trans cooler

[scarborough]

i'm in the process of ordering a tran cooler for a olds 455 with a 350 transmission . looking to buy the hayden 678 or 698, would like to know if there is a big difference, and maybe some advice on the best one to choose . i'm planning on bypassing the radiator and just run the lines to the trans cooler. i saw a post where someone used what seem like a inline filter is that something to also consider doing . will appreciate any advice or opinion.

 

[Clone TIE Pilot]

It is better to run the ATF through the rad first, then run it through a external liquid to air cooler. Otherwise, you will need to run a external cooler that is double the surface area. The rad cooler removes a lot of heat because liquid to liquid heat transfer is way more efficient than liquid to air.

 

[64nailhead]

It is better to run the ATF through the rad first, then run it through a external liquid to air cooler. Otherwise, you will need to run a external cooler that is double the surface area. The rad cooler removes a lot of heat because liquid to liquid heat transfer is way more efficient than liquid to air.

Please explain how coolant at 180 degrees can keep my trans fluid below 160. Perhaps I’m missing something in the land of thermodynamics.

I’ve been using a Hayden 11x12 bar and fin style that keeps the trans below 180 all the time. It’s pretty cheap and readily available at both Advanced Auto and Autozone.

 

[olds307 and 403]

I bypass the rad cooler on everything except my Dakota which sees -40. I used the 698 with thermal bypass on it. The idea is until the fluid gets warm and thinner, it bypasses most of the cooler, therefore not over cooling it.

 

[Clone TIE Pilot]

Please explain how coolant at 180 degrees can keep my trans fluid below 160. Perhaps I’m missing something in the land of thermodynamics.

I’ve been using a Hayden 11x12 bar and fin style that keeps the trans below 180 all the time. It’s pretty cheap and readily available at both Advanced Auto and Autozone.

That is because going by your vague description of your cooler, you are likely using a 30,000 GVWR cooler which would normally be oversized for a G body that still used the in rad heat exchanger. If you still used the rad heat exchanger, you would only need a 20,000 GVWR cooler. However, you really should be using a 40,000 GVRW with the rad bypassed as you probably only have barely better than stock cooling capacity, could even be slightly worse.

Most trans cooler sizing recommendations assume that the buyer will still use the in rad heat exchanger. The in rad heat exchanger also aids in trans warmup. In general, a liquid to liquid heat exchanger is 33 times more efficient than liquid to air exchangers. Without the rad heat exchanger you will need to run a much larger external cooler.

The rad cooler lowers the ATF to the temp of the coolant on the exit side of the rad, while ths install of an trans cooler further cools the ATF and helps prevent heat spikes. You did not mention your engine and trans type or the intended useage of your car which are additional factors. My CVPI uses both an in rad heat exchanger and a external trans cooler from the factory. It also use a engine oil to coolant, oil cooler.

Also I would suggest against a external ATF filter unless your trans has been modified. Many GM trans only bleed off 10% of the pumped ATF to the cooler through a small hole inside the trans. Unless a rebuilder has enlargered this hole or added extra feed tubes, a external filter can cause excess resistance. Its also why you should never run two external coolers in a series.

 

[64nailhead]

800whp daily driven turbo’d 414 Motown LS with a well built 200-4R.

 

[lilbowtie]

800whp daily driven turbo’d 414 Motown LS with a well built 200-4R.

Even though the Kitty's are up there can't imagine that kind of HP on the street

 

[pontiacgp]

It is better to run the ATF through the rad first, then run it through a external liquid to air cooler. Otherwise, you will need to run a external cooler that is double the surface area. The rad cooler removes a lot of heat because liquid to liquid heat transfer is way more efficient than liquid to air.

I have read that the reason they use the rad is that the coolant temp will bring the transmiison fluid up to operating temperatures quicker at start up.

 

[Clone TIE Pilot]

800whp daily driven turbo’d 414 Motown LS with a well built 200-4R.

What type of radiator fan are you using? Does the 2004R have a stock size or deep pan? Does the pan have cooling fins or tubes? Has the trans been rollerized as part of its build up?

I have read that the reason they use the rad is that the coolant temp will bring the transmiison fluid up to operating temperatures quicker at start up.

That is one major factor, most wear occurs at cold start up. The other is that heat conduction from liquid to liquid is about 32 times faster than liquid to air heat radiation, a higher delta P. Most aftermarket external trans coolers are designed and intended to be auxiliary coolers and are marketed as such. They are not designed to be the primary and sole cooler for a trans. One can get away with bypassing the rad cooler at the expense of running a much larger external cooler. Many transmission specialists like PATC recommend keeping the rad cooler plumbed in for this reason.

 

[pontiacgp]

Please explain how coolant at 180 degrees can keep my trans fluid below 160. Perhaps I’m missing something in the land of thermodynamics.

I’ve been using a Hayden 11x12 bar and fin style that keeps the trans below 180 all the time. It’s pretty cheap and readily available at both Advanced Auto and Autozone.

The engine temp sender/sensor is in the intake or head before the thermostat and does not give you the temperature in the radiator. If the coolant flowing from the radiator to the engine was at 180 the engine temperature would be much hotter by the time it hits the sender/sensor.