MG Sports Cars

One of my shop buddies was watching me tinker with the firewall sheet metal and said "you’re going to have an overheating problem with that little grill opening and such a narrow radiator." I explained it was all curable, but that said, has that been all that much of a problem for you guys?

In my car I had a core the size of 19 x 17 less tanks overall 19 x 21 it was a crossflow unit for a mustang that I converted to a downflow to fit in the frame rails with a fan on front/back. the biggest problem I had was the hot air returning through the core so I then added the air dams on the side and top to stop the recirculation.
Generally in traffic it would climb to 230 but wouldnt boil over, heck I didnt even have a catch can. Running down the highway it ran 190 right at the tstat. Im looking into a bigger core just to take the worry out of standing traffic though.

We use Walker Cobra four core radiators on the T-Buckets and never have diffaculty cooling big blocks but the engine itself is open. I'm thinking of a multi core with duel fans also. "P"

With my Ford 302 I am using an aluminum radiator from D&D which is designed as a bolt in rplacement for a stock MGB radiator. I am also using the less efficient standard MGB rubber bumper fans. This combination has worked well with no overheating. Note that I also have through the fender headers which may help.

Thanks Larry, I've also been reading the article Curtis wrote about re-coring and extending a stock MG radiator. "P"

For the sake of discussion I'd like to post what I have learned about radiators and cooling.

Brass conducts heat at the temperature that gets radiated to the air. It is a better conductor of heat in a cooling application.

Two core radiators drop the temperature of coolant more than three or four core radiators, but they hold less coolant.

Thermostats slow down the rate of flow through the cooling system. If the coolant flows too quickly it won't be able to drop its heat as it passes through the radiator.

'Overflow' tanks are actually 'de-gas' tanks. Their primary purpose is to purge air from the coolant system by creating an air trap. Air in the system causes the coolant (glycol) to degrade and attack the engine water passages.

The coefficient of friction between aluminum (pistons) and iron (cylinder walls) is lowest around 220 degrees Fahrenheit, so a 195 degree thermostat will make an engine run cooler than a 180 degree thermostat.

In an iron block engine, much of the heat generated is from the bearings. Synthetic oil will reduce friction and make an engine run cooler.

Hypereutectic pistons have a higher silicon content and reject the heat of combustion better than standard cast or forged engines.

Coating the combustion chambers of an aluminum head with a thermal barrier will help lower heat transfer to the coolant. (Iron heads are much more efficient than aluminum heads.)

RobertShaw thermostats are pressure equalized thermostats. Use them.

Glycol is an anti-freeze and anti-boil coolant, but it carries less heat than pure water. Glycol has a specific heat of approximately 2.4, water has a specific heat of 4.2, or almost twice the heat carrying capacity of glycol. The optimum mixture of water/glycol is 60/40.

Pressurizing a cooling system increases its heat carrying capacity.

Best of luck.

Edit: Exhaust Gas Recirculation (EGR) reduces combustion chamber temperatures. Many people don't understand exactly how EGR reduces pollution. It's not an attempt to re-burn exhaust fumes, its a technique to reduce creation of NOx by reducing combustion chamber temperatures.



Edited 1 time(s). Last edit at 05/22/2010 08:45PM by pcmenten.

I think Paul's list is a real good start.

However, I suspect this section might be a bit off:

Quote:

Thermostats slow down the rate of flow through the cooling system. If the coolant flows too quickly it won't be able to drop its heat as it passes through the radiator.

With regard to flow rate:

water pumps - When water pumps are operated at higher rpm than they were designed for - either due to high engine rpm, or changed pulley ratios, or both - they're likely to have problems. Many racers have discovered that slowing their water pumps down can help greatly, but I propose that the problem they're correcting is cavitation at the pump and has nothing to do with the actual flow rate through the radiator (or any other specific part of the system.)

thermostats - Rather than thinking of a thermostat as something that regulates speed (assuming it's fully "open") I believe it's more useful to think of it as a planned restriction which has the effect of keeping pressure relatively high on its upstream side as part of a strategy to keep vapor in suspension (to prevent cavitation.)

radiators - The cooling system is a closed loop! I propose that any given ounce of coolant doesn't care how long it's actually in the radiator because if it's traveling more rapidly, although it'll exit sooner it will also return sooner!

In radiators, surface area trumps core thickness every time. If more cooling is needed, increasing the core area is the way to get it. Air recirculation through the radiator after it has passed through and absorbed heat is a problem and steps should be taken to prevent it.

