Cost effective ways to reduce under bonnet temps

davekmoore · Postby **davekmoore** » Thu Oct 16, 2014 7:26 pm

A tuner has the car for a couple of weeks from tonight while I'm away overseas.

He has instructions to make it start, idle, and run like standard by getting the ECU properly set up, and without doing anything with vents etc.

Magpie · Postby **Magpie** » Thu Oct 16, 2014 7:30 pm

Form over function in some instances.

I have proven that my GV bonnet with a vent behind the radiator does decrease the under bonnet temp as some of the radiator air goes out this vent and does not have to pass through the engine bay. I have also proven that a well placed vent in the bonnet can reduce the engine bay temp (at the intake). However I have not proven if air is going in or out the vent that is for another day...

greenltd I have an air temp sensor in the mouth of my NA6 (in front of the radiator) and another on top of the ITB dome filter. I can then measure ambient air temp and temp at the ITB's. Since I also log speed I can then compare temps to speed. Further, the temp sensors are of the same type brand so this error has been removed. But I digress.

Danny's build has ALL the radiator air going out the vent. The engine bay gets ambient air that is capable of greater heat exchange as it has not passed through the radiator and already heated.

Another solution is to increase the air velocity through the engine bay, up to a point of diminishing returns. However this will still have to use air that has been heated as it goes through the radiator and has less ability to absord.

Tune is another issue that I'm happy to say I have no knowledge of and is a black art (in my book).

davekmoore · Postby **davekmoore** » Thu Oct 16, 2014 9:58 pm

Thanks Magpie. You make complete sense, too.

In a perfect world, as well as free and well meant, every piece of advice would be perfect, complete and consistent.

track_addict · Postby **track_addict** » Sun Oct 19, 2014 5:34 pm

Whats everyones thoughts on these vents? http://www.good-win-racing.com/Mazda-Pe ... 1523A.html

I'm looking into getting a serious cooling system set up and vents are definitely on the cards.

Magpie · Postby **Magpie** » Sun Oct 19, 2014 8:04 pm

Just found this http://www.motoiq.com/MagazineArticles/articleType/CategoryView/categoryId/142/Project-Frankenmiata.aspx

Was taking a break from a uni paper on tax law looking for ideas on changing the radiator mounts so that it is angled forward to allow a duct on the back. Plus since I run a splitter I could lower the radiator a bit.

davekmoore · Postby **davekmoore** » Sun Oct 19, 2014 9:40 pm

But there are those who say in this thread that ducts are not needed.

gslender · Postby **gslender** » Sun Oct 19, 2014 9:50 pm

davekmoore wrote:But there are those who say in this thread that ducts are not needed.

No Dave - I think most were saying that they only serve to improve the cooling effectiveness of the radiator. The under bonnet temps are either not relevant or only marginally improved by ducts.

Magpie · Postby **Magpie** » Sun Oct 19, 2014 9:53 pm

Ducts do provide an effect provided they are placed correctly.

davekmoore · Postby **davekmoore** » Sun Oct 19, 2014 11:40 pm

gslender wrote:
davekmoore wrote:But there are those who say in this thread that ducts are not needed.

No Dave - I think most were saying that they only serve to improve the cooling effectiveness of the radiator. The under bonnet temps are either not relevant or only marginally improved by ducts.

Understood.