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Above: A Type 1 centermount housing with paper air vanes being taped on during development tests. People usually buy this design for cosmetic reasons or for the added dual carb clearance on ech side.

AIR DUCTING THE CENTERMOUNT BLOWER HOUSING

The Centermount Blower Housing is a popular item sold by many VW parts vendors but has one big drawback. It is a hollow shell and relies on the general shape of the housing -- which is about perfect for a circular turbine type blower -- to force air out of the bottom. The result is a great deal of turbulance inside the housing and less "focused" air to the cylinders.



Porsche used the "centermount" design on the four-cam Type 547 engine. The ducting pattern of the 547 blower housing was used as the model for our VW Type 1 centermount housing, insomuch as the Type 547 housing was a dual-fan configuration and drew air from front and rear.



The prototype blower insert shown here is made out of thermoplastic and designed to slip directly into a Type 1 centermount blower housing.



The air is drawn into the center plenum, separated for left and right direction by flow over the contured vanes, and forced down three ducts per side to the cylinders below.



The plastic assembly is designed to slip up inside the Type 1 centermount blower housing, and be Pop-Riveted into place.

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This is an applied design change to make the centermount housing at least as efficient as a standard Type 1 housing.

We're road testing the design with thermocouples on both heads while racing, and if successful, will be making them available for sale on the upcoming PCP Speed website.

FJC

FJC,

Super post! Very cool.

What is the real attraction to the center mount style, if goal is only to replicate Type 1 std. performance? Just the "look"? Better access to dual carb set up? Weight?

doc

Hi Doc,

I think most guys buy the center-mount for cosmetric reasons. It looks purposeful. They might not even know about Type 547 blower housings!

I am lucky enough to have a retired NASA-project fluid-dynamics engineer on my team nicknamed "Paul Ray the Rocket Scientist." He showed me how the empty center-mount housing would deliver plenty of air to cylinders 3 and 4, but not cylinders 1 and 2., all the while creating a real buffeting storm inside the housing, requiring more HP to turn the fan.

Apparently a couple of Forum guys have been working on a vane system to improve the center-mount housing, with some good-looking solutions out there.

I am building a terror of a dry-sumpted 1600 sprint engine for HSR, and this prototype fan housing is there for visual intimidation effect. From a practical standpoint, all I expect out of it is "normal" cooling. We have a special engine test stand with dry sump hookups we'll use with thermocouples to make sure we're getting the cooling we expect.

FJC

With reverse-flange manifolds you can get to the idle jets and screws w/o cutting holes in a T1 body for access, or slicing up your hands trying to get to them via force.

If you can get it to work a well as stock, you have accomplished a great deal--- VW spent decades getting that right.

The only issue I see is lack of the ability to install the factory thermostat flaps, although you have ~duplicated them to some extent.

Can you visualize setting up a plenum air dump thermostat (ala Corvair)? or would it be possible to cut part of the lower sections off to allow for the flaps?

Looks very nice, looking forwards to results!

Looks great. I see a lot of resemblance with my housing ducting.

Hi Hebster,

If there was ever any proof to the "great minds think alike," it's that both of us followed the Type 47 blower housing design and came up with very similiar patterns for the Type 1 engine.

I saw your video where you demonstrated flow. That was excellent.

Maybe we'll have something to add to VW racing development.

FJC

True!
Hopefully so, and your slipin design is avesome! Would have been perfect without the indent caused by the tiny "vein" that is inside the housing originally
I understand you designed this so it would be bolt-on.

Rough ETA? Cost?

Hi Piledriver,

Our plans are to create a website and sell mostly plastic air dams, spoilers, wings, vortex generators, Lexan windows, etc. One of our partners owns a nice big CNC table. We only want to sell the parts we've tested at the track, which includes Bonneville.

This fan housing has to work. We're running it this year at Daytona with the Historic Sportscar Racing people, both in sprint and a four-hour enduro we qualify for. As veteran 14 and 24 hour Chump and Lemons guys, four hours is only about enough racing to keep us awake.

www.hsrrace.com

Now, I expect the fan housing to work. But before we talk costs, we have to see it. -- FJC

I respect that logic.

Guys how about one of these inserts for the non doghouse 36HP style shroud. They left out all the fins on the 3-4 side because of the oil cooler but most people run with an external oil cooler so the fins are non there causing all kinds of misdirection of air. You just need to copy the doghouse shroud fins and it should slip right on in. This would be for the SCAT or EMPI 36hp non-doghouse shroud.
Thoughts? I would pay up to 50 bucks as it is a pain in the ass to get the fins out of a doghouse shroud.

vw_chuck wrote:Guys how about one of these inserts for the non doghouse 36HP style shroud...

Great idea.

Gentlemen,

Yes, I believe an aftermarket 36-hp fan housing could be pursued to accept an insert ...

Good thinking.

FJC

How quick can this be brought to market? Please put me on the list for one.
My email is [email protected] when you are ready to sell.
Thanks

Awesome! I look forward to your CHT/thermocouple results.