why did my car slow down?

Kegracing · 05-21-2014, 06:44 PM

I raced the Super Chevy show at Texas motorplex last weekend. Went a couple of rounds on Saturday, and then made it to the finals on Sunday. Lost about .12 in final.
67 Firebird convertible, zz4 IHRA crate motor stocker legal motor. 3400 lbs. Set up soft, shifting about 6800, big bias tires, leaving at 2500 footbreak. 5-30 full syn oil. Turbo350, deep pan, syn fluid, no cooler. Was about 85 degrees and sunny out.
5 round race, and car had been in the 11.58-11.60 all weekend. They were hot lapping us late Sunday. Had been running about every hour, 4th round was a 40 minute run to run per the time slips, and 5th round was at 20 minutes, per time slips.
Car lost .05 in 60' then about .02 every break rest of way down track... 60' had been within one # all weekend. Did not feel it spin. Had .023 light in finals... playback tach of run shows that converter flashed same (5200) as earler runs, shifts were on the mark and did not flash between. Lost about 3/4 mph at 8th mile mark and about same at finish I am guessing, as I tapped brakes since I was behind.
I have ran valves, and did not find any issues. Changed oil and cut filter, all looks good. Trans fluid is clean. Car does not have any miss or any noise. Everything ran fine and felt fine on the run, just slow. Everything sounds fine now. Good oil pressure, etc.
Water temperature was back within 5 degrees of other runs when I staged, and pump and fan were on and working. Staged at 155.
Was motor and trans just hot?
I cant find anything wrong with it... ?

Sorry so long, but wanted to give all data.
thanks,
Ken

Stock 412

05-21-2014, 06:44 PM	#1
Kegracing Member Join Date: Jun 2002 Location: Red Oak, TX Posts: 441 Likes: 0 Liked 0 Times in 0 Posts	why did my car slow down? I raced the Super Chevy show at Texas motorplex last weekend. Went a couple of rounds on Saturday, and then made it to the finals on Sunday. Lost about .12 in final. 67 Firebird convertible, zz4 IHRA crate motor stocker legal motor. 3400 lbs. Set up soft, shifting about 6800, big bias tires, leaving at 2500 footbreak. 5-30 full syn oil. Turbo350, deep pan, syn fluid, no cooler. Was about 85 degrees and sunny out. 5 round race, and car had been in the 11.58-11.60 all weekend. They were hot lapping us late Sunday. Had been running about every hour, 4th round was a 40 minute run to run per the time slips, and 5th round was at 20 minutes, per time slips. Car lost .05 in 60' then about .02 every break rest of way down track... 60' had been within one # all weekend. Did not feel it spin. Had .023 light in finals... playback tach of run shows that converter flashed same (5200) as earler runs, shifts were on the mark and did not flash between. Lost about 3/4 mph at 8th mile mark and about same at finish I am guessing, as I tapped brakes since I was behind. I have ran valves, and did not find any issues. Changed oil and cut filter, all looks good. Trans fluid is clean. Car does not have any miss or any noise. Everything ran fine and felt fine on the run, just slow. Everything sounds fine now. Good oil pressure, etc. Water temperature was back within 5 degrees of other runs when I staged, and pump and fan were on and working. Staged at 155. Was motor and trans just hot? I cant find anything wrong with it... ? Sorry so long, but wanted to give all data. thanks, Ken Stock 412