Engine Shrouds

[chris_seven]

I am struggling to understand some of the basic configurations of engine shrouds for standard cars.

There is the original shroud which I believe was black on the early cars and red on the S



This fan seems to have a small duct pop-riveted inside the shroud.

The verison above seems to be for carb engines and I am interested to know if this was also used with an MFI engine.

The next variation seems to have a large duct rivited to the outside



This one seems to share some of the features of the fan on a CIS engine

The manifold cut out is different and there seems to be a witness for cut outs for MFI injectors

The final shroud is a CIS type wheremost of the duct is moulded in position.



There are also some small square depressions moulded toward the top of the housing.

Can anyone help with when changes were made and what fits what.

Thanks

[Walt Fricke]

They will all fit, depending on what you are doing.

Note the CIS version has three round holes by the front (as installed in the car) left of center. These are to hold up a bellcrank assembly for the throttle. You also need a plastic extension to get the air over the oil cooler.

The middle ne should work on a CIS motor if you just made those holes. Same with the red early version, though you won't get as much cooling done to the oil, which is why Porsche added that ducting to the later motors.

I don't know about MFI, but carbs don't need an engine mounted bellcrank - it is mounted to the intake manifolds.

The early style is useful for race motors, where no engine oil cooler is used.

[chris_seven]

I am looking to improve the cooling on a 2.0 litre race motor fitted with an engine mounted fan and Solex Carbs.

I have a variety of shrouds and when I have made the right choice was planning to have a mould made as it must be cheaper to make new than then repair/repaint.

I was considering fitting the 'intermediate' air duct to the early pattern shroud.

[Flieger]

Sounds like a good idea to me.

[Walt Fricke]

Chris

If it is cheaper for you to make a mould and lay up something than it is to repair what you already have, you are certainly a master mould maker and layer-upper. And have a stock of the required materials already on the shelf. And happy to work with that nasty stuff.

I'd think you could take the MFI shroud you have and use it. Or the CIS shroud, which just needs the end piece to do the final directing of the air down onto the cooler.

What is difficult about painting? I've painted several shrouds, and it worked pretty well, even with just spray can paint! And patching over the odd hole or reinforcing broken out edge fastener holes isn't that much of a challenge.

But your standards are likely more exacting then mine.

[Walt Fricke]

When I went to use an early shroud on my short stroke 2.8 (3.2L heads, 46 to 40 PMO manifolds), I ran into two interference issues. The first required enlarging the holes where the induction goes through the shroud.



The second involved interference between one of the redundant bosses on the manifold (there so only one casting is needed to make the manifolds for both sides, I imagine). I solved that one by grinding the manifold.



So I can't swear that any mixing and matching of shrouds and other bits may not take a bit of adjusting.

[chris_seven]

Walt,

I couldn't possibly make the mould or the moulding I just don't have the skill and would probably end up glued to a shroud but ....

I have a local guy that will charge me $300 for the mould and $120 per shroud - I need 3 straight off. He makes seats for Caterhams and quite a few other parts that have a decent level of finish and quality and it just seems to be a good idea.

I don't mind repairing and painting a shroud but Body shop and Spray shop charges here are around $80 per hour - hence my interest in making them from new.

We will repair and paint the 'master' which will probably take a day but over the course of a couple of years it still seems quite good value.

[304065]

Chris,

The undisputed master of fiberglass engine shrouds is Damon Josz, owner of Series900 in Sunapee, New Hampshire. (Not Old Hampshire, unfortunately, but the freight is cheap).

He will tell you (I have requested that he join this thread) that there are many more variants in the shroud than originally outlined above. And he has molds for all of them.

You can even order them trimmed, which means he will fit them on an engine and grind the fiberglass for a perfect fit, or raw, and do the final fitting yourself.

Here is a tongue-in-cheek presentation of his work

A shroud of secrecy

He also does clear shrouds a la S/T, 911R and has the correct "twill" material which I like to call " German weave."

You might try him on series900 at nhvt dot net , where at is replaced with the ampersand and the dot a period.