Worzey
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| posted on 1/5/13 at 05:18 PM |
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Overheating on idle
My car is overheating when idling since getting the supercharger fitted.
Its fine on the open road but it quickly overheats on idle.
I've checked the obvious items.
1) Fan is working correctly
2) No air in system (bleed multiple times)
3) Correct coolant levels
I've discovered that everything is fine when the bodywork (nose and bonnet) is off the car. Fan kicks in, cools the car down and turns off
again. Once its all back on the problems start. I assume that its under body heat that is the issue.
I'll look into getting a bigger fan on the basis more air will give better cooling but if the hot air is being trapped that might not cure the
problem.
The exhaust isn't heat wrapped. Is that likely to make much difference?
Any other ideas? The velocity has a bonnet scope but I'm not sure how much heat that lets out. More vents?
Caterham R400
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Ben_Copeland
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| posted on 1/5/13 at 05:30 PM |
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More vents at the back of bonnet. Wrap the exhaust or some sort of heat shield would be best.
Ben
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britishtrident
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| posted on 1/5/13 at 05:37 PM |
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What is the ignition timing at idle ? retarded timing makes the gas temperature at the end of the combustion stroke very high which means a lot of
waste heat gets rejected to the cooling system and exhaust.
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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Worzey
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| posted on 1/5/13 at 05:43 PM |
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Good question, I'm not sure how the timing is configured but it was retarded to reduce power. It made 260bhp on the dyno and got retarded to
248bhp for engine longevity.
Think I've got room for a second or bigger rad fan but its going to be a squeeze. Hopefully this plus exhaust heat wrap might be sufficient to
expel enough air.
Caterham R400
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rusty nuts
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| posted on 1/5/13 at 06:32 PM |
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I found cutting some vents into the rear of the bonnet and lagging the exhaust manifold reduced the under bonnet temperature on my Luego locost .
Water wetter also reduces coolant temperature
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ss1turbo
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| posted on 1/5/13 at 06:43 PM |
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What management are you running - or is it stock and the dizzy tweaked to reduce the maximum advance? If the latter, then it's retarded way too
far on idle now, hence the mixture is still burning whilst going down the exhaust, rather than being used to propel the engine!
If the "only" thing you've done is add a supercharger, then the blame can't be put on a water pump.
Long live RWD...
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Worzey
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| posted on 1/5/13 at 06:56 PM |
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Its running an OMEX 600 ECU. All I've done is add the supercharger although the fan was changed from an 11" pusher to a smaller puller
due to space requirements.
It's running a 7.5" Revotec fan now. Not sure a 9" Revotec fan will fit but surprisingly I might get two 7.5" Revotec's
side-by-side.
Need to see if I can pick-up a fan tomorrow or Friday so I can drive to Stoneleigh on Monday.
Caterham R400
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ss1turbo
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| posted on 1/5/13 at 07:11 PM |
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7.5" sounds rather small for a single fan IMHO..
If you've added an intercooler in front of the rad, the (small) added restriction plus a smaller fan won't help matters at all. Might be
enough to tip it over the edge?
Long live RWD...
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Worzey
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| posted on 1/5/13 at 07:28 PM |
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Just purchased a second fan so now I'll be running two 7.5" Revotec's. Hopefully that will do the job.
Might also grab some bonnet vents at Stoneleigh and exhaust wrap to be on the safe side.
Caterham R400
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madteg
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| posted on 1/5/13 at 10:23 PM |
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What temperature does the fan kick in at, might be worth lowering it if you can.
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Worzey
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| posted on 2/5/13 at 06:37 AM |
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Fan kicks in at 92 and goes off at 90. I've changed the settings to on at 90 off 88 and it does slow the overheating down but doesn't
stop it.
I could try using 88 and 86 as short-term thing to buy me a little more time.
Caterham R400
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britishtrident
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| posted on 2/5/13 at 07:22 AM |
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I still suspect one of the causes is the advance curve around idle speed.
However it is also apparent you need more air cooling the only things that will help the symptoms is to get more flow air in contact with the
coolant ie a bigger rad and or fan(s) and extractor vents.
Extractor ducts will reduce the back pressure (aka "blockage" on the fan -- but be careful as a duct positioned in a high pressure area
such as too close to the base of the windscreen can cause reverse flow at speed. The area towards the rear of the nose is usually a low pressure
area because the air is flowing faster at this point, hence "nostril" vents on the upper surface of nose behind the rad on late 1960s
early 1970s F1 and CanAm cars. such as the Lotus 49B
Link to Lotus 49B photo http://cars-database.com/data_images/gallery/03/lotus-49b/lotus-49b-05.jpg
McLaren M7 picture link http://en.academic.ru/pictures/enwiki/72/Hulme68.jpg
[Edited on 2/5/13 by britishtrident]
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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Worzey
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| posted on 4/5/13 at 06:37 AM |
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Thanks for the comments and advice 
Second rad fan now fitted. Problem appears to be resolved.
Caterham R400
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rusty nuts
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| posted on 4/5/13 at 07:05 AM |
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Thats good news, see you at Stoneleigh
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