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Wed Jun 24, 2020 3:11 pm

I have 3 fans. 1 of them has all it's blades, so I figured I would use that.

I suppose it is older. It has the plastic center cap and the raised center. The bolts can be inserted, but they are recessed in this model. Does this model fan use Allen Head bolts.

Wed Jun 24, 2020 3:42 pm

malcolm2 wrote: Does this model fan use Allen Head bolts.
Triple square, not allen.

Thu Jun 25, 2020 6:35 am

and make ABSOLUTE sure that they are not too long, else they will remove the crank seal in quick fashion. DAMHIK

Thu Jun 25, 2020 7:35 am

Even one missing fin may ruin your day. Check for balance or wobble.

Thu Jun 25, 2020 7:40 am

rastomas wrote: Even one missing fin may ruin your day. Check for balance or wobble.
Right, so, really, you have 1 fan and two interesting pieces of metal.

Thu Jun 25, 2020 8:53 am

just thinking out loud. With modern computer technology one would think that someone could have redesigned the fan on these buses for more air flow. Think of how far jet engines and turbines have come since the 70's. One could probably design a fan that moved more air and more efficiently than these designs. Every vehicle out there with a T4 engine would be a potential sale.

Thu Jun 25, 2020 11:12 am

SGKent wrote: just thinking out loud. With modern computer technology one would think that someone could have redesigned the fan on these buses for more air flow. Think of how far jet engines and turbines have come since the 70's. One could probably design a fan that moved more air and more efficiently than these designs. Every vehicle out there with a T4 engine would be a potential sale.

Sure...someone could do that...but its also not so simple. And...this "type" of fan has not actually been able to be improved much. Its pretty damn efficient for its space and size already.

Its a space versus efficiency issue. Its not just how MUCH air volume it moves...its how much static pressure it generates at what rpm and with what torque/power load.

And that static pressure....just like fuel pump volume with and without the restriction of the fuel pressure regulator....is also partly a function of what restrictions inside of the shroud and sheet metal and cooling fins....the air column comes up against. A sh*tload of considerations go into radial fan design.

And...then you get into casting issues. This is not a cheap sand cast. Its either die casting or at worst pressure molding.

So yeah...sure with computer modeling I am sure "some" improvements could be made....with a lot of work. Then finding a foundry to make this affordably in limited numbers.....probably not.

To Jtauxe:

Although between 411, 412, 914 nd bus there were a handful of fans that were different in timing mark and probably had a different part # somewhere....there were only two primary casting #'s for the fan.

the one you have with the snout and rubber spinner was first/originally used on the earliest 411's....into the 412's....and even for a while in the early bus to a specific point.

There are two part #'s

021 119 031 A
022 119 031

......and...before you start thinking that the 021 and 022 designates it as originally a type 2 bus part...that would be no.

021 119 031 A is from a 1968 VW 411 with carbs. Long before buses ever dreamed of getting the type 4 engine.

In the 411/412....type 4 cars.....for motor parts especially.....the factory designation for carbed chassis was "021". The factory designation for fuel injected chassis was "022".

Here you can see these designations and you will see them again at the right end of the part number line in the diagram in a minute.

So here is the diagram:

Notice the 021 and 022 unit designations

#1 is the fan assembly and #6 is the bolt.

So...the bolt you need for that early style fan is this one:

Its 8mm X 39mm. Part # 021 119 127. It was used UP TO July of 1972

The longer one was 8mm X 45mm and used from August 1972 and onward in the flat faced fan.

Also....though these bolts are 8mm....they use a smaller triple square bit because they are a "shallow" cheese head type triple square. I cannot remember but can check at my storage unit....its either a 6mm or 7mm.

And I believe they are a finer thread...maybe 8mm x 1.0? Don't qoute me on that until I check.

Ray

Thu Jun 25, 2020 11:21 am

I seriously doubt that one would lose much in the way of air flow by using full depth allen head screws. VW went to the flat nosed fan when they used the flat surface to mount the air pump pulley on early Type 4 bus engines. After the air pump was deleted they didn't bother going back to the cone style fan.

Thu Jun 25, 2020 12:34 pm

Wildthings wrote: I seriously doubt that one would lose much in the way of air flow by using full depth allen head screws. VW went to the flat nosed fan when they used the flat surface to mount the air pump pulley on early Type 4 bus engines. After the air pump was deleted they didn't bother going back to the cone style fan.

From my testing.....while there is a flow difference between the two fan types.....I cant say its significant. There is a difference in sound......but I doubt you could ever hear it in a bus at all. You can hear it in a 914 or a 411 or 412 wagon. Less so in a 411 or 412 sedan.

The bolts I dont see making any appreciable flow difference, however the length is the difference. The early conical snout fan uses the shorter cheese head allen bolt because it has to fit down down in the hole.

