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MG Midget and Sprite Technical - Radiator shroud necessary?

Hi, I'm in the process of replacing my radiator (vertical flow) and fitting an electric fan.

Tha fan will be mounted on the front of the rad and I am doing away with the water pump driven one.

In the effort to increase access under the bonnet I was wondering if I could remove the shroud from the back of the rad,

Is the shroud only effective when there is a fan itting inside it?
Thanks
Mark
Mark Whitmore

Mark, i used the shroud to mount the fan.


Brad 1380

Yes, you can remove the shroud, but it's best to leave a triangular fillet at the top to support the tank.
Dave O'Neill 2

Shroud at front of rad is essential, to direct air from the grill through the rad rather than bypass.

When I first drove the Kseries conversion, I had no shroud; coolant temps were fine around town, but above 50mph it quickly overheated, making me think std rad wasn't up to the job of a 1.8 engine. (It cooled down when I slowed, so total panic was averted.)

I fitted a simple shroud using ally sheet (using corn-flake cardboard template), and next drive was fine.

A
Anthony Cutler

I agree with Ant

Mine is a non standard rad and pop up front. I have an alloy shroud that directs most of the air at the front through the rad.

I also removed the engine fan but replaced it with an electrical version set behind the rad. This has a shroud around it that came with it when sourced in the local scrapyard. :)
Bob Turbo Midget England

Mark,

As well as the shroud, you really also need an arrangement which prevents air from the fan spilling out sideways rather than being forced through the rad. Fans operating within a closure plate of some sort are more efficient although they do then restrict the speed induced flow when the fan switches off.

Guy
PS Horns and wiring have been tidied out of the way since my re-spray!
Fan is ex-scrappie, Rover 400


Guy Weller

Hi thanks for the replies, Its a kenlowe fan that I have which sits flush upto the front of the radiator with its own surround, its the shroud at the rear of the radiator (vertical flow) that I'm looking to modify as per Daves comments.
I have no shroud at the front like the cross flow rads other than the standard arrangement.

Thanks
Mark
Mark Whitmore

What Dave O'N says...

I also agree with the others that if you were to fit a fibreglass front (so removing the front panel assembly) you need to fabricate a shroud to encourage the air to go through the rad rather than round it...

JB
James Bilsland

leave the front as is
you can remove the back

The rear shroud on the vertical flow rad is only there to improve the working of the std fan.
early cars did not have it and suffered a bit the addition of the shroud improved the working of the fan.
Onno Könemann

That rover 400 fan is designed to work the other way around, if you switch the voltage direction then you'll probably burn thru the brushes quickly as they are designed to work the other way.

I had some studs mounted to the bcak of the rad and then used the original lugs on the fan to fit it - fits perfectly the 1500 radiator (well, you need to shave a little of the plastic off around the outlet pipe, but no biggie).

Of course, I have a K-series and cant comment as to the probability of clashing with the water pump if you mount it as a puller.

Will Munns

Will,
"the other way round" - How do you mean?

Guy
Guy Weller

Sorry, forget it, looked a little more closely and you do have it the right way around!

And more importantly, because of the distance from the fan to the radiator it will be more efficient than a normal pusher fan (as log as the air doesn't leak out elsewhere!)
Will Munns

I've got my K series fan (from a rover 200) is in the same place as that: the first time it went on it blew all the dead flies through the radiator and into my eyes... all standard shroud at the front, fan pressurises the air in front of the radiator so much air comes out the front as well. works much better than i thought it would
Rob Armstrong

I have a puller/sucker behind the radiator and also the radiator shroud.


No clue if a there is a reason to go for a sucker or blower except for room/space-avalability on eitherside of the radiator.



Arie de Best

That's a very clean engine Arie. Either it is an old photo from when you first installed it. Or you need to get out more!

Guy
Guy oneandahalf Sprites

I have a bottom section of shroud only without cooling problems.

