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Airflow, Scoops, Vents and High Temps....
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Jon_slider
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PostPosted: Sat Aug 05, 2017 2:01 pm    Post subject: Re: Airflow, Scoops, Vents and High Temps.... Reply with quote

Team WorldTour wrote:
yup


and?
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E1
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PostPosted: Sat Aug 05, 2017 2:16 pm    Post subject: Re: Airflow, Scoops, Vents and High Temps.... Reply with quote

I don't know the vagaries of airflow around the diesel, but the leafblower idea is interesting for testing the correlation of the window vents vs. the side vents. But that ignores or assumes what the air is doing in real terms, and there's not a sufficiently wide enough wind path to learn anything underneath.

In general, ignoring the scoops and window vents for a moment, when air flows under the van, it is sucking air OUT from the engine bay as it passes underneath. Aero 101 in racing.

As air rushes by the side vents, it creates a vacuum that pulls air UP and out of the engine bay. Picture those two working together and you might see what I mean.

All this would be obvious if the vent fins faced into the passing air of course, but then too much rainwater would get in. So angling the fins to remove unobstructed, upward air provides the greatest vacuum for bringing air up and out. Angling the fins the other direction would keep far more water out but impede the exiting, rising air.

On a racecar engine-air scoops, radiator scoops, and brake scoops, note they're ALWAYS placed in as an undisturbed airflow as possible to draw air IN.

On our Vanagons, the air against the sides is pushed well away from the sides at the nose, and never much comes in solid contact with the sides again with enough real force to cause a proper ram-air effect. Add a scoop a foot wide and I believe the result is a turbulent meeting of incoming and outgoing air.

If one were to (carefully!) place a smoke bomb to the bottom of the channel under question, without a window vent or a scoop, at speed the smoke would pour out the vent like crazy.

Another way would be to put duct tape strips inside the channel going both directions, and on all four sides of the channel to see which direction made the tape stick.

All why VW didn't integrate an incoming-air scoop -- even in the early days of air-cooled motors desperate to stay cool! Wouldn't they have, if only to save on engine warranty issues?

Remember, ours is a sister company to the most-winning brand to ever run Le Mans. I suspect they learned everything needed to solve this mystery there and elsewhere.

To wit, in my view the window vents would disturb the passing air and reduce the vacuum pulling hot air up and out. Adding scoops would just make it worse.
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PostPosted: Sat Aug 05, 2017 2:38 pm    Post subject: Re: Airflow, Scoops, Vents and High Temps.... Reply with quote

They seem to work when used this way.
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PostPosted: Sat Aug 05, 2017 2:46 pm    Post subject: Re: Airflow, Scoops, Vents and High Temps.... Reply with quote

E1 wrote:
To wit, in my view the window vents would disturb the passing air and reduce the vacuum pulling hot air up and out. Adding scoops would just make it worse.

the OP has already determined that his scoops are not preventing his engine bay from running cooler than ambient.

we don't know which way the air moves through his vents, but, it doesn't matter

something else is causing his vehicle to overheat, unrelated to the scoop

Imagine this is a top view of our Vans, and the airflow you see is along the sides. Notice the vacuum at the rear will suck air out of any opening towards the rear of the van. In fact, the rear window vents also have holes on their back edge, and air IS sucked out of those. Even more if you open a front wing window.

Bon Apetit!
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PostPosted: Sat Aug 05, 2017 2:56 pm    Post subject: Re: Airflow, Scoops, Vents and High Temps.... Reply with quote

That looks good, do you deliver?
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PostPosted: Sat Aug 05, 2017 3:16 pm    Post subject: Re: Airflow, Scoops, Vents and High Temps.... Reply with quote

turbulence, but not cheese-sucking turbulence...


BTW, some of the newer Pooscheys have airfoils that are motorized and will erect at a certain speed...

