Should there be flames?

[Comper100]

Hiya all

This has happend on a few occations that i know of, but a few months ago me and a freind did some filming (all under the limit ). and after a hard run i let off and the video picks up some yellow flames from the exhaust, also last night i was going to a party in convoy and i went past my mate after an AMG (silly me) and flat out between gear changes he said that a blue flame that turned yellow poped out.

Now i still have the downpipe cat in place and although it pops and bangs all the time, does this mean that my cat is getting hot, disintergrating and igniting the unburnt fuel?

Should i be worried?

Cheers
Comper100

[THAWA]

no there shouldn't be

[legacy92ej22t]

Flames are OK if it's on shifts. I shoot about a foot long flame out between shifts on WOT pulls. It's from running rich. You have all this fuel pouring in and then when you shift you blow unburnt fuel out that's igniting when it hits the exhaust turbine or cat.

[tris91ricer]

..which is hella cool.. I can't say I've done that in my N/A...


..lucky bastards...

[Comper100]

Oh well at least im not the only one!

I wonder if it will continue when i get the decat downpipe too?

Cheers
Comper100

[LegacyT]

probobly will be even more spectacular with a decatted downpipe

Mark,

[Comper100]

Ooh thats good then!

Haha

We have to be carefull in England because most subaru lovers seam to hate spark induced flames so i should be ok!

Comper100

[free5ty1e]

Backfires rule. Since I had my 3" turbo-back exhaust installed (without any cats, thanks to a friend in the business) I don't even have to be coming off a WOT pull for a flame. Just heat up the exhaust a bit with some partial throttle boost and let off, and there it goes. A nice side effect of letting the stock ECU run your engine pig rich all the time. I suppose this'll stop happening when I finally get proper fuel management, so I'm enjoying it while I can!

[BAC5.2]

What the fuck?

I almost NEVER backfire, and I have never been told that I shoot flames. I get some crazy burble and that's about it.

Fuck it, my resonator is getting hacked, and I'll be getting my test pipe fixed. Fuck cat's. They are for pussies. I want some fire goddamnit!

[jake15]

hehe, i've never had flames or much backfire either, i think its the resonator as i have not cats. lol i want flames.......

[free5ty1e]

well, its usually catalytic converters that prevent the unburnt fuel from reaching the back of the exhaust... should just be a matter of the resonator removing enough heat so the exhaust piping doesn't act like a glow plug like it needs to for a backfire.

These cars, especially the turbo ones, deserve to have nice free-flowing exhaust systems, so that people can ask why they sound so much like Porsches, and so that Honda owners driving near you will get off their throttle in order to hear your car passing them. The flames are like icing on the cake

[turbonator]

I guess you guys dont have to do emission testing every year??

[jake15]

i have to every 2 years i think, i just had it done with the stock exhaust. when i need it to be done again, i'm going to swap the stock on back on, go to the emissions place, get it tested, come back, and swap it back. hehe

[free5ty1e]

Sounds like a plan to me. Florida never tested me for emissions, and they don't plan to before I move to Nevada, where I believe it shouldn't be a problem either. Screw emissions - them's bad for horsepower and torque.

[Nomake Wan]

Damn straight. Though I was really lucky my car was in top-condition the day of my road test... the inspection ran out that day, of all days.

That said, exhaust modifications are on my "important stuff to do" list. Gotta remove some things... add some things... stuff like that...

*harboring the thought of blowing flames from his tailpipes*

[free5ty1e]

Just keep in mind when we're properly tuned, guys, we're gonna have to resort to mounting a spark plug in the exhaust pipe and spraying some sort of flammable medium into the exhaust stream.

...Or get some valve overlap. Or rev higher before letting off, which should sling 'em just a bit further and perhaps accomplish the same thing. lol

I'm all for tuning but I'm certainly going to miss me backfire. ...y'aar.

[FreddexTurbo2Go]

Hey guys,
I haven't posted in ages and I was going to ask if our cars are supposed to be shooting flames out of our exhaust. So was happy when I saw this post! Interesting stuff! I've had two people tell me that they have seen flames in my exhaust over the years. I thought it was just some freak thing the first time. But just last week I had a young kid tell me he once saw flames out of my exhaust too. He always thought I had NOS but I never knew why. But now he tells me that he forgot to mention that he had once seen flames out of my exhaust so he thought I had NOS.

My Legacy SS has a 3 inch exhaust with a 2.5 inch high flow cat. So would these flames only occur under wide open throttle gear changes?

Thanks,
Fred

[crappyrice]

is this fire thigey possible if u ave a auto trnasmission, with a turbo legacy 1991

[azn2nr]

yes its possible.

i dont ever shoot fireballs unless im autoxing. mostly because when i do theres alot of feathering the gas and alot of bov discharge meaning running rich folowed by popps.

[crappyrice]

can u say that in laymans terms, im an idiot. autoxing? also, like when should it happen in the auto, like should i press the throttle, let it change gears at over 6000 rpm, and then let go of the trootle so it goes back a gear?
also shuldent the torque converter stop the flame thingey from hapening?

[free5ty1e]

auto Xing = autocrossing

Autocrossing sounds like a crapload of fun. Bunch of cars see how fast they can slalom back and forth around road cones, I think. I bet our cars'd do great in that event.

[AWD_addict]

also shuldent the torque converter stop the flame thingey from hapening?

I think this is all about unburned fuel igniting somewhere from the turbo outward. How would the torque converter prevent this?

[free5ty1e]

if your torque converter somehow gets in the way of flames exiting through your exhaust pipe, I do believe your Legacy is quite crippled. Timmy-style. (Timmy!)

[crappyrice]

haha, timmy, well i was thinking torque converter cause i was under the inpression theat the flame was casue afer the gear change in a manual becasue when u clutch ur engine disengages from the transmission, in an auto the torque converter keeps on spinning so it mmigh not help?

[free5ty1e]

ahh - thats where the confusion comes in. No, a backfire is caused by unburnt fuel in the exhaust combusting from the exhaust heat. When you're accelerating and heating up the exhaust and spraying fuel through the engine, you're preparing for a backfire. When you let off the gas, the throttle plate slams closed. For the instant before the plate closes, your injectors spit enough fuel to make it through the engine to the exhaust, as there was no air to combust with for that cycle. This unburnt fuel would normally be taken care of in the catalytic converter(s), but if it ignites it just blasts out the exhaust pipe.

Removing catalytic converters helps the most in creating a backfire-friendly environment. Another thing that seems to help create more backfires is an atmospheric blowoff valve. The recirculating blowoff valve keeps the turbo spooled, and keeps air ready in the intake piping for the engine to consume. But an atmospheric blowoff valve immediately gets rid of the pressurized air when the throttle plate shuts, so it is very tough for the engine to even pull in idle air after that. Makes for an even richer condition during a shift like that.

And if you really want control over your backfires, stick a spark or glow plug in the exhaust system and run power control up to the console so you can ignite your exhaust gasses at any time and see if you have gas in there It'll make pedestrians think twice about approaching your car, and might discourage potential tailgaters...