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Adding modern scoop for split bus engine bay cooling / pres.
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slow36hp
scott wimberley


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PostPosted: Mon Feb 13, 2012 8:36 pm    Post subject: Reply with quote

i wonder what effect the positive pressure in the engine compartment would have with the fan. i know the max a fan can produce is based off of zero pressure meaning you need a unrestricted flow. but at positive pressure are there really substancial flow improvements?
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flemcadiddlehopper
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PostPosted: Mon Feb 13, 2012 8:52 pm    Post subject: Re: cooling air Reply with quote

Cptn. Calzone wrote:
No doubt about it a 2 litre engine will be needing more cooling and combustion air especially with dual Dells lets say and a header. The cooling system and air into the engine bay although ingenious is designed to cool a much smaller engine turning slower speeds and generating less heat. So more air in will be beneficial, provided it is not at the expense of tinware or seals.


Well said, Not to worry I understand the value of proper seals in the engine bay. You've hit the nail on the head with the cooling and combustion air.
With a set of big webers pulling for all there worth they can flow up to 1000cfms and a porsche style fan can flow as much as a possible 3000cfms. All this through those little side vent, and having to be sucked in, not forced in. Forced air induction is nothing new for the engine to breathe better, it only makes sense that it would help the cooling system work better too.

Thanks for all the input, even those who think it's a dumb idea help me think it through and plan better.

gordo.
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flemcadiddlehopper
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PostPosted: Mon Feb 13, 2012 9:00 pm    Post subject: Reply with quote

slow36hp wrote:
i wonder what effect the positive pressure in the engine compartment would have with the fan. i know the max a fan can produce is based off of zero pressure meaning you need a unrestricted flow. but at positive pressure are there really substancial flow improvements?


important to remember we are talking about inches of water pressure, not PSI. If all I do is maintain zero pressure while increasing air flow, then I would say my mission was accomplished. Also as mentioned previously by someone, all the extra air would just flow out the intake vents. To me again that sounds like an efficient addition to the cooling system, more cool air than the engine needs.

gordo.
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Sambafraser
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PostPosted: Tue Feb 14, 2012 12:17 am    Post subject: Reply with quote

Rolling Eyes The ugly DTM fan shroud blows more than the Porki one. However I think as others have mentioned you are trying to solve a problem you don't have.
You live in B.C Canada which isn't known for its hot weather so if you are overheating an engine that will rarely see an air temperature of 32 deg C you have a more fundimental problem with the engine rather than what cools it.
There are some good books written by engine builders specifically for the aircooled VW. Where they have gone thru adding something, running it, stripping the engine down and then changing if needed. All of which was done systematically over decades.
Trying to use wikipedia and e-how has its limitations - this is one of them.
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flemcadiddlehopper
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PostPosted: Tue Feb 14, 2012 7:45 am    Post subject: Reply with quote

summers here do get to 40 deg C and dry. It feels hotter here than in california....I am only 1 hr away from Canada's only true desert, or is that dessert? .
I have read many of the good books....remembering that most of them were written in the 70s and most of them about drag cars. Although the parts that come to mind to me are the formula vees. Those little cars that ran no cooling fans on them at all and only relied on ram air to cool them...with two little air intakes, no bigger than the rain gutters that started this thread....hmmm, maybe they were onto something.
Gordo.
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flemcadiddlehopper
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PostPosted: Tue Feb 14, 2012 7:51 am    Post subject: Reply with quote

"use wikipedia and e-how has its limitations - this is one of them"

I was only disproving a statement made that a 4" pipe could only flow 85cfms.
Wiki sucks.
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PostPosted: Sat Nov 10, 2012 4:57 pm    Post subject: Reply with quote

Well, I'm back at this again.