I cannot wait for one of you guys to add that feature the the Vanagon dipstick flap Twisted Evil
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E1
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PostPosted: Sat Aug 05, 2017 3:30 pm    Post subject: Re: Airflow, Scoops, Vents and High Temps.... Reply with quote

Tristar Eric wrote:
They seem to work when used this way.
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I'll bet that works great!

Some distinctions from stock:

-- No side windows or side-panel deflection draws air more inwardly;

-- Wide scoops;

-- Air goes straight into the coolers (any amount would help);

-- Chimney effect disabled.

If the stock inlets drew air IN, the channel bottoms would be a vile, electrically-hazardous mess every week.

The stock felt panel encasing the air inlet would make no sense either, as it would live in a permanent, constant, force-fed onslaught of water and dirt -- all while blocking any potential cooling air from entering the engine bay.

So more on topic, I think the window vent in question compresses the passing air and directs it further away from the stock vents or anything else. In the OP's pictures, this would provide even less air around the rear vents.

I am convinced there'd be little clean air left over in the window vent's wake to give any real ram-air effect to those narrow scoops.

Signed,
Another Eric Racing Junkie

Edited for clarity
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Last edited by E1 on Sat Aug 05, 2017 4:11 pm; edited 3 times in total
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PostPosted: Sun Aug 06, 2017 1:37 am    Post subject: Re: Airflow, Scoops, Vents and High Temps.... Reply with quote

Waldi wrote:
Team WorldTour wrote:
No, not any more. I had to remove it after I broke a weld on the cooler replacing the hoses.

I still have it in a box in my garage. IF I can find a replacement cooler, and if I can find a replacement temp probe, I would definately reinstall it.


Thats your problem with high temps.
The AAZ oil on summer temps highway will heat up over 120C.

http://www.ebay.de/itm/Olkuhler-Motorol-Original-V...SwRXRZPSfK

Check my gallery how to mount it.
You have a Mocal adapter with thermostat ?



Nico,
there you got your awnser.

The engine can never been cooled down from outside (scoops) more than from inside (oil and good watercooler).
If you would have digital gauges for water and oil temps, and you would do the test with and without scoops, you would see a difference.

The watertemp you get now while driving 120 is totaly normal and not too hot.
Your very hot oil (too hot) makes the water hot in the stock oil-water-cooler, which goes directly again to the engine,

Why do i need always repead what i say ? (bad scool children Wink

But do you agree now, seeing the temps, that the scoops work with your vents ? Wink

Was your gauge on the flor of the pillar or on the high of bat top ?
Standing still with engine on the temps are lower, than with engine off. Try it.
But this is also not important.
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PostPosted: Sun Aug 06, 2017 1:44 am    Post subject: Re: Airflow, Scoops, Vents and High Temps.... Reply with quote

E1 wrote:
Tristar Eric wrote:
They seem to work when used this way.
...

I'll bet that works great!

Some distinctions from stock:

-- No side windows or side-panel deflection draws air more inwardly;

-- Wide scoops;

-- Air goes straight into the coolers (any amount would help);

-- Chimney effect disabled.

If the stock inlets drew air IN, the channel bottoms would be a vile, electrically-hazardous mess every week.

The stock felt panel encasing the air inlet would make no sense either, as it would live in a permanent, constant, force-fed onslaught of water and dirt -- all while blocking any potential cooling air from entering the engine bay.

So more on topic, I think the window vent in question compresses the passing air and directs it further away from the stock vents or anything else. In the OP's pictures, this would provide even less air around the rear vents.

I am convinced there'd be little clean air left over in the window vent's wake to give any real ram-air effect to those narrow scoops.

