I see a few posts once in a while about flames coming from people's exhaust. I understand the rotary has higher exhaust temps, but what exactly causes it? My exhaust is stock except for a bonez system that goes from the manifold and has a high-flow cat then i have the stock cat-back. I don't think I've had any flames and waswondering if it was oly happening with aftermarket higher flow exhaust systems? Sounds like something that will get you pulled over alot

 

Some PPl put a spark plug in the exhaust and make the fuel air ratio real fat. the problem it can and will shorten the life of your engine! not a good idea....

 

Most of the time it is caused because unburnt fuel is burnt through the exhaust system. Sometimes it is caused by bad timing as well.

 

Removing the cat, especially without retuning (especially on carb'd cars), will almost ALWAYS cause backfire (flames). If you take a stock RX7, remove the cat, you will have flames. No need for a spark plug ...

 

13b+huge ports+modded nikki= flames

a stock rx without the cat will shoot flames, any holes or leaks in the exhaust will make it worse.

isaac

 

Streetport+racing carb+rich tune+open exhaust=backfires and flames=no tailgaters

 

If I replace the thermal reactor with a header is it gonna flame? Does it do whenever you let off or only under a high load?

 

^^^ right, your adding fresh air to the equation.

 

Will it do it shifting at 3.5k? Or only at high load?

 

Usually running up to 6k, back off, pause, then add throttle pedal will do it. I takes practice as each individual setup will vary.

 

As long as it not a "everytime I let off the throttle" type of deal its cool then. Im hesitant to do the exhaust on my car for fear of it being obnoxious. I think Ill just do it and if it ends up being that bad Ill just undo it. The fab work isnt a big deal for me, and I have plenty of time :o

 

My 84 was blowing serious flames out with no cat, street port, race beat exhaust and headers, and poor conductivity on my primary wire from the coil. It was running rich, but the higher RPMs got, the spark wasn't getting through the wire enough. This lead to some monster flames on heavy acceleration, and atleast a couple that were long enough to curle up 2-3 feet of the back bumper...... but I fixed it, and now I just get the occasional backfire blurp on rapid down shifts.

Also, a friend of mine used the old school method of dumping raw fuel just after the turbo to reduce lag on his race car.... this got some sweet flames as well

 

^You'd have to put in fuel before the turbo to reduce lag, it works because the fuel ignites when it hits the hot impeller blades, spinning the turbo faster.

 

Flames will usually occur with an open exhaust and cool ambient air such as night time or a rainy day. Rotaries run on the rich side naturally anyway, so this helps induce the exhaust ignition.

Any exhaust leaks will help prevent flames. You will still get a back fire but the pressure doesn't build as equal with a leaky exhaust.

 

I'm feeling cheated here. RB exhaust, Sterling carb, fuel pressure at 4.2 psi and I still can't get flames! The only time it flamed on me was when my leading ignition died. In my opinion, if its tuned properly (mostly timing) and there are no holes in the exhaust, then there should be no flames... I'm running rich as all get out, and if I can't have flames then nobody else should get to have them either dammit!

 

id say the rb exhaust is holding you back. i have a yaw carb, rb header/glasspack(soon to be replaced with magnaflow)/magnaflow set up and when i run it up to about 7500rpm and clutch to shift, i get some good flames. no noise, but flames.

 

would a short cat with a 3 inch exhaust leading to a racing muffler(basicly straight through)do it.
i havent really drove it fast and let rpms to get high yet because i have brake problems and need to fix that before driving it like that.

 

I have the full RB streetport system...the first time we fired it up after the engine rebuild and re-paint, the ignition was 180* off, the carb was WAAY rich...there were 2 foot flames jumping out of the tail pipe, had about 20 people standing around and everytime, they would cheer when it produced a flame. Thats how we got the initial tune, when people stopped cheering we knew it was close, lol.

 

Amazingly enough I've got RB Street Port exhaust and I don't flame. If I rev it up to 6k at a standstill then just completely let off the gas I'll get a small backfire, but nothing big.

I think that tuning and timing would be the biggest factors that cause backfires and flame.

Jon

 

for the pass week I've notice I've been backfiring and flame alot more than usual my mod list are

::;
Greddy elbow
Greddy IC pipping
Greddy/Trust Dragger 3.5" pipping 4-5" can?
Mid Pipe
Down Pipe
Greddy TT
Greddy Pro-fect B Boost controller
Cut the bottom of my airbox for more air

sadly I don't have a EMS yet so I've been shift at 5000 rpm's no matter what. I've even had a time when I started the car up ( at night with stock cat on let it warm up alittle and let timer shut it off. car shot 4ft flames when it shut off )

I know my car is running really rich because of the yellow disordered color on my rear bumper where the exhuast is

people have been honking their horns at me more than before now ( due to shooting flames) I've actually had a guy tailgate me then shot some flames so he backed off before


I'm not to sure why i've started to shoot out more flames than usual starting this pass week. my set up has been the same for about a month now... anyone have any idea's?