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MG MGB GT V8 Factory Originals Technical - Picking a radiator

Which radiator fits these bills for cooling a 302: Cools well, is inexpensive, and comes from a stock vehicle?
Geoff B

mid 60's Ford Falcon with an iron block 289. Heavy duty core if available. With a little cutting of the mounting brackets (it's really easy and takes about 10 minutes) it will drop between the frame rails. Make sure you have a big fan! Preferrable a puller fan. I have a walker fan on my rad that moves 2750 cfm of air. It's like a wind tunnel!

Also "duct" the area between the backside of the front spoiler and the bottom front of the rad. Basically you're going to build something shaped like this: T___T Where the top of the T's get screwed up into frame rails on either side of the rad, and sheet metal forms the vertical legs of the T and also the bottom horizontal plain. Use some plumbing pipe insulation (the brown foam stuff with a slit so you can slide it over a pipe) to help seal off the area between the front of the rad and the new duct. Also do the same between the front of the duct and the back of the spoiler.

This setup prevents hot air from coming forward from the engine bay and back through the rad again.

If you need a picture I have some of mine.

Justin
Justin

MGBGTV8 - plus two pusher fans. No mods.
RMW

Justin great idea, thanks. Do you have a part # for the radiator?
Paul Steelman

Paul,

I believe that the following is an example of a mustang/falcon radiator that will work:

http://www.mustangsplus.com/Merchant2/merchant.mv?Screen=PROD&Store_Code=MPFMP&Product_Code=00772&Category_Code=4-Row

They also have the same radiator with the bottom outlet on the driver's (left) side if you are using a 302 with the serpetine system and a reverse flow water pump. If you really want to spend some money they have aluminum models. Once in awhile you can find a used 3 or 4 core mustang radiator on Ebay for next to nothing. For less than $200 I'd go for the new one.

Ryan
Ryan Reis

Geoff, I faced the same issue with my 302 MGCGT. I looked around at all kinds of rads at wreckers and new alloy models but didn't find the "exact" dimension that would fit. So I drew up the dimensions which would give me maximum height and width within the mounting flange dimensions in the car and had a new one made to fit. With a heavy duty, high density new core, it cost $225 at a local radiator shop and they made it in two days! As they re-core old radiators all day long, all they need to make up are the upper and lower tanks. Additionally, you get a new dense core which is much more efficient than the old style "open" cores used thirty years ago. On top of that, you get to have the inlet and outlets right where you want them and in the correct diameters to suit your engine inlet and outlet. You might consider this option as otherwise it can be a needle and haystack issue! Mine is a three core and I have an engine fan and a pusher to assist if needed. It runs cool on hot days but will slowly heat in traffic on hot days but has never boiled. My feeling is that this is mainly due to poor hot air exit capacity from the engine compartment rather than the radiator itself as it runs cool - about 160 dgrees underway. Good luck, Bob Elwin
Bob Elwin

Roger: the guy's cooling 302 cubic inches in an iron block, which DOES NoT dissipate heat like the aluminum blocks do. On this one, you really need to upgrade.

Paul: Napa part number MO2301 $222.00 Depending on your setup, you may need to switch the inlet and outlet positions. My local rad shop did it in a morning.

I couldn't be happier with my setup. Infact, I have a difficult time getting my car up to running temp. Even on brutal days it never overheats. At the end of a long freeway run the temp will spike close to red, but the fan kicks in and a few minutes later its back to normal. It amazes me how efficient the whole thing is.

Funny story: When I bought my walker fan (from Mr Walker directly at the Knoxville Southeast NHRA show) I asked for a shroud too and he said: "you don't need it, trust me" and I replied "yeah but I'd rather be safe." and he said "look, if you end up needing one, I'll give it to you for free!" Sweet!

