Engine bay temps

bax

Torque Junkie
Points
157
Location
Mars
Car
Rexton 270xdi 2005
so since my car is a diesel and a remapped one with other mods on it , the temps in the engine bay tend to peak and one can barely touch anything in the engine bay after a few heavy runs , needless to say things get much worse while offroading and pushing the engine to its limits .
i have looked into wrapping the turbo and the downpipe but it was made clear to me that its quite risky and im basically shifting the strain to a different spot and things could really get ugly if the wrapping fell apart at a certain area as the days went by.
so lately ive been considering buying a bonnet from a junkyard and modding it to allow the hot air to escape out of the engine bay , basically a hood scoop ..

now the thing is rain is common thing here especially in winter and fall .. i know water going into the engine bay on a diesel isnt as problematic as it is on a petrol but id still rather avoid having the water go into the engine bay as it could wear out the wires and other components (plus it will really make the engine bay look dirty) .
so a reverse scoop is what i had in mind , something that dosnt get in the way of the aerodynamics and dosnt reduce my field of vision ... however the main issue remains ,even though this way i will get far less rain coming into the engine bay it would still slide into the scoop when the car is parked or when slowing down enough for the water to slide off the windshield and into the scoop ..
maybe if i create some sort of bump before the scoop it will divert the water to the sides and solve that issue ..
i think a reverse scoop with its upper lip sticking forward will block the rain coming from above and this bump would block the water sliding from the windshield and such ..

what do you guys thing ? anyone has experience with those ? perhaps theres some sort of vent for the scoop that allows air to pass but not water ?
 
You may want to consider the following before you fit any sort of vent,scoop.
1 if you do a lot of low speed crawling then raising the rear of the bonnet is the way to go.

2 If speeds are relatively high then raising the bonnet will not help as that area becomes a high pressure area and will not allow hot air to exit..

3 The front 1/2 of the bonnet is a low pressure area so installing EVO or Cosworth style vents will allow hot under bonnet temps to flow or be drawn out thru the vents in that area by the air flow over it and consequently let more incoming air flow thru the radiator due to reduced underbonnet pressure.

4 Have a look at the Cossie and Evo vents and placement as the car makers do have a few clues :)

PS be careful when installing vents not to remove any of the bonnet bracing as it may render the car unroadworthy in some jurisdictions.
 
thanks for the reply
by raising the rear of the bonnet you mean to simple use some nuts and longer screws to have the rear end of the bonnet rise a few centimeters off the fenders and create a gap that would allow the air to escape ..... if thats correct then im afraid this isnt an option because to me it ruins the look of the car as it resembles a car that has rammed into something and now the front is all dented in ... though it could be a decent temporary mod while offroading to help cooldown the engine bay

im not sure what you mean by relatively high but this SUV maxes out at around 200Kmh and the average speed at which its driven on the road is around 160Kmh , but assuming that fits what you mean then does the same apply for a reverse scoop ?

the main problem with such vents is that they are completely exposed , which is an issue when it comes to rain .. also having them at the front is pointless (atleast thats how it seems to a rookie like myself) since the turbo and the downpipe and the exhaust manifold are all located way back
but yeah the main issue is rain and such .. correct me if im wrong but these wont stop the rain from going in .

i plan on avoiding cutting any of the strengthening parts of the bonnet , ill build two small reversed scopes on the sides of it if having one in the center will require cutting of vital parts of the engine

i came across this ... i can attempt to do the same and then wield plates to the sides to fill the gaps ... true this may render the car unroadworthy like you said but for now im just trying to understand how the whole thing works
11-10-09_2230.jpg
 
Wrapping the turbo and down pipe doesn't cause any problems to the rest of the system, as long as it is in a good condition. However, wrapping a turbo is tricky unless you use a bespoke cover, like this (top left):

 
Brother TC , unfortunately i dont have a garage or such to shelter my car from Rain when its parked and it seems too troublesome to cover the car and uncover it daily in the rainy season .. also wouldnt stopping at stop lights or traffic jams count as parking ? i understand its not that big of an issue on a diesel engine but since im going this far why not go for the best option that would fulfill all my needs be it cooling the engine bay or keeping the rain and water out .

Steve ive been convinced that wrapping the turbo and keeping the heat in it would put extra strain on the turbo bearings and other parts of the turbo and shorten its life span , i believe such a high quality wrap like the one you pointed out isnt exactly cheap ... if you were in my place and had the tools to build a custom hood with a scoop would you go for that or would you still go for the turbo wrap ?
 
oh thats alot cheaper than i expected , why did your one cost that much though ? or prices were crazy 5 years ago ?
so lets say i wrapped the turbo .. its still just 1 item that generating crazy heat , theres the Downpipe and the exhaust manifold .. i know i can wrap the downpipe with wraps from ebay but ill need to do a good job wrapping them but then theres the Exhaust manifold .. i doubt theres anyway to wrap it .. probably needs to be coated with some special material .. but i hear if that material gets scratched then the area of the scratch will get super hot and will crack or deteriorate ... is there truth to that ?
 
If you mean the turbo, because it had a lot of work done to it :)

If your manifold is a cast iron unit rather than separate pipes then, yes, ceramic coating is the only effective way of covering it. I had to do this with mine.

Although I also had the exhaust ceramic treated as far as the exhaust box, wrapping is almost as effective if done properly.

Who the hell is feeding you this garbage? Properly applied ceramic coating is very tough so difficult to scratch through to the metal. However, even if you did why would the scratched area get any hotter than the rest of the system? Where is this extra heat coming from? If anything, due to the lack of ceramic, it will get cooler due to heat loss through the area not covered in ceramic.

You really should stop listening to these people :)
 
oh thats alot cheaper than i expected , why did your one cost that much though ? or prices were crazy 5 years ago ?

Steve prefers to spend the money on a turbo that will perform under the heavy conditions that it will be subjected too and then carry on doing this for some time to come; an unlikelihood of this ever being achieved is if he buys a turbo from China with a warranty guarantee no longer than the delivery schedule to the UK. In other words my friend, if you don't buy high quality don't expect high performance.
 
My bad .. i thought he meant the wrapping not the turbo itself ... makes much more sense now xD .. ill look around see if anyone in my region does that ceramic coating .. ill have to reconsider everything ive been told it seems , ill dig deeper and see what i can find

thanks alot i really appreciate it
 

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