If you try to use a CV bolt or something longer thqn 39mm on tbe early fan it will destroy the seal. Ray

Thu Jun 25, 2020 12:53 pm

the airflow between the early and late fans has been discussed several times. It comes up every few years. I believe JR found that the early fan puts out a tiny bit more air with the fan cone. Someone said they were going to design one for the late fan with 3-d printing but nothing every came of it that I know of.

Thu Jun 25, 2020 5:11 pm

SGKent wrote: the airflow between the early and late fans has been discussed several times. It comes up every few years. I believe JR found that the early fan puts out a tiny bit more air with the fan cone. Someone said they were going to design one for the late fan with 3-d printing but nothing every came of it that I know of.

It would be really nice to have a spinner/cone for the flat faced fan....if for no other reason than to keep water and muck out of the bore so it does not corrode.....but the difgerence in airflow between the two is not from the spinner or cap. Its because the cone shaped fqn has more surface area with its raised center.
Ray

Fri Jun 26, 2020 9:54 am

Here is a pretty decent article covering optimization of centrifugal fans:

https://www.hindawi.com/journals/ijrm/2011/537824/

Which gave me a pretty good idea on how to increase output of the type 4 fan relatively easily.

Anyone with a 3D printer want to help me out?

Mon Sep 14, 2020 7:14 pm

Sorry the picture is upside down. You would think a computer could fix that, I mean Facebook does. Anyway, I found one reason for the difference in this fan. It is from BEFORE THE AIR PUMP. Or at least "without". I suppose that could mean Non-California busses. And it even says to use allen (socket head) bolts. So I got it right. :D

Mon Sep 14, 2020 7:24 pm

malcolm2 wrote:

Sorry the picture is upside down. You would think a computer could fix that, I mean Facebook does. Anyway, I found one reason for the difference in this fan. It is from BEFORE THE AIR PUMP. Or at least "without". I suppose that could mean Non-California busses. And it even says to use allen (socket head) bolts. So I got it right. :D

What book is that?

Yes.....you "could" use allen head bolts...if they are the correct length. But....fr9m the factory Im pretty sure those bolts were triple square and not allen head. I can look at some in the am.

If that is a Chiltons or Clymer book.....its accuracy is suspect.

I also think its an Australian edition. Probably why its upside down and the computer wont fix it. :lol: Ray

Mon Sep 14, 2020 7:58 pm

If you are honestly spending any time debating Allen vs. 12-point fasteners here, put down the keyboard and go drive your Volkswagen.

Robbie

Mon Sep 14, 2020 8:33 pm

raygreenwood wrote:
From my testing.....while there is a flow difference between the two fan types.....I cant say its significant. There is a difference in sound......but I doubt you could ever hear it in a bus at all. You can hear it in a 914 or a 411 or 412 wagon. Less so in a 411 or 412 sedan.

I believe it. We "knife edged" a couple T1 fans (grinding the flat entry point on each fin to a sharp edge to cut down on turbulence)...and I can say that tiny change made a very NOTICEABLE difference in sound.

Mon Sep 14, 2020 8:37 pm

metahacker wrote: raygreenwood wrote:
From my testing.....while there is a flow difference between the two fan types.....I cant say its significant. There is a difference in sound......but I doubt you could ever hear it in a bus at all. You can hear it in a 914 or a 411 or 412 wagon. Less so in a 411 or 412 sedan.

I believe it. We "knife edged" a couple T1 fans (grinding the flat entry point on each fin to a sharp edge to cut down on turbulence)...and I can say that tiny change made a very NOTICEABLE difference in sound.

Now this I can get behind! Can you describe the difference? Did you monitor head or oil temperatures after?

Mon Sep 14, 2020 8:43 pm

SGKent wrote: just thinking out loud. With modern computer technology one would think that someone could have redesigned the fan on these buses for more air flow. Think of how far jet engines and turbines have come since the 70's. One could probably design a fan that moved more air and more efficiently than these designs. Every vehicle out there with a T4 engine would be a potential sale.

Let's say the fan presently draws 5 hp, if you could reduce that to 3 hp it would probably be noticeable in the gas mileage.

If it cost $200 to produce and got you an extra mpg, would there be a market for it?

Mon Sep 14, 2020 9:00 pm

Wildthings wrote: SGKent wrote: just thinking out loud. With modern computer technology one would think that someone could have redesigned the fan on these buses for more air flow. Think of how far jet engines and turbines have come since the 70's. One could probably design a fan that moved more air and more efficiently than these designs. Every vehicle out there with a T4 engine would be a potential sale.

Let's say the fan presently draws 5 hp, if you could reduce that to 3 hp it would probably be noticeable in the gas mileage.

If it cost $200 to produce and got you an extra mpg, would there be a market for it?

That could be worthwhile. Thats along the level of savings (not quite but decent) that modern AC compressors made.

Along with drawing less HP...which is load....there would be less heat?

And...no one says it has to be a fantastic die-cast part like the original. If its uniform...it could be welded steel. Ray

Tue Sep 15, 2020 12:48 am

If one worked in some uneven spacing between the vanes it would quiet things up a bit as well.