For my ls1 swap into my 68 Camaro thinking about mounting PCM under passenger seat?how hot does PCM get?

 

I would certainly think it would be cooler there than under the hood (stock 4th gen location) so it should be fine....

 

Thank you

 

They get aweful warm, I wooooodn't want to be sitting on it for a long time. Its the reason they moved it out under the hood.

 

The aluminum fins on the PCM are a heatsink. You can think of the heatsink as a radiator without any coolant flowing. The heatsink is how the PCM gets rid of heat generated by electronics within. In order for it to do this efficiently it needs airflow across the heatsink aluminum fins.
The one thing i would be worried is not getting enough airflow under the seat to cool it properly. The number one enemy of electronics is heat next to water/moisture. Overheating will destroy the power transistors and processor inside your PCM.

Sure it's hotter than heck in your engine compartment but the minute you get rolling their is all kinds of airflow rolling through your engine compartment.
Think of it like this....say the heat radiating off your engine is 200 degrees and the heat coming off your exhaust is 350 degrees.....sure its hotter than heck but the air flowing in your engine compartment is 90 degrees coming from "outside" because the ambient air temperature is 90 degrees so this is a rush of "cold air" perfect for cooling. Heat is attracted to Cold because cold air has alot less heat so the cold air can absorb the heat more readily which is perfect for a cooling effect. (basic air conditioning principles).

I would say its gonna be a crap shoot as to whether your underseat spot is going to eat PCM's. Not too mention the wiring harness going to that PCM is going to have to be routed underneath your center console or underneath passenger side floor carpet area (which i wouldnt do, that is setting you up for a potential broken wire or pulled connection out of your PCM Plug).

The underneath seat spot would be a nice spot to rest the PCM but i wouldn't chance it considering the pain of a PCM dying would cause. Cost, time to replace with current flash and potential for it happening again.

 

Its not next to the engine, /Its actually on the side and stays very cool. I've already touched them mounted under the dash and they get smokin hot IMO.

 

You might want to go back reread what i wrote...and get back to us......here on planet earth. Try not to smoke so much of THAT before you turn your computer on!

 

so then the people that are moving the pcm to the inside under the dash, might not be too good of a move being that there is not too much moving air under there?

 

Don't do it, they get hot thats why they got moved out under the hood.

 

What a load of BS in here

Several FWD cars mount the PCM in much more cramped locations even under the dash. Almost ALL 3rd gen swaps mount it under the dash in the stock location

It'll be fine under your pass seat. About the only places it wont be OK is submerged in a fluid or touching exhaust. Near the exhaust is fine, just no contact

 

Yeah ever touch one under the dash after its been running for a hr?

 

There is alot more area for air to circulate under the dash than under the passenger seat.
Ive seen alot of ecm's fail back in the 80's that were .....under the dash.

Never seen a pcm fail under the hood. (idiots that dont know how to jump a car, failures dont count).

And those air conditioning principals have been around alot longer than you and I.

You got what 3-4" for heat to rise off under a seat. You got all kinds of distance under a dash with alot more "enclosed" volume under a dash vs. a seat.

Ever put a thermometer in your car on a 90+ degree day to see what the temp gets up to? Its called radiant heat. Have a dark interior? It gets hotter then.

 

How hot is hot, how long is a piece of rope, what we need is real facts. Someone with a pcm mounted in the car, please run the car, measure temps outside the car, inside the car, and the actual pcm surface temp. Then post your response. this way we have real information to make decisions, not theoretical guesses.

 

Had it on my lap troubleshooting a different issue. Its gets pretty warm but wont burn your skin. Currently it's wrapped in an old towel to prevent rattles stuffed up in the dash. Had it on several long distance road trips with the heater blasting. Never had a hiccup and never seen any other modern PCM fail from heat. You just cant compare the new stuff to 80's ECMs. Hell, some of the newer GEN IV stuff is mounted directly to the engine block under a manifold

 

Everyone i touched after an hrs running time was smokin hot.