Under bonnet temperature
Turbo Mini Forums

I have started posting on Instagram also my name on there is turbomk1golf

Nothing is impossible it just costs more and takes longer.

As well as ducting etc, have you had your car set up yet? If your timing is sqiffy, it can cause it to run hotter than necessary.

I was out in mine yesterday. Less room under the bonnet and lots of abuse. It didn't seem too bad. It wasn't much hotter under the bonnet then in the cabin.

Maybe the louvred bonnet works better than I thought?

In the 13's at last!.. Just

one small thing i spotted in the pic was no rubber flap/strip between the rad and body get the air flow in the grill throw the rad and out/away from the car dont allow it to recirculate and get hotter and hotter also might be worth putting that ruber bonet/body seal on back on
what im getting at is cool air needs to get in extract heat and get out in a controlled way so as not to be reticulated

Edited by alaskanow0 on 15th Jul, 2013.

Class C 3rd Place Avon 2011 14.18 @101mph

My integrale evo featured massive bonnet louvres right above the tubular manifold/turbo for rally homologation purposes blocked off with sound padding to satisfy EU drive by noise regulations...

...naturally one of the first things I did was remove the sound insulation, in dense summer traffic the air escaping the louvres was so hot that vision almost got blurred from the mirage effect

using the big fan to pump hot air out makes most sense. but you need full cowling and it should be sealed to make that work properly.



Things that could help a bit.

JetHot/Ceramic coating on the header (edit .. you have it wrapped so probably not then)

turbo timer (just let it run at a bit above idle after stopping to keep the coolant running and the fan as well so to clear the heat before stopping and going into heat soak mode

Weird ideas:

how about an tiltable bonnet (hydrolics/linear actuator whatever should be good for all kind of constriction headaches). Basically push a button/pull lever and the rear of the bonnet pops up when needed ( at low speed ).


I could imagine using the demister/heater fan ( unless you offered that the gods of anorexia) to pump out heat as well .

I though about using a RC ducted fan into a venturi ( should mode some air pronto..) but then i noticed that they pull 110 amps@20v.

Edited by Sir Yun on 15th Jul, 2013.

That sir, is not rust, it is the progressive mass reduction system

http://aseriesmodifications.wordpress.com/

By re routing my boost hoses for the intercooler and my air filter feed I should have adequate space for a decent sized air duct and pipe work to the turbo area from the left lower panal area, below the intercooler

Class C 3rd Place Avon 2011 14.18 @101mph

Yes Yes Yes!

that should make a difference.

with intercooler too?

Edited by Brett on 15th Jul, 2013.

Yes i moved to the darkside

Instagram @jdm_brett

Looks good but cant help think that orange one would force air against the bulkhead
If it where me i'd go underneath the oil catch hoses and try and point diagonally up

only costs another zip tie to try so let us know the results

the air hose position looks perfect though

Reading up on RTS Clutches

long post at the risk of sounding like a total prat

I'd say intake hose good. although you need to insulate it because in runs across a hot radiator, but that is easy ( chrome)

now for the long bit:

The other hose will do nothing for the under bonnet temps. Think about how the pressures are. I even doubt it will actually move air at all.

You want the air to move through the engine bay (only way to get the heat energy out) . If you where to seal the entire bay (for discussion sake.. so no rad no fan) and just have the hole in front. You would just have a big high pressure area under the bonnet that would increase at speed until an equilibrium was reached and no flow would take place but for a bit of mixing at the forward boundary layer depending on if the cavity would resonate.

To have any type of flow you will have too allow or provide a pressure gradient

(I.e the air needs an escape route (make the box leaky) and that preferably needs to be at a low pressure point (so not near the windscreen as this is a high pressure point that is why the vent intakes are often taken from here).

Look at the CFD image of this land rover (actually somewhat similar in shape to a mini) for the general idea. Remember the cooling slits in the right front fender for the old mercedes turbo diesel with intercooler, now look at the colour of the Range rover. they where placed there for a reason: not a bad place to dump the heat from the intercooler. although your feeling might say differently
but as you want to dump heat

right hand fender well is probably a low pressure zone as well. so you probably be better off routing the hose with one end in the fender well as it will the transport the air from the high pressure zone to the low pressure zone ( The hose is now positioned to blow across the turbo , which very probably won't happen because the pressure gradient from pipe front to pipe end is not different to the pressure differential parallel along the pipe on the outside ( or no pipe for that matter). Even if it did ,you will be just heating up the engine bay more evenly) because you basically have build a fan oven .

Any intercooler/radiator/heat exchanger works on the basis that you need a gradient (be it pressure or temperature) across it. In general you need the front to be fully separated from the back so as not to have recirculation of (hot) air, and the back end need to be a lower pressure than the front. i.e. it needs to be a sealed pressure conduit I really does not matter where the duct is pointing to as long as it is sufficiently big not to give overly high frictional losses as long as the air pressure is lower there (either provided by vehicle movement or a fan (pulling through a heat exchanger is about 20 % more efficient when using a fan).

So one sensible route would be to take the air in front of the windshield and duct it across, say an intercooler forward to the inner fender ( if it is indeed a low pressure zone) even though it is against the vehicle direction


Sticking in a big intercooler will help as well as the amount you cool will be reflected in the exhaust temp (drop 30 degrees in the front.. you get ~30 degrees lower at the back).

well either this, or the DON approach : make the box very leaky and put the very hot bit outside . Thermodynamically one of the more sensible solutions, but it kinda does give the game away

that said. the heat soak situation is the worst case : run it at full power then shut it down completely in high ambient temperatures.

there will be zero air movement, zero coolant movement, and only the pressure in the system caused by it being hot (the pump provides around 30 to 60 psi of pressure depending on rpm increasing the boiling point of the coolant by quite a lot).

cool it down with the engine running at reasonable rpm at no load (at low rpm the pump does not move a lot of water at all). that will keep oil (also a major part of a minis cooling capacity) and water running and the fan will pump out the hot air as well.

end of cermon.

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Edited by Sir Yun on 16th Jul, 2013.

That sir, is not rust, it is the progressive mass reduction system

http://aseriesmodifications.wordpress.com/

Theres a similar set up on the escort cosworth, if you can picture the slim vents at the rear of the front wing (against the door edge) , there are slits in the rear of the inner wing, (they look like gills), so the hot air moves through the bay and exits through these vents, if you stuck your hand out of the window you could feel the warm air!!.

Now to mats problem, It needs to look stock !, no silly holes or vents on the outside you he needs to be clever to discretely position them out of sight

I still say an intake fan on the left and another exhaust fan on the right. (As you look from the front) Creating a wind tunnel effect pulling the hot air out of the bay

how about a splitter on the front end to stop some air going under that car this should make the low pressure area under that car larger makeing a larger sucktion to draw the air out or some holes in the iner guards also low pressure as said above