Standalone or piggy-back ECU for auxiliary blower fan control?

Hey all!

I'm planning out my first custom project and I'm not sure where to start looking for the appropriate ECU hardware.

I've got a 2011 987.2 (2.9L) cayman, to which I'm planning to add an auxiliary blower fan for the engine bay. My goal is to use a CAN->PWM controller to set the speed of this aux fan based on engine load and engine bay temps, although I'm not sure what kind of hardware I'd need to accomplish this. This build is mostly for the street/canyons so I want to leave the stock ECU in place if at all possible.

What would be the most straightforward way to pull CAN bus traffic off the stock system (engine load, RPM, vehicle speed, temps, etc) and apply it to my aux fan? A piggy-back ECU connected to the CAN bus? A full-on additional standalone ECU?

Thanks for your help!

Ricky

Most ECU won't be able to keep up with the current needed to directly drive a fan in PWM. If you plan on ONLY using this device and not additional one, a Kaizen Solid State Relay would be a good option. They have an optional CAN module and they support PWM.

https://www.kaizenspeed.com/products/kaizen-relay

https://www.kaizenspeed.com/products/control-module

You will need to sniff the CAN to find the addresses with the data you need to trigger the relay, then program the Kaizen control module. I don't know if you have an engine bay temp sensor connected to the ECU, but if not, you won't be able to use this parameter to trigger the relay.

You could always use an aftermarket electric fan controller, there are a couple ones on the market like Flex-A-Lite, Derale... but they probably won't have PWM features.

Most straightforward way would be to make it a temperature only trigger, with the sender in a position where it is only going to heat up when the engine bay is actually getting hot.

If you are, or a friend is, handy with a soldering iron, there are several simple kits that will do the job, which can control a solid state relay that has the switching frequency range you need and the power rating needed for the fan(s)..

That said, you may need to give the positioning careful thought so it actually moved the hot air out/cool air in - sometimes air movement in engine compartments is counter intuitive and you could make things worse.

If hot running is a known problem, I expect there are already louvre/ducting options on the market you can buy, or take inspiration from?