In an All-Motor application, in regards to the air-fuel ratio, what is considered too rich, where one should be concerned about washing out their rings?

I see a lot of dyno sheets where people shoot for the magic number of ~13.1 AFR.

Would say, 12.1 AFR on a WOT pass be something to worry about?

Furthermore, it seems that the fuel acts as a cooling agent, and if you run lean, the combustion chambers can potentially get too hot and melt. (with that said, I'd rather flood my rings and replace them than melt them altogether)

Just curious, hopefully someone can educate me.

 

Its a hard call to make but from what I have seen, the ratios have to be pretty far off to do serious damage. Really depends on the setup though. 12:1 for a wot pass is not going to hurt. if the ecu is literally dumping fuel at part throttle and idle you may stand a chance of washing the rings out. And unless you are really ******* it lean under very hard loads you are likely not damaging anything on an all motor car. Turbo cars have more heat and pressure and bad things can happen very quickly if someone is not careful, especially with forged pistons that can expand very rapidly.


Modified by Runnerdown at 1:25 AM 12/1/2007

 

now that's the kind of knowledge i'm looking for, thanks runnerdown

(my street tune is in the 12's at WOT, but it still works after 28,000 miles, and I feel much better after reading that)

 

I do not dispute ANYTHING Runnerdown said but feeling better about anything after you have read about it on the internet is not smart.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Natural Aspirations &raquo;</TD></TR><TR><TD CLASS="quote">I do not dispute ANYTHING Runnerdown said but feeling better about anything after you have read about it on the internet is not smart.</TD></TR></TABLE>

LOL very true. However I have been here long enough to have an idea of who has knowledge and experience on this forum, and I believe he qualifies.

 

Its a tough subject to get specific about numbers and such, just too many variables. Sort of a general sum of what I have seen over the years.

I have a collection of damaged pistons, spun bearings and various other abused engine parts that I have removed from cars and I like to study how and why they failed. Maybe I could post some pictures up, I have some good ones..... and the storys behind them.

 

No dis-respect meant, just making a point

 

I would say the same thing.

Seems like 75% of advice given on this site is sketchy at best and often times given by people who don't really know, just regurgitated info that sounded good at the time.

 

Just from my personal experience with them, you can't really shoot for a magic number when tuning anything. My all motor car was tuned to a 12.0-12.2 AFR under WOT because that was where it made the most power. Both HP and Tq would fall off (not significantly mind you) with the so called magical 13.1 AFR. Since we are dealing with all motor 4 cylinders though, 4-5 whp is enough for me to want it where it makes power, not where the internet says it "should" be.

 

bump for some good info!!

 

This is better info than I have seen on most posts. I was wondering about the same thing for my car. If anyone else has some input I wouldn't mind reading more either.

 

Im having a problem with my Acura Cl it has a F22b vtech. It will run leaner as the fuel level goes down. My question is does this sound like a fuel pump getting weak as the fuel temperature goes up and pumping less fuel to the engine. I checked the plugs today after i filled up and went for a drive they were brown still a little light for what I would like to see.