[Rodgebone]

a relatively smaller stacked plate unit will outperform a larger fin and tube unit. thus the reason why you wont find huge stacked plate coolers - a larger surface area simply isnt necessary due to the better cooling efficiency. plate and fin fit somewhere in between the two for performance (this is your third choice to confuse things even more). i just went for max cooling effect thus the smaller stacked plate unit. b&m had the biggest and best construction i could find after extensive research. pwr had shit and i just removed a fin and plate pwr unit from a wrig and fit the b&m stacked plate in its place (on a JK auto). also, stacked plate units are usually deeper so basically give you the same volume as the larger, cheaper fin and tube units. my choice will always be stacked plate for anything.

and just an update for my setup: i've been doing a lot of rush hour traffic driving this week (1.5 hours or more each way). ive found without the 3 aux fans switched on the tranny was hitting 210*F. with the fans on it came down to 180*F at speeds of less than 30kph. generally tho, around town and without the aux fans on it never goes over 180*F at speed (and usually much less). this is the stacked plate unit and bigger cfm aux fan (the 4th fan) making a bigger contribution. the three smaller fans dont usually get switched on in this circumstance. offroad temps hit 230*F until the aux fans were switched on to keep things in check at 185-190*F. so far so good but i can see temps exceeding the max 190*F spec on hot days (its spring here so ambient temps are only about 24 at most right now). im not too sure anything can be done about that but at least its only sporadic on hard climbs. i can live with that rather than going 250*F in most situations (or worse).

i will also say this: i never ran a cooler on my car for the first 5 years and i wheeled it hard. i am quite sure my tranny temps well exceeded 250*F much of the time. the important thing to say is it never hurt the tranny (mine is original w/235K on it and never been apart or had a problem). i just keep the fluid fresh every other year. so are coolers really necessary? i think so here in WA but only in the respect that they will promote tranny life. the xj tranny is pretty stout to begin with. even without a cooler it will rarely fail. but i do like helping keep things going longer than normal so coolers ARE justified in my opinion however not really necessary. i think we have made too much out of this in this thread. but i would do it again in one form or another. after all, too much cant hurt! seems to be the Jeep theme