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VZ Engine Bay Airflow?

routier1642

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Is there any information available on airflow inside a VZ engine bay?

Air comes in the front, obviously, through the radiator & various gaps, but where does the hot air from the radiator & the engine exit when you're moving?
The top back of the bonnet? At the bottom, under the car?

Where does it exit when you're stationary?


Just curious.
 

Big-Al

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When you're stationary and things get too warm the low speed cooling fan comes on and pushes air out the bottom of the end bay.
 

comvs95

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Spot on Big-Al
 

routier1642

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The slow cooling fan does come on, but it doesn't cool things enough on my beast.
Engine bay temp, coolant temp and inlet temp all rise markedly when I'm stationary.

So today, I just fitted an 8" auxiliary fan (Davies Craig), pointing down (thanks for the info) at an angle, on the other side of the engine bay, just aft of the air intake.
The intention was to take the heated air from around the intake box (a Growler), the intake tube, and that side of the radiator; it also blows air onto that side of the engine block.

On my test runs tonight, it worked well. It's not really needed when in motion, though it does keep the intake and coolant temps a little lower, but when I come to a stop, it really makes a difference - the temps build up extremely slowly, if at all.
Success!

I tried using it to relieve heat soak once the heat has built up, but that doesn't seem to work as well.
Or maybe I didn't wait long enough; movement works a lot faster, that's for sure.

Now if I could only rig it run for a couple of minutes after ignition off...

The experiments continue....
 

try_again

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I'm wondering if you are treating the symptom and not the cause?

If the vehicle is overheating it's probably because something is not right with the cooling system. What you are seeing might be an early warning sign of something more serious about to happen.
 

routier1642

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I'm wondering if you are treating the symptom and not the cause?

If the vehicle is overheating it's probably because something is not right with the cooling system. What you are seeing might be an early warning sign of something more serious about to happen.


No, it's not overheating, I'm just trying to get the air intake temperature down as low as possible.
The effect of my experiments on coolant temperature is just incidental.

Thanks.
 

Big-Al

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just plumb the intake into the aircon system or rig up something similar.
 

routier1642

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just plumb the intake into the aircon system or rig up something similar.

Believe me, I've looked into it.
I don't think that the aircon system delivers enough cold air to make much difference to the airflow; not to mention that I'd be using more energy to have the aircon on, and maybe not even getting that much back.
I haven't given up on the idea totally, but the air plumbing would be a bit more complex than I'm currently willing to do, going through the firewall etc.... I will investigate one day.

Would love to hear from anybody who has successfully done this, BTW!
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

However, the exposed aircon plumbing in the engine bay does have some "waste cold" that I looked at using, trouble is the coldest part is on the other side of the bay.
(I know that there's no such thing as "cold" only heat, but using the term makes discussion less clumsy, so bear with me)

Options were to either
(a) extend the intake airbox to a ridiculously large size to encompass the cold plumbing (moving the intake box not practical - it's a Growler which takes its feed from behind the headlight) or
(b) transfer the "cold" from the plumbing to the airbox by use of (1) an air-air intercooler, with some additional air pipe and some sort of air pump or (2) a water jacket around the cold plumbing, and a water pump with some cooling coils in the airbox.

Option (a) - crazy, with unknown ramifications on airflow
Option (b1) - expensive and too difficult to implement with the Growler
Option (b2) - would probably work, but a bit complicated for a max 6% gain in power (figured on 10 degrees C drop = 3% power), given that, when moving, IAT is 2-4 degrees above ambient anyway, and currently ambient is about 22 degrees.
There was a US company which made packages to implement option (b2), but they seem to have gone out of business.... so maybe it wasn't that great an idea.

The auxiliary cooling fan was a cheap and easy compromise which seems to have solved the main problem - heat soak when stationary.
I'm going to put in a thermal switch so that it only comes on when necessary.

And I insulated the exposed "waste cold" aircon plumbing - this seems to have made the aircon a little more efficient, oddly enough giving a flow-on effect to the engine coolant radiator (which is right in the airflow path of the aircon radiator), dropping my normal coolant running temperature by about 2 degrees.

Yes, a lot of mucking around for little gain, but a man needs a hobby.
 

Group C

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sounds like a little bit of knowledge is dangerous here, doing all that to a NA engine WASTE OF TIME,how much performance gain does you r engine have in the first 2 mins of starting????? compared to N.O.T???? SFA love your mental process and enthusiasm but waste of time.. forces induction is the only way to go
 
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