I recently got the corksport power series exhaust cat-back for my 91 coupe na. including apex power intake those are the only mods on my car. The backfiring only occurs at a certain time, when the clutch is engaged at the redline (8k) and when i press back on to the gas after moving up to the next gear following a red line and i continue to floor the gas. I don't think it is because I have the clutch and gas pressed down at the same time and I don't think it is because i come back onto the gas too early after the gear change. My exhaust before the corksport was a stock dual exhaust and the backfiring never occured when redlining

 

Raw fuel is getting into your exhaust pipe then burning off, shooting a fireball out of the tail pipe.
It is normal on rotaries with open exhaust

 

"after burn" is the technical term. after a high RPM pull raw fuel is dumped into the exhaust, you can figure out the rest.

 

+1 for karak.

"backfire" is one of those terms like "turning over" that's almost totally meaningless. i have never turned over a car, although i have crashed a couple.

technically a "backfire" is when the engine can fire back in to the intake. its kind of an old timey thing, from back when you had to change the timing (usually on the steering wheel) to start it (picture a hand crank). in that case backfires are bad, cause it takes your arm off.

most "backfiring" is probably gone by the mid 1920's, unless you have a porsche.

i did actually get my PP to spit fire out of the intake, but this required timing that was at least 1 tooth retarded

"afterburn" i guess would technically be fuel that is burned AFTER leaving the engine. the rotary has no exhaust valves, and there is a small amount of unburned gas that is pushed out of the port after every cycle, so they are a little notorious for this. if you're lucky that noise you're hearing is fire coming out of the tailpipe....

 

I can see this catching on. "Yeah, my rotary is equipped with an afterburner STOCK!"

 

There is an anti afterburn valve in the ACV as well as a dashpot for the throttle to stop the afterburn. Honestly it's an old rotary, I wouldn't worry about it.

 

Cool I learned something new. I always thought it was called a backfire.

 

thirded, fourthed, whatever on 'afterburn'.

 

as long as your bumper isn't melting it shouldn't be an issue

 

well i was surprised it was happening because i have a cat and it's not high flow, just 170$ or so priced model from schucks

 

You should be proud.

 

Do it at night (rev it up in neutral then let off quickly) and have someone watch, it's impressive.

 

reminds me of my brothers 240 bumper burning while I was driving on the highway. Damn thing shot flames as I lifted and burnt the entire driver side rear. Was doing body work in that section too....there was also paint thinner in the hatch near the fire...glad the fire truck came quick :P