Trav’s Race Build: from B6 to Big Bore BP-Z3

[plohl]

do the rear roll hoop stays go through to the boot? It looks like they're just mounted onto the parcel shelf?

[Scoota]

do the rear roll hoop stays go through to the boot? It looks like they're just mounted onto the parcel shelf?

Hi Shane. Yeah, they appear to end on the parcel shelf, by design. They do actually go all the way through as a continuous bar, all the way to the landing right in front of the top of the rear shocks. This is what it looks like in the boot (prior to painting)....







It’s a similar story for the boxes midway down the main hoop. The bars are continuous through the box and down to the floor...



I will preempt the questions about the teeny tiny battery with the following info... It’s from a mob called LiFe-Tech. It’s a Lithium Iron Phosphate battery, and it is uber-light. You can find their contact details here...

https://lithbattoz.com.au/

I’ve been really happy with mine. Not cheap, but comparable to other lightweight options. There’s not a lot of info on their website, so just give them a call. Every scrutineer that has inspected my battery has been amazed by this little jigger. The normal response is... “What the hell is that? Is that your battery??” Yep, it’s a beauty. It starts the 1.6L engine no worries. It’s never let me down. When I first got it I did 20 cold starts back to back. The 20th was just as strong as the first.

Will it start the new engine reliably...? Time will tell. I’ll provide an update in approximately 4 weeks.


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[bruce]

Yes, I was going to ask about the battery.

[Scoota]

As promised, more roll cage photos!!









I’m sure you all agree, it looks spectacular!!



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[Scoota]

I’ve also made some good progress on the brakes. The SE front rotors and calipers are fitted, sans brake lines and pads. What I thought would be a shirt of a job turned out to be pretty straightforward. Thankfully the backing plates are made from really soft steel, so the chopping and bending was pretty easy.

Here are some “before” shots...





So the issue is that the SE rotors foul on the lip of the backing plate, because they are larger diameter. They also foul on the caliper near the mounting bolts. Some chopping and bending is required, as shown by the red marks...





I used a good set of side-cutters (Knipex) and a pair of multi-grips to do the snipping and bending. A few different shapes files were used to tidy up the edges. Here is the finished result...







(Ignore the white rag tucked in there. It was just to keep the filing away from my new hub assembly)

On goes the (slightly rusty) freshly machined SE rotor!!



You can just see the edge of the backing plate peeking out at the top.



They still look kinda little, but they’re a huge upgrade over the NA6 setup.

Now, master cylinder and booster conundrums....


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[Scoota]

Okay folks, here comes a question...

I’ve had a browse around this forum and it seems that when it comes to fitting NB8B brakes to an NA6, the consensus is that the change in pedal travel and pedal effort is small and pretty much unnoticeable.

Therefore, I am going ahead with the front and rear SE calipers/rotors, but without swapping the brake booster or master cylinder. I have them on the SE master cylinder and booster on the shelf here, but they need some TLC, and I need to move onto more wiring loom work. If a master cylinder seal kit arrives in time I may swap it in, but otherwise I won’t.

Any serious objections to this approach?


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[Magpie]

Any serious objections to this approach?

You may need to swap the brake bias valve as well. I'm trying to find the different bias valve setting to give you an idea.

However for a track build delete the booster!

[Scoota]

Okay folks, here comes a question...

I’ve had a browse around this forum and it seems that when it comes to fitting NB8B brakes to an NA6, the consensus is that the change in pedal travel and pedal effort is small and pretty much unnoticeable.

Therefore, I am going ahead with the front and rear SE calipers/rotors, but without swapping the brake booster or master cylinder. I have them on the SE master cylinder and booster on the shelf here, but they need some TLC, and I need to move onto more wiring loom work. If a master cylinder seal kit arrives in time I may swap it in, but otherwise I won’t.

Any serious objections to this approach?


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[Scoota]

Hey Magpie, thanks for your comments.

At this stage I’d like to keep the booster, to maintain a somewhat “normal” pedal pressure requirement. I’ve never dríven an MX-5 without a brake booster, but I remember that my old HK Premier was a nightmare without one. Chalk and cheese, I know, but I’ll keep it all the same...

...unless the ITB air filter doesn’t fit in next to it. (Shrug)

Regarding bias valves, don’t stress. I have a Wilwood Brake bias adjuster, as per the photo...



I’m just about to pull all this apart, hence the drop sheet. I want to move the Wilwood bias valve either outboard of the master cylinder, or perhaps underneath it. I need to size it up. I haven’t decided where to put it yet, but it can’t stay there. I’m expecting interference with the air filters. Custom brake lines will be required. I’ll probably hit up Pirtek or Enzed or someone like that.