I'd really like some of Carl's wing vents so I can get more air OUT of the engine bay and thus allow more cooling air in as well as reduce service drag.



Daniel Thirteen-Twelve

Mark, I agree with Onno and Dave; they seem to be the only replies which refer to the same rad that you have - all the others have later crossflow rads and/or different engines completely so maybe aren't really relevant.
David Smith

Guy, notice Arie's new (J)envy TB's!
Alex G Matla

Guy, I do need to get out more, you still have your daugthers number for me? ;)


Daniel, you still dont have them wingvents?
Ive got them send by Carl 2 months ago...
No im kidding but it does make you wander what carl is doing in his windtunnel if he dont make wingvents or finish his car...
Poor Carl. LOL

Alex, ive ordered SU-stickers to make them look original so I wont lose points at the big concours-events, you think theyll notice? :)
Arie de Best

David,

I think mark is converting from a vertical to a crossflow, was my understanding.

I thought from past topics on this subject that it was better to put the fan as a sucker and NOT as a pusher inorder to get more air to the rad, esp during Hwy speed when the fan would naturally shut off. due to the increased airflow over the rad.

BUT So agree with arie, heat vents will be our best friend

Dont most people get collage degrees in 4 years, perhaps By the time carl makes up our vents will all have our Masters degrees....HAHAHA

Prop
Prop

when the fan is not running, what difference is there whether it is in front or in back of the radiator?

the interference to the airflow would be the same in either case, wouldn't it?

I think we answered his original question way back a bunch of posts ago: if an electric fan is used, the shroud downstream of the radiator can be removed. In either case, the upstream shroud should be retained.


Norm
Norm Kerr

I put mine on the upstream side of the radiator. I thought it was neater there and I haven't suffered before or since with undue overheating. But I generally don't do traffic jams which I think is the worst situation for these cars. Otherwise the fan very rarely comes on so the rad must be working well enough with just the normal airflow and the fan cannot be impeding it too much. The fan does spin all of the time, running as a generator. In theory a spinning fan will be letting more air pass than a stationery one would.
Guy Oneandahalf Sprites

Hey norm,

>>>>>>>>when the fan is not running, what difference is there whether it is in front or in back of the radiator?<<<<<<

In the view of others...(I have no experince Myself, Im just being a parrot (talking bird)) it would be like putting a piece of card board infront of the rad. equaling a limited air flow over the rad fins to steal the heat from the coolent=ineffeinctcy....

But if you put the cardboard is behind the rad then the air has a much better chance to cool the rad fins and rob the heat from the coolent. = better effencany

NOW the question your about to ask is .... Wont the heated air just get stuck between the rad and the cardboard aka. (fan) behind the rad?...

Thats my thinking also ... I never said its a perfect world, LOL. but I think the argument is the air flow has a better chance of escaping thur the rad and past a sucker fan(then cardboard) and into the air closed off engine bay and in doing so rob the heat from the coolant in the rad.
Prop

basically put another way...

a pusher fan will create an obstruction on the front side of the rad. and not as much air can pass over the rad fins to steal heat from the coolent

but a sucker fan is BEHIND the rad so the air will have already passed thur and over the rad fins and have robbed the heat from the coolent before hitting the sucker fan obstruction on the back side of the rad.
Prop

If overheating isn't a problem, then the fan position can be a matter of choice anyway - whichever is more convenient or looks better.

I am not sure that Prop is right anyway. The air flow still has to pass the fan blades whether they are upstream or downstream of the rad they still restrict the air flow. Only if air can spill out to the sides of the fan behind the rad would it form less of an obstruction. And if air can spill past the fan then it will also be less efficient when it is working.
Guy Oneandahalf Sprites

I believe Prop is right. A fan behind the rad is more effective than one in front, and doesn't cause as much obstruction to heat exchange when its not operating.
Mike Howlett

I think that in my case the fan is far enough away from the front of the rad to make only a small difference to the airflow through the rad - about 4 inches. this should be enough to allow the air split by the fan to recombine and get through the rad. in front also has the advantage of pressurising the air in front of the rad when the fan is on - might be more efficient?
Rob Armstrong

I fitted an electric fan in front of the rad on my racing A35 - many years ago - and I found that I had to turn the fan on when driving at speed to keep the temp down. I think that the fan was blocking air from the rad when switched off, so a fan fitted behind the rad would PROBABLY be a better bet.

