ok...

so in a nutshell:

richer or leaner than 11.8:1 results in slower flame front, this means you may need more timing to make the same power
richer than stoich = cooler
richer (11:1) = dirty burn, carbon deposits etc
leaner (12:1) = cleaner burn, hotter burn

I would have thought that in an effort to keep temps down, running richer is better???

I do notice a difference in how the engine "sounds" when running 10.5 vs 11.5 - less "grindy" if that makes sense...

 

I'm not 100% on the theory as to why the burn is better when leaner ( I have my ideas but not enough proof to make a confident claim yet), but yeah over rich mixtures tend to burn poorly and also increase the chance for missfire..

Give it a shot and let me know how it works out.. Next evo I do I'll post up some graphs at different AFRs to show the difference in power.. Hopefully they won't delete my post. We posted up a graph a couple days ago and they deleted the post since were not a sponser.

And if you go leaner, you will probably make the same power with less timing due to the effeciency of the burn being better, but MBT will be reached with slightly more advance then if it was richer. All of this of course is assuming you can even reach MBT on this motor without knock on pump gas which I don't think is very likely.

 

That would be good, i don't have _free_ access to a dyno, otherwise i would do it myself.. so it's just road tuning for me...

 

I've been wanting to try your rom out.. I've got a customer thats gonna let us use his EVO8 for testing some parts and what not, and he was down to let me test your rom on his car.. Anything special I need to know? Or just flash and tune like normal??

 

not really... make sure you copy the XML in as well...

depending on what evo8 he has you will need to change a few things around, but thats all explained in the second post in the V7 thread...

 

I'll give $500 to the person that can hit MBT on pump gas on a Evo

- Bryan

 

time to shoot some WATER in man ! my toy has arrived ... post some pix up man. I;m still thinking on how to and where to hook it up. let's do it at the same time and share some ideas but i'm only on water.

 

yeah definatley..

however i need to find this problem first... no point in doing W/I if the car is going back to mitsu for warranty...

 

Good read, I actually noticed this with my car. If I tune for a bit leaner usually the knock goes away. It may be the case that these engines prefer a slightly leaner AFR. Not super lean, just leaner than the norm.

I will we could have direct injection the Sky/Solstice turbo cars run like 12.8/13's AFR at WOT.

 

LOL.. Yeah I doubt it's possible just from the handfull off evos I've done so far.. maybe with a really good manifold and a good sized turbine housing and wheel and some good cams. But I havn't had the chance to do one like that yet.

 

most informative post yet, subscribed. KUDOS to the OP

 

I see these threads pop up every half year or so.

Hopefully we don't start seeing melted pistons after people think they can run 12.5-12.8 AFR's on pump gas

- Bryan

 

E85 comes from a pump in MN, does that count

 

Lol no.

- Bryan

 

My thoughts as well..12 AFR can be just fine for NA K series engines..but for evos/turbo cars it could be dangerous...EGT's will be high...but nonetheless OP has quite interesting points there..subscribed..