Discussion and questions related to the course Practical Reflash Tuning
Good day gents,
I recently wrote an article about remaps for a local magazine. I tried to keep it as simple as possible (to avoid getting too technical and end up losing the reader). So just want to find out if you guys feel that this was a decent effort and that I haven't conveyed any misinformation. Cheers
Chip tuning is becoming an increasingly popular phenomenon among car enthusiasts. We take a look at some of the details involved.
What is chip tuning?
The phrase “chip tuning” is actually a misnomer, as it is no longer applicable to today’s cars. Back in the day when electronic fuel injection was in its early years, in order to gain more power from the engine, tuners had to physically replace the computer “chips” with custom programmable ones. Today there are various companies and individuals who specialise in recalibrating, or “tuning”, the factory ECU (electronic control unit). There is no longer any need to swap chips as all changes made are simply modifications of the factory software. But the term “chip tuning” still remains simply out of tradition, nowadays it is simply referred to as “tuning”, “remapping”, or “reflashing”.
What changes are made?
The most common reason for chip tuning is to increase the power output of the engine. Since the entire engine’s operation is controlled by the computer, modifying the computer’s software will have a direct impact on the engine’s operation. For normally aspirated and supercharged engines, this will include changes to the spark advance and amount of fuel being injected. For turbocharged engines the amount of “boost” being produced can also be changed in addition to spark advance and fuelling. Supercharged engines also produce boost, but it is a fixed amount of boost depending on the engine’s RPM, and therefore cannot be changed by making modifications to the ECU software alone. What is perhaps most appealing about a remap is that the software can be changed to make the engine both more powerful and more fuel efficient (although making it more fuel efficient will, in most case, increase emissions too). Experienced tuners can even add features to the software, such as launch control, anti-lag, and map switching (a number of different “tunes” on the same computer).
Are there different types of tunes?
Often people speak of “stages”. Stage 1 being the most common, followed by Stage 2, Stage 3, etc. which refer to the level of mechanical modifications that have been done to the engine. Stage 1 is when only software changes are being made to the engine and is completely safe for any stock (as produced by the manufacturer) engine. Stage 2 and 3 involves hardware changes (exhaust system, intake, intercooler, bigger turbocharger, water-methanol injection, etc.).
Is it safe?
Breaking an engine is actually rather difficult, unless you have absolutely no idea how an engine works….in which case breaking the engine can be exceptionally easy. Stage 1 is the simplest tune and is completely safe to do. Only when you progress to and above Stage 2 should caution be exercised with regards to making the appropriate hardware changes.
If it is safe, why don’t these engines produce more power from the factory?
Actually, they do. Manufacturers have to consider several variables when deciding on the power output:
- Available fuel (octane rating) and climate
Manufacturers take into account that the vehicle will be sold in various places around the globe. Not all countries have the same fuel available, nor do they have the same climate; so the manufacturers have to decide what amount of power will be safe for the engine in each of those areas
- Emissions and fuel economy
In many areas (Europe specifically) there are exceptionally strict emissions laws in place by which the manufacturers have to adhere to, and this too influences how much power they can produce from the engine. As such, the engines are calibrated to operate as close to “Lambda 1” as possible. Lambda 1 is the stoichiometric ratio of fuel to air (that is the theoretical perfect ratio for which all fuel will be burned, and produces minimal emissions), and for petrol that is 14.7 parts air per 1 part of fuel. Anything over Lambda 1 is called “Lean”, and anything below is called “Rich”, and both lean and rich conditions will increase the amount of toxic emissions. Lambda 0.85 (12.5 parts air to 1 part fuel) is much safer for the engine in terms of producing power because a richer mixture helps to cool the engine, but because more fuel is being used, this will increase both consumption and emissions.
- Price of the vehicle
Often manufacturers may offer the exact same engine in a number of different cars, and the most expensive one might produce more power than the cheaper model. In most cases there is absolutely no physical difference between the engines, and the extra power is only due to the computer software.
What precautions should I take if I do decide to have my car tuned?
- Use a reputable tuner. They have loads of experience, and know how much of a power increase is safe for an engine. A general rule of thumb for normally aspirated and supercharged engines is roughly 10% more power, whereas for turbocharged engines it is usually around 20%.
- Always use the best available fuel. In the UAE that’s Super (98 octane). The higher the octane number, the more resistant the fuel is to knock (uncontrolled combustion; the #1 engine killer).
- Don’t worry too much about the numbers. One tuner might offer 5hp more than another tuner, but you really won’t notice a difference of 5hp.
At the end of the day, tuning cars can be a lot of fun, and getting a few more ponies out of the engine is not only quite rewarding, but can be just as safe as a stock standard engine.
It's hard to write an all encompassing article about reflashing without it either ending up the size of a novel, or being overly technical (or both), and I think you've done a pretty good job with what you've written there. I guess I'd mention that the correct AFR will depend on the engine and the application and there is no single AFR that is safe or appropriate for every engine. The 'staged' tunes or upgrades are difficult to really detail accurately because every tuner or tuning shop has a different interpretation of what it means or what is done.