Automatic cooling fans to combat heat soak

[olivierfr]

Hi everyone,

I’m based in France and own a 1998 TVR Chimaera 400.

After several months of design work and testing, I finally finished developing an automatic cooling system this summer to help manage the heat that builds up under the bonnet after switching off the engine. With outside temperatures in France reaching 40°C this summer, it’s an issue that seemed worth addressing on our cars.

The aim is to help reduce premature ageing of components exposed to this heat, such as hoses, wiring and electrical connectors.

The system automatically activates the cooling fans when the temperature calls for it. It also includes battery protection to help ensure there’s enough charge left to restart the car, and draws 0 mA when idle. The installation is fully reversible, with no cutting or modification of the original wiring loom.

I’d had some interest from a few owners, so I ordered extra components to build a handful of additional units. I have a few left for anyone who might be interested in fitting one over the winter, ready for next season.

I thought it might be of interest to other Chimaera and Griffith owners on here, so I wanted to share the project with the community.

I’ve included a couple of videos showing the system in action.

Happy to answer any questions or discuss how it works.

vidéos : https://drive.google.com/drive/folders/1vczpqYu1Mp...

[olivierfr]

Accès vidéo ok !

[Andy70]

Maybe I'm stirring up something here, but I don't mean to, I've just learned from my low temp otter switch thread that having the fans on too much actually fries the engine components as the fans seem to be blowing hot air around the engine bay much more than normal, I experienced miss fires etc as a result, so switched it back to standard, I still replaced everything though coil, leads etc for piece of mind, I know I keep going on about it and I know it isn't cheap, but in my opinion the best way to keep the engine bay cool and gain a few horses in the process is ceramic coating on the manifold and Y piece surely? it's supposed to be proven formula 1 technology. or maybe your system works different I don't know.. I like your term though, 'next season' Maybe TVR's are better in the winter, I know my fan doesn't come on hardly at all now the weather is cooler, I know i'm going to use mine as an every day driver in the winter, I'll just be lighter on the right foot!
Sorry if i missed something with this thread though!

[olivierfr]

Thank you for your message. Your components must have already suffered from the heat to have to replace everything. How old were they?

I am not aware of any cooling system that would damage the components. In my opinion, the deterioration of the engine accessories (hoses, wiring harness, ignition, etc.) is rather due to heat peaks and stagnant air above 80 °C, in the absence of air evacuation.

The *heat soak* TVR unit turns on a single fan at mid-range: it doesn t blow too hard, but it stirs the air and evacuates it long enough to prevent this destructive phenomenon, which is responsible for most avoidable failures.

I completely agree with you about the ceramic coating on the manifolds and exhaust line: it s an excellent solution to reduce heat under the hood. On the other hand, this will not remove the inertia of the aluminum block and the other elements at rest, which radiate and cook everything that is enclosed under the fiberglass. I haven t done it yet because it represents a certain cost; passive ventilation remains a very good solution at low cost to preserve everything.

Edited by olivierfr on Tuesday 13th October 10:53

[Belle427]

Most of these cars are over 30 years old so in reality the wiring and components have not done that bad to be fair.
People tend to overthink it, no offence intended to anyone.
Kudos though to anyone who engineers good solutions, I'm not clever enough to do that!

[cliffords]

I open the bonnet when I put it away if I was bothered it was hot .

[olivierfr]

You are absolutely right, the age of 30 years is taken into account, but personally, I’m just trying to prevent the fuel lines from being changed; everything is 2/3 years old, as well as the ignition parts or water hoses and some false electrical contacts due to "cooking". under the hood.
A breakdown of a Bendix starter after 30 years is largely acceptable and honestly this v8 is very reliable, contrary to what some people say!

[Sardonicus]

Having the fans run on will absolutely not fry anything in fact on the contrary , for those that need it its a fab idea i.e Boosted, heavily tuned, hot climate etc

[olivierfr]

cliffords said:

I open the bonnet when I put it away if I was bothered it was hot .

yes, it’s a technique that works perfectly and you have to leave the hood open for at least 15 minutes with the inertia of the aluminum block to avoid heat soak!

But honestly, who does it every time it should be done? And when to do it?

Last Sunday, it was 24°C during the day, perfect for rolling your hair in the wind. With the return of traffic, a few slowdowns in town, and when parking my chimera, I can see that the air temperature sensor under the hood is 75°, After 5 minutes, always 70°C with the case in operation, without the case with the heat soak, more than 85°C with certainty for more than 5 minutes. And it was a non-summer temperature, but 15 minutes at very low speed in the city... this is the acceptable limit temperature for the premature aging of a few devices under the hood of our toys!