Where the project is at — what’s next?
Got the car to ~213 bhp N/A on one dyno, ~224bhp on another. Solid torque everywhere, a curve I’m happy with, and a tune that behaves itself. But that’s not the end of the project, it’s just the end of this chapter. So — what next?
Long-term goal is supercharged with some silly numbers (350bhp target). The question I keep coming back to though: is the car actually ready for forced induction yet? (and i dont mean 350! lol. i just mean, a quick and dirty install for a quick power bump)
I don’t think it is. Here’s where my head’s at.
The five buckets
| Bucket |
What |
| A. Side quests (non-power) |
Underfloor v2, bonnet vents, rear wing, bushings |
| B. Power side quests (N/A) |
Intake manifold, exhaust manifold redesign |
| C. BulletProof the engine |
ND1 head rework + forged internals + ND2 crank, run as 11:1 NA |
| D. S/C prep (drivetrain) |
Rear diff, gearbox, clutch, flywheel |
| E. The goal |
Supercharger |
A. Side quests (non-power)
-
Flat underfloor v2 — welding required, brand new design
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Bonnet vents — need fitting
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Rear wing — still in many minds. Not sure what’s right for my taste and application
-
Bushings — wear and tear item. Nothing I can feel or hear yet, but probably time to start considering. New OEM, performance rubber, or poly — undecided
B. Power side quests (NA)
Intake manifold and exhaust manifold (design changes). Bolt-on territory, stack with everything else, fairly low commitment. but will cost some high £££ for these. in reality, good fun to be had here but i think i’ll be chasing very very low Hp return on the £.
C. The big build — the new head
Here’s where it gets interesting. I’ve made solid torque and a good NA result, but the engine isn’t flowing big numbers. Three limiting factors I can see:
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Valve sizes — ND1 vs ND2 is +0.5mm
-
Valve shrouding — looks like ~1/3 of the intake valves are completely shrouded (Mazda design issue)
-
Compression — too high (13:1+) for optimal ignition
I’m debating shipping my now-spare ND1 head off to a specialist for bigger valves, bigger combustion chambers, and porting that uses the ND1 split-port design to advantage. That addresses all three issues in one go.
There should be a torque reduction in favour of high-RPM power — but that’s fine. S/C will fill that void later on.
The plan: pair the head work with bottom-end work. Cheapest way labour-wise — engine’s out once, do everything at the same time. Forged pistons, rods, ND2 crank, run around 11:1 compression as the NA build. That gives me high RPM headroom, room to play with ignition advance, and a bulletproof engine ready for whatever comes next.
After that, everything is essentially bolt-on.
*editors note. Now im thinking about it, the valves here are everything. if the general answer from the tuner is ‘nd2 valves are as big as you will get’ then that knocks most of this bucket on the head… (ha! double pun)
D. S/C prep (drivetrain)
Rear diff, stronger gearbox, clutch, flywheel. None of these are urgent — they’re “before any high power numbers” items. Some of them (clutch/flywheel especially) could go in during the engine-out window for the big build, which would save a second labour bill later.
E. The supercharger
The goal. But it lands on a platform that’s actually ready for it, rather than fighting the limitations the current setup has.
Why NA-first
The case for the big build before any FI:
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The car’s currently knock-limited on fuel at 13:1, i am already seeing ecu pulling timing at certain points. so any boost has to fight that same wall — just with more cylinder pressure stacked on top
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Head flow is the bottleneck above 6,800 rpm regardless of N/A. tbh with a s/c i the RPM limit might not be in the sky (injector limitation), so maybe this isnt so bad…
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Stock internals at 350 bhp isn’t an “if” — it’s a “when”. bottom end MUST get done. and this means the head MUST come out again anyway.
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Tuning a SC on a high-flowing head means less boost needed for the ame power output. keep everything cooler, and extends lifetime.
Plus — there’s still genuinely a lot of fun to be had perfecting the N/A side first. N/A gains multiply later. Every bhp gained N/A is a bhp not asked of boost pressure.
OR DO I:
Just bolt on a s/c as the ‘next step’, gain 30bhp+, and then work through this list accordingly? i think thats going to be my worst option as i will be screwing from day 1 that theres power i cant access, and that i will have to unbolt the s/c again to remove the engine. just more £ in labour.
but worth mentioning as an option.
Open to thoughts.
