Wondering if anyone's tried to measure the engine bay temps, specifically down near the ECU, or over by the relay board.

I'm in the planning stages of a Megasquirt retrofit, and I'd like to mount the whole thing in the engine bay, rather than run a LOT of wires through the firewall. If the temperatures aren't too high (above 125dC, or about 250dF), then all I need is a waterproof enclosure and waterproof connectors in and out of that enclosure. Those are available (though they're expensive, and not part of the usual MS setup). If this works, I'll only have to run three new wires through the firewall for the serial programming connection (using the MegaView unit), rather than 14 to hook up to an MS mounted in the cabin.

I'm pretty confident it's cool enough, as 125dC is bloody hot, but if anyone has any actual data, that would be useful. If it's normally below 80dC (180dF), then even cheaper lower-grade parts can be used.

Those areas of the engine compartment don't get particularly warm when the car is running. The hottest temps it will see is when you shut the engine down. At that time the cool air through the engine compartment stops and the hot engine will heat things up considerably. But I wouldn't expect you will have any problems with exceeding 250F, but you very well may exceed 180F.

I did some air temperature (car running) experiments a few years back which led to my cold air intake setup. Maybe some of that info might be useful to you.

http://members.rennlist.com/demick/coldair.html

Demick

Thanks, Demick. I vaguely remembered that page, but couldn't mentally drag up the pointer to it.

Sounds like I'll probably stick with the higher grade 125dC parts. Not that much more expensive, and there's much less risk of failure.

Since I don't have a temp gage (yet), I customarily measure the temp of my engine case (top area) with an IR temp gage. That part of the case usually measures 150-160 degrees.

Other engine surfaces are usually around 100-120 degrees. So the area you're considering should not be a problem for you. I have a mallory hyfire CD box where the battery used to be - no problems.

Shoot, if the case is only getting to 160dF, then the air temp even above the case will be much cooler than that.

I'd expect the Hyfire to work fine in the engine bay, since it was designed to live there. The MS wasn't specifically designed for that use, nor are the ECUs offered by some other places (SDS, for example). However, from looking over the temperature specs on the parts used in the MS, it appears the only reason they don't recommend mounting it in the engine bay is because they're not using waterproof connectors or enclosures (easily, if expensively, fixed), and some engine bays get really hot (not a problem here, apparently).

Shielding from stray EMF from the ignition system is the only remaining concern, and I'm hoping a well sealed and grounded metallic enclosure will solve that.

How about that rear trunk. When I pulled the stuff out yesterday all of it was pretty warm including the tire. enough to dry my pants which were totally soaked from working the course in the rain.

On a real hot day (about 90F) I've seen intake temps of a hair over 50C, this is on the gauge mode of my SDS system.

My SDS is mounted inside a gutted stock brain box...the engine connectors are waterproof but the ECU (and ECU connectors) are not.

SDS reccomends mounting the coil packs at least 3 feet away (to prevent EMF) from the ECU. My coil packs are on the left side, but may be a bit under 3', with no issues.