fan shroud-- pros and cons

[AA-ron]

Hello everyone,
I'm debating whether or not to do a fan shroud on my Roadster. I'm just now installing the radiator and wondering what the pros and cons are of adding one.
Thanks

[rich grsc]

shroud=correct temps, no shroud=hot temps?

[Fman]

Definitely want a shroud. This one fits perfectly on the FFR radiator, also recommend Breeze upper and lower mounting kit.

https://breezeautomotive.com/shop/radiator-fan-shroud/

https://breezeautomotive.com/shop/lower-radiator-support-kit/

https://breezeautomotive.com/shop/heavy-duty-hinged-radiator-shroud-mounting-kit/

[Blitzboy54]

I don't use one and have no overtemp issues. If anything I run cool. I however only have a 306. The guys running the big boy engines need them from what I hear.

[wallace18]

In Maine you may not need one. In FL it is a must.

[Ted G]

Haven't run mine yet (427 stroker) but the shroud sure looks better INHO.

[Jeff Kleiner]

All pros and no cons to using one.

Jeff

[john42]

I don't have and I've run some hard racing all day long on 100F days. Even measured the heat on the tarmac at 140F. Engine was steady all day long at 180.

Tempted to get a shroud anyway for looks!

[Hoooper]

The only con to a shroud that I can think of on a street car is if you are using a really small fan it could limit airflow through the radiator at speed. I can say though the standard fan is plenty big to let enough air through at speed. I use the standard fan with a Breeze shroud and it has no trouble keeping 210F water temps on track at 600hp.

[JohnK]

I don't have and I've run some hard racing all day long on 100F days. Even measured the heat on the tarmac at 140F. Engine was steady all day long at 180.

Tempted to get a shroud anyway for looks!

A shroud isn't going to do anything to improve cooling when you're moving. Air will flow through the entire radiator. The benefit of the shroud is when you're stopped. The fan can pull air through the entire radiator, rather than just through the area that it's sitting against.

I guess if you're only using the car for racing and don't really care about cooling when standing still, the weight of the shroud might be a con (but what is that... a pound or two?). other than that, I see no reason not to install one.

[John Ibele]

I would do it. I didn’t think I’d need it, but my engine kicks on the fan fairly quickly when I’m at a standstill. I’m happy to have the extra effectiveness.

[Jeff Kleiner]

I don't have and I've run some hard racing all day long on 100F days…

Now go drive in traffic on a 100 degree day and get back to us. ;)

Jeff

[GTBradley]

I know with a Coyote the shroud has no benefit and if your radiator is sized properly the shroud shouldn’t be needed in any case. Personally, I think they clean up the looks a bit. To me though, there is a down side. If the shroud is compressing all the air flow by forcing it through the radiator then there will be less air flowing through the engine bay. Without the shroud some air flows unrestricted over the radiator and I tend to believe that this would reduce engine bay temps more.

Edit: I conflated the shroud and the upper cowl cover. I should have said the downside of the cowl cover rather than shroud.

[JohnK]

I know with a Coyote the shroud has no benefit and if your radiator is sized properly the shroud shouldn’t be needed in any case. Personally, I think they clean up the looks a bit. To me though, there is a down side. If the shroud is compressing all the air flow by forcing it through the radiator then there will be less air flowing through the engine bay. Without the shroud some air flows unrestricted over the radiator and I tend to believe that this would reduce engine bay temps more.

I think you're confusing the fan shroud with the upper cowl cover. The fan shroud will have no impact on how air flows through the engine bay when you're moving.

[GTBradley]

Yep, working and posting at the same time is never a good idea.:)

…and I did do the shroud.

[J R Jones]

As stated previously YMMV. If you do not have a shroud and run hot, you likely need one.
Basics on heat and airflow:
The engine radiates heat energy from the surface, not efficient.
The radiator transfers heat to the air. More radiator or more air improves the ratio of exchange.
Visualize a table fan with a blade and no shroud. The air is uni-directional going in and coming out; not managed.
Puller fans are more efficient than pushers.
Fan pulling the air or dynamic air flow is uni-directional in front of the radiator. It can pull hot air from the engine compartment at no/low speed and at speed the airflow can take the path of least resistance, around the radiator.

Your forced air furnace is another analogy, it ducts heated air out and it ducts cold air return; managing for efficiency.
jim

[Papa]

I initially didn't have a shroud, but hated the cheesy fan mounting parts that the kit came with. The Breeze shroud makes for a very clean fan install and that alone may be what drives the decision to buy/make one for some builders.

