As a supercar fan, you’ve no-doubt seen countless videos where one of your favorite cars is flying through a tunnel with flames coming out of the back and making a sound that resembles something you’re more likely to hear on the 4th of July. Personally, I think it sounds awesome but why exactly does it happen?
So, why do supercars backfire? Although not all supercars backfire, the majority of them do and in fact, they are designed to do just this. The sound of the car is an integral component of the design and the pops, bangs and sometimes flames that are generated from the exhaust are all part of the supercar experience!
Not All Supercars Backfire
Firstly, and just to make it clear – not all supercars backfire! In fact, some supercars just wouldn’t suit it. Let me give you an example – it’s arguable whether you could say that your $400,000 Rolls Royce is a supercar but that’s for another article. However, it would just sound wrong if a Rolls Royce or Bentley backfired every few minutes. In fact, any kind of Grand Tourer would look out of place doing this!
However, if we’re talking about Lamborghinis, for instance, that’s another story (well, perhaps apart from the Urus). These are cars that are designed to be aggressive and uncompromising. They are designed to be loud and you almost expect your V10 or V12 to likewise make some aggressive, uncompromising sounds – and they do! The same can be said for Ferraris, Aston Martins and many others.
For many supercars though you will have the ability to change the mode that you drive in. There may be a normal, comfort mode that keeps some valves in the exhaust closed. Great for when you’re just popping out in town or want to move on out without waking your neighbors! Then, you can switch it to Corsa/Sport mode which opens up the valves in the exhaust and make things somewhat noisier.
What Causes a Car to Backfire through the Exhaust?
So, why does a car (any car) backfire in the first place? Well, I don’t want to get too technical here but you may find this quite interesting:
Rich Air/Fuel Mixture
When you are running rich and not all the fuel is burnt off in the chamber, some of this fuel then gets into the exhaust. What happens next is that eventually, as the fuel travels through the exhaust pipe it will encounter oxygen.
At that point and assuming the exhaust is hot enough, all three combined (fuel, oxygen and a hot exhaust) will cause the fuel will ignite. This can cause not only the pops we hear but also a visible flame out of the back of the exhaust as the fuel ignites.
The second reason which can cause backfiring is something called ‘ignition delay’. When the ignition within the chamber is slightly delayed it can cause the ‘bang’ stage (you may have heard of ‘suck’, ‘squeeze’, ‘bang’ and ‘blow’ when we talk about combustion engines) to still be occurring whilst the exhaust valve is still open.
So, the explosion partly occurs in the exhaust, which can manifest (like the first reason) in the audible pop and potential flame seen out of the exhaust.
Lean Air/Fuel Mixture
With this, bear in mind that a lean air/fuel mixture will burn slower than a rich mixture. Again, this can cause the explosion within the chamber to still be occurring whilst the exhaust valve is open.
What’s interesting though is that these three causes for backfiring can actually be manufactured. The ECU can be programmed to generate any of the above on-demand. So, when the driver hits that ‘Sport’ button in their exotic car, it can also make tiny changes to the fuel mixture, causing an increase in backfiring.
Why Would You Want Your Supercar To Backfire?
It’s a good question, why exactly would you want your car to do this? Well, it’s simple really – because it sounds awesome! Assuming it is spluttering and spitting flames out of design or choice and is not indicative of a problem then the supercar backfiring just complements ownership.
You see, the sound a car makes, at least for many owners is a big factor in them deciding which car they buy in the first place. If I own a supercar, I want it to sound like one! This, on a personal level, is what has disappointed me with the majority of the McLarens these days.
Arguably, they are the best looking and performing supercars available to us today but….they just don’t sound like it! It’s with examples like this that I think manufacturers need to build into the engine/exhaust a nicer, more aggressive note. It may look the part but it doesn’t sound like it!
Therefore, a backfiring supercar is all just part of the package.
Can Backfiring Be Indicative of A Problem With The Car?
Of course, not all backfiring is good! Fortunately, examples of cars backfiring due to problems are a lot rarer these days than they were a few decades ago. You might think that all of that sputtering and backfiring is a bad thing.
So yes, sometimes when a car backfires it is most certainly a symptom of a problem. Probably the first thing I would do is speak to other owners to see if this is normal, expected behavior. Remember, with many supercars, it is totally part of the setup and you should not be concerned. However, if it has just started doing it then you should try and find the root cause.
Unless you know what you’re doing, it’s advisable to get a professional to check this out (as they will have the right tools) however you can hook your car up with an ODB2 scanner. This is a small device that allows you to read the error codes that your car is producing.
From here, assuming that is generating some error code you may be able to localize the issue. If you want to try one of these I’d really recommend the Nexpeak, which you can find over on Amazon here. I have one and can definitely recommend it to you, all those reviews can’t be wrong!
Often, the problem could be as simple as a deteriorated spark plug or an issue with a fuel injector house so it won’t necessarily cost the Earth to get it fixed. Don’t sit on the problem though. Unless your car was designed to handle these explosions in the exhaust chamber it can lead to some other issues – so if you don’t know what you’re doing – get it booked in with a garage asap.
Examples of Supercars Backfiring
There was no way I could write an article about supercars backfiring without showing you some examples!
Firstly, and perhaps my favorite, take a look at this Lamborghini Aventador with a custom exhaust fitted by Brooke Race Exhausts. The flames and sound coming out of this thing in the tunnel (which is where I’ve started the video) are absolutely insane.
For those of you who are more into their Aston Martin’s than their Lambo’s, check out this Vantage:
Next, here’s the amazing Ferrari F40 showing off big time. Oh, to have the money to be able to get one of these…
Conclusion – so why do Supercars backfire?
Hopefully, I’ve made it clear that although not all supercars will backfire, many of them do. It’s by design though and it’s usually a little bit disappointing if they don’t!
I was fortunate enough to have a drive in the Lamborgini Huracan Evo a few weeks back. I actually think what I enjoyed most about the experience wasn’t to do with its looks or performance, but how it sounded! I could’ve driven it for hours just playing with the throttle, generating those little pops.
In fact, one of the first things I did when I got home was Google’d how to make my car backfire more 🙂
If you’re wondering whether you can afford a supercar then check out my article. Many people are surprised to learn that after looking at the numbers they can actually buy one for themselves!