I can't tell if that exhaust leak is coming from between the flange/gasket or from the actual weld area. Can you?

Can someone educate me why a leak like this is bad? Aside from the fact that ideally it shouldn't. I don't see it hurting the car unless the leak was before the turbo or wideband.

 

It is coming from the weld area. It was a pinhole leak from the weld. The soot just spread from the pinhole all over the falange.

The pinhole can corrupt the AFR signal even if it is after the wideband. It is not likely, but it is possible. That is why you should not have any leaks in the exhaust.

 

However no doubt it makes power that way. Unfortunately evo's like to spin rod bearings to begin with and forcing the car to detonate will take the bearings out even quicker. I actually started tuning evo's from DSM's because a good friend spun a rod bearing at an autocross from a mail in tune. Thats yet another thing that I don't get, how can you do a good job tuning a car that you can't sit in, hear, and feel is beyond me. Block tuning the timing took out his rod bearing, heated up the crank and ruined it. I'd have to check but it took about 10K miles for this to happen.

 

Of course. I am just curious about your AFR technique. So, on 91 octane, do you also aim for close to 12 AFR? How stable do you see that on 91?

 

I just checked the boost logs in 4th gear on this Evo and compared them to the 3rd gear. I was able to achieve the same peak average boost in both



This is the second Evo that I have used this method on. Mine was the first, the test mule

 

I'd say those are pretty damn near exact.

 

I don't have hardly any experience working with 91. I ran 89 octane in my car one day to try to save gas but that was retarded and I'll never try it again.

I do go from race gas to pump gas in my DSM a lot. Last time out I was running 25psi boost and hovering around 12.0:1 with 5 degrees peak torque to 17 degrees at 7000rpm's. On pump gas I keep my fuel exactly the same, same boost at peak torque but only ramp it up to 10-12 degrees at 7000rpm's. I run the same 25psi boost. If it was summer I'd probably have to drop it to 22psi but I still wouldn't change my fuel. If you send me a PM with your email I can send you a log of some pump gas pulls.

 

Is this with a larger turbo and a ported and built head? Do you also try to keep this strategy on stock turbo/stock motor Evo's?

 

I have ran mid 12's on my stock turbo evo. Right now its high 11's mainly because I'm too lazy to reflash it. The DSM has seen 12.6's on race gas and 30psi, 12.2's on pump gas and 26psi, and currently sits at high 11's and 12.0 at 25psi on pump gas. When I pull the head on the DSM everything is nice and tan, really great looking stuff and real clean.

Last year I went 11.5 at 130 on the stock longblock, ARP's, and stock cams 12.6:1 AFR. This spring I went 12.0 at 122 on a built motor, cams, and the stock 14b weenie turbo (half the size of an evo turbo). Since then I put the 50 trim back on but haven't made a noteworthy pass as I've broken 2 cam angle sensors and am running into ignition breakup issues over 25psi. I can only run it to 7K rpm.

 

I call shenanigans on this high flow cat business causing loss of power. A properly constructed HFC should have no perceivable effect on cars making less than 500 horsepower. Even beyond that, I would still question any affect attributed to a properly sized and functioning cat/exhaust system.

True story: My car (1G Talon with a big 16G) was at AMS 2 weeks ago getting tuned. Put it on the dyno, and spool and power were poo. After checking over the car and the only problem we found being a wastegate that only closed 90% of the way (fixed by bending the actuator) we concluded the car had a clogged cat. Took the car off the dyno, removed the catback and put it back on. Car made better power instantly. Conclusion? The cat was in fact clogged.

Also, we were initially getting all kinds of erratic knock even at *really* conservative timing and boost. Removing the cat fixed this instantly. Got the car tuned up without a catback and made respectable power (275awhp/275tq). Spool up problems disappeared, as did the knock.

Just for ****s and giggles, I wanted to see one more dyno run after the cat was back on. Guess what? No loss! Imagine that.

Conclusion: I am willing to go out on a limb and say that the "high flow" cat on this car is at least SOMEWHAT clogged, hence the gains you saw from a test pipe. The fact that the car in question was running uber-rich backs up my theory.

As an aside, I also find it extremely environmentally irresponsible to not be running a cat, in Southern California/L.A. of all places. You guys have the worst smog in the country next to New Jersey, and having a bunch of idiots run around without cats isn't helping this any.

 

Taken to PMs.

 

Every little bit helps! Think about the children!

Seriously though, do you leave your lights and your shower on all day? ...probably not because that only impacts you directly within a month or so....

 

You really have no clue, do you? Neither you nor I have any idea how many people are out there removing their cat, but anecdotal evidence around these forums and performance forums for other manufacturers suggest that it is quite a few. Frankly, it doesn't matter what % of cars on the road it is, as it all adds up.

I guess what I don't understand is what makes you so g-ddamn special to think the rules don't apply to you. This is EARTH, we all live here, and honestly it really pisses me off that jag bags like you are driving around cat-less on a daily basis because you can rationalize your actions to yourself

Only in good ol' do you find such selfish people with overinflated senses of entitlement. Enjoy your "extra horespower"

 

Great job Naji! Welcome to the looney tuned club!
Looney Tuned FTW!
<still running stock CAT... LOL

 

I think you have it there. Take gallons of unnecessary extra fuel, dump it into a cat, bring the temps up to 900-1000 degrees, and **BAM** you have melting-flow clogging-catalytic soup.