A popular "mod" to the Miatas engine is to advance the spark engine from the factory 10 BTDC to 14 BTDC, this moves the peak torque earlier in the rpm range and is claimed to also increase horse power. Now as long as the mixture does not detonate/ping in the combustion chamber before the firing event is this sort of advance safe? Can it put extra stress on the crank/seals? How far can you go with something like this? Can you for example go to a 20 degree advance with the highest octane fuel? How is spark advance generally safe for engines?

People usually do this by changing the cam angle sensors position by rotating it anti clock-wise. Can the same be achieved by changing the timing between the cam shaft and the crank pulley or is this a different type of modification?

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    What year of Miata are we talking about? IIRC, Mazda modified the MX5 engine in the latter 90's to allow for an aftermarket supercharger option (bolt on addition without internal engine modification). This may affect how to answer your question. Mar 31, 2017 at 12:58
  • @Pᴀᴜʟsᴛᴇʀ2 thats very interesting are you talking about the oil feed plug? mine is a 93. Are you also mentioning this because the internals are different in those engines or is it because I wouldn't want to advance timing with boost?
    – method
    Mar 31, 2017 at 17:58
  • The 93 is before the time when Mazda made the engine as I was describing. Mar 31, 2017 at 18:11

1 Answer 1


So, changing the spark timing is easy as you state and the main issue is detonation as you point out - if you stick to the range 10 to 14 BTDC then the stresses should be fine. The manufacturer will have tested to the extreme and chosen a setting giving the "best" performance for what they decided was suitable for the car depending on the quality / range of fuel available in the countries it was to be sold in.

The timing between the crankshaft and the camshaft is not the same and, yes, you could change it but it is VERY dependant on the design of the engine - there may not (probably won't) be enough clearance between the valves and the pistons and if you do alter it you could severely damage the engine.

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    This is a very generic response ... do you have anything specific to the 93 Miata which might help the OP? Mar 31, 2017 at 18:13
  • I'm downvoting this answer because it has very little information about the vehicle in question as well as much in the way useful information at all. Mar 31, 2017 at 18:15

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