Type 4 Prototype Venturi Ring

[RalphWiggam]

This is something Ive been thinking about for a few months based on some engineering and fan design research papers I came across awhile back.

One of them here:

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

Another one here:

http://www.j-mst.org/on_line/admin/files/13-j2010-689_2267-2276_.pdf

In addition to seeing the obvious improvements on the type 1 engine with a venturi, as well as Porsche, I thought I would try and see what I could do on the Type 4 engine.

The type 4 fan has somewhat of a venturi built into the design of the fan and pulley itself. Not much of one, but there is something. Ive also talked with a few others who have looked into different fan designs, running the fan at higher RPMs etc. A lot of $$$ work and not much measured benefit.

So I got to thinking of how I could make something relatively cheap that could possibly help increase the efficiency of the fan we all have and are stuck with.

Here is what myself (and a yet to be named vendor) have come up with (keep in mind this is the very first rough prototype):

The ring is more centered than it looks in this pic...

This is shown mounted (obviously) on a little fitment rig off of my bus. What I am thinking for future revisions is incorporating a stainless steel mesh over the intake, possibly reducing the outer radius so one can still check timing, and revising the mounting tabs a little bit. Maybe get it made out of clear plastic?

I will be testing in the next couple of weeks...Moving the ring closer and further away from the fan and measuring differences.

Mainly for right now I will be measuring oil temps on a fixed driving loop with recorded ambients, etc. No ring, ring, different spacing of the ring, etc.

I am welcome to any (constructive) feedback anyone has regarding design or improvements that they would like to see on further revisions.

And for the record before anyone jumps down my throat and says this is stupid and VW was smart, its not going to do anything, etc...Just keep it to yourself. I dont really care. There is basically no money tied up in this, and I like doing it.

[alman72]

^damn right! have fun, and enjoy the scientific method. Data makes me hard, too.

[raygreenwood]

It may or may not improve.....but it will change. This will be interesting!

I know from testing there is a noticable amount of change when you change the position of the fan inward or outward relative to the shroud. Whether the operative change was opening or closing up of the gap in front or rear between fan and shroud or the position of the blades relative to the opening for air to enter the shroud....or changing the entry angle of the air to the fan.....I dont know. It was back in 1999.

A couple of things to wrap your head around just to think about.
One of the biggest air velocity increasers on these fans.....is the flat floor. At that contacts the floor surface is accelerated and slung toward the fins by centricugal force. So if one were wanting to increase that effect.....you might have a venturi dumping toward the center.

On the other hand.....that same effect may cause further air entry issues.....so it may help to have the air rounding the edge of the venturi, changing angle and entering the blades in a more straight on fashion.

This will be interesting if nothing else!

Ray

[SGKent]

were it me, I'd be sure it fits the bottom tin, and I would add a dome on the floor of the fan. Just make sure it can't come loose, welds breaks etc and sling into the fins. Venturi rings do increase flow by reducing turbulence.
_________________
“Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin

[RalphWiggam]

[Jeff Geisen]

Have you tried a type I venturi ring?
_________________
I Corinthians 4: 1 thru 5

‘63 ragtop - ‘68 single cab

[raygreenwood]

[SGKent]

[Clatter]

Nice.

Love this kind of stuff.

I'd question the viability of using oil temp to measure success.
Oil temp unfortunately only has a sort of tangential relationship to head temps..
Perhaps you could install a CHT (or four? ) ?

You might see differences between cylinders WRT cooling..?
It's known that the factory fan setup does favor some cylinders over tohers.

If no CHT, then an IR temp gun, used in a controlled manner would certainly help.

While not exactly related to the subject at hand,
Ever see this? -->
https://shoptalkforums.com/viewtopic.php?t=63829
_________________
Bus Motor Build

What’s That Noise?!?

[RalphWiggam]

[RalphWiggam]

Ok. Here is the ring finally installed in my bus:

Good clearance all the way around and not close to the belt or anything else. Im going to take some progressively longer shakedown runs just to make sure everything is good to go before doing some comparison testing.

[alman72]

is the dome at the center of the fan off balance/center? looks like it in the pics. sorry if it was addressed elsewhere on the page..

[ivwshane]

It certainly looks pretty! I may have missed it but how do you plan on measuring performance differences? It seems like you'd need to have the fan housing off with the fan attached to an electric motor with some sort of cfm measuring tool on the outlets in order to measure the differences reliably.
_________________
77 westy 2.0 FI
69 ghia coup 1600dp
70 single cab

[SGKent]

make room for a timing scale in the next one. Looks good. I'd expect a 3% to 5% increase in CFM - just a gut feeling.
_________________
“Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin

[metahacker]

@RalphWiggam any updates on this project?

[RalphWiggam]

[RalphWiggam]

Update on this...Im all ready to collect some data, but a key piece just decided to flake out on me....my VDO CHT gauge.

I still have my oil temp guage, but I feel like I need a working accurate CHT gauge to know if this venturi ring provides any benefit.

It appears to be the gauge itself and not the sender or the wire so Im going to see what I can do to find some thing else.

[airschooled]

If you can wait a few weeks for me to get home, I’ll donate my Dakota Digital CHT gauge to the cause.

Robbie
_________________
Learn how your vintage VW works. And why it doesn't!
One-on-one tech help for your Volkswagen:
www.airschooled.com

[busdaddy]

I wonder if you could sub an Ohm meter in place of the gauge for now?, the readings will likely not make much sense, but you'd have a baseline to see if they change with the ring installed.
_________________
Rust NEVER sleeps and stock never goes out of style.

Please don't PM technical questions, ask your problem in public so everyone can play along. If you think it's too stupid post it here
Stop dead photo links! Post your photos to The Samba Gallery!

Слава Україні!

[SGKent]