Transmission cooler BTU question

[burijon]

I am looking at a B&M 70255. It is the smallest one of the "stacked-plate" design. Marketing would have me to believe that this is a better design than a normal cooler design. B&M's website lists the heat exchange in BTUs.

These are the ratings from B&Ms website:SuperCooler 11" x 5-3/4" x 3/4" BTU rating 9,800........................70255SuperCooler 11" x 7-1/4" x 3/4" BTU rating 13,000......................70268SuperCooler 11" x 5-3/4" x 1-1/2" BTU rating 14,400...................70264SuperCooler 11”X 5-3/4”X1-1/2” (new size) BTU rating 15,000 ...70273 *SuperCooler 11”X 8”X1-1/2” BTU rating 20,500 ..........................70266 *SuperCooler 11”X11”X1-1/2” (new size) BTU rating 29,200 ........70274

I understand 1 BTU to heat one degree per pound of water(roughly speaking in layman's terms). http://www.answers.com/topic/british-thermal-unit

I want to know what the difference in temperature rating is between the BTU ratings. I looked for conversion tables but they all look greek to me. If someone could explain it in plain English that would greatly benefit me and possibly others. Will the smallest one cool 50 degrees while the larger will cool 75? I don't know!

In other words how much more benefit would it do me to pony up the cash for the slightly larger cooler? The summers get very hot and humid here.

Thank you smart people.

[Q45tech]

1 horsepower of heat is ~~ 12,000 BTU per hour so one needs to know how much slippage loss in horsepower is being lost.

A liquid to air heat exchanger depends on the delta between the two temperatures but usually drops the input to out temperature by 10-15-20F only.

Think about the 150,000 BTU engine radiator vs a 15,000 BTU transmission radiator.

10 quarts of ATF weighs about 17 pounds so 17 BTU might cool it 1F in 1 hour so 17 x 60 = 1020 btu might cool it 1F in 1 minute so 10200 BTU might cool it 10F in 1 minute.

The flow rate is 2.5 quarts per minute.

The question is not how fast you cool at STEADY state ATF but how fast it get reHEATED back in transmission.

Around 15,000 btu seem ideal except for really hot places where the ambient exceeds 100F.

Under WOT a quarter mile will probably create 5% slip or 15 HP of heat for 15 seconds 180,000 btu/4= 45,000 btu how many minutes do you want to wait until it cools down ................15,000 = 3 minutes

The 176F normal ATF would increase by 45F to 221F in the quarter mile run.

The above uses water and we all know ATF is much less efficient [50%] at heating up and cooling than water so at worst it might be double.

The problem is if the ATF id half as efficient as water then the heat stays in the metal so the TC and clutches might go up 90F while ATF goes up 45F and the metal would take longer to cool.

Engine coolant [50/50] is 50% more efficient than ATF.

http://www.engineeringtoolbox.....html

The following patent has equations which will help you calculate an exact load:

http://www.patentstorm.us/pate....html

Confused? I am a little since they just GIVE a thermal mass of 23 BTU/F for a combination of ATF, aluminum and steel disregarding heat flowing back into engine block and radiated into the air/body from transmission case.

[maxnix]

I use a 70268 on one car but upgraded the other two to 70264.
Modified by maxnix at 11:13 AM 3/13/2007

[Jesda]

I cant find the 70364 anywhere.

On my last Q I think I used a Flexlite cooler.

[Q45denver]

I cant find the 70364 anywhere.

On my last Q I think I used a Flexlite cooler.

Probably 70264.