Fan shroud

[70herald]

Since most of the cooling air being blow around by the fan seems to just be going around the fan, and entirely skipping the radiator, I am planning on making a shroud for the radiator / fan.

As the engine / fan move separately from radiator / chassis any guesses as to how much clearance I need around the fan?

I want to make a basic box area which will cover the entire radiator, and a round shroud which will fit around the fan.

I am planning on making up a prototype of out "polygal" a sort of corrugated plastic and if it makes a significant difference I will have a tin shop make up a sheet metal version.

 

[toysrrus]

Hi There,

I`ve installed several shrouds in a TR4 & TR6. Purchased from Moss Motors or equiv. Its a very "Inexpensive" fix and their custom made to fit without any alterations.

Why go thru all the hassle of desinging and building one if you can purchase an OEM style one for the fraction of the cost!

"THEY WORK BY THE WAY"!

Regards,

Russ

 

[70herald]

Hi There,


Why go thru all the hassle of desinging and building one if you can purchase an OEM style one for the fraction of the cost!

Russ

Well because there is no such thing as an OEM shroud for a Herald. In any case, anything that I might save by buying a pre-made one will be exceeded by the cost of shipping / customs .....

 

[Tinster]

Yisrael !

I made my own as well due to outrageous shipping costs.
Mine is painted, .032 aluminum sheet that cost me less
than $5.00 The tin snips I already owned. I made my
cutting pattern/template out of the orig. cardboard.

Here's some decent photos of my process.

https://good-times.webshots.com/album/552796059ncPSMi

regards,

d

 

[swift6]

Yisrael,

As far as clearance goes... I take it you are still using the mechanical and not an electric. 1/2"-3/4" should allow enough clearance to keep the fan from striking the shroud when your engine mounts begin to get soft.

 

[DrEntropy]

Or torque movement puts it to the thrust side...

...oh, wait! It's a Herald engine... do they have enuff torque to move onna mounts?

 

[Andrew Mace]

Hi There,


Why go thru all the hassle of desinging and building one if you can purchase an OEM style one for the fraction of the cost!

Russ

Well because there is no such thing as an OEM shroud for a Herald. In any case, anything that I might save by buying a pre-made one will be exceeded by the cost of shipping / customs .....

Mostly to "play Devil's Advocate" here, what sort of problem are you having that makes you think a shroud would help?

 

[70herald]

The main problem I have is lots of traffic jams, driving up mountains etc. At least now that I rebuilt the engine it is not overheating however it clearly has very little excess capacity right now, and summer temps haven't hit yet.
The engine is properly tuned (checked it on the 4 gas analyzer 3.5%CO at idle - just a tiny bit on the rich side) and timing is correct.

Now taking a look at the layout as is, even at idle, the fan (stock 4 blade metal) move allot of air. However, with a rather large gap between the fan and the radiator (about 2"), clearly very little of the air that is being moved around actually goes through the radiator.

An interesting point, in general the common knowledge is that the 17" wide rad is insufficient. It seems to me that the real problem is that it is thicker than the older, wider radiators and presents much greater resistance to airflow. The result is that the air goes around rather than through the radiator.

 

[70herald]

Or torque movement puts it to the thrust side...

...oh, wait! It's a Herald engine... do they have enuff torque to move onna mounts?

with the 13/60 engine they do! Eventually I would like to swap the cam with a spitfire GP2 and a few other little enhancements.

 

[MGTF1250Dave]

Aloha,

The shroud in front of the radiator like the one Dale fabricated is useful in forcing most air entering the grille to past through the radiator. This generally requires the car to be moving forward at about about 20 MPH or so to create this ram air effect.

I believe you are talking about fabricating a shroud at mounted to the rear of the radiator extending back to the fan with a round opening to accommodate the diameter of the fan. This is a very common part of modern car cooling systems. This should improve the both air flow through the radiator and the amount of air moved by the fan. As you deduced, an axial propeller fan can have a large amount of air spill off the blades radially. The shroud will greatly reduce this and force most for the air to move out of the fan along the axis of rotation. The shroud will also contain the lower pressure area in front of the fan to induce more air flow through the radiator. Air like water follows the path of least Resistance. I suggest you add the rear shroud first and then consider adding the front shroud if you think you need it.

