https://www.miataturbo.net/ For all you misguided souls. en Sat, 16 May 2026 05:58:58 GMT vBulletin 60 https://www.miataturbo.net/mt2011/images_td/misc/rss.jpg https://www.miataturbo.net/ https://www.miataturbo.net/supercharger-discussion-38/what-expect-my-m45-setup-111213/ Sun, 05 Apr 2026 21:12:10 GMT Hi everyone! I'm new here. As a short intro, I have owned my MX-5 for 10 years now in Spain and finally decided to supercharge it. So far I think it is working well but I'm not sure about a couple of things and decided to ask the experts here.
My setup:

• 2002 Mazda MX-5 1.8VVT
• Engine rebuild recently
• Megasquirt 3, 640cc BOSCH Injectors and AEM wideband.
• M45 Supercharger from Mini Cooper S with KAVS 17% pulley
• Intercooler with 2.25" pipes
• Dual throttle bodies
• Coolant re-route, upgraded radiator and other non-relevant stuff

I have made a safe tune to test everything and the car is running fine, I can already feel more power. But I want to make sure everything is perfect before taking it to a professional tuner.

My main question is the boost that I'm able to make with this setup. I've read somewhere that the M45 with the smaller pulley should get around 8 PSI but I'm seeing 5.2 PSI maximmum. The thing is that it reaches peak PSI quite early and then it stops rising even if the rpm increases:


The red line in this graph is the MAP and as you can see it gets more or less stuck at 130 kPa (~5 psi) from about 3300 rpm. It seems that I have no leaks and the belt does not slip.
White is RPM and green is TPS.
Any ideas why I'm not making more boost? Maybe Bypass valve leak? It looks fine. Maybe this what you get with the 1.8 and M45?

I have logged some pulls, please let me know if you need me to show anything else.

thanks!

Mark.





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