I will be running no heat on my bus , so the heater channel tube can be used for other purposes now.
I picked up a bilge blower fan which flows 170 CFMs open and as low as 90 CFMs in the system. The upper engine volume is roughly 20 cubic feet, so being conservative it would change the air out five times a minute (engine off).
Next I have the rear heat distubution tube from under the rear seat. I will mount this in the engine compartment at the top, near the gas tank but behind the fan shroud. This should help spread the cool air evenly in there.
At the front of the bus, the heater tube will be cut just before the elbow that leads through the floor to the front floor/defrost distribution. An air intake (scoop) will be added to the pedal pan (approx. 2"x18") that will be connected to the heater tube that leads to the engine compartment distribution tube.
The bilge fan will be mounted inline on the main heater tube and will be connected to an ambient temp switch (in the engine compartment) and to a dash mounted switch. That way the fan could run for a short period after engine shut down too.
Image may have been reduced in size. Click image to view fullscreen.


The added bonus is I may tap the front floor/defrost into the scoop to get cool air at my feet.

Once again for those who haven't already tossed this, I am not fixing an engine overheating problem, just improving things that I can.

Gordo.
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joe cool
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PostPosted: Sat Nov 10, 2012 5:51 pm    Post subject: Reply with quote

Your stock bus will be fine in summer. I'm afraid you will freeze in winter. Quit effin about a fix your heat!
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PostPosted: Sat Nov 10, 2012 7:48 pm    Post subject: Reply with quote

joe cool wrote:
Your stock bus will be fine in summer. I'm afraid you will freeze in winter. Quit effin about a fix your heat!


I won't freeze in the winter...my Flex has nice heated seats. The bus will be for April 1st to October 31st and heated seats for those cooler days. I had enough of the heat on hills only...this is all about cooling though, thanks for your concern...thoughtful.

Gordo.
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joe cool
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PostPosted: Sat Nov 10, 2012 8:07 pm    Post subject: Reply with quote

Well if you fixed your heat you could enjoy your bus in winter, too. Just saying...

Remove the front most piece of tin and you will achieve the same effect as your scoop. I think you are going over the top with this cooling thing, though. It is not necessary in a properly tuned bus with all tin in place. "Won't boil over in Tunisia, won't freeze in Stalingrad", etc.
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PostPosted: Sat Nov 10, 2012 9:26 pm    Post subject: Reply with quote

So, all those other issues that arise with ACVWs won't happen if I have all the tin in place....like, ... hot soak starter solenoid? Hot start carb issues?

As mentioned before, I don't have a problem...this just makes good sense. Water cooled cars today come with electric water pumps that circulate the water in the engine after it is shut off, they incorporate ducting to help the air flow out of the engine bays, they use ram air to help feed the induction, they even use forced air flowing over the injector rails. Just because something was good enough for the 1940s and it still works today, doesn't mean that there is no room for improvement.

I am going to be running a 2110 motor with dual carbs, straight axle conversion and yes lowered a bit. I will also be helping the air exiting the engine by adding diffuser venting to the engine lower sleds.

Gordo.
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PostPosted: Sun Nov 11, 2012 12:46 am    Post subject: Reply with quote

Based on some random observations of my own bus, over a few years of infrequent use, and a big dollop of logic and common sense I have come to the following conclusions:

A stock engine, in a stock bus will if all in a good state of tune and with all tinware fitted as designed, cope pretty well in most outside temps. Or at least, most I've had to deal with here.

However fit a bigger motor (in my case a 2007) complete with big air hungry carbs, and drive it hard, and you rapidly come to the conclusion that things are not the same.
In my opinion one of the biggest issues is that the carbs suck so much of the available cooling air into the engine. The solution here would be to build an airbox and take induction air from somewhere else. Not from inside the engine bay.
Secondly, if you are running an early bus with the outward pointing vents, I suspect you're getting less air to start with than a later bus with inward vents. I don't believe the vents were changed just for looks, but rather because more air was deemed a requirement.
Thirdly, air cooled engines aren't just cooled directly by air, much of the cooling is by oil which is then cooled by air, indirectly. So adding an external oil cooler (with a stat) and making sure that that is placed out of the engine compartment (and away from the engine compartment airvents where it cannot rob air flowing in) and then giving that cooler a sufficient flow of cooling air, can pay dividends in reducing overall engine temps.