I didn't end up needing one ;-)

Justin
Justin

Thanks Justin, that is a big help. I have a 302 that uses the stock V8 radiator, overheats in the summer and runs hot in the spring.
Paul Steelman

Justin--any idea of diameter of your Walker fan and cfms ?--I have found a Perma-Cool fan that is 14" and claims 2950 cfm--which should cut me back by at least 1 fan.
Bob-- When I put louvers in my hood --bonnet --it made a world of difference so I agree trapped heat under the hood while not moving is a big problem. I can run all day on highway with no fan.FYI my rad is a 4 core 65 Mustang brass/copper .
Gil Price

Hi Gill,
I have the same radiator as you and I have a Zirgo 3300cfm fan.
http://www.zirgo.com/detail.lasso?itemid=ZF16S
Regards
Tony
Tony Bates

My math may be wrong, but consider this…

Stock V8 radiator core is 18” by 14” has 252 square inches and allows a 14” fan with 153 square inches, which is 60% of the core size.

A core size 18” by 16” if that’s the size of the Mustang radiator has 288 square inches and a 16” fan covers 70% of that with 201 square inches.
George Champion

Tony --Thanks for the info on fan --Are you using this as a pusher fan and is it your only fan ?
Thanks --Gil
Gil Price

I think this really comes down to climate as well as rad efficiency. Up here 80+ is hot. With the dual shrouded fans mounted on the radiator pulling my car has stayed extremely cool this last year. I also have a STOCK flow water pump. You CAN move the water to fast in the system. there is a certain flow rate to get maximum effectiveness out of the cooling fluid. I fit cycles to fast it does not dissapate enough heat. I think that was 1/2 of my problem before as I had a high flow water pump. I also have Alum heads and vents into the wheel wells for the headers...

Stock rad in stock location with a stock explorer water pump is working well so far.
Larry Embrey

I live in south of france, in summer the temperature is often higher than 35°C (95°F). A very good cooling system is necessary. I have a very good system and I don't have problem with that.
regards.
http://membres.lycos.fr/mgcontact/fileupload/uploads/1105020935_fan.jpg
http://membres.lycos.fr/mgcontact/fileupload/uploads/1105020935_alyrad.jpg
michel

George, what would 18 x 16 be with an 18" fan just out of curiosity?

Larry, I'm not sure I buy the "too much flow" argument, though I've heard it from a lot of sources, many very reputable. Here's why: This is a closed system and with the radiator temp at about 180-200 degrees it is going to dissipate a given amount of heat for a given airflow and this is not going to change a whole lot within that temperature range. Turbulence in the core tubes from high flow also contributes to heat exchange whereas laminar flow such as you have at low rates (unless the core tubes are dimpled)does not. The heads and block are in a constant state of quench so any heat that is produced is going to be absorbed by the coolant. As the temperature of the coolant increases system-wide, the heat dissipation at the radiator will go up proportionally, so given an adequate radiator there really is no reason why you have to have a large temperature differential from the top of the radiator to the bottom as you would have in a low flow system. In fact that would make the system less efficient.

On our cars I think a much bigger problem comes from having the radiator too low in relation to the heads.

Jim
Jim Blackwood

I didn't believe it until I tried myself Jim. Water/coolant can only dissapate heat at a set max rate regardless of the rad used.. If it is in/out of the Rad faster than it can release more heat than it gained from the engine, then you will have a system which does not cool well.

The other issue you can run into (maybe even bigger than heat dissapation) is one of cavitation of the pump.. This happens with a high flow pump and a small pulley as the pump is spinning faster than it is designed to go.

I don't doubt the head/radiator levels also play a part.

I used to have cooling probems, with the new water pump and ducted fans, that issue seems tbe gone completely, can't wait until summer!!!
Larry Embrey

