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Monitoring Knock/Boost/AFR best practices

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Hi all,

I plan putting a turbo an my NC Miata (2009) and tune it like a big boy! ;) After watching a lot videos most of it seems pretty straight forward, just a lot of experimentation and patience. One thing I should say is that boost will relatively low at first, eg 7-8 PSI, but as upgrade parts (clutch, wheels, tire, intake etc) I plan to push it to 15PSI, still relatively low from what I can gather. Also worth mentioning, this will be on stock ECU, so a reflash. Octane used will be 94 (US specs) or 91 if I can't find any better.

That being said, I know I'll need to be more mindful with a few things, most notably Knock, Boost and AFR. I first had plan to setup a Torque Pro/Android head unit to keep an eye on these parameters but a lot of issues became obvious with this setup, most notably, low refresh rates with most bluetooth adapter, Torque won't be accessible if I plan on using the GPS, need to start the application everytime I get in the car. So I've decided that I would use dedicated gauge pods for both Boost and AFR monitoring.

However, It implies that knock won't be monitored, at least not with a dedicated gauge. I'll have something setup during the time I tune the car but beside that nothing.

So my question is, how safe is that approach once the engine is safely tuned in regard to NOT being monitored for knock ? I know 99% of Turbo cars don't have knock monitor so I'm guessing it's not necessary unless I really want to push the tune to it's limit in which case I'd just use an Octane booster. Also worth mentioning, the ECU will switch to a low or high octane map depending on the amount of knock which adds a small layer of safety.

Do you guys have any recommendation in this regard, let's monitoring best practices ?


hi Chuck, Check this item out for monitoring knock. it is the knock light sold by link just one of the products available on the web but one i have used a lot with great results


Best practice would be to map ignition to MBT/knock limit on a load control dyno then take a couple of degrees out for safety, that should cover all eventualities and be safe providing boost pressure is stable and controlled.

Being an NC it should already have knock monitoring in the OEM ECU so depending on what reflash SW you're going to use this functionality should be maintained. The issue with the driver visually monitoring knock intensity and backing off is that this generally takes too long and the damage will already have been done where as knock control can pull timing on the next ignition event saving the motor. Monitoring knock with a stand alone system is vital for calibrating the ignition map and periodically overchecking and the Link products mentioned above are great, Phormula and Plex also do some great knock monitoring kit.

https://bbrgti.com/collections/mazda-mx-5-nc/products/bbr-stage-one-mazda-mx-5-nc-2005-2015-turbo-upgrade take a look at theses guys for some inspiration

@Ross : That G4KNL looks wonderful although pricey for a DIY initiative.

@Scotty88: The stock ECU does a great job at keeping knock under control and the reflash doesn't take that away.

There more I think of it, I don't think I'll to keep an eye on the knock events as long the ECU is configured to handle those events properly. I mean during the tuning process I'll be extra careful but after that I think I'll just trust the ECU to do it's job.

Thanks guys,


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