Why does a rally car backfire

That is when the raw fuel gets sucked into the exhaust. I had a camaro with a big cam and open headers that shot flames like that. I think she looks like a cheap whore from the 80's. Sorry man, just not my kind of woman.

Loeman came pretty close to the point I was going to make. A big part of it is exhaust valve timing combined with ignition timing. Most street cars raise the timing advance significantly when you let off the throttle, or even just reduce the load by lifting a little bit. It's likely that they don't bother to do this on race cars, and the timing is a liitle less advanced. Any time the timing is less advanced or more retarded, same thing the combustion event takes place later in the cycle, and closer to the exhaust valve opening, leaving the mixture still burning as it leaves the chamber.

Race cars also have a very free flowing and quite short exhaust path, making it more likely that the mixture will still be burning as it leaves the tail pipe. Street cars cutting the fuel at 0 TPS is an emmisions thing, which is obviosuly not something race car EMS programmers care about. The ignition timing is the main factor used in setting up the DSMlink antilag system. When on the stutterbox ignition retards to a set level, the misture is still burning as it enters the turbine housing, providing a ton of extra energy to spool the turbo.

It can also inject a set amount of additional fuel at the same time to enhance the effect. This puts out some serious flames in addition to adding to the boost, but I always found that if I didn't get a perfect launch the plugs would foul and I'd end up forfeiting the run, so I stuck to just timing changes. On the 2g even with the 2. With even just mild settings on the antilag it would help tremendously. I could get psi with typical settings.

I didn't have enough traction to make use of the higher boost anyway though. On the EVO the 16g with the divided housing and all that twin scroll stuff, I found that the turbo builds too much boost with the typical antilag settings. With no antilag and a rpm stutter I get the usual psi associated with 14bg sized turbos. Turbo lag can cause loss of time.

It might only be split seconds here and there however that can add up. Say over a 20 kilometer special stage you could lose one to two seconds per kilometer. The solution was to find a way to eliminate turbo lag hence the name anti lag. There were a few primitive and semi effective methods of anti lag in the early days of turbo rally cars.

Some were technical solutions and some were driving techniques. The most common was for the rally driver to keep their foot down to keep the revs and therefore the boost up!

It came about due to the advances in engine electronics and tuning. A specific set of conditions needs to be met for the anti-lag to work. The engine management senses that the throttle is closed and the engine is revving above 4, RPM so it runs the anti lag part of the map. What anti lag does is fire the injectors and the spark plugs on the exhaust stroke of each cylinder. The very rich fuel mixture is ignited however instead of producing power it actually exits the engine into the exhaust manifold creating a pressure wave.

The explosive nature of that somewhat external combustion keeps the turbocharger spinning at high rpm to maintain maximum boost. The sensation of anti lag that we hear and see when watching a rally car is the back firing and the flames from the exhaust. Legality in the United States Porsche didn't provide the United States Department of Transportation with four cars required for destructive crash testing, so the car was never certified by the National Highway Traffic Safety Administration for street use in the U.

Why rally cars backfire? Asked by: Miss Sally Hackett. Can you daily a rally car? Is car backfire illegal? Why do Formula 2 cars backfire? Do some cars backfire on purpose? Are rally cars safe? How are rally cars so loud? Why do rally drivers drift? Why do exhausts pop and crackle? What makes flames shoot out of exhaust? Do F1 cars spit flames? Why do sparks come out of F1 cars? Search titles only. Search Advanced search…. Everywhere Threads This forum This thread. Search Advanced….

Log in. Trending Search forums. What's new. New posts Latest activity. Why do rally cars backfire? Thread starter ugh Start date Nov 21, Sidebar Sidebar. JavaScript is disabled. For a better experience, please enable JavaScript in your browser before proceeding. Previous Next. Feb 6, 2, 0 0. Someone told me that those blasts of fire from the exhaust are due to the brake pads being to hot That isn't so rite?

ThisIsMatt Banned. Aug 4, 11, 1 0. Brake pads? That guy been sucking on the exhaust?