Hi Phil and I am very sorry to hear about these misfortunes. Did the VVT actuator give in right at the same time as the conrod let go?



Unfortunately there are many stories with the MPS cars blowing up. This is especially true of the MPS6 since it generates a higher load on the engine being AWD and heavier - even ones that are completely stock. I have myself done in-depth analysis of what goes on with these cars and it appears that detonation kills the engines slowly, the rods bend, and eventually give up. Mazda has calibrated these cars very aggressively in terms of VVT from the factory (which causes a high dynamic compression ratio) and on the highway it is common for the car to stumble when you get on the throttle after a longer cruise. Have you noticed this with yours? Also a tell-tale sign of the engine starting to let go are vibrations in the clutch pedal. Did you experience these?

Going off this then, what should be replace to prevent this? Any links anyone? And more importantly, how much we talking?

The root cause is aggressive VVT timing and very hot combustion. It causes some severe detonation that over time weakens the conrods and they let go. This is of course unless something else happened at the shop. Starting with 2010, the VVT timing was revamped from the factory and new pistons fitted to the DISI engine and the cars no longer blow up.



On my own MPS3 I had the same issues and have resolved them with a reduction in VVT timing - and since then I have not had the car stumble once. All the MPS cars I tune I make these changes to keep them safe but it is sometimes too late as the damage is done over time.



There are many resources on blown speeds here: http://www.mazdaspeedforums.org/forum/f10/mazdaspeed-2-3l-disi-turbo-blown-engine-resource-thread-6113/



I can refund you the price for the tune to help things out a little.



Thank you,

Alex