Here is the post from the SWJFA forum.
Posted by Jon Hansen on April 28, 2011, 1:37 am
Some of you guys might have noticed, starting with the 1'st SWJFA event I attended, Evadale 08,I was taking engine temps with my infa-red temp gun as you guys were staging. Even holding back a few racers waiting/hoping the engine temp would get hotter.
Alky burners run better with more engine heat. I shoot for 180°to 