OK so its all off again, and I've got the core out and found there was a tiny leak on the core. a healthy dollop of steel reinforced epoxy and then used a vaccum pump to draw the glue in. once set this seems to have done the trick as it now holds pressure
so all ready to go back on, once I've swapped the core engine over , back to running NA now which feels quite slow....
on a side topic thought I'd show the method I've used to dial in the spark
with the tune tweaked to allow the 'knock retard' channel so its logged on Tactrix you can drive around then analyse the data with Mazda edit
you then get this
you can see the retard channel occasionally spiking
highlight the part you want ( ie once its warmed up) and then use the custom template to copy the spark map as a template to give you a map overlay that matches the ignition timing map
then you can see how much retard the ECU is applying and tickle the map accordingly
Last edited by 350matt on Tue May 05, 2026 7:12 am, edited 2 times in total.
I should also say that even on NA the knock retard is active and pulling spark on the higher loads, not much tweaking 1-2 degrees here and there - this is normal practice for a modern car
The knock sensors on these engines are renowned for false positives as the engine vibrates naturally at the resonance frequency of the sensor.
The oem PCM load doesn't gradually retard in response, it just ignores, to point, and then panics.
The result can feel like the traction control kicking in.
Old oem or some aftermarket engine mounts can make this more likely, as can having the exhaust joint at the rear of the cat clamped solid.
The easiest way to confirm diagnosis is to (temporarily) unbolt the sensor from the engine.
Even with an lp supercharger, you shouldn't be close to inducing knock, as there's no benefit from pushing ignition advance.
Can't say I agree with that Dave as with the charger fitted the knock retard is definitely more active and you can hear the knock when it comes in, so pulling spark once boosted is prudent even at this low level of boost
NA power at the wheels on a hub dyno and corrected to ISO1585, 188 Bhp
1st attempt with SC 203Bhp
Best SC power, same dyno and corrected the same 208Bhp having tweaked the cal and fitted a better intercooler pump
With octane booster 211 Bhp
OK its not much more in the grand scheme of things but 20-25 Hp across the rev range is rather useful and it makes a splendid noise
New pullies are in the works to tease a bit more boost out of it as it 3-4 psi at the moment with the boost dropping by that 1psi over 8000rpm so need to get it spinning a bit quicker
