Track days with automatic tranny?

[Tapani]

Is there anyone else doing track days with automatic transmission ?

I'd like to hear your comments on fluid temperature balance.

To me it looks there's so large difference in heat generation compared to rejection capacity - even with an aux cooler - that this might be mission impossible for any extended period. Starting at 180 F I reach 240 F in less than 10 minutes @ 15 C ambient temp. Not cool.

I remember reading somewhere that Mike modified the valve body for increased cooling flow. Does anyone know what exactly he did? Did he increase the converter flow (TCC released) or the much smaller flow rate of the TCC engaged circuit? Does this mod affect the line pressure (by bleeding more flow to the converter circuits)?

We all know the TC is THE heat source.

I have an Ecutune valve body on the shelf, but have not installed it in the JDM tranny yet.

Please - any comments are most welcome before I decide which way to go next.

Since I drive the SVX every day I do not wish to convert to manual - at least not yet. I may think about a lower stall speed converter, this would reduce heat generation and also allow me to use the LP turbo torque band better.

Kind regards,

Tapani

[92snowmachine]

i have considered two things that would help keep the trans cooler

one: wrap the exhaust next to the trans. when i check my trans temp with a infrared heat gun on the pan the sides of the pan closer to the exhaust are quite a bit hotter than the middle of the pan

two: this one is a little weirder. i have an air cooled trans on my '56 belvedere. the bell housing has several vents on it and the tc has a bunch of fins welded on it to move air around the converter. trans made it over 300k miles before losing reverse. applying the same concept i think would help cool the trans for virtually no money, just a lot of work.

[Svx95]

Althought I'm not tracking the car, I have been thinking A LOT lately about autocrossing. The only hesitation in me is the fact that I DON'T want to grenade the 4.44 auto tranny as it is also my DD

Tapani, what do you mean by rejection capacity??

The temperature spike, taking into consideration the 60*F ambien temp, is a lot worse than I ancticipated.

Sorry I don't know what mike did to the Valve body.

The two ideas are great in theory. Air cooling the BH would be a lot of work though and not knowing exactly what the outcome would be kind of takes away from the task.

One: Wraping the exhaust would be pretty easy to do, and a simple before and after test would "prove" if it is actually benefical and how much.

Two: Air cooling the bell housing is cool, but the 4.44 bell housing is nothing in comparison to the '56 belvedere you talk about.

KEEP THE IDEAS COMING!

Originally Posted by 92snowmachine

i have considered two things that would help keep the trans cooler

one: wrap the exhaust next to the trans. when i check my trans temp with a infrared heat gun on the pan the sides of the pan closer to the exhaust are quite a bit hotter than the middle of the pan

two: this one is a little weirder. i have an air cooled trans on my '56 belvedere. the bell housing has several vents on it and the tc has a bunch of fins welded on it to move air around the converter. trans made it over 300k miles before losing reverse. applying the same concept i think would help cool the trans for virtually no money, just a lot of work.

Originally Posted by Tapani

Is there anyone else doing track days with automatic transmission ?

I'd like to hear your comments on fluid temperature balance.

To me it looks there's so large difference in heat generation compared to rejection capacity - even with an aux cooler - that this might be mission impossible for any extended period. Starting at 180 F I reach 240 F in less than 10 minutes @ 15 C ambient temp. Not cool.

I remember reading somewhere that Mike modified the valve body for increased cooling flow. Does anyone know what exactly he did? Did he increase the converter flow (TCC released) or the much smaller flow rate of the TCC engaged circuit? Does this mod affect the line pressure (by bleeding more flow to the converter circuits)?

We all know the TC is THE heat source.

I have an Ecutune valve body on the shelf, but have not installed it in the JDM tranny yet.

Please - any comments are most welcome before I decide which way to go next.

Since I drive the SVX every day I do not wish to convert to manual - at least not yet. I may think about a lower stall speed converter, this would reduce heat generation and also allow me to use the LP turbo torque band better.

Kind regards,

Tapani

[Tapani]

I mean the capacity to dissipate heat from the tranny to ambient air. Both from the tranny surface (this is actually a BIG factor) and the cooling system.

An aluminum finned pan is one option, but uncontrolled. Even ths stock setup cools the tranny too much during winter. Does anyone know if one exists?

The aux cooler location is not optimal in mine. I will consider moving it to the front. There's no space for the fan, though. Probably not needed on race track anyway.

I will also experiment by removing the thermostatic bypass valve. Maybe there's some cross over from outlet to inlet..... it's a single cast aluminum piece - there's a heat flux from the hot side to the cool side for sure.

I've had Mikes valve body installed now for two days - it APPEARS that the tranny does run a bit cooler. The weather has been most forgiving, though, and I've only been able to commute...... I will not have time for another track day until later in July/August.

How long (time) is an autocross heat?

