I need to repair or upgrade my cooling system. I did a track day at Lime Rock a week ago, where I overheated and the radiator ruptured a leak at the seam on the top. For sure, I'm going with an electric fan wired into my Megasquirt, with an override switch in the cabin. But the radiator itself... am I better off taking mine to a radiator shop for a flush and repair, or going with a universal aluminum Griffin? I'd appreciate some advice. Would like to not worry about cooling next time I'm at the track. Thank you!

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280zx NA to T... http://z.modeltrainguide.com

["280zx NA to T...'']

Does this mean you have turbocharged your car? If you did, you must expect to upgrade your cooling capacity and brakes equally. Not just "repair" them when they get over-worked; upgrade them to correspond with the increase in heat/power/speed.

Years ago I replaced my skinny 2-row factory aluminum radiator (when it fell apart) with a fat copper radiator, and since then I've added a fan shroud to accelerate the airflow thru it. Makes all the difference in the world.

Just out of curiosity, did your tank seam burst ON the track, or after you pulled off and got afterboil?

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1970 240Z

Frank,

Thanks for the reply. Yes, the car is the NA block with a manifold and turbo bolted up from a T. Fuel and timing are controlled by Megasquirt. I am running 4 or 5 psi of boost right now, not the full 7 that the zxt's have. I don't actually know the order of the failure. I noticed steam spouting from the hood where the overflow bottle is at the end of no-name, so I ditched the car in the grass just past the uphill and waited for the session to end. Then I drove it gently to pit lane, and when I popped the hood noticed the radiator was spraying from the seam directly onto my alternator.

So you're saying the stock radiator is insufficient? I suspect my radiator is original to the car, and probably gunked up inside. If I had it cleaned out and repaired by a competent shop, would it still be insufficient? Just looking through the member gallery I see a good mix of stock and aluminum radiators, but most folks have electric fans. Hmm, decisions.

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280zx NA to T... http://z.modeltrainguide.com

In the case of the 1970 240Z, the whole car seemed to have been expected to last "about 10yrs". At that point, major systems began to fail (except for the air pump, which locked up after about 5yrs). My stock 2-row radiator died precisely on time with that schedule (1980) and stranded me ~ ironically ~ in the front parking lot of a NC radiator repair shop . Am I blessed, or what? The owner convinced me to replace my 2-row aluminum core with a 4-row copper unit which fit perfectly inside the stock shell. I've rebuilt it once (5yrs ago) and added a fan shroud (air-accelerator) since then. It cost very little more than it would have to repair/replace the stock unit and handles nearly any kind of heat conditions without complaint.

I don't know if the 280Zs were expected to last longer than the 240s or not, but the fact that they had turbos, A/T and A/C available put additional strain on the engine, which equates to more heat. I have recently learned that the 280 radiator will not fit into the 240Z without a bunch of drilling, and then it hangs down below the valance, so we know they are different radiators. That shows Datsun/Nissan recognized a need for greater cooling capacity due to the larger engine and more goodies on it. Turbo cars usually have larger cooling systems and even intercoolers for the Turbo units themselves. Since your car was originally an N/A unit and you added the turbo, I would suspect there is a good possibility your stock N/A radiator wasn't expecting to have to fight the added heat at age 37 and committed suicide.

I would personally go with a larger capacity unit and a well-thought-out electric fan plan. Bryan Little specifically went hunting graveyards until he found two electric fans off a Volvo station wagon, because his research showed them giving the highest airflow of any fans which would fit behind a Z radiator. His L28 is pretty maxed-out for power but his cooling system handles everything the engine can throw at it. Here's what Bryan has to say about cooling in his Datsun Z Garage:

"RADIATOR:
I bought a new 3-row 240Z Datsun radiator off the internet for $120 a while back, excellent quality. Mine was worth every penny: it dropped my temperature about 10 degrees and my needle barely goes over 160 now. If yours is 30 years old it might be time to let it go.

"3-rows are said to be the largest for use on the street as a 4-row can have less airflow due to the extra thickness. But unless you have a some serious needs a new 3-core radiator with a pair of 12" cooling fans is going to do just fine. If you want to use a 280 radiator in your 240, I measured one and it's bolt holes are offset and its too tall to fit a 240Z. The V8 crowd has talked for years about using a Camaro radiator which is about the same size as a 240Z model. I used one for a while but found the Datsun version was superior in fit and finish so I got rid of the Camaro model. Keep it Japanese.

"FAN DISTANCE:
Be careful if you are dropping an L28 with a 3-row front balancer into a 240Z. The fan clutch is the same, but ZX fan design extends a couple of inches closer to the radiator than earlier fans. And upon flexing, the fan can cut into the radiator. It happened on mine. The reason is that 3-row pulley fan hubs were made longer to clear the long balancer".

I have learned to listen to the man.
If you intend to do track days with your car, that's heavy-duty heat. I wouldn't recommend trying to rehab your original radiator after 30yrs of use. I'd suggest getting a larger unit, and taking the opportunity to professionally flush your block out while the radiator is out of the car.

PS ~ And if I might ask, what did you do about your compression ratio when you added the Turbo? The turbo block L28s had dish-top pistons to lower the CR and prevent overheating and blowing head gaskets (and heads!). The NA blocks had flattop pistons which, if using a turbo, wouldn't last long under the elevated compression ratio.

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1970 240Z

Still running flat tops. I run 93 octane and pull the timing significantly when in boost. She pulls like a freight train, well, it used to when the radiator wasn't leaking all over the place!

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280zx NA to T... http://z.modeltrainguide.com

I suspect as soon as you arrange for adequate cooling, she'll be fine.
Remember the emergency trick of running your heater full-blast to take some heat off the engine when the gauge shows dangerously high. It's murderous inside the cabin to run the hater in the summertime, but you'll sweat worse if you have to walk home because you blew the head or gasket or core plugs.

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1970 240Z

I would just get a bigger radiator. If you have the F54 block, well it has the Siamese cylinders, and could use all the cooling upgrade if your racing it. Hopefully you have an oil cooler as well with the turbo. Also, upgrade the last exhaust bolt by the fire wall to a higher grade steel, before that snaps.