'83 Rabbit GTI that I run in ITB. Currently has a thermostat. Has always run a bit warm-and sometimes hot. What do you guys suggest? Thanks, Al
'83 Rabbit GTI that I run in ITB. Currently has a thermostat. Has always run a bit warm-and sometimes hot. What do you guys suggest? Thanks, Al
Properly shroud the radiator to make sure all the air coming in the front of the car passes through the core.
Shrouding the radiator makes a huge differnce. I have the stock radiator (83GTI) shrouded on all 4 sides with a slightly lower thermostat and a 1/8" hole drilled in it for bleeding the air out. With the new motor before I put the oil cooler on I had temps at exactly 190 never went over even a mm on the gauge and the oil temps were pretty high I also don't run a fan so you get much better flow through the radiator.
What are your current water temps running mid race? End of race? I run an mk2 golf in IT prep using a stock 190F T stat with 3x3mm holes drilled into it which drops it to a 170Fish temp (cheaper then buying the lower temp models and you can get one from any store.)
What are your oil temps? Do you run an oil cooler? If so give me a run down on the setup.
--
James Brostek
MARRS #28 ITB Golf
PMF Motorsports
Racing and OEM parts from Bildon Motorsport, Hoosier Tires from Radial Tires
If you remove the thermostat, you will need to block the hose between the head and the waterpump. The stock thermostat closes the bypass as it opens for the main flow. The thermostat is on the suction side of the pump. Any type of restriction on the suction side of the pump will increase the chances of cavitation. Spinning the pump faster than designed will also cause cavitation. Using a radiator from an 85 golf that came with factory AC is a cheap upgrade. Another mistake I see people make is with the fitting on the back of the cylinder head and the resevoir tank. We run the coolant tme sender in the hose fitting. The resevoir should be plumbed into the middle fitting on the waterpump. This insures all coolant flow is out the head into the top of the radiator. Plumbed this way, it should be self bleeding. Ducting between the radiator and the front grill as the factory did does help. If you find the engine runs too cool, you could fabricate a restrictor to fit under the coolant flange on head. We have not found that we need one in the Southeast.
If you get rid of the thermostat you will run significantly cooler.
The best solution, I would believe is to buy lower temp thermostat. They are not that expensive and defiantly will keep the engine in optimal temp range. Instead of too cool when running at full power without the thermostat.
If I remember correctly, there is a 78C thermostat available. The stock is 92C, I think.
My math I did before is retarded and wrong, but gets the approximate thermostat temp. thermostat temp - (Your normal running speed temp - desired temp)= new thermostat
I remember reading a SAE paper on temp vs power. They suggested to run significantly hotter engine to make maximum power. I think the number was 105C or something. Converting a 90C engine into 105C would require recalculating the clearances.
Most likely I am wrong and forgot the details. Correct me if I am wrong.
I run a restrictor plate. Took a thermostat housing, and tore off the spring the perch. End of story. Who cars how long it takes to warm up the water. You need to warm up the oil, brakes, tires, and tranny along with the water, so just take it easy the first couple of laps.
One less thing to fail and/or worry about.
Actually, you will overheat your motor if you remove the thermostat. You need to slow the water down, or it won't cool down enough when it goes through the radiator.If you get rid of the thermostat you will run significantly cooler.
Last edited by racer_tim; 07-06-2008 at 08:58 PM.
Tim Linerud
San Francisco Region SCCA
#95 GTL Wabbit
Convert from GP to GTL
http://www.timlinerud.com/racing/index.html
racer_tim @ yahoo dot com
It's a little $$$$$$ at $275 but I switched to an AFCO alluminum racing radiator from Summit. It's actually called a "scirocco" style radiator on their website. It runs perfect temps and the dual electric fans are over kill. No shroud needed.
Tristan Herbert
2011 World Challenge TC Rookie of the Year
2011 ARRC ITB Champion
2011 IT Fest ITB Champion
2009 MARRS - ITB Champion
BRIMTEK/Germanautoparts.com
I run a tworn apart t-stat as a restrictor, and no fan 200F most of the time. less to go wrong. I have had a Whaller t-stats fail at the track. The golf W/ a/c rad works well@ 70-100bucks.........some day an all alluminum rad, after the LSD would be sweet!
______________
Waterhaus Racing is Back!
NRSCCA Competition Chair
BOG Member
"Nebraska organizing committees
to race in Iowa & Ne board thing "
Still working on a name...
X-MVRG Member...
ITB Rabbit/ITA Miata
I was constantly running too hot, especially in 90 degree July weather!! I ended up shrouding the radiator (most important), gutted a thermostat to make a restrictor, blocked the water pump bypass hose and the hose going in the side of the head so all coolant goes through the radiator before entering the radiator, put on an oil cooler (2nd most important!!) and eliminated the OE water cooled oil cooler and finally switched to water wetter. I also added a small electric fan for paddock cooling. It runs perfect now. good luck
Lots of discussion regarding this over on the 'Open Wheel' site. The consensus is that slowing down the cooling flow to help cooling is a myth. The higher the flow rate, the more effective your cooling will be.
http://www.apexspeed.com/forums/showthread.php?t=29010
Some really good discussion by some very sharp people...particularly Mr. Weitzenhof (7-Time National Champ).
2002 Cen-Div ITC Champ
(Converted to G-Prod in 2003)
(Bumped to H-Prod in 2008)
2008, 2011 HP Cen-Div Champ
2011 HP National Champ
this past weekend with my setup listed above stock rabbit radiator(new) slightly lower thermostat, no fan and completely shrouded radiator in 100+ weather the temp never even got above 200
The fact that IT cars spin revolutions more than "stock" and that in order to slow the water pump down to spin at a more efficient rotation, that's why the larger water pump pulley is the way to go.
The entire reason that a thermostat is on all street cars, is to allow the water to warm up faster, and then with the water temp reaches the t-stat temperature, it opens up and lets water flow through the radiator. We don't need this on a race car.
That's why a restrictor is a good idea. One less thing to fail, and still allows the car to warm up, but not at the same "speed" as with a thermostat.
Last edited by racer_tim; 07-14-2008 at 11:12 PM.
Tim Linerud
San Francisco Region SCCA
#95 GTL Wabbit
Convert from GP to GTL
http://www.timlinerud.com/racing/index.html
racer_tim @ yahoo dot com
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