Tranny Temperatures

[ypnas777]

I recently installed a tranny cooler from ipt where my smic used to be. After installing the temp gauge I noticed that the temps seem a bit high. Just cruising around on a cool night it reaches 180 degrees. If I do a few WOT pulls the temps go past 200 and I stop before the temps keep climbing. My tranny is running stock fluid, would synthetic fluid significantly lower my temps? Also, I tapped the temp gauge to the hose closest to the firewall....I have a 1998 gs-t and I dont know if that is the return line since nobody seemed to have a definite answer. Is it possible that I am tapping the feed line instead of the return line which would explain my high temps? Thank you

 

[SlowSpyder]

i have my temp sending unit on the line closest to the firewall and my temps on a cold night vary from around 150 ish to 195. Ill get 150 and below if im doing a 60 mph cruise, if im doing city driving and driving conservatively it will get to 175-180. If I start punching it ill get to 195. Once it got to 195 i just cruise till the temps drop. By the way im running a long cooler(same as ipt) mounted in front of the condenser, an external tranny filter and im running royal purple max atf. This is all on a turbo 2.4 spyder gs.

Also if you want see any difference just swap the two cooler lines, it shouldnt take more than 5 mins to do and that way youll see it makes a difference.

 

[ypnas777]

the reason I was asking was because I have seen other threads where people state that their temps hardly ever reach 180, even on WOT pulls. So is the line closest to the firewall the return line?

 

[SlowSpyder]

the return line is the line closest to the firewall. I looked it up on mitchell on demand and thats what john from ipt said.

 

[ypnas777]

any ideas why my temps are so high then?

 

[jabinya]

What size cooler did you get?

Do you have any type of air duct to direct the air at the cooler?

 

[kiggly]

The rear port is the return line, the front port is the converter fluid out to cooler line. This is true in a 2g at least, I never checked on a 1g to see if it is the same.

I'm measuring temps at the front port. Things get hot very, very quickly here when building boost on the brakes. If I start a pass with the fluid leaving the converter at 180F, its usually in the 300-350F range at the end of the pass.

There are a few things to consider and remember here. When you brake torque the car, all the power the engine makes is being absorbed by the torque converter and the fluid in it. This could be 300hp being absorbed by the ~30lbs of metal the converter is and the 2-3qts of fluid contained in it. That is a lot of energy being pumped into a fairly small mass, so it heats up quickly. There is very low fluid flow through the converter when the car is sitting still. Flow picks up as soon as the input shaft starts spinning (neutral or moving down the road). You will see temps rise a little even after a pull is done because the converter is still hot and the fluid flushing through it is cooling it down.

As you're going through a pull and past stall speed, the converter absorbs power based on how much it is slipping. For a good converter, you will see less than 10% slip. When I was weeding out some problems earlier this year I tried an IPT raised stall 2g converter (not the billet unit) and saw about 8% slip at 7000rpm and 390whp (low boost), then only about 4% slip at 8500rpm and just under 300whp. I thought that was doing pretty darn good. The % slip multiplied by the horsepower (at the crank) is how much power the converter is absorbing. That power simply becomes heat.

For a best practices drag racing suggestion, let the car run in neutral after a pass to cool the converter. The converter gets more pressure to it in neutral than park. Measuring temps in the pan or at the cooler return line really doesn't show what is going on very well.

Also, 350F doesn't burn redline type F at all. I don't know what temp it takes to start burning the fluid, but after multiple passes seeing near 350F it doesn't smell at all.

Kevin