Larry, I think you are missing the point here. If the water is circulating that fast it means that hot water is always in contact with the cores at all points, meaning the cores and fins are going to be at the temperature of the water which is at the temperature of the engine and the issue now is not how fast the water will absorb heat from the engine, it's how fast the radiator at operating temperature will dissipate heat from the metal into the air. If the engine is hot and the radiator fins are significantly cooler it means something else is going on here. As far as the water's ability to transfer heat out, it doesn't matter which particular water molecules are in contact with the metal, and the more the merrier. Heat transfer between water and metal is very rapid. If you've ever quenched red hot steel in a bucket of water you know that the steel can go from 1500+ degrees to sub-boiling in seconds or less. It only slows down when steam begins to form on the metal, and the more agitation there is in the water the more the onset of steam formation is delayed. Transfer from the water back to metal makes use of the exact same mechanism so the rate of transfer can be expected to be the same going the other direction, or very close. If you can measure any temperature drop at all going down the radiator then it means the radiator is not operating at peak efficiency. I would be willing to bet that if you used one of these infrared sensors to measure the temperature in the upper tank and at various points on the cores you would see very little difference if any, and the engine block and heads should be the same. If they are hotter then the problem is getting the heat out of the engine, not out of the coolant and this means looking for something that interferes with total quenching of the water jacket surfaces. This could be from cavitation, as you mentioned, or it could be from air pockets. With the radiator mounted low the likelihood of air pockets is increased more than you might suspect, especially when combined with a top tank radiator. Why? Well first obviously enough, is because any air in the system is going to be at the high point, and if the top tank inlet is below the top of the water jacket in the heads the air will be in the heads. On my car it is very likely the floor of the water jacket in the heads is above the radiator inlet, and I expect this applies to other MGB-V8's as well. But would a coolant recovery tank and a cap at the highest point eliminate that problem? Maybe, but not likely. This is where the crossflow radiator comes into it's own. Under operating conditions the outlet side of the water pump will show a significantly higher pressure than the inlet. I've been told by experts in the field that this differential can reach as much as 50 psi during surges from engine speed transitions, but at any time it will be a significant pressure difference. Given the configuration of a top tank system it's pretty easy to see what is going to happen here. Coolant gets purged to the recovery bottle and the resultant volume is made up by water vapor. Enough surges and the head starts generating steam and the engine overheats, blowing coolant out of the recovery bottle in the process. The cap that is supposed to vent at 16 psi is venting at an effective system pressure well below that, plus acting as a purge valve during transitions. The side tank by contrast which has it's cap on the pump inlet side sees significantly lower pressures, and does not experience those pressure spikes at all, so it does not let the coolant out and everything works much better. But there is one more ingredient. We still need to get all the air out and keep it out. That's usually the job of the radiator cap but it cannot eliminate air which is at a higher point than it is, and if it is mounted in the upper hose as mine was, then there is no opportunity for the coolant and air to separate so coolant still escapes. The answer is a surge tank, but it needs to be one that is properly designed. Some of the older cars had a small tank above the intake manifold. This was a very simple system but it was effective. The tank was kept 2/3 full and any air in the system migrated there. With that much air in the tank, pressure spikes vented air, not coolant, and although any venting of the system after startup represents a loss of cooling capacity, it still kept the coolant in and kept the water jacket wetted. The crossflow locates the surge tank on the inlet side and eliminates even that problem, so how would it be possible to duplicate that configuration with a top tank radiator? Actually not too hard. The surge tank needs three things: A pressure cap, a drain line, and one or more bleed lines. The drain needs to go to the pump inlet and it just so happens that plumbing into the heater return satisfies this requirement just fine. The cap needs to be the highest point in the system, and at the very least needs to be above the water jackets in the heads. The bleeds are where things begin to get interesting. First, they need to go to where they can eliminate troublesome trapped air, and if they can go to areas where the coolant flow slows down so much the better. However, with our drain to the pump inlet the surge tank is on the low pressure side and all our trapped air is on the high pressure side. On a crossflow they simply locate the bleed at the top of the inlet side tank, and it's all at the same pressure and gravity does the rest. We don't have that option, so the clear solution is to restrict the bleed size to a point where there is not a significant amount of flow bypassing the radiator and causing turbulence in the surge tank, yet still large enough to let any trapped air get to the tank. A line to the top of the bend in the upper radiator hose might do OK, but that is also a high flow area so it might not be as effective as we might wish. The good news is that it would function with the engine not running, even if it did not do a perfect job with, and even so some air should get out with the pressurized coolant. A bleed line to the upper radiator tank would be a preferred location if the radiator was a little higher and when running it should work properly, but when sitting that air would just go up into the engine. The bypass wouldn't work because it's at the bottom, and the temp sensor is in a high flow area. The solution is two or more bleeds. One to the upper tank, and another one either to the upper radiator hose or to the sender location. These lines should be small, probably no more than 1/4" ID, and perhaps even less. On mine, I may or may not be able to install a fitting on the upper radiator tank and if I can it will be no larger than a 1/8" pipe thread so that line will be quite small. A second line will go to a fitting installed in the hump above the temperature sensor bulb and probably the same size as the first. This will leave the hump in the upper radiator hose to collect air, but between the high flow in that area and the two bleeds that may eventually be eliminated. The main thing is that the coolant will be maintained above the top of the water jackets, and air will not be allowed to flow through the radiator core. And what of the radiator cap? For this system to work the cap on the top tank must be eliminated and sealed to a minimum pressure of 50 psi so basically the filler neck needs to be removed entirely, or replaced with a higher pressure design if you feel you absolutely have to be able to look in the radiator. The system pressure cap now resides on the surge tank and all fill operations take place here. Admittedly, coolant changes will be slower with only a 5/8" drain into the system, but for the benefits, and the simplicity of the connection that is a compromise I'm willing to make. The drain itself will consist of a hole in the bottom of the tank end mated to a matching hole in the wall of a piece of 5/8" diameter tubing which bends down to match the hose neck on the water pump and extend rearward to allow the hose to connect, eliminating the hose bend in the process. The tank itself will have a capacity of a little less than a quart, with an overflow going to the coolant recovery tank. The coolant recovery tank has a pressure cap, so all I'll need is a suitable fill cap and the system will be complete. One last compromise is that the recovery tank is positioned lower than it should be, mounted on the pan beside the radiator, But I'm taking the economic approach using as much existing hardware as possible, and I believe it will serve the purpose. Soon as warm weather hits we'll see if real world testing proves out the theory.