Signed,
Another Eric Racing Junkie

Edited for clarity


Another ignorance of the facts ?
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PostPosted: Sun Aug 06, 2017 8:33 am    Post subject: Re: Airflow, Scoops, Vents and High Temps.... Reply with quote

Yeah, I guess I'm a gonna have to rig sompthin up.......
I guess I'll have to find a new cooler that fits.
And something for the temp sensor...
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PostPosted: Sun Aug 06, 2017 10:17 pm    Post subject: Re: Airflow, Scoops, Vents and High Temps.... Reply with quote

Team WorldTour wrote:
the scoops might actually be hurting my cooling ability

let us know what you find out after you remove them?
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PostPosted: Mon Aug 07, 2017 1:00 am    Post subject: Re: Airflow, Scoops, Vents and High Temps.... Reply with quote

Yeah, I've got to find the tape first and do that test.
I'm pretty sure I need the oil cooler back. I think Waldi is right: The temp spike comes from the oil/ coolant heat exchanger, driving my coolant temps up from the hot oil.
Remedy: Reinstall oil cooler.
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PostPosted: Mon Aug 07, 2017 1:15 am    Post subject: Re: Airflow, Scoops, Vents and High Temps.... Reply with quote

If you want to get shocked, install the oil temp gauge first Wink
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PostPosted: Mon Aug 07, 2017 9:01 am    Post subject: Re: Airflow, Scoops, Vents and High Temps.... Reply with quote

Team WorldTour wrote:
Yeah, I've got to find the tape first


as far as your scoops go, it has raised the question whether they are chimneys, heat rising out of them, or drains, fresh air flowing down them.

one way to settle that argument is to tape a ribbon inside the scoop and see if it gets sucked out into the airstream, like the hamburger shows..

and yes, this whole scoop discussion has nothing to do with the fact that you need to reinstall an oil cooler, lack of which is the actual source of your motor coolant overheating

I do think your temperature readout at least informs to that extent, that the scoops are not part of your overheating issue..

I look forward to your experiments Smile
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PostPosted: Mon Aug 07, 2017 9:36 am    Post subject: Re: Airflow, Scoops, Vents and High Temps.... Reply with quote

Abscate wrote:
Add a post saying "no" after post one and delete the rest.


I think this:
jonslider wrote:

as far as your scoops go, it has raised the question whether they are chimneys, heat rising out of them, or drains, fresh air flowing down them.


could be the logical second post. The fact that there is no consensus on which way air flows in the pillar/at the vent seems like the first thing to sort out.
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PostPosted: Mon Aug 07, 2017 9:48 am    Post subject: Re: Airflow, Scoops, Vents and High Temps.... Reply with quote

Jon_slider wrote:


I do think your temperature readout at least informs to that extent, that the scoops are not part of your overheating issue.. Smile


True. I hope to get on this tomorrow. Been sick here lately.....
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PostPosted: Mon Aug 07, 2017 11:29 am    Post subject: Re: Airflow, Scoops, Vents and High Temps.... Reply with quote

feel better soon

there is nothing wrong with the scoops acting like a chimney, if that is what they are doing..

you might be able to figure that out by taping a streamer inside the scoop, then watch to see if it blows out when driving.. if it does, that would suggest that the scoops could be best oriented to the rear, where the suction is.. as the hamburger in the wind tunnel illustrates Smile

You could start by simply covering the scoops with plastic, and checking if that has any effect at all on your engine bay temperature. I suspect there will be no change, as it appears your engine bay is cooled by air running under the van, not down the scoops.. just a guess.

I really like your temperature tests, they quickly put to rest any speculation that the window vents, or the scoops, are interfering with motor cooling.

as an aside, note the back of the window vents have holes in them. This is to allow the vacuum behind the hamburger to suck interior air out. I think you would also find that opening a wing window, will increase airflow out the back of the window vents.

I still don't think any of the window venting, nor the scoops, affect your motor cooling, at all. I look forward to your tests to confirm I am right.. LOL!
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PostPosted: Mon Aug 07, 2017 12:33 pm    Post subject: Re: Airflow, Scoops, Vents and High Temps.... Reply with quote

Just to add a little info here.
I owned a 1990 Syncro Tristar that came stock with a JX 1.6td that was converted to an AAZ. I had problems with high temps so I ended up (after checking all the cooling system) with an external oil cooler.
Here is the original saga: https://www.thesamba.com/vw/forum/viewtopic.php?t=...mp;start=0
Page five has the post with the parts list I bought.