I'm of the opinion that separating the induction air from the cooling air is the first step, and removing as much extra heat as possible from the oil, keeping it at the correct temperatures will go a long way to ensuring a happy engine, trying to get more air into the engine compartment as is suggested in this thread is fraught with difficulties. Making the most of what is in there to start with is the way to go.
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PostPosted: Sun Nov 11, 2012 11:48 am    Post subject: Reply with quote

Well said.

I was just in my engine bay making some measurements and such, the air distribution tube is almost as wide as the engine is. If I add a small Y to the driver's side (incoming air side) air will be more equally spread between the two carbs. I had thought of hooking the carbs directly up to the distribution tube, giving a ram air effect, but this could be a tuning nightmare. Supplementing the air supply in the engine compartment should not effect the tune of the engine (other than just having more cool air).

The plan is to have the same effect as adding the side scoops, but to keep it all hidden. I think those side scoops are hideous add ons, but that's just my taste.

gordo.
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PostPosted: Sun Nov 11, 2012 2:27 pm    Post subject: Reply with quote

I don't quite get the goal here. I understand what you're doing but don't understand why. I have a 2110 efi with 3.88rp and 82 4th with 30 inch tires and I only get up to about 375 cht at 100f outside on the freeway. I'm running an external cooler with thermostat fan. I also have a Tstat control oil flow to the cooler. I'm running a 36hp doghouse with functioning flaps and Tstat. It's all in the tune.
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PostPosted: Sun Nov 11, 2012 7:08 pm    Post subject: Reply with quote

Really, that's pretty much what I am running too, less the EFI , and I'm running stock R&P. Why did you put an oil cooler, oil t-stat and a fan on your bus? everyone else has no problem with cooling....you did it because it's a good idea to help, suppliment , aid the cooling...not because there was a problem. But an oil cooler is the industry standard....everyone does it, I am too. Maybe one day this cold air intake will be the industry standard...Oh wait, it is...see "ricer".

So, if you're not sure what my goal is? Mine will be cooler than yours....and isn't that what anyone is after?

Really though, I know everyone is asking why...I am just looking for the why not. What would the down side be? I did have a PM from someone who ran a air scoop supply air directly to his cooling fan, which he felt caused cavitation and had a detrimental effect on cooling. That is notable info and a reason to change plans to a distribution tube.

Keep asking question though, it helps me, really.

Gordo.
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PostPosted: Sun Nov 11, 2012 7:27 pm    Post subject: Reply with quote

flemcadiddlehopper wrote:
I am just looking for the why not. What would the down side be? .

No heat in the bus and foggy windows, Brrrrrr..........I do hope you are installing full gauges with the senders in the same places as everyone else puts them so we can see some empirical data to back up this endeavour.
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PostPosted: Sun Nov 11, 2012 10:37 pm    Post subject: Reply with quote

It seem's if you put half of this effort into getting all the correct tin in place, timing, abd sync the carbs your motor would cool fine

I run a 1600 dual carbs stock height bus and have 0 overheating issue's in the heat of arizona summer

running a motor too cool can be just as bad as to hot
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PostPosted: Sun Nov 11, 2012 10:53 pm    Post subject: Reply with quote

flemcadiddlehopper wrote:
Really, that's pretty much what I am running too, less the EFI , and I'm running stock R&P. Why did you put an oil cooler, oil t-stat and a fan on your bus? everyone else has no problem with cooling....you did it because it's a good idea to help, suppliment , aid the cooling...not because there was a problem. But an oil cooler is the industry standard....everyone does it, I am too. Maybe one day this cold air intake will be the industry standard...Oh wait, it is...see "ricer".

