s2konroids

It depends on parts really, the length of the primaries on the header,manifold, length/diameter of exhaust etc etc.

Its certainly not going to run lean all the way through the rev range (it will run too lean in some areas i gaurantee that), I know its a bit different but my AP1 ran too lean and actually too rich in some areas and i have all bolt on's - i tuned it though.

Its WOT you need to be concerned with where the AFR should not exceed 13.2 to be on the safe side.

Narrowband is pretty useless for tuning.

Cheers

iDomN8U

The numerous charts i've seen with A/F ratios have shown lean (14, 15, 16) in ap2 with I/H/E

Are you running lean in WOT? I would say so. Am I sure? No, go get a A/F reading on a dyno going WOT.

A/F in WOT changed in 04-05 and even more lean 06+

drewmob

(See mod list below) I'm running h/tp/e with a drop-in and my afrs *are* leaner than factory trim. I see 12.8s @ WOT on my early ap1 ecu (which is known to run rich.) IIRC an early ap1 can be in the high 11s to low 12s @ WOT? I know later model ecus only got leaner so I'd be even more inclined to worry about afrs on an ap2.

I intend to keep my car for a long time so I'm very concerned about engine health. For that reason I bought the Uego. I highly recommend a wide-band to anyone that intends to put their car through its' paces.

Chris S2K

Thanks for all the input guys, obviously, my main concern here is to get a better understanding of how bolt-on mods affect the engine and possibly mitigate the risk of damage on the engine. But I'm still not sure if I fully understand this yet.

I was finally able to find some A/F graphs on a stock engine (AP# unspecified) and this particular engine runs a bit lean at partial throttle, but rich at WOT (which is safe). Is this a graph of an AP1? It makes sense to me that Honda engineers would have made the engine run rich in WOT in order to protect it from detonation, but I'm now hearing conflicting stories on that

https://www.s2ki.com/forums/index.php?showt...0&#entry6505186

Drewmob - thanks for posting; looks more and more like I should be getting a wideband.

rps13sr

what you stated means running richer after the mods.

lets say 14.7-1 ratio is stock air-fuel ratio

when u mod it and you see your wideband go to 13-1 or 12-1 that means its getting richer in fuel.

air =14.7
fuel =1

now lets say u get 10-1

air=10
fuel =1

that means less air to the same part fuel means you are getting more fuel at 10-1 than at 14.7-1 which means you running richer than 14.7-1

anyone please correct me if you know for a fact that what i said.. thank you

drewmob

Your argument is flawed from the beginning. 14.7 is stoich, but not stock. Stock @ WOT is MUCH richer than stoich, especially in an AP1.

In my comments that you quoted, I stated that I went from high 11s-low 12s @ WOT (STOCK) to around 12.8 @ WOT (modded.) This means that I was running significantly leaner after modifications. FWIW, I do run pretty close to stoich @ idle...

Later model ECUs ran progressively leaner from the factory which *can* cause them to run lean after significant airflow mods (i/h/tp/e...) I'm not sure where the danger line is here since my knowledge is relative to my car.

Like I said before, it is best to keep an eye on your afrs as you modify your car...

Hope this helps.

Chris S2K

Has anyone heard/read stories of anyone damaging their engine from running too lean from bolt-on mods?

drewmob

its more of a long-term wear issue as opposed to a retainer cracking and immediately destroying an engine.

rps13sr

[QUOTE=drewmob,Nov 10 2009, 12:19 PM] Your argument is flawed from the beginning.

drewmob

Yeah, as a generalization cars run rich @ WOT from the factory.