JB

As often as possible I sat in the garage, turn on the TV, smoke a cigar (please don’t lecture), and ponder what to do next; anything but actually accomplish work. This morning I was looking at my stock ‘72 radiator and it crossed my mind that the lower tank is very tiny. If I re-core it, change the location and size of the water inlet and outlet, and the lower tank, is it a good idea or should I just buy a new one. I should also point out, though you may have already suspected, I also have a computer in the garage which is why I type stuff in without taking time to think about the stupid stuff coming of my finger tips.

Have you thought about a stock replacement radiator for a 65 mustang? Thats what I plan to use for mine, I figure with proper shrouding around the radiator and the fans this would be plenty sufficient to cool most ford engine swaps (hopefully including my 351) without breaking the bank.

What are the dimensions of the 65 Mustang radiator; will it fit between the frame rails? "P"

Just a quick search on google has the rad at 21 1/2 tall by 17 1/2 wide. I've looked at a few builds in the MGB photo gallery here. Joe Schafer's build comes to mind, IIRC a little trimming of the mounting flange is all thats needed.

Thanks so much Pete, I think thats the way I'll go. In fact, a friend is building a 66 Mustang and might have an extra radiator. "P"

It's definitely worth your time to look through the How It Was Done articles and photo gallery. Mustang / Comet radiators are available in various versions, quality levels and cost levels. You can get'em with brass tanks that polish up real nice, and you can also get aftermarket aluminum versions. Either should give you plenty of cooling capacity and the relatively low cost (from high sales volume) makes them attractive.

Paul, I'm sure you're probably already aware that when people install tall radiators they usually shift them forward of where MG mounted the anti-sway bar. On your '72, you'll obviously have to cut out a bunch of shelf to do that. You may need to move the radiator forward anyhow depending on where you locate your engine and how much space your pulleys and water pump take up.

edit: Bruce Mills used a Falcon radiator...


note the anti-sway bar location, as revealed in this view:




Edited 1 time(s). Last edit at 05/26/2010 09:44PM by Moderator.

The shelf where the oil cooler mounted has already been removed and I plan to mount the radiator where you mentioned just forward of the anti-sway bar and dropped down a bit. I’ll also fabricate a bulkhead on each side of the radiator to reduce if not eliminate recirculation. I’m not too fond of Ford pulleys but I haven’t found a good source for something better; still looking. I also think I’ll replace the stock water pump with a short one. I’ll definitely go through how it was done, no point reinventing the wheel. Thanks Curtis, “P”

Found a 65/66 Mustang Radiator at Mustangs Unlimited (2593R) for $149.95. Dimensions are about right but the inlet and outlet are both on the right side. Is this a problem or can a radiator shop change the inlet location? "P"

I've had the same problem, but try a different application, I think the 6cyl radiator has the offset inlets and outlets we need. Maybe the falcon/comet v8 radiator has the correct outlet location. The early falcon and mustangs share much of the same parts and some with minor differences in a few.

I think you might have a winner there Pete. The water outlets are a little smaller but I'm not sure it's enough to make a difference. If it does, I sure a radiator shop could fix that and the outside numbers are the same.

Paul, IMHO, a puller fan inside a shroud will cure most problems. I had my aluminum radiator checked before I had a custom shroud made and I was losing 30% cooling via fan efficiency by not using a shroud. Considering that these MG engine compartment run positive pressure (hood closed) that affects radiator air flow, I would also use through the fender headers to the negative pressure wheel area. It acts as an extractor and improves radiator air flow

Fast un-obstructed air flow is the key to good cooling, it can also compensate for smaller core dimensions, but, you must have a high fan efficiency pulling the BTUs out of every square inch. I can hold a credit card in either corner of my radiator, turn the electric fan on and the card will hold in place, I could not do that before I had the shroud made, looks good too.

As far as circulating the coolant too fast, there is part truth to it; if I can locate the formula of material conductivity versus flow CFM I will post it. If I have my coolant moving so fast that it exceeds material heat conductivity then I would go with the easiest material "copper". A quality thermostat acts as a flow regulator anyway; don't believe me? Have one hang part way, full open or stucked closed. Coolant capacity is also an often overlooked problem; there is a proportional balance with thermal efficiency. Most of these postings carry goog advise, include most of them and you should be the coolest guy in town (LOL)

Here's a link to the guy that made my shroud, he has some testing equipment to make a believers out of non-believers:
[www.mahaffeymotorsports.com]

Here's two photos of my radiator set up, it has almost the same dimensions as an early Mustang radiator.

Here is a simple and cheap way to help with overheating problems. Add a heater core to the system. It's worked on my Alpine-Ford v6, my Spitfire- Ford v6, and my latest (finished) project, 64 B-Chev 2.8 v6. I omitted the heater system so it is simple to run the heater hoses to the "aux. rad." core. BTW, if cabin heat is still needed, use tee's in the coolant hoses. I also discovered that cool air to the carb helped.