Track data for C4 auto.
04-18-2007, 11:37 AM
#1
Race Director
Thread Starter
Track data for C4 auto.
Once in a while I read someone asking about tracking the auto. So I thought I would post this for reference. I have an L98 auto, it's what I have so I run it. I have a bad back and the manual would be to much anyways. I'd like to make the car a full track car some day but that will be a few years off.
I installed a trans temp gauge to monitor the pan temp, and also a trans cooler in line after the radiator. From what I saw the temps without a cooler would be OK in autox but not for road racing. Also, I would add a fan to the cooler. The temps really take some time to decrease.
On a 55° day at Road America I saw trans pan temps no higher then 160°, this would be around 200° on the output side, not a bad temp. Leaving the car in OD gave lower temps but slower laps. I had max coolant temps of 190° with a 180° 'stat. Max oil temp was 235° not much higher then the stock fan turn on temp. I lost about a 1/2 of a pint of ATF from what looked like sloshing out, per track day, about 210 miles. On the stick it read exactly full, after one day it was right in the middle of the hash marks. I have installed a shift kit as well, the car ran well and I no trouble at all with unpredictable downshifts and oversteer. I ran the car hard all day with no problems.
Last season at the end of a track day I lost 4th gear and there was delayed shifting. I did not have a temp gauge then. I found hard plastic looking debris in the valve body, I am guessing this is varnish from the trans temp getting to 250°+.
The gauge was very easy to install and cost around $55 total. I used a trans pan drain plug kit and put the sender in instead of the plug. This will double as a drain. The sender wire very easily goes through the rubber boot on the firewall behind the battery. It was very simple. I installed the gauge in the top air vent above the DIC, this was also very easy.
The cooler cost about $75 total. It was not difficult to install. My front aux. fan did not work, when I removed it I noticed a slight drop in temps, better flow to the radiator. So I used the holes in the shroud to mount the trans cooler. I have not seen a slight increase in temps, the cooler takes some load off the cooling system. Speculation, I have not driven the car tons yet. I used a hose and clamp on the hard stock line. On the radiator I used -6 an fittings, one is an inverted flare to AN adapter and the other is a 90° bend.
Cruising on a cool day, the trans temp is maybe a little to low. The cooler may have to be blocked spring/fall/winter. 105° pan cruise temps so far but it's been cool out. Around town I saw temps getting up to 130° but I rarely do much city driving. Perhaps for a street only car, adding the cooler in before the radiator would be of benefit for in town driving.
Right now I think that it would be best to add a fan to the cooler. When the car sits in the paddock the trans temp doesn't really go down between heats.
I hope this helps someone in the future.
I installed a trans temp gauge to monitor the pan temp, and also a trans cooler in line after the radiator. From what I saw the temps without a cooler would be OK in autox but not for road racing. Also, I would add a fan to the cooler. The temps really take some time to decrease.
On a 55° day at Road America I saw trans pan temps no higher then 160°, this would be around 200° on the output side, not a bad temp. Leaving the car in OD gave lower temps but slower laps. I had max coolant temps of 190° with a 180° 'stat. Max oil temp was 235° not much higher then the stock fan turn on temp. I lost about a 1/2 of a pint of ATF from what looked like sloshing out, per track day, about 210 miles. On the stick it read exactly full, after one day it was right in the middle of the hash marks. I have installed a shift kit as well, the car ran well and I no trouble at all with unpredictable downshifts and oversteer. I ran the car hard all day with no problems.
Last season at the end of a track day I lost 4th gear and there was delayed shifting. I did not have a temp gauge then. I found hard plastic looking debris in the valve body, I am guessing this is varnish from the trans temp getting to 250°+.
The gauge was very easy to install and cost around $55 total. I used a trans pan drain plug kit and put the sender in instead of the plug. This will double as a drain. The sender wire very easily goes through the rubber boot on the firewall behind the battery. It was very simple. I installed the gauge in the top air vent above the DIC, this was also very easy.
The cooler cost about $75 total. It was not difficult to install. My front aux. fan did not work, when I removed it I noticed a slight drop in temps, better flow to the radiator. So I used the holes in the shroud to mount the trans cooler. I have not seen a slight increase in temps, the cooler takes some load off the cooling system. Speculation, I have not driven the car tons yet. I used a hose and clamp on the hard stock line. On the radiator I used -6 an fittings, one is an inverted flare to AN adapter and the other is a 90° bend.
Cruising on a cool day, the trans temp is maybe a little to low. The cooler may have to be blocked spring/fall/winter. 105° pan cruise temps so far but it's been cool out. Around town I saw temps getting up to 130° but I rarely do much city driving. Perhaps for a street only car, adding the cooler in before the radiator would be of benefit for in town driving.
Right now I think that it would be best to add a fan to the cooler. When the car sits in the paddock the trans temp doesn't really go down between heats.
I hope this helps someone in the future.
