[Diy_efi] keeping electronics cool

[chrism at cnx.net]

The Cummins QSB's used to (and may still) run a PCM on the intake side  
of the block. I believe they are fuel cooled but I could be mistaken.

Chris

Quoting Michael Richards <michael at fastmail.ca>:

Many import vehicles stored the ECU in the passenger compartment near
the passenger kickpanel for many of these reasons. As things became
more complex the wire count increased as did the price of copper.
ECUs subsequently did move to the engine bay and domestic american
vehicles certainly led the way in this area with the majority of
their vehicles using engine compartment mounted PCMs. One slick place
I've seen that protected against engine heat but still gave the
advantage of shorter wire runs was a number of euro models would
frequently mount their ECUs in the windshield area behind the
firewall where the wiper motor and wiper transmission typically sits.

Finally, electronics design plays a factor. Typical heat range on the
components used is -40C to +125C. Some models of V8 Mercedes SUVs have
the ECU mounted on top of the engine itself!

Another thing to consider is that engine bay mounted PCMs required
more expensive weatherproof connectors and cases.

-Michael

On Tue, 30 Oct 2012 11:08:33 -0700, jayjunk at laserpubs wrote...

> Keeping electronics cool under the hood - there are (at least) two
> factors here-
>
> 1) keep heat of motor and headers from roasting electronics stuff
> 2) cooling the electronics, because they make heat also.
>
> If you just put the electronics in a nice insulated box, they will
> burn up, even if there isn't any heat being added by engine or
> headers.
>
> I'm currently stripping a '98 Buick Regal (donor car).
>
> The ECU was in a nice plastic box that kept engine heat away from
it.
> The air inlet for the engine pulled through the box.
>
> Yes, it heats up the air into the engine a bit. But you know damn
well
> that if the engine is running, there's at least  outside air
> being pulled across the ECU to keep it from roasting.

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