RazorLab

iTrader: (8)

I agree.

The only differences I have seen in my 10+yrs of tuning experience is that the wideband in the tailpipe lags behind a little at the onset of load/boost. (When logging both widebands pre cat and post cat.)

LetsGetThisDone

iTrader: (1)

Modern cat's introduce their own oxidizer into the exhaust to burn any excess hydrocarbons and don't generally effect AF ratio seen by a tail pipe sniffer.

nemsin

iTrader: (19)

I have been to enough dyno days to quess that 350whp is probably a full bolt on 92oct street tune.

danb

Can someone clarify all this motorhead jargon into something an old fart like me can understand regarding the settings? Is here or is there not an issue with the engine settings for the FE? I am not planning on pushing the limits of my car, but would be forever in someones debt if the issues can be explained in laymen's terms.
Thanks

LetsGetThisDone

iTrader: (1)

There is no issue. You're fine. Drive the car, have fun, don't worry. In connecticcut, you probably have 93 octane anyways, so you're even more fine.

danb

Thanks for responding. Good to know CT has some good things going for it!!

e_kobz

iTrader: (36)

I was curious if it was 91 cause I did 355/355 on crappy ACN 91

Gh3ttoRoM3o

iTrader: (1)

Now only if we could get more e85 spots. Since the ones we have are like concentrated in one small *** radius.. -.-

UT_EvoX

Do you not know how combustion works?

Any raw O2 left in the exhaust will be consumed as extra fuel and other combustion byproducts are combusted and catalyzed in the cat. The Evo X has a two-stage cat unit (that's why it's so big), so it drastically affects the tailpipe wideband reading.

Fuel burning = combustion... O2 is consumed in order for combustion to occur. Ignition source, oxidizer, fuel. What am I missing in explaining this?

An HFC makes very little difference however. Usually 0.2 - 0.3 AFR.


Anyway, as I suspected, I was correct. The Final Edition map can't hold up on 91. Here are my findings as posted elsewhere: https://www.boostedforums.net/showth...ll=1#post12656

RazorLab

iTrader: (8)

I have nothing to say to this other then your attitude is really unappealing and toxic some times.

You are dismissing years of experience in the real world.

Your findings: "In the mid-range they were pegged at 10.0 AFR floor on our wideband probe, and then 5500+ we started to see it climb to 10.5 AFR or so until 6500+ RPM"

How is that too lean? It's totally inline with what both Aaron and I have seen logging and tuning FE's (With widebands pre AND post cat), even before you logged a wideband on one.

You are blinded by your righteousness of having to be correct. It's a bit shocking, to be honest.

This will be my last post about it, I have zero interest in having a conversation with somebody this stubborn and toxic in his replies.

e_kobz

iTrader: (36)

I'm pretty sure he does being one of the best Evo tuners in the country

UT_EvoX

I've also been dyno tuning since 2007. So I have my own YEARS of experience data logging in the real world.

Did you see the logs? I don't give a **** what the tailpipe sniffer read, as I had stated, it's irrelevant.

You guys are so stuck on AFR being "safe" or "not safe" and not the combination of AFR + timing advance and placement of PCP...

UT_EvoX

In summary from my linked findings: after three pulls on the stock FE map on 91, we experienced 11 knock sum up top.

Heat soak was not an issue as shown by IAT and MAT on that log.

Read my whole explanation if you have any skepticism about this whatsoever, because then I got the car further heat soaked to finish up tuning on a 3-port EBCS and was able to deliver more power and peak torque safely over the knock-happy FE map.

Again, this is on 91 at 4500' elevation.

LetsGetThisDone

iTrader: (1)

You're missing that the catalytic converter IS the oxidizer. It doesn't use the oxygen present in the exhaust. That is why its called a catalyst.


http://auto.howstuffworks.com/catalytic-converter.htm


Go to the 3rd page and see how it works. I'll cliff it for you: the first stage brakes apart the NOx, which ADDS oxygen to the exhaust, the 2nd stage then uses the additional oxygen to burn the excess hydrocarbons. So you end up with near zero net change in O2 coming out the tailpipe. As evidenced by NGK's website saying placing the wideband after the cat makes no significant difference, it's a <.2 (digit, not percentage) change in AFR.


http://www.airfuelratio.com/qna.htm#22


"Q: Will installing the AFR sensor after the catalytic converter affect the readings?
Answer: The reading are shifted slightly but are generally less than 0.2 AFR. For most engine tuning this is a small difference and are not a large influence."

I think a company that manufactures and sells wideband O2 systems has a better knowledge of this than you. Given the empirical data Aaron has gathered by tuning 5-10 evo's a week for the past (IDK how long), and razorlab's input, you are barking up a tree that doesn't even have a squirrel in it.

UT_EvoX

That's completely untrue for a factory two-stage catalytic converter. I guess I'll throw a test pipe on just to show this to you...

Ignoring all other components of the chemical reaction chain, take the original fuel and the original remaining oxygen into account. That fuel combusts as it travels through the cat, and the oxygen is the oxidizer in the combustion chemical reaction.

The oxygen produced by breaking down the NOx and such is consumed in other parts of the catalyst chain, yes, but this doesn't change the fuel and O2 components that were there to begin with, and have now combusted whereby converting the O2 into CO2 and CO.

You're over-thinking this to try to prove me wrong, and you're just incorrect.

The 0.2 AFR figure is true for a wideband sensor and an HFC-style cat or a single-stage stock pre-cat, but doesn't hold anecdotally true for any stock-catted Evo X I've worked with. They will always read richer at the tailpipe sniffer.