 

[TR3driver]

I agree with Dave, except that IMO it depends on what conditions you are trying to improve. At low speeds, the fan shroud will definitely improve airflow through the radiator, but at high speeds it will actually tend to impede it. Some OEMs even provide a flap valve to release the high pressure air inside the shroud at high speeds.

The shroud in front of the radiator will make much more improvement at speed (when the fan is mostly irrelevant anyway).

 

[70herald]

Thanks Guys
My problem is at low speeds. Massive construction projects (light railway, a cable stayed bridge....) have turned the entire city into one huge traffic jam. I made up a mock up of a shroud and will try it out soon.

 

[kodanja]

I picked up a polished aluminum shroud kit on ebay for 60$
it fit perfect!


not a great shot , ill try to take a better shot tonight

 

[Opa]

made mine out of 20 gauge aluminum and had it chrome plated.Used the original pressed unit as pattern and is still underneath cover. I used door edging on the edges to prevent cutting of hands while cleaning.I used edging on the fender lip under the hood for same reason...

 

[kodanja]

Looks nice OPA

wanna make me one....lol

 

[Tinster]

Opa-

Slick looking!!

Please explain how you got the gold coloring?

Rattle can, powder coat, other process?

thanks,

dale

 

[Opa]

Thanks Dale
Thermostat housing and alt. are dupli color Cadillac eng gold out of a rattle can

 

[rotoflex]

Tinster, kodanja, & opa: those are radiator shrouds, not fan shrouds.

Fan shrouds isolate the fan (in the case of cars, to the radiator). They increase the efficiency of the fan & cooling enormously, amazingly.

Here are some random internet photos of fan shrouds.

It is interesting that you are retaining the stock mechanical fan & adding a fan shroud. I like the idea (I'm an OEM junkie on these cars). The clearance will be an issue, which is why a fan shroud is usually attached to the fan. That makes it easy to do with an electric fan. If you weren't retaining the original mechanical fan & were instead going electric, I'd say survey the junkyards first & see if some existing car had a fan & shroud assembly that would fit.

Also spend some time on Dr. Andy Mace's couch to examine why you think you need a fan shroud. I do perfectly understand that in some climates cooling needs to be improved, but often the problem lies somewhere else. On the US coast of the Gulf of Mexico, My GT6's factory engine cooling system was never inadequate when in repair, but my XK140's was overwhelmed until I added a fan shroud.

Mocking it up in cardboard (flattened cardboard boxes) seems like it would be easier.

 

[Opa]

here's a shot of the edging on the fender lip

 

[Andrew Mace]

Also spend some time on Dr. Andy Mace's couch to examine why you think you need a fan shroud. I do perfectly understand that in some climates cooling needs to be improved, but often the problem lies somewhere else. On the US coast of the Gulf of Mexico, My GT6's factory engine cooling system was never inadequate when in repair, but my XK140's was overwhelmed until I added a fan shroud....

First, thanks for the compliment ("Dr."), but it's actually my brother who's the psychologist. Instead of a couch, I use the back seat from a junked Herald.

Some of those older Jaguars are nearly legendary for cooling woes, are they not? But then, they weren't necessarily engineered for rough duty, right? Believe it or not, most Standard-Triumph products were, the Herald in particular being as much or more of a "world car" than even the Standard Vanguard was. Heralds were assembled all around the world, in places such as Australia and Peru as well as the UK and Belgium, and were sold just about everywhere...even Vietnam!

Yisrael, you've since noted that you determined your original gauge's reading to be a bit high, which is not surprising. What sorts of readings are you getting with the electronic gauge you used, and did they remain steady?

And, of course (Andy's cooling system mantra ON), getting and keeping the engine's cooling passages free of crud is crucial, as much so as a good radiator and a correct thermostat and maybe a new water pump if the impellers on your existing one have seen a bit too much corrosion/erosion over the years. (Andy's cooling system mantra OFF) :wink:

In a consistently hot climate, you might easily be able to get by with something as cool as a 160 degree (F) thermostat. In summer here in upstate NY, that works fine for me in, say 70-80 degree (F) temps. Later fall and early spring, I always need to go to a hotter thermostat to get a: decent warmup and running; and b: decent heat from the heater.