Tapani

[Svx95]

Originally Posted by Tapani

I mean the capacity to dissipate heat from the tranny to ambient air. Both from the tranny surface (this is actually a BIG factor) and the cooling system.

An aluminum finned pan is one option, but uncontrolled. Even ths stock setup cools the tranny too much during winter. Does anyone know if one exists?

The aux cooler location is not optimal in mine. I will consider moving it to the front. There's no space for the fan, though. Probably not needed on race track anyway.

I will also experiment by removing the thermostatic bypass valve. Maybe there's some cross over from outlet to inlet..... it's a single cast aluminum piece - there's a heat flux from the hot side to the cool side for sure.

I've had Mikes valve body installed now for two days - it APPEARS that the tranny does run a bit cooler. The weather has been most forgiving, though, and I've only been able to commute...... I will not have time for another track day until later in July/August.

How long (time) is an autocross heat?

Tapani

Oh I see. Usually no longer than 1 min 30 sec

[Tapani]

Ok, mine takes the "heat" for app 10 minutes before I need to back off @ 240F

/T

[Chucksta]

Well, one of your concerns seems to be flow through the transmission cooling system. The easiest check would be... How long to pump one litre of warm fluid, at idle, out of the return line at a point past ( in the cooling circuit ) the aux cooler. If it's less than ten seconds, I'd suggest that fluid flow through the system is sufficient.

"Even ths stock setup cools the tranny too much during winter."

I'm not entirely sure what you mean by that. Do you mean that it ( the stock through the rad and back to the transmission ) cooler, reduces the trans temp below 10 degrees Celsius? ( minimum temp required for TC lock up).

"The aux cooler location is not optimal in mine. I will consider moving it to the front. There's no space for the fan, though. Probably not needed on race track anyway."

So, where exactly is it? Air flow and road speed do not necessarily have the linear relationship we'd like. The easiest "McGuyver" way to check actual airflow over the aux cooler would be to take a DC computer fan and hold it out the window at arms length, connected to a volt meter. Check the fan's voltage output at various speeds to establish a baseline. Now zip tie the fan in front of the aux cooler and compare the voltage readings at the same speeds. That would give a comparative reading of air flow over the cooler at various road speeds. You might be surprised at the readings.

"I will also experiment by removing the thermostatic bypass valve. Maybe there's some cross over from outlet to inlet..... it's a single cast aluminum piece - there's a heat flux from the hot side to the cool side for sure."

I'll probably get flamed for what's next, but .. Oh well.. it's IMHO LOL.. The SVX, like many other vehicles, has a "dead zone" on the temp gauge. You don't really know if it's at 180 F or 205 F unless you have auxiliary gauges, because the gauge stays at the same point. Some will argue that the stock transmission cooling system provides ample cooling for the trans fluid, as it is metal in coolant transfer, which is highly efficient. But, I've got to as, how can it cool trans fluid below it's own internal temperature? The SVX cooling system is based on high flow, which means less of a temp drop in coolant temps between the upper intake and lower return. Even based on a 20 degree F drop in coolant temp between the upper and lower rad, it's not possible to cool the trans fluid below 180 - 185,if the coolant entrance temp is in the 200 F plus range, and, as cooling is based on the temp difference between the trans fluid and the coolant temperature, it's hard to see how trans fluid entering the rad cooling circuit at ... let's say 200 F could be cooled much. The majority of the cooling job, especially under autocross conditions, falls mainly to the aftermarket cooler.

Once again, IMHO.. The aux cooler should be in the right fender well, with a thermostatically controlled fan. A really, really big fan. In a perfect world, I'd have "T" valves, so I could run the trans fluid through the rad in the winter, bypassing the aux cooler ( not thermostatically controlled ) , and bypass the rad and run through the aux cooler in the summer and for sessions of auto crossing.

But Hey!.. that's just me.

Oh .. almost forgot.. Heat flux from the hot side to the cooled side through the aluminum?.. Ummm.. I would've thought it wouldn't much matter much, as the heat load was still being dissipated. The hot fluid got cooled a bit by the cooled return.. Wouldn't it be the same result overall?

[Tapani]

Flow rate is one core parameter in cooling..... it appears, that Mikes valve body does increase this.

During winter with the stock cooling setup the TCC releases and engages every three miles.... too much cooling.

The aux cooler is inside the drivers side fende and has a shrouded fan, controller by the pan temperature.

I have an aux pan temperature gauge - no dead zone.

I also have a thermostatic bypass valve, which redirects all fluid flow back to the trans - starts to open at 160F and is fully open at 180F.

You are correct on the low delta T in the engine cooling, across the engine - but this not the case across the rad... there's the thermostate which regulates the flow between the bypass circuits and the rad. The rad bottom is actually rather cool when the car is moving at road speed - and at cruise rpm. This naturally does change under track conditions and depends on a number of things.

I need to experiment more, maybe measure the fluid temp at rad inlet, between rad and the aux cooler and aux cooler outlet.

