Good grief! Let’s get this clear: Jaguar was the first, and for many year the only, car company to use electric fans. The electric fan in the 1961 E-Type was the very first fitted to a production vehicle. They were also reliable, ESPECIALLY the S3 E-Type.
So why did they change? Clutch fans were a US invention from the mid-sixties, which gradually caught on industry wide. An engine mounted fan has a couple of advantages, which may not be apparent:
- Speed is proportional to engine RPM, so that the fan is quiet when the car is idling, and doesn’t become noisy until the car is moving along so fast that other noise sources become more of a problem.
- Engine fans don’t require large alternators.
- Small alternators make the belt system simpler to design, since there’s less inertial stress.
The main disadvantage of a mechanical fan is that they can consume a LOT of horsepower: The fan’s horsepower consumption increases with respect to the cube of RPM. Which is why the inertial clutch was key…it limits maximum fan RPM, preventing massive power loss.
The disadvantage of an electric fan is that they are full on, all the time. So the power draw at idle is the same as the power loss at high speeds. The same is true of noise. Only the recent invention of proportional fan control makes the noise factor acceptable for refined luxury cars. And proportional controllers have proven to be marginally reliable in long term use, so many luxury brands still use mechanical fans with clutches.
So let’s return to that first E-Type fan and look at the engineering. The motor is very low performance, drawing only five amps. It pulls a whopping 400 CFM. The good news is that at this performance level, it doesn’t make much noise. The bad news is that it draws just enough air to cool the car at idle, and not one CFM more. So if the carbs are in poor shape and can’t idle at 500, the car overheats. If the car is crawling in traffic, the car overheats. And even at extended high speed, temperatures creep up, depending on ambient conditions. This seems to have been the plan: the old wrench’s tale that cars don’t need fans when they’re moving. Doesn’t really work that way.
The S2 and S3 E-Types had dual fans, better blades, and better motors. The fans were noisier, but more adequate. By the time they came to XJS, they were searching for a way to dispell the notion that Jags were cars with chronic overheating problems. And a way to add a little more grace to the pace with a quieter fan.