Euro 3.0 Pistons Passing California Smog?

[86 911]

I'm currently rebuilding my 1978 911 SC engine. Depending on what my machine shop tells me about the condition of my existing pistons & cylinders, I may want to upgrade my pistons to the higher compression Mahle Euro 9.8:1 piston. I was told that the higher compression will make the engine run a little hotter and increase the NOx.

Is anyone here running Euro 9.8:1 pistons in California? If so, have you had any issues passing smog? I've searched but have only seen 10+ year old threads. Interested to see if there are more recent experiences.

[runner4fun]

I have a set of the Euro 9.8:1 pistons and cylinders available for sale. The cylinders have been honed and are ready to be installed. I was going to use the set on my SC engine rebuild but decided to go a different direction.

I can't comment on passing CA emissions.

[86 911]

PM sent!

[PeteKz]

The increased CR should not affect your emissions significantly. What are your current smog test results?

[AndrewCologne]

Originally Posted by 86 911

I'm currently rebuilding my 1978 911 SC engine. Depending on what my machine shop tells me about the condition of my existing pistons & cylinders, I may want to upgrade my pistons to the higher compression Mahle Euro 9.8:1 piston. I was told that the higher compression will make the engine run a little hotter and increase the NOx.

Is anyone here running Euro 9.8:1 pistons in California? If so, have you had any issues passing smog? I've searched but have only seen 10+ year old threads. Interested to see if there are more recent experiences.

Hotter engine running does not affect NOx in a way not passing smog test.
What lets NOx rise is a too lean mixture. So you just should set the CO correctly, thats it.

[86 911]

I pulled my previous results and they were well below half of the max. allowable values. Thanks for easing my nerves if I go this route.