Dave

[john42]

Now go drive in traffic on a 100 degree day and get back to us. ;)

Jeff

I have! Many times. in stop and go traffic too.

[GTBradley]

As stated previously YMMV. If you do not have a shroud and run hot, you likely need one.
Basics on heat and airflow:
The engine radiates heat energy from the surface, not efficient.
The radiator transfers heat to the air. More radiator or more air improves the ratio of exchange.
Visualize a table fan with a blade and no shroud. The air is uni-directional going in and coming out; not managed.
Puller fans are more efficient that pushers.
Fan pulling the air or dynamic air flow is uni-directional in front of the radiator. It can pull hot air from the engine compartment at no/low speed and at speed the airflow can take the path of least resistance, around the radiator.

Your forced air furnace is another analogy, it ducts heated air out and it ducts cold air return; managing for efficiency.
jim

Yeah, but the pusher fans look cool!

[john42]

A shroud isn't going to do anything to improve cooling when you're moving. Air will flow through the entire radiator. The benefit of the shroud is when you're stopped. The fan can pull air through the entire radiator, rather than just through the area that it's sitting against.

I guess if you're only using the car for racing and don't really care about cooling when standing still, the weight of the shroud might be a con (but what is that... a pound or two?). other than that, I see no reason not to install one.

on race days... there's lots of time spent idling while waiting to run. That's when my temps spike to 185/190.

[BEAR-AvHistory]

Bought a Breeze shroud for the car after it was built & painted. Car was built with Breeze top piece and Eversons intake sheet metal. Never got around to installing the shroud. car runs most non rainy days. Been in traffic at over 100 degrees coolant has never exceed 210*F when stopped for congestion. Two blocks down the road & its back to 180*F. Some day might install it as a project to clean up the engine compartment.

System works because the entire airflow from the front opining is forced through the radiator. Key I believe is the Breeze part sealing the top of the intake tract.

https://thefactoryfiveforum.com/attachment.php?attachmentid=176541&d=1670519898

[drewr]

Its like most things on these cars. It depends on many variables. A shroud will make a fractional improvement in airflow. Modern cars use them efficiently. They also have bumpers and restricted air intakes.
Necessary in a Cobra? It depends on your car, where you live, and how you drive it. The original cars didn't have it, and it's not like every Cobra engine burned up. The Cobra and the Coupe also have giant oval intakes. The shroud looks cool, and it's certainly the going trend. Are you making a mistake to leave it off? Probably not. Build it how you want it to look.

[toadster]

also, the rear shroud from Breeze is awesome https://breezeautomotive.com/shop/radiator-fan-shroud/

like Fman, I upgraded the fan (https://thefactoryfiveforum.com/showthread.php?34952-25th-MKIV-9772-Build-NOR*CAL-coyote-is-in!&p=461741&viewfull=1#post461741) to a Flex-a-lite Flex-Wave LoBoy Electric Fan (Puller), 16" (https://amzn.to/3HlgDCs) - not only is this fan quieter, it moves more air than the FFR provided fan...

it's all about modern efficiency to be honest, you can run these cars with none of the shrouds, or with all of them
I believe with shrouds you may have quicker response times with heating/cooling spikes in temp, just my 2c :)

[Nigel Allen]

When I was building my car and unsure of a particular way to do something, I took a look at my daily driver/s for guidance. Every, car, tractor, forklift, diesel generator has a shroud. Hmmmm, their designers must be on to something I reckoned.

[Railroad]

It is easier to put on before than after!

[GoDadGo]

Another Vote For Breeze Automotive & Their Amazing Fan Shroud!

I built my own "Mr. Reynolds Inspired" radiator mount & used Mark's Fan Shroud to make it work.

https://youtu.be/PCngiKoopkA

While you are at it, consider getting his seat brackets too.

[steno]

No cons… only pro’s

[Dave Tabor]

I use the Breeze shroud as well.

The main reason for me was to keep the fan off the radiator and not held on by those zip-tie push-through thingies.

I had already holed one radiator by a fan center shaft clip when the bearing tolerance opened up a bit- a costly mistake.

Dave
Gen III Coupe #17
16,000+ miles

[skidd]

I too built a fan shroud for mine. Not totally convince I needed it, but it's there. I'm planning to also upgrade to that LoBoy fan, and a better rad in the future.

That said. A fan shroud for a mechanical fan is a MUST. They simply can't work correct without one. So, if comparing the need for a shroud with an old school mechanical fan car, not a clean comparison.

Modern cars of course all use electric fans now. And, they need a clean mounting mechanism, so a combination shroud&mount is an easy choice. As stated, a well designed shroud is never a con.

