How Much Heat does an Auto Trans Produce?
#1
Registered User
Thread Starter
Join Date: Jul 2004
Location: VA
Posts: 785
Likes: 0
Received 0 Likes
on
0 Posts
How Much Heat does an Auto Trans Produce?
How efficient is an automatic transmission? How much heat does it produce. Trying to figure out how they size the tranny cooler.
#2
Registered User
Join Date: Aug 2006
Location: baltimore, md.
Posts: 1,157
Likes: 0
Received 0 Likes
on
0 Posts
with the stock tranny, id see right around 130 in stop and go traffic... id be alittle lower than that just cruising. with the goerend, i see 130-160 stop and go and 130 cruising..
#3
Registered User
Thread Starter
Join Date: Jul 2004
Location: VA
Posts: 785
Likes: 0
Received 0 Likes
on
0 Posts
I'm not interested in the temp, but what is the heat load (kW or BTU/hr). Another way of looking at this is how efficient is the transmission (including the slippage in teh torque converter). 50%? If so, then 400 Hp would have a 200 Hp heat load on a transmission if it were 50% efficient.
#4
However, that doesn't help as the amount of heat generated will vary depending on the energy input. I would suspect the trans cooler is sized at the bottom end of efficiency for the max load, average resistance, average energy input.
In other words, a SWAG.
#5
Registered User
Thread Starter
Join Date: Jul 2004
Location: VA
Posts: 785
Likes: 0
Received 0 Likes
on
0 Posts
For the purpose of what you are trying to calculate, in lockup it is 100% efficient. In fluid coupling about 75%.
However, that doesn't help as the amount of heat generated will vary depending on the energy input. I would suspect the trans cooler is sized at the bottom end of efficiency for the max load, average resistance, average energy input.
However, that doesn't help as the amount of heat generated will vary depending on the energy input. I would suspect the trans cooler is sized at the bottom end of efficiency for the max load, average resistance, average energy input.
Maybe for us a SWAG, but for the guy sizing the cooler, better not be.
#6
Registered User
When deciding what size cooler to use I have always used the term "Big is best, more is better". I buy the biggest one I can find and cross my fingers, that was until I stopped buying automatic transmissions to use for towing.
#7
Registered User
Join Date: Mar 2005
Location: North Carolina
Posts: 1,376
Likes: 0
Received 0 Likes
on
0 Posts
For us dummies that haven't a clue what a SWAG is we rely on the ole BIB* way !!!!
Besides, check how hot your tranny gets when you put it in reverse, you'll be VS **
* (Bigger is Better)
** Very Surprised
Trending Topics
#8
Even at full lockup, the tranny is not 100% efficient, but it also does not requrie a cooler. Heat generated will obviously depend on how much power goes thru it. what is worst case? At full slip, 100% motor power does not go thru. Also, at full slip, what is the efficiency?
Maybe for us a SWAG, but for the guy sizing the cooler, better not be.
Maybe for us a SWAG, but for the guy sizing the cooler, better not be.
Back to my original answer, how much heat is generated is a function of input energy and a whole slew of variables. A formula to claculate it could be developed but each variable change is going to give a different answer. The best you can do will be an average.
Even the coolers ability to transfer heat is going to be impacted by a bunch of variables, flow, fluid temp, ambient temp, etc. Once again an average that will meet the most conditions at the least cost is going to be a determining factor irregardless of what a formula says.
If you are asking about efficiency in power transference then like I said, 75% in fluid coupling and probbaly about 90% in lockup after parisitic loss. You can use those figures to run a heat calc but it is still a SWAG.
Thread
Thread Starter
Forum
Replies
Last Post
bob95065
12 Valve Engine and Drivetrain
9
07-17-2012 12:27 AM
HawaiiCTD
3rd Gen High Performance and Accessories (5.9L Only)
2
08-09-2006 07:29 PM
06dmc
3rd Gen High Performance and Accessories (5.9L Only)
19
08-09-2006 12:54 AM
Commatoze
General Diesel Discussion
1
07-27-2006 08:05 AM