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Removed my trans cooler from my old radiator to point out how inefficient these are. Extremely small and sit in 180F + coolant. Virtually any external cooler would be better.
thing is it does exactly what its supposed to do for stock cars. what most people dont realise is that auto transmissions actually need heat to function properly. the quicker the transmission can warm up the better, and thats why vehicles use an oil to coolant heat exchanger in the rad.
adding an additional cooler needs to be evaluated carefully. if at all possible, the factory heat exchanger in the rad should be run in series with the aftermarket cooler, the oil flow going from the trans to the rad, and out of the rad and into the aftermarket cooler. this helps the transmission reach operating temp. you also should always use a stacked plate style cooler, these coolers are designed so cold oil only flows through part of the cooler so it will act as a thermostat. a tube and fin style cooler should never be used on a modern transmission as they dont allow the transmission to come up to temp properly, along with not being very efficient when the fluid is hot.
now, if you have a high stall converter or a bunch of performance stuff done then an additional cooler is something to consider, however for a mostly stock car the oem system works just fine.
My car is far from stock and getting further from it every day.
It doesn't get driven in cold weather with all the magnesium chloride they throw on our streets.
The new ZZP radiator does not have a trans cooler built in.
I plan to run a thermostat controlled fan assisted cooler out of the path of airflow.
its actually not just for fuel economy, although that is one of the reasons. despite being computer controlled, the transmission is still very analoge. you have hundreds of little passages with calibrated orifices for fluid to flow through. when the fluid is cold its harder for it to flow through these channels, ultimately making for a longer shift. a long shift causes excessive wear in the clutch packs. now the transmission control strategy does have shift adapts, however they only come into effect when the transmission has warmed up.
if your not driving it in the cold and you have a higher stall converter warm up wont be an issue.
As much money as I will have into my transmission I am not about to have heat related failures. I went with the larger ZZP radiator to get the transmission heat separated away from the engine. Manufacturers put them in radiators because the coolant (conduction) is a much better heat transfer than air (radiation) for the money. When extra cooling is needed (heavy duty cooling package) the manufacturer adds on an additional external cooler in the path of air flow. I plan to run a slightly higher stall converter but not so high that it makes daily driving difficult.
Not to be that guy but I'm going to be that guy since you nitpick as well I'm sure you can handle it. Technically heat transfer by air is called convection, not radiation. Radiation heat transfer is typically infrared like the heat you feel from a blackbody, a fire, the sun or your header/exhaust. "Radiator" is a misnomer. Though your "radiator" does radiate some, heat transfer via radiation becomes more significant at extreme temperature differentials. None of this really matters for the points you are making just a technicality lol.
Anyways, what are your ultimate goals with this car? Way you are going I would think you would be strapping a TVS or turbo on. Far as I have seen with the M62 on pump gas the stock transmission holds up fine. I know I have a F23 but it has over 100,000 hard miles on it with 20,000 of those supercharged and it is still holding up and from what I have read the automatic can take even more of a beating. That's just what I've seen though.
I know the difference between conduction, radiation and convection. The radiator is called a radiator because that is how it transfers heat. With the addition of a fan it becomes convection but that doesn't change the fact that it is still a radiator and heat transfer to the ambient air is radiation. I didn't say air flow above, I said air.
I don't have an ultimate goal for this car. I just want to enjoy driving a very good looking and very quick street car that still passes Colorado emissions.
12-15-2017, 08:50 PM
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