So, is a shroud "necessary" on our cars? If you are using not enough radiator, I'd say yes. If you have plenty of radiator, I'd say no.

My future upgrades will have me replace an OEM rad, with a 3 core alumnium one. And the LoBoy fan. I'm not adding a shroud at first. If my temps remain in check in 100F Texas summers, I'll leave the shroud off.

[CraigS]

When I was building my car and unsure of a particular way to do something, I took a look at my daily driver/s for guidance. Every, car, tractor, forklift, diesel generator has a shroud. Hmmmm, their designers must be on to something I reckoned.

Bingo, we have a winner. Every manufacturer Nigel mentions has a heck of a lot more engineering and testing capability than any of us so their answer is worth following.

[drewr]

These kinds of threads tend to drift. The original poster asked about the pros and cons of a fan shroud. Many said there are many pros, not really any cons. Maybe the only con is that it is not really necessary. I suspect the underlying ask in the question was, "Should I put a fan shroud in my car?". I don't think the question was, "Is a fan shroud good technology?" It certainly works as advertised and is used in most modern applications. We tend to get in these conversations that say "this is better than that," implying that one should do what is better. This applies to many frequently asked questions by new builders. Your hear many of the same kinds of replies. "Power steering is better than manual, roller lifters are better than flat tappet, Coyote is better than a small block Ford, more horsepower is better than less, IRS is better than a 3 link, more clecos are better than less, steel bell housings are better than aluminum, drive shaft safety loops are better, etc".

But, I wonder if there is really not a "technological imperative" here, meaning "just because a technology exists, you should use it." Plenty of these choices are tried and true and are fine options. It really gets back to what a builder is trying to accomplish. We are all gear heads and love to extoll our knowledge of tech. We should be careful not to imply that making a different choice is a mistake. Obviously, we want everyone to build a safe car.

My 2 cents.

[BEAR-AvHistory]

These kinds of threads tend to drift. The original poster asked about the pros and cons of a fan shroud. Many said there are many pros, not really any cons. Maybe the only con is that it is not really necessary. I suspect the underlying ask in the question was, "Should I put a fan shroud in my car?". I don't think the question was, "Is a fan shroud good technology?" It certainly works as advertised and is used in most modern applications. We tend to get in these conversations that say "this is better than that," implying that one should do what is better. This applies to many frequently asked questions by new builders. Your hear many of the same kinds of replies. "Power steering is better than manual, roller lifters are better than flat tappet, Coyote is better than a small block Ford, more horsepower is better than less, IRS is better than a 3 link, more clecos are better than less, steel bell housings are better than aluminum, drive shaft safety loops are better, etc".

But, I wonder if there is really not a "technological imperative" here, meaning "just because a technology exists, you should use it." Plenty of these choices are tried and true and are fine options. It really gets back to what a builder is trying to accomplish. We are all gear heads and love to extoll our knowledge of tech. We should be careful not to imply that making a different choice is a mistake. Obviously, we want everyone to build a safe car.

My 2 cents.

Don't think it a flat either or when it comes to these threads. Its more how is it to be used based. Take power steering. My car is manual because I like it and for most of my driving its the "best". That said if I was serious about AutoX instead of just having fun days then in my case power steering would be a must therefore the best choice.

Personally I like threads that wander a bit as long as the stay in the same general lane. Lots of interesting & in many cases useful to you info you have not thought about will fall out.

On the shroud these are a number of potential best answers. Yes if you have nothing & live in FLA but maybe no if you live in VT. No it you already have the Everson/Breeze parts & the car is assembled. Yes if you have the Eversion/Breeze parts & the car is still being built and so on.

[rich grsc]

If you don't want a shroud, good, don't use one. If you overheat, then you can do the extra work and add one. If you do want one and use it, when the car doesn't overheat, you don't need to do anything. :)

[Theshandman]

I do have the Breeze shroud, and also fabbed up a cover to hide the top of the radiator. It looks like it’s downward deflected but it’s at the same plane as the flange of the Breeze unit.
176662

[GFX2043mtu]

From a thermal engineer that does this professionally for a very large company... you want a shroud. There is no down fall but a spending a few bucks, and the return as worth it. It will certainty keep the temps down when idling for extend periods and at slow speeds where there just isn't enough air flow. With out a ducting shroud air flow is very centralized and only cools one small doughnut shaped ring area on the radiator. Hot coolant will bypass in the tubes with no air movement which causes high temperatures. A shroud helps to even out air flow over the entire core face which reduces coolant temps more effectively.