If only I had an engine in the car to work some of this stuff out. My camshafts are reportedly stuck in Belgium, waiting for heat treatment. I’ve given my engine builder the green light to assemble the head with the standard NB8B cams. This makes me sad, and it’s going to cost more in the long run (more Dyno time), but I need my engine as soon as possible. My assembly and testing window is shrinking daily.

Magpie, I am considering your clutch master cylinder reservoir delete idea. Is it as simple as removing the pot from the top of the clutch master cylinder and plumbing in a line from the brake master cylinder? If so, where do you plumb it into the brake master cylinder? I can’t see an available fitting. I’ll scroll back to your photos, but can you give me a bit more detail on that job?


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[Magpie]

Magpie, I am considering your clutch master cylinder reservoir delete idea. Is it as simple as removing the pot from the top of the clutch master cylinder and plumbing in a line from the brake master cylinder? If so, where do you plumb it into the brake master cylinder? I can’t see an available fitting. I’ll scroll back to your photos, but can you give me a bit more detail on that job?

I have moved on from that ages ago, now have no booster and love it for the track!

But yes you can plumb the clutch into the brake master. If you ring Dave from Automotive Plus and ask about what they did for me he may remember.

[Scoota]

If you ring Dave from Automotive Plus and ask about what they did for me he may remember.

Thanks so much! I’ll chat with Dave.


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[Scoota]

Hi Folks.

I’ve mauled the rear brake rotor backing plates too. This is a less elegant solution compared to the front ones, but there’s beauty in simplicity, right?

Before...







...aaaaaand, after...



The side-cutters were sidelined for this effort. The tin-snips did a much better job. I probably should have used them the first time.







I have yet to assemble the rear calipers, hence the delayed fitment.


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[Scoota]

Holy Jeeberz, it’s almost time to install the engine!!!!!

Here are some photos of the bottom end assembly...



Look at the crown on these pistons!!!
And the rods... Oh my.



Crank in, measuring... axial float, I assume?



It’s almost a complete bottom end!!



Here is a shot of some of the port work...



Okay, some other news... The engine will be assembled using the standard Mazda BP-Z3 cams. My massive race cams are not yet in Australia, thanks to Cat Cams and their failure to deliver. Competition Systems are managing this order for me, but it’s not entirely their fault. I’m disappointed, but at least I’ll be able to put the engine in and work on getting the car running. The cams will have to wait. I may have time to slip them in after it’s tuned and prior to Bathurst, but I guess we’ll see.

So, the head is being done this week, due to be finished before the weekend. Ange, my engine builder, has committed to getting the engine assembled over the weekend, so I will take delivery either Monday or Tuesday at this stage. Yeah baby!!!!

I’ve been beavering away at the wiring, which doesn’t translate to exciting pictures, so I won’t post any. I’ve just been labeling connectors, updating my wiring diagrams and pulling unused wires from my NA6 ECU connector. New wires/connectors will be inserted and run to the sensors in the engine bay as required, but I don’t actually have all the various wire colours yet, so I haven’t created those wire runs.

I mounted the fuel rail onto my spare head tonight. I’m using a 99-00 fuel rail and the 99-00 regulator. This is different to some advice on the web, but it’s a beautiful fit. By a fluke, I managed to get my hands on the 99-00 regulator that doesn’t have a bend in the return line. This makes it perfect for my build. The “VVT Swap Definitive Guide” recommends fitting a 1989 regulator onto the 99-00 fuel rail, but that requires straightening the bent hard-pipe return line. I’m not keen on that.

I’ve had to order a few things this week...
1. Two 2-port sensor blocks: fuel & oil in one (desperate sensors, obviously), and coolant pressure in another. The sensors don’t like being mounted to the engine, apparently, so sensor blocks are my chosen remote-mount solution.
2. Fuel pump: Walbro 255L/hour. This may be overkill, but I don’t want to be on the Dyno and find that I’m running short of fuel. I don’t have time to faff about, so I’m installing it.
3. Coolant pipes, 32mm aluminum, swaged ends. Two 100mm lengths and one 300mm length. These will hopefully neaten up my coolant reroute, which previously used a long rubber hose section. I prefer hard pipes. I’ll post photos when that’s coming together.

My custom ITB inlet manifold has been modeled and I’m getting quotes for manufacture (5-axis CNC using the STEP file from the model). The first quote was $1680, so I’m shopping around. That’s way too much!!!

That’s it for now. Next week is going to be epic!!!!!


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[Daffy]

Its great to see everything just about ready to fire! I’m looking forward to seeing all your hard work in action

[plohl]

I had started a custom itb manifold when I was doing a machining course, but for a few reasons it was never finished

Why do you need a custom manifold? You might be able to find a jenvey set for cheaper than it'll be once you get the manifold done?

The set I had for a while just had some blocks welded to a chopped up manifold, that used the 4age throttles as well.