Jim
Jim Blackwood

Could you repeat that again please!
Paul

Um,... No
Jim Blackwood

I shortened the axis of the water pump roverp6 for the gap with the radiator and I use a pulley with lower diameter (slightly). I use also a water tank in load.(water distil + anti-freeze for liquid coolant
Regards.
http://membres.lycos.fr/mgcontact/fileupload/uploads/1105086327_watertank.jpg
http://membres.lycos.fr/mgcontact/fileupload/uploads/1105086327_pulley.jpg
michel

Gil
I use the fan as a puller. It's the only one I use?
Tony Bates

Jim,

Wow, I thought posted long replies.

As I said earlier the 18 by 16 radiator has 288 square inches. An 18” fan would move air through 254 square inches, but some would be lost because it extends past the 16” core height. If centered the lost area is 11 square inches and if placed to the extreme the lost is over 15 square inches. If centered the fan covers 243 of the 288 or 84% leaving only 43 uncovered square inches. If space permits a very good shroud could angle in and recover that. If left exposed air will pass through much more easily than where the radiator restricts airflow. None of those calculations take into account the loss area where the fan motor is.

I still dream of a fan with an angle drive so the motor can be placed remotely passed the side of the radiator. That would allow the unit to require less depth and have a smaller hub to block airflow.
George Champion

George check out the Sidewinder fan made by Matson Radiator in s ca it has an offset motor driven by a cog belt. I am real happy with mine. I run a 293" with A/C and it gets over 110 here and i use a custom built alum rad. No hood loovers because i want my car to look stock on the outside.
r milner

That Sidewinder fan is very intriguing and just about what I had in mind, but try as I might I can’t find good pictures or dimensions other than a diameter of 16”. I did find a site for Mattson Radiator with two “t”s.
George Champion

George,

Try this link.

http://www.streetrodderweb.com/hotnews/0000sr_technlolgy/

Pete
Pete Mantell

Thank you. That link says the fan is 1 7/8 inches in the center and shows the motor within the diameter of the fan and the other site showed the motor outside the diameter of the fan. Even though they don’t show a diagram giving all the dimensions and configuration it’s nice to see someone has produced a thinner fan where we need the clearance, in front of the water pump.
George Champion

I've been thinking about something like this for myself...

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1&item=7946295071&category=33602


Scott
Scott Wooley

This thread was discussed between 04/01/2005 and 10/01/2005

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