Long story short; install the oil cooler up front and all your cooling problems will disappear.

Since the Doka truck body has very limited air vents I decided to run oil lines to the front of the vehicle and placed the cooler in direct air flow in front of the radiator. This made a huge difference and if I had done this from the start I would have saved a whole lot of trouble. If fact with the new oil cooler the 80* thermostat I installed made the truck run a bit too cool.

So, how does this relate to the story at hand? The way that VW built the Doka body there is only very small vent slits above the wheel wells to allow air into the rear bay and in the diesel Dokas this vented area is closed off from the engine with noise reduction panels, allowing air to the turbo cooling fan and air cleaner only. You can see the panels in this photo. (these are made of new materials but are the same size and shape as originals)
Image may have been reduced in size. Click image to view fullscreen.

So in the case of the Doka body VW was not worried about cooling the engine with air intakes into the engine bay, only with providing air to the air cleaner (and the separate turbo aux cooling fan).

On the stock Syncro Vanagon body the engine intake air is directed from the sealed passenger side D pillar, allowing zero cooling from that pillar.
The original air-cooled Vanagons used air flowing in through the vents to supply the cooling of those engines, but I think that on Wasserboxers the vents serves more to allow hot engine air to escape while parked. (I have my doubts about any chimney effect while driving, VW placed the air intake snorkel there and you want cool air for that!)

That doesn't mean that we can't repurpose those vents to force more air through the D pillars into the engine bay for additional cooling in newer motors.
For my Zetec powered Syncro I plan to make or buy scoops to aid in cooling my engine bay and will most likely add an opening beside the license plate (or move the plate and use that opening) to help with air flow past the exhaust manifold. As it is now I leave the license plate holder unlatched allowing a bit of air to pass, and open it all the way after stopping on hot days to let hot air out. Helps to keep the rear bed cooler.
The conversation about whether the window vents affect air flow into scoops is a good one and I think has been answered by VW when they redesigned the body for the newer SA vans.
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PostPosted: Mon Aug 07, 2017 1:13 pm    Post subject: Re: Airflow, Scoops, Vents and High Temps.... Reply with quote

Jon_slider wrote:
it has raised the question whether they are chimneys, heat rising out of them, or drains, fresh air flowing down them.


The question is of the rear vents as a whole and, thus, whether the scoops aid in their purpose. Frankly, why does it have to be one or the other, why not both? When the vehicle is in motion, it's a ram-air style effect; when stopped, it's a chimney effect.

My personal experience: Climbing the Palm Springs Tramway road at 9.5% grade, unknown to me there was a power steering fluid leak, which dripped backward onto the exhaust pipe. There was no "smoke" coming out of the right vent until I pulled into the parking lot (it did not exit the left vent). That alone tells me the vents are both an intake and chimney path.

No question regarding the OP's oil cooler... engine would benefit from one for sure.
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PostPosted: Mon Aug 07, 2017 6:17 pm    Post subject: Re: Airflow, Scoops, Vents and High Temps.... Reply with quote

kamzcab86 wrote:
When the vehicle is in motion, it's a ram-air style effect


not according to the OP:

Team WorldTour wrote:
As I was hanging out with some of VFW buddies last night, we came upon a problem with my airflow setup.

...I took apart some 550 cord, and tied some of the little strings around the vents to see airflow (in the mirror).

It looks to me that the window vents are pushing air OVER the scoops, therefore negating them.


my reading is that when he is moving, the strings did not go down the chimney

similarly, the video he posted shows the strings on the scoop flow to the rear of the van, not down the scoop.. seems pretty clear there is no significant suction down the chimney

Link


similarly, when you went fast, the streamers did not go down the chimney, they flowed over the grille, in a tumbling, turbulated, airflow
Image may have been reduced in size. Click image to view fullscreen.


at best, it is still unclear which way the air is moving at the OP's scoops, when he is doing 65mph..
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