We were massively surprised by the outcome of the dyno testing of our SR1 Supercharger kit. Granted, this engine has a 4-1 (used, old-school) exhaust manifold and a 17% reduction pulley but still… We turned up and the first pull netted us 160WHP, which isn’t far off what we expected to leave with – as that’s about 180BHP, not bad for a 1.6.

Without boost tuning to worry about, playing with the timing and fueling netted us 196WHP (220-230BHP) at the HUBS! We were absolutely jumping, high fives all around. With the 4-1 header providing about as good flow through the head as is possible, we turned the timing up until it returned no more power at the top of the rev range. Typically, this means we’ve found MBT (maximum brake torque) for this combination at that RPM (5500-7000).

It’s a little knock limited between 3500-4500rpm, as is common around peak torque, on a mix of 95RON and VPower. But we’re not done yet, we’ve picked up a set of used HKS 264 cams and while I can’t find too much info on the exact specifications of them, based on the 9mm lift I’m expecting a 10-15WHP increase at the top end. You can see the torque fall off at the end with the boost increasing, which means there is a restriction of flow, more lift and duration should allow that airflow to carry to the end.

We have a little running joke, that this car is at a disadvantage of power vs the turbo cars it’s allowed AR-1 tyres at 5Fest in Llandow (which is like 4 weeks away and leaf is still broken and we have 2 engines to run in!) but now we’re regretting that decision. I’ll have to turn it down again and tell Leigh “It might blow up, better make it slower” just so I don’t have to be bullied out of the way by this utter weapon.

Seriously. This thing is an absolute RIOT.

Anyway, here’s a dyno plot – and a shot at Cadwell, enjoy!

Want to turn your MX5 into a screaming banshee?


  1. Andrew 21st June 2019

    Hi, Where can I get one of the front lips that the red supercharged Mk1 has on?

  2. Robert Colvin 26th September 2019

    What sort of power gains can I get with the supercharger kit on a 18vvt.? And what does the kit comprise of?. Thanks in advance.

    1. Daniel Marshall 26th September 2019

      Hi Robert,

      It includes an ECU, Injectors, Intercooler Kit, Bypass Valve, Twin Piston BOV, Supercharger and Salon Motorsports Fitting KIt.

      200WHP would be a reasonable expectation on a 1.8VVT, perhaps a touch more.

  3. Virgil 27th September 2019

    What PSI figures did you get running the 17% reduction pulley?
    Did you consider of upgrading the crank pulley as well?

    1. Daniel Marshall 27th September 2019

      It’s running about 8-9psi.

      17% is already about the upper limit of how much you’d want to overspin the supercharger at 7200rpm engine speed, so no need to change the crank pulley.

      1. Virgil 27th September 2019

        What is the pulley diameter with 17% reduction?


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