Looks a little high to me. Anyone know for sure? -thanks

 

You're fine.

 

Whew... Thanks Cody. Would the addition of a cat-back to my mods lean me out some?

 

you are fine as far as danger is concerned, but for best power, I believe 12.5-12.8 is the optimum ratio.

 

Latest I have heard is 12.8 -13.3 according to TS.

 

That is interesting because we had a Z with TS ECU at Dyno day and in addition to a disappointing 231 HP he was running between 14-15.

 

A/F looks great! You are not running lean.

 

Outstanding. I guess the R/T Cat discussions about them causing you to run lean is not apparent with my setup then. thanks for the reply's.

 

Yo Anthz, where you get your work/dyno done at? Im in Austin too and was jes curious.

 

How lean is lean? how rich is rich? The higher the number the leaner the fuel is??

 

Got the work done (intake and cats install) at Protech Performance http://www.ptpmotorsports.com/ (ask for jesse)

Dyno was done at Colvin Automotive off of 45th.

 

Personally, I think you are running lean. Your at or near 14 all the way up to around 5k RPM. This is exactly what my a/f looked like (I have the RT cats and TS ECU) untill I talked to Doug at Crawford and Danny at TS.

TS now has a program specifically for the RT cats that keeps your a/f in a range from 12.8-13.2. This is the range they and Crawford like. I went from 244 hp/242 tq to 253 hp/250 TQ just from having TS redo my ECU to get the a/f right.

 

Interesting. Thanks

 

lean bump @ 3.5-4.5k seems to be common with RT cats. I believe it may have something to with the location of the o2 bung.

 

Your A/F ratios appear to be high in my opinion. The majority of the graph is well over the comfort zone of 12.8:1. Well if you are still running NA i dont think it will affect your motor as adversly as it would on a FI application. With that kind of A/F ratio and turbo it is a formula for disaster.

 

The theory behind the O2 sensor is that an engine running at correct air-fuel ration of 14.7:1 will consume all of the oxygen and all of the fuel simultaneously. If the engine is running rich, then the oxygen will be consumed before the fuel. The average oxygen sensor has difficulty distinguishing between a rich-running and perfect-running engine. However, a lean running engine will leave large amounts of residual oxygen in the exhaust.

How can you say he is running lean, I don't think his car is running dangerously lean, its just running like most Z's do. I idle at 14.7 to 15.2 A/F ratio, would you call that lean? Under WOT, the car should start out in the high 13's even 14's and then slowly come down to ~12's near 6,000 RPM. Now maybe high 13's under WOT is lean to some people, but under normal curcumstances on a N/A engine this is how we keep emissions down. I am running high 13's A/F ratio in my car at WOT, and put out 263 RWhp. (Origional baseline was 232.) I have put in Injen exhaust, crawford plenum and cats, and Nismo headers and my A/F ration is the same as it was when the car was all stock. Now maybe the ideal A/F ratio is in the mid 12's for maximum power, that is what Crawford and TS are talking about, but this guys A/F ratio's is perfectly fine for a N/A setup, just don't run a 100 shot of nitrous through engine and everything will be ok. Also I have a Wideband UEGO O2 sensor in my car, so I get to constantly see my A/F ratios.

Now if this guy was runing a 15 A/F ratio at 6,500 RPM, then I might worry a bit.

 

"The theory behind the O2 sensor is that an engine running at correct air-fuel ration of 14.7:1 will consume all of the oxygen and all of the fuel simultaneously. If the engine is running rich, then the oxygen will be consumed before the fuel. The average oxygen sensor has difficulty distinguishing between a rich-running and perfect-running engine. However, a lean running engine will leave large amounts of residual oxygen in the exhaust."

How can you say he is running lean, I don't think his car is running dangerously lean, its just running like most Z's do. I idle at 14.7 to 15.2 A/F ratio, would you call that lean? Under WOT, the car should start out in the high 13's even 14's and then slowly come down to ~12's near 6,000 RPM. Now maybe high 13's under WOT is lean to some people, but under normal curcumstances on a N/A engine this is how we keep emissions down. I am running high 13's A/F ratio in my car at WOT, and put out 263 RWhp. (Origional baseline was 232.) I have put in Injen exhaust, crawford plenum and cats, and Nismo headers and my A/F ration is the same as it was when the car was all stock. Now maybe the ideal A/F ratio is in the mid 12's for maximum power, that is what Crawford and TS are talking about, but this guys A/F ratio's is perfectly fine for a N/A setup, just don't run a 100 shot of nitrous through engine and everything will be ok. Also I have a Wideband UEGO O2 sensor in my car, so I get to constantly see my A/F ratios.

Now if this guy was runing a 15 A/F ratio at 6,500 RPM, then I might worry a bit.

Someone please educate me if I am wrong