So, if you're not sure what my goal is? Mine will be cooler than yours....and isn't that what anyone is after?

Really though, I know everyone is asking why...I am just looking for the why not. What would the down side be? I did have a PM from someone who ran a air scoop supply air directly to his cooling fan, which he felt caused cavitation and had a detrimental effect on cooling. That is notable info and a reason to change plans to a distribution tube.

Keep asking question though, it helps me, really.

Gordo.


Why? Too cold. It is possible to be too cold. If you've done some testing and demonstrated an understanding of cht and egt you'd know that under conditions I demonstrated 375 is actually low when considering over 475 is considered overheating. On the street I cruise 250-275. My cooling fan never turns on on the street...meaning it doesn't hit 180. My fan only turns on under extreme highway conditions or sitting idle for 30 minutes.

The way my system is running I can adjust air, fuel, and spark from the driver seat. I can watch my cht gauge go up, peak, and drop off as I lean it out. I can watch the cht go up as I retard Orr advance and watch them drop as I get close to optimal. I am currently running 15.5 air to fuel ratio (crazy lean) at idle with a peak cht of 250f. If I lean it out more it gets colder and loses rpm (no fuel).

It shows that tuning has more to say about temps than cooling alone. It also shows...lean under the right conditions is not bad. Look into lean of peak tuning for more info.

I have seen this motor run from 425 to 250 from a malfunctioning over retarding distributor.

The reason I went external cooling and my tstat system? 1 talked into it by builders and forums and wanted absolute reliability being my daily and adventure vehicle. The reason I went with the flow control tstat was because my oil was too cold and not cooking off the fuel and water it gathered. Too much fuel causes an acidic condition to build and etch bearings....too much water and things corrode.


My intake doesn't fight my fan or my af ratio would show it....what does happen is at speeds 50 and higher the lower pressure running down the sides is preventing the fan from having adequate air to cool the same as at low speed. Granted it well within limits but its not optimal. Unless you are running some wild rpms (hard to do with my gearing) you won't see a problem. Maybe highway combined with 5000rpm might cause a problem, but I'm only turning 3000rpm at 65mph......I couldn't imagine cranking 5000.
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PostPosted: Sun Nov 11, 2012 11:27 pm    Post subject: Reply with quote

busdaddy wrote:
flemcadiddlehopper wrote:
I am just looking for the why not. What would the down side be? .

No heat in the bus and foggy windows, Brrrrrr..........I do hope you are installing full gauges with the senders in the same places as everyone else puts them so we can see some empirical data to back up this endeavour.


No down side with no heat...shiny bus, not winter driven. We have real winters in Kelowna, not like Surrey rain.

I plan on oil temp, cyl head temp , engine compartment temp, map sensor ( to be moved from cool air intake tube to engine compartment for reading pressure differential). I hope that this will be enough. What I hope is that the results will show no negative pressure in the engine compartment and a drop in engine compartment temp both at speed and parked, engine off cooling fan on.

Gordo.
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PostPosted: Sun Nov 11, 2012 11:44 pm    Post subject: Reply with quote

sub-hatchtim wrote:
It seem's if you put half of this effort into getting all the correct tin in place, timing, abd sync the carbs your motor would cool fine

I run a 1600 dual carbs stock height bus and have 0 overheating issue's in the heat of arizona summer

running a motor too cool can be just as bad as to hot


Yup I get that alot.

Just to set the record straight...2110 engine. 36hp doghouse fan shroud. T-stat and flaps in place. super cool tin trimmed. sleds and side seals due to j-tubes. new engine seals. OG fan. oil cooler with t-stat and fan. straight axle lowered bus not being painted what the m-code plate says.

My motor is still sitting on a stand. The bus is at the primer stage being sanded daily. I don't have an over heating problem. Do all the bug guys with their engine lids popped at the hinges get told to tune their engines too?

Still looking for input as to why this won't work.


Gordo.
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