EFI- backfire and flames

[hockey44]

Just curious have Kinsler in 502 alum. Shelby block and recently dyno'd-- it is amazing and the backfiring and flames (visible on track at night--cool!) are mind boggling-- runs like a charm. However, can one 'dampen down' the backfires so you don't wake the neighborhood when you "sneak home late at night"? Or is this just part of the Kinsler amazing visceral and aural experience (not to be missed!). Thanks

[philminotti]

Don't know much about the Kinsler system specifically, but I'd guess you're running really rich, which is strange considering you had a dyno tune. Exhaust backfire is usually an exhaust leak, but the flames... Is it both banks or just one? If it was just one I'd believe you're dropping a cylinder, but if it's both I'd head on back to your tuner. You obviously have a big, hairy cam, but it's not a top-fueler for chrissakes.

[427 sam]

Iwould be interested in the outcome as I have the same problem, but mine Is booked for rolling road and retune 7th july, I will post results as and when, regards sam

[CSX4815]

It's the deceleration curve that has too much fuel. This can be changed in the fuel map. I had the tuner leave mine somewhat fat so it does as described above. It is pretty cool and when going thru tunnels at night the backfires when decelerating can really light up the way.

It can be removed by an experienced tuner. Not just a characteristic of the Kinsler injection. They will all behave this way if told to by the ECU.

[J.Jensen]

Many tuners do this on purpose with high performance engines because the added fuel on overrun provides cooling. The fuel then ignites in the hot headers and sweet flames come out.

[Mr Jody]

In addition to this being evidence of an overly rich mixture, it could also mean that the spark timing is possibly somewhat retarded (occurring late) when you come off the gas, which gives spark to that slower burning rich mixture as it is exiting the exhaust valves. In addition to checking the mixture on deceleration, you may also want to check the spark timing to make sure it is sufficiently advanced, or that it is not allowed to drop off too fast as engine speed drops.

While it may look cool, I think there is a potential for damage to your sidepipes and headers, or at least to the associated gaskets. The same force of that explosion that you see coming out of the pipes is also going the other way, back up towards your engine, as your combustion chamber is now the thin wall of the headers and sidepipes instead of within the confines of the much thicker cylinder walls. You may have heard of some passenger cars blowing up mufflers in this manner.