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#1
07-21-2024, 05:49 PM
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You could certainly try experimenting with restrictor sizes to help, it may make a difference if you have steam pockets. If you have enough pressure as the system is, likely you'll see little difference.
Having run on circle tracks for much longer durations, the 3 changes I made to my cars were to increase the coolant capacity, run the A/C small pulley on the water pump, and run a 6 blade RV composite fan blade with nearly 90 degrees of pitch. Pic of fan blade:  This took the temps from an engine killing 250 degrees, down to 180 degrees running for 20 laps in high temp, high humidity. Closed course racing is the absolute worst case scenario for a underperforming cooling system. You'll find out in a couple of minutes if you need to upgrade your system. One other thing is to be sure you have the GM designed, cast waterpump impeller. The tin cheap aftermarket impellers do not move the necessary amounts of water because they are inefficient, as well as aerate the coolant at high RPM. They also do not build necessary pressure to eliminate the steam pockets. If you've ever been around a circle track after a feature race, you'll see some crews dumping water over the radiator as the throttle is held at about 3000 RPM. As Eric has said at WOT you're putting 10 times the heat into that cast iron heat sink engine. The water splashing over the radiator fins, and misting over the engine cools the cast iron down in a matter of seconds. An engine stores a lot of BTU energy after a full throttle run.
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Brad Yost 1973 T/A (SOLD) 2005 GTO 1984 Grand Prix 100% Pontiacs in my driveway!!! What's in your driveway? If you don't take some of the RACETRACK home with you, Ya got cheated    
Last edited by Sirrotica; 07-21-2024 at 05:55 PM. |
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#2
03-29-2026, 11:11 AM
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Seeing a lot of positive comments on the Mark VIII fans.
I was wondering if the tightness of the shroud was an issue but I didnt realize a fan could be too close to a radiator, steve25. AG/taman - possible to see a pic of your setup? Thanks DV
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1965 GTO Cameo White, Red Interior - 389, ST300 numbers matching 1965 GTO Black, Black Interior "Post" car - 389, M-20 numbers matching 1965 GTO Silver, Black Interior 100% dedicated drag car w/1968 400(461), 16x Heads, TH400, 3.90 9" Rear 1.656 60' 7.566 90.057 (1/8th) 1971 GTO Black (orig. Quezal Gold), Gold Interior - 400, TH400 numbers matching 1972 GTO Cardinal Red, Black Interior - 455, TH400 almost numbers matching |
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#3
03-31-2026, 07:15 PM
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Quote:
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1967 Firechicken, 499", Edl heads, 262/[email protected]" duration and 0.627"/0.643 lift SR cam, 3.90 gear, 28" tire, 3550#. [email protected] mph with a 1.45 60'. Still WAY under the rollbar rule. |
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