I noticed Stillen is selling test pipes for around $250. Are you guys buying the cats because of emissions? sound? It seems that a set of test pipes would alleviate worries about sucking in the cat's guts and they're cheaper.



03 Sedan ~ 5AT ~ aero ~ 19x8" Axis wheels ~ Tein H-Tech springs ~ Garnet ~ premium ~ NISMO body kit ~ clear front corners ~ Stillen Cat-back ~ Injen CAI ~ Crawford plenum ~ TS ECU

 

I talked to tadashi face-to-face yesterday at technosquare. he was telling me with a high flow cats that the stock ecu will lean out the mixture too much(17 and 18 a/f!) and the cats will get too hot. that's why these cats are falling apart. they need to flash their ecu's for the high flow cats so the computer will spray more fuel.

 

Interesting fact with an air cooled aviation engine that I'm sure applies here as well: There is a point on the A/F curve where a lean condition will actually REDUCE your exhaust temps. Unless he's measured this I would speculate he's speculating.

On my plane I have an exhaust temperature gauge as well as a fuel mixture **** and fuel totalizer. I can lean the mixture and watch the EGT climb and climb and if I keep leaning the temps will begin to go down.

I'm no ECU expert, but when the A/F gets that high, what does it do? I'd be interested to know how Tadashi arrived at this conclusion. Did he take EGT measurements and correlate to A/F ratio? Is the same true on a 2004.5? (As far as I know they haven't cracked that ECU yet).

2004.5 Coupe/5AT/Ivory/Everything but front spoiler/Nismo CAI/Crawford V5

 

I'm actually surprised the ECU doesn't have a fail safe and retard timing and enrich with fuel when A/F gets too high. What happens is the charge gets very hot, in extreme cases, detonation can occur and/or you can throw a rod. I doubt that would happen here, though. It would be easier in a FI car where the charge is too lean and more dense, then you really run those risks.

I can't believe the exhaust gases are getting so hot they screw up the cats. If so, those are some weak cats. I see temps up to 1800c on my car, but it's turbocharged. I'm not disputing TS, I think they are correct that the ECU should be adjusted, I just can't believe how weak those cats are.

 

does anyone know the difference in exhaust temps from a vq running stoich and one that is running in the +16/1?

 

bunnone IM'd me with the following message...

<blockquote><font class="small">In reply to:</font><hr>

I have the Crawford cats and love them. I did however, ask Doug Crawford why this is happening with RT's. He said it could happen with any of the cats. The prob is not waiting until they warm up, causes the filter element inside to become weak and break. No {edited} high revs to warm up the car and race. Must warm up first, then should be OK. Regards, bunnone.


<hr></blockquote>

Apparently there just might be something to this theory.

301-bhp!!! ...and growing!

 

Yes...It is imperative with any hf cats to let the car warm up before getting on it. I ususally drive the first mile or 2 keeping the revs under 3k, or at least until the water temp comes up.

Also, I have pop-charger, borla exhaust, and r/t cats. When I dyno'd, I had a pretty perfect a/f ratio for N/A. Take a look: http://img78.photobucket.com/albums/...2/f96ca40a.jpg

btw, I've had my cats for ~5k miles, no problems whatsoever.

<P ID="edit"><FONT class="small"><EM>Edited by cryhavok on 06/17/04 03:09 PM.</EM></FONT></P>

 

I dont know why....well I do....why Technosquare keeps telling people they are going to run lean....The reason the cats are going bad is that to much fuel...running rich...makes cats fail...I guess he has made alot of cash with that statement...and when you get your ECU back from him your running a little to rich...as was my car...12.5 to 1 is to rich for a N/A car

Couldnt afford it when young...gonna play when Im old

 

Say what 12.5 AF is ideal at the torque peak rpm and 12.1 AF is usually ideal at the HP peak rpm.........any extra richness is programmed by factory to cool combustion chambers since knock sensors/ecu run out of calculation time above 5,000 rpm.......unable to descriminate between accelration noise and real knock.

Usually above the speced HP peak rpm the engine goes dead rich to protect cats.......works for 15 seconds but after that the cats over heat..........why you shouldn't hold redline for long.......the cats would need to be 4-6 times larger to dissapated WOT heat in a road race exceeding a few minutes.

95% of dyno shops don't have very accurate AF meters and most don't take the hours [customer charges] necessary to install bungs prior to cats [the only accurate spot when trying to read richer than 12:1AF.

The cat action [storing and releasing oxygen always makes tail pipe reading appear lean]. You would think they would know this and explain to customer but they charge extra for AF readings even though they may be inaccurate.

 

yes 12.5 is good A/F at high rpm's .But at low rpm's its not...to rich...as soon as I got into the throttle it dropped to 12.5 ...at around 3,500 rpms .The A/F should gradually drop as rpm's increase

Couldnt afford it when young...gonna play when Im old

 

You would think that the same percentage of people with Crawford and Kinetix cats would be "not letting the cats warm up" at the same rate as the R/T people, thus experiencing the same rate of failure.. I haven't noticed any of them complaining. It appears that the R/Ts may be more susceptible to failure than the others.

2004.5 Coupe/5AT/Ivory/Everything but front spoiler/Nismo CAI/Crawford V5

 

Consider that regulations require oem cats to still be functional to 100k.............ever see that kind of warranty on after markets which are supposed to last 25,000 miles minimum but most don't. They get you thru another year of emission testing that's about it.

Since most states don't dyno [just you MIL data] on newer cars the owners don't realize th cats are worthless unless they just melt and clog.

Hopefully EPA will wise up and demand dyno test after a visual shows changed cats..........even on new cars.

The tiny gains are just not worth the hassles and costs.