Why Prop thinks Mark was converting from a vertical to crossflow is beyond me.




Hey Prop..........how's that engine coming along?
Dave O'Neill 2

My point was that efficiency isn't all. If your car isn't prone to overheating then one can afford to settle for maybe a slightly less efficient option if it gives a neater or easier installation.

In the interests of efficiency you might discard all of your clothes when driving so as to save weight. But in practice it probably wouldn't make you significantly faster and it could well make your car less aesthetically pleasing!
Guy Oneandahalf Sprites

>>>>>In the interests of efficiency you might discard all of your clothes when driving so as to save weight<<<<<<

Guy,

Your 1/2 correct, Just removing your clothes wont turn the trick... You have to shave off ALL the body hair for a more slippry arodynamics... then you can be really effeciant with the high speeds...LOl

All laughing aside...You make a good point, but Id imagine 90% of the time if your going to an electric fan then you are searching for effienctcy and that last 2-3 hp you can get by not running Hp robbing engine fan is going to make a big differance at the track...Im one of the 10% that will do an electric conversion for 3 reasons that have nothing to do with that last Hp effenitcy your tying to squeeze out of your engine...Total cool factor, an better gas milage,and the experiance of installing a fan but yes that extra 2-3 Hp is a welcome benifit.

With my Larger aluminum custom made Afco racing double pass rad and an oil cooler, and future "carl" fender heat vents, over heating just wont be an issue (Im hoping). But the fan will definatly add to the cool factor..PUN!


Prop

BTW...I did mis-read marks intial posting, Apperantly he is going to replace the vertical rad with another vertical rad.

Ive alway seen the replacement of the vertical rad for the newer crossflow rad because its MORE effeciant... so thats where I made the assumption

sorry about that mark and to any others that I may have instilled some confusion...like thats never happened before.

Prop
Prop

My race car had a vertical flow rad, and the first thing I had to do when fitting the fibre front was channel air into the rad as everyone says....but on the other side, I improved the cooling by bending the shroud outwards so the hot air was allowed to spill either side of the engine and disperse quicker. otherwise it tended to swirl around the water pump pulley and create turbulence.

I expect removing it altogether will have a similar effect and look neater.
Max max-at-midgetmax-dot-com

Prop
why would one change to a diffrent style of rad when the original style (for which you have all the bits and bobs) with an other when the original can cope with the heat easly?
Onno Könemann

Sorry Onno,

Im unclear...

Are you asking why I went with the custom made aftermarket aluminum double pass racing rad?

Total Cool factor! LOL

Seriously... My old crossflow was in need of replacement or rebuild as the cooling fins where badly damaged, mangled, and patched with JB weld by the PO, I spent alot of time using a rad comb to staighten fins and I did get a much better result but it still got a bit to warm for my likeing in late july an aug never over heating but enough that my eyes watched the gauges more then the road,

the cost was almost the same to have the cross flow rebuilt as to have a custom made the new aluminum rad built... plus the new aluminume rad looks way cooler and will really do the job and then some as far as cooling...considering the additional heat the new engine will eventually pump out, so it was a no brainer! just to many advantages

If your asking why convert from the vertical to the cross flow?

Its not really my recommendation, as i dont have an opinion one way or the other, i never really looked into it that much. Its just what Ive read, appeartly you get better results with the crossflow rad...Im not sure what that really means, does it circulate better or does it allow air to better steal the heat fom the coolent? I cant say, Ive never really looked into it
Prop

This thread was discussed between 15/09/2010 and 19/09/2010

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