What causes rev limiter backfire under boost?

[nissan240boy]

okay I hear it in some drifting videos, but when im drifting my car in first gear under full boost and shes boucin off the rev limiter it backfires very loud, it sounds awesome, and egts are at 1150 so its running good, I was just curious what the technical reasoning is as to what causes it to backfire under boost cause if im in neutral and just slam the pedal to the floor and hit the rev limiter there is no backfire, only under load and under boost, thanks just curious what causes it

[Jbaker1121]

Isn't backfire caused by pre-ignition in the combustion chamber from running rich?

[kouki munster]

Spark cut rev limiter, under heavy load/high boost pressure there is a good amount of fuel being injected into the engine, and when it hits the limiter spark is cut so all of the fuel is unburned and getting flung into the very very hot exhaust where it will ignite once it comes into contact with enough oxygen, usually near the end, and cause the popping you hear.

[alms24sebring]

^ This, although I thought it cut fuel and the O2 from that cycle ignites any unburned gases in the exhaust. I could be wrong.

[kouki munster]

The stock ecu uses a fuel cut limiter function and is pretty drama free, the reason his car "back fires" is most likely because the tune he is running is dumping way more fuel than his engine can possibly burn at the rev limiter, (to try and keep the pistons from melting) and all the unburned leftover fuel ignites in the exhaust when it get enough oxygen.

Fuel cut limiters are a big gamble with forced induction as it causes a super lean condition to stop the cylinder from firing, which in turn can kill the pistons.(go to the rb section and search stuff about the fuel cut limiter killing the ringlands)But, nearly every car ever produced that has a catalytic converter still uses a fuel cut limiter, because catalytic converters don't like large amounts of unburned fuel, it can(and most likely will) burn them up, and in very rare cases turn the cat into a pipe bomb. Spark cut limiters are also rather violent sounding(looks violent when it shoots fire balls as well) and will most likely freak out the owners and make them think that the car is messed up when it sounds like there are m-80's going off in the exhaust while they are revving the nuts off of it in an attempt to impress high school girls.