I had issues with getting subs working properly along with the right shims, eventually sourced a good set from a chap in australia and altered to MazdaSpeed Subs; so will have to see how those work. I ended up having to grind away a bit of material on the pistons in order for the valves to clear at max vvt angle, but may choose to limit how much or if at all I use VVT as I'm a bit nervous as to how well it works in this instance, especially at higher RPMs.
At the moment the engine is still sat on the stand but pretty much ready to go back in altogether with the new diff. Then once all run in will be back to tuning and dyno again. Should be quite a different car with all the new refresh work, new parts, more power (fingers crossed) and diff ratio change.
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