Also in the past fuel became rather warm. In a distributor type injection pump you could measure up to 80°C. If
you estimate for today's systems a quadrupling of the
injection pressure, you may easily have a notion of how high the fuel temperatures would be without cooling. The petrol engine does not need cooling as of yet. But also here the pressures rise with the direct injection.
Moreover, petrol is more receptively for vapour lock.
How it works
Probably the plastic tanks also contribute to the problem that the fuel does not have enough cooling. In any case, it can become too hot. Therefore, in the runback most often below the vehicle floor a fuel cooler is
arranged. It consists of aluminium, making it not only light, but it also conducts the heat well. With fully panelled floors it must be fastened from the outside. Some fuel coolers are connected to the air-conditioning. In any case, the fuel is well-cooled by the time it reaches the fuel tank. Heating of fuel, by the way, only partly concerns the cooling,
because it is switched on only from certain minus degrees on.
It seems that there is always something to sell. Whether it makes sense or not. In earlier times so-called ignition amplifiers, now they offer, in combination with a quick and conclusively sounding argumentation, fuel
cooling for petrol engines. Sounds logically at first, thicker fuel brings about a fatter mixture with the same injection time what would entail more performance. However, this is not true, because the control unit
evaluates the signal of the lambda oxygen sensor and the injection time is reduced. Maybe a very small (one
thousandth) consumption improvement is possible, but no measurable
increase in output for cars featuring a lambda oxygen sensor. You should absolutely require a before and after-comparison!