Miata Turbo Forum - Boost cars, acquire cats.

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-   -   Passed emissions, hooray (https://www.miataturbo.net/general-miata-chat-9/passed-emissions-hooray-25660/)

tilt 09-04-2008 11:12 AM

Passed emissions, hooray
 
State inspection emissions can be a pain to pass with turbo cars! Thank you for those that posted their results in other threads - they were helpful. Here's my results so it can help others too. ;)

This is on a 1.8L 1995 Miata, T25 turbo no EGR, MSPNP with high res 10g code, and closed loop turned on (wideband corrected, AFR table targeted).

http://tilt.sexyracing.com/miata/tur...sions_2008.gif

Ben 09-04-2008 11:17 AM

Damn, 87 octane FTW
What does the alcohol do?

tilt 09-04-2008 11:31 AM

It burns cleaner than gasoline (lower HC), leans out fuel, and also has a cooling effect (lower NOx). My thought process is to target fuel a little richer than it should be then dump about a quart of alcohol to lean it out and reap the benefits. It may be overkill/unneccessary in some cases but I've had good results doing this method so far. If you do not add alcohol, I would probably target 14.7AFR @ 25MPH and 15.0 @ 15MPH.

Ben 09-04-2008 12:17 PM

Interesting. I targeted 14.7:1 and left timing alone. Passed fine with a new cat.

Most people fail because of High NOx due to aging cat. Which can sometimes be remedied by going a little rich and a little hotter exhaust (retard timing).


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