sgraber
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| posted on 19/9/03 at 03:35 AM |
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Where to put the ECU?
So! I'm finished tacking up the exhaust (turned out great - photos by tomorrow) and soon moving on to the wiring. I've decided to use the
stock MR2 looms as there seem to be only a few pounds (Kg's) of extra wiring in there and I'm not up to the challenge of deconstructing
the entire rats nest just to remove a few circuits. But maybe I'll do that some other year.
I do have to move the ECU from it's stock location because it's currently setting directly above the exhaust system. Question is, where
should I put it? Inside the cockpit behind the passenger seat? or on the firewall in front of the transmission? Somewhere else in the car?
Alan, where will you be placing yours?
In regards to splicing the loom, would ye all recommend a wee bit o'solder or crimping?
(See, I can speak like a brit, even though I don't really know what the word 'Bollocks' means...  )
Graber
Steve Graber
http://www.grabercars.com/
"Quickness through lightness"
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Alan B
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| posted on 19/9/03 at 04:09 AM |
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Easy Steve....
bollocks = testicles
ECU position.....erm....not sure yet...
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kb58
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| posted on 19/9/03 at 05:23 AM |
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Easy, someplace out of the way, cool, and dry. I put mine behind the passenger seat.
For shortening the wires, solder and shrink wrap.
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stephen_gusterson
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| posted on 19/9/03 at 09:13 AM |
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I have a trademark on 'bolloxs' use it sparingly 
ECU need to be ideally kept out of cold hot or wet areas, so inside the car would be preferable.
Electronics will only workbetween certain temperatures, and will malfunction if cooked or chilled.
atb
steve
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tadltd
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| posted on 19/9/03 at 09:41 AM |
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We had problems with ECU temp' on the first LMP - to the extent that it fried and needed replaced.
It was mainly due to being located in a hot spot in the engine bay. A bit of re-location, some heatshielding and venting of the engine bay took care
of the problem.
But make sure you have plenty of engine bay venting if you're doing a mid-engine installation. It's not so much a problem when running,
it's after a hard run, when the car's not moving and the all the heat's building up in the engine bay; that's what causes the
problems. That's also the time when plastic connectors melt, so be careful where you place them!
Steve. 
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GO
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| posted on 19/9/03 at 10:01 AM |
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The MR2 puts the ECU on the rear of the bulkhead behind the engine, i.e. in the boot. It gets pretty warm in there, but not hot.
I'm guessing you're not having a boot behind the engine tho so thats a non starter.
As you've not got a roof  , I think behind the passenger seat is a bit risky, too open to rain, unless you can cover it well (see below for
my plans...)
I'm also guessing that without massive mods to the wiring you're not going to have an awful lot of choice about how far away from the
engine it can sit.
So, I think your best bet is going to be in the engine bay, but with decent heat sheilding.
I'm going to make an alu box for mine, leave a hole for the wires to poke out (obviously!) and seal up the edges with silicone, and mount with
wires pointing down. That'll stop any water getting in, but you'll have to be careful of the heat still, I think I may have to put vent
holes in the sides. At the moment I'm thinking of mounting it on the underside of the top of the passenger footwell.
Are you going to be using the engine fan off the MR2? There's a fan at the side of the engine bay that sucks in cold air through the side vent
when it gets too hot (this actually causes another common problem on the MR2 - exhaust manifold cracking. The fan sits to the side of the engine and
the cold air only hits one side of the manifold, so one side cools down while the other stays hot, crack!  )
PS. have you got any more views of your design yet? Love the side view, wanna see the rest of it though!!!
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kb58
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| posted on 19/9/03 at 03:13 PM |
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If it's put in the engine bay, consider a vented box. Cool air in at the bottom and hot air out the top.
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sgraber
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| posted on 19/9/03 at 03:24 PM |
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Thanks all. I think that I'll keep it in the engine bay, but route it under the fusebox that sits in the front lefthand corner of the engine
bay. It looks like I'll have to add about 2 meters of length to the ECU wiring harness.
With regards to engine bay heat soak. I did intend to use the original fan in it's original location, but now that the manifold cracking was
mentioned, and my cars manifold was cracked on #4 cylinder, I think I'll try to place it somewhere else.
I am building a complete Flat ali undertray for the engine bay and was simply intending on drilling a number of round 25mm holes in the ali (15 or so
tightly spaced) just underneath the manifold area. The decklid will be vented and the rear will also have a large vent area. The side nacelles (sp)
will also vent directly into the engine bay for cooling while moving. This is ARIZONA where it can be 120f in the shade!
How about if I attach the fan to the undertray directly over those vent holes so that it moves air up evenly over the exhaust and forces the air
upwards out the decklid vents? With adequate care taken to waterproof the motor... It's a pretty compact fan. and moves a lot of air.
I haven't made any more progress on the body design. To busy replacing all the flooring in my house....
[Edited on 9/19/03 by sgraber]
Steve Graber
http://www.grabercars.com/
"Quickness through lightness"
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kb58
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| posted on 19/9/03 at 05:40 PM |
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quote:
Originally posted by tadltd
We had problems with ECU temp' on the first LMP - to the extent that it fried and needed replaced.Steve.
I didn't realize you had built one before...
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stephen_gusterson
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| posted on 19/9/03 at 10:40 PM |
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the jag xj-s has the ECU in the boot - and the wires and vacuum pipe to the V12 run the whole length of the car....
!!!!
atb
steve
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JoelP
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| posted on 20/9/03 at 12:38 PM |
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consider a computer fan, like the one on a processor. That should help and you can mount it directly on the ECU.
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Spyderman
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| posted on 20/9/03 at 01:17 PM |
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If you isolated the exhaust from the engine bay with a heat shield, you could mount it at the rear of the engine bay.
Your idea for the fan sounds good. Might even give a little down force like the ducted F1 cars!
Terry
Spyderman
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tadltd
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| posted on 28/9/03 at 09:43 PM |
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The fan over the floor vents is a good idea - not only to pull in cool air (the excuse used on Gordon Murray's Brabham 'fan' car),
but it will aid downforce quite considerably (which is why it was banned!! ).
You may want to use a mesh panel, though. That'll stop most of the larger pieces of road debri getting sucked into the engine bay!
Steve.
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Spyderman
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| posted on 28/9/03 at 11:03 PM |
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quote:
Originally posted by tadltd
The fan over the floor vents is a good idea - not only to pull in cool air (the excuse used on Gordon Murray's Brabham 'fan' car),
but it will aid downforce quite considerably (which is why it was banned!! ).
Steve.
Erm!
Read my post above!
The fan is not that powerful or very large anyway!
[Edited on 28/9/03 by Spyderman]
Spyderman
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