EARZ

[Moseley]

The actual air requirements required for the fan / engine are not really relevant in this discussion revolving around the earz. A naturally aspirated engine (and the cooling fan in this case) draws in the air it needs using a pressure difference between the engine / fan inlet and the air in the engine bay. So long as the cross sectional area of the fresh air into the engine bay is greater than that of the fan / engine inlet, there will be no starvation.

What these earz are presumably trying to provide is a means of positively pressurising the engine bay at speed using a ram air principle. If your engine bay is well sealed then this could well help out with the cooling, as technically the fan will flow a higher rate than it is 'rated' for because the air entering it is denser.

The reality is that the benefit is probably more from the ram air effect forcing extra air out between the gaps in the tinware and seals giving the enhanced cooling effect, rather than actually providing benefit to the stock fan setup.

 

[Busman73]

I use Earz on my van and can confirm with Christophe said,
with them fitted they do make a difference of about 10 degrees, especially on a hot day loaded up with camping gear

The main reason I used them was the engine in the bus was quite worn out and having to work increasingly harder so therefor increased the temperature on long runs and having fitted the Earz more than likely stopped me cooking my the engine allowing me to source a replacement and not have to take the bus off the road

I still use them today

 

[monkeyvanwestybike]

Just a thought
How do the Splity boys get on
Do they run hotter?

 

[rlepecha]

I took some measurements this morning and have recalculated, the area for each vent is actually only approx. 11.75 in^2, which is 0.0815ft^2 per vent. So 0.163ft^2 of total area.

I've updated my previous post to show this.

Based on those values there is negative air pressure in the engine bay and therefore the fan is required to pull air and thus is likely to be less efficient.

At a guess the ears probably double the catchment area, producing a similar amount of flow as previously calculated.
Approx. 1900cfm.

Ultimately the fan and engine shouldn't struggle to draw this air in, and air doesn't cavitate like liquids do so the fan shouldn't be that inefficient.

Splitty guys fit vents on the sides when they use bigger engines don't they?

Sent from my Siswoo C55 using Tapatalk

 

[vinvan]

Wow
only just got up to my 7x table

 

[paul_q]

Some Australian splits came with bigger vents.

 

[monkeyvanwestybike]

A bloke said to me once talking about vws
We had them out in Algeria when we were working out there back in the 70s
we would run around with the engine lid open!! :?
which I thought Why?
To me that seems like you just draw more hot air in from the exhaust and from under the engine where its blown out from the fan.
Anyway
All this about stuff about engines overheating and the the need for a piece of plastic stuck on the grilles
if you have your tinware and everything in place and engine etc running right there is no need

They might be useful on the near side
Rear wing of a Hillman imp
If you cut some slots

 

[ozziedog]

I'm sure a simple calc can solve this, albeit without taking into account losses.

At about 4000rpm the fan can pull 1350cfm.

Say 4000 rpm is 65mph, thats 5720ft/minute.

An approximate area of one vent is 11.75in^2. We are talking actually frontal area not the area of the vent at an angle.
That's 0.0815ft^2 each

So 5720*0.163=932.4cfm

Take the amount of air the engine uses for burning, 85.5mm dia barrel (1600) is 3.366in, PI*r^2=8.89in^2

69mm stroke is 2.717 in, so 8.89*2.717=24.15in^3. Which is 0.014ft^3
1 rev is two cylinders firing so 0.014*2=0.028ft^3.

0.028*4000rpm=112cfm required to feed the engine at wide open throttle and assuming 100% cylinder filled with air which is not correct.

112+1350=1462cfm minimum required air flow into the engine bay to meet the requirements of the engine at 4000rpm.

Thus 932.4 cfm provided by the vents would not be adequate to provide positive air pressure.



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Are you sure ?????????????? Now tell me again about the fan, what does it pull ? :shock:

Ozziedog,,,,,,,,,,,, Now we wants it right dunnas :mrgreen:

 

[Rikki James]

On a recent visit to Cairo I noticed that probably 90 per cent of all taxi's where knackered (and I mean really beaten up!) bay window buses, all of which had their engine lids either open or completely missing!! :lol:.

 

[Trikky2]

On a recent visit to Cairo I noticed that probably 90 per cent of all taxi's where knackered (and I mean really beaten up!) bay window buses, all of which had their engine lids either open or completely missing!! :lol:.

I would comment but it would probably be construed as racist by those who firmly believe it's possible to pick up a turd by the clean end.

Good news for local engine builders though.



MOD EDIT -

We have no idea what you might be alluding to here, but no racism or racist comments will be tolerated on this forum. Ever.

 

[monkeyvanwestybike]

Good news for local engine builders though.

indeed!
I wonder what oil they use

 

[Trikky2]

MOD EDIT -

We have no idea what you might be alluding to here, but no racism or racist comments will be tolerated on this forum. Ever.

Oh whoops Only just spotted this mod edit because this thread was linked to.

My comment was a tongue in cheek about "political correctness". Doubting the validity of a Cairo taxi drivers understanding of airflow and thermo dynamics might be fuel for the PC extremists :lol:

 

[tellimhesdreamin]

What about a Buggy or baja bug? How do they fit in with the earz debate?

 

[tellimhesdreamin]

What about a Buggy or baja bug? How do they fit in with the earz debate?