Thanks for your thoughts !

/T

[Stevebsy]

I ran mine with 4.444 gears on a 2 mile roadcourse track several times. I have a cooler in the wheel well (the fan one, but I never hooked up the fan), and one in front of the radiator and condensor. I also have the same thermostat as you hooked in.

Yes the ATF gets hot! into the 250+ range, but I never made the 'trans temp' light come on. You have to drive around after your session to cool it down but it is not so bad.

Funny what helped was on the straightaway, if you could get it up to 4th gear with the TC locked, the temp would start to decrease, but I suppose there is a lot of airflow at 100mph Also, take out the waterfall/lamp grille for better airflow.

My trans is a used one from a 98 legacy outback supposedly had about 100k on it when I bought it for a whopping $200. I only used standard ATF. It still works just fine today, nearly 10 years later.

A replacement is cheap enough...just relax and go do it!

[Chucksta]

Well then.. Some more thoughts..

"During winter with the stock cooling setup the TCC releases and engages every three miles.... too much cooling."

That would indicate that the coolant temperature, at the bottom of the rad is below 10 C., as that's the ( at least on mine ) set point for TC lock up. Even at -35 C., mine will stay locked once it's warmed the fluid to that point. My aux cooler is thermostatically controlled, and I have left it hooked up through the winter. The exception to that is, for whatever reason, it doesn't want to stay locked when I'm using the cruise control. Weird, I know, and it drove me crazy until I figured out that the intermittent lock up was only occurring with the cruise on. I haven't checked to see if it still does it now that the weather is warmer, but I definitely will now. The other thing about your lock up coming and going, when you say "with the stock set up", do you mean that you bypass the aux cooler in the winter? The reason I ask is that if the fluid is passing through the thermostatically controlled aux cooler, the coming and going of the TC lock up would seem to indicate that there's at least some flow still going through the aux cooler.

"I have an aux pan temperature gauge - no dead zone."

I was referring to the dash engine coolant gauge. Most SVXs' have a "dead zone" where the gauge sits dead still in the middle unless the coolant gets very hot. My sending unit threw a hissy fit and started reading way low, but it now no longer has a dead zone. I correlated it's readings against the readings from the OBD2 sensor, and now know what where it points to actually means. I was surprised how quickly the coolant temp started to rise in stop and go traffic, as opposed to sitting rock steady at 180 F at highway speeds. My point about that relates to what you noted about the rad flow. If the engine coolant temp is high enough that the fans are on, the T-stat is open, the flow is increased, and the bottom of the rad no longer has an as significant temperature difference to the trans fluid. At least, that's my hypothesis ..

"I also have a thermostatic bypass valve, which redirects all fluid flow back to the trans - starts to open at 160F and is fully open at 180F."

That's the other part that makes me wonder if the thermostatic valve is working properly, because of the intermittent loss of TC lock up in the winter.

( Infra red thermometer + GoPro + smart phone App = instant remote, real time telemetry ) Duct tape, zip ties, and other implements of security may be required. If the first end tube on the aux cooler show 140 F when the line only shows 150, it's not closing tight. If the first end tube on the aux cooler only show 140 when the lines show 200, it's not opening properly. Those numbers aren't exact, but I think you get what I mean..

Best of luck, Sir..

[Tapani]

Thanks for your thoughts.

The engage / release in winter (below -10C) is with totally stock setup. No bypass, no aux cooler.

The position of the engine thermostat depends mostly on the rad bottom temp. It tries to control engine (water pump) inlet temp. See my post in the "cooling again and again" thread.

The fan control is a bit funny - engine exit temp only (+ac on).

My set up now is such that both coolers are bypassed if the valve is open. It appears to be working as supposed.

/T

[Tapani]

I relocated the 11x11x3/4" Hayden 679 cooler to the front. It is now sandwithced between the condenser and the rad and fills the passenger side fan area totally. Had to bend the power steering cooler tube a tad down to get a bit more clearance...

Have not been able to load the vehicle much in normal traffic, but we have a track day on Sat the 28th.

Under normal driving the pan temp is now 160F when the TCC is engaged and app 167-172F when released.

Removing the waterfall grill for the track day may be a good idea. It seems to open up the front quite nicely.

I will let you know if there's any gain while at the track.

/T

[Tapani]

I disconnected the thermostatic bypass and removed the grill.

The peak was 200F after app 8 fast laps. Ambent was +18 C. Max speed was around 95 MPH on this track, so quite slow and lots of hills too - very nice. Only second and third gear required.

I think the issue is solved for now, the cooling capacity is sufficient for my application, though not balanced. The temp was creeping up all the time, but slowly enough.

When I stopped pushing it started to go down almost immediately.

On highway I think it's overcooled, the pan temp is around 135F under these conditions, though the TCC does engage.... but I think it's very close.

When the weather changes I think I need to disconnect the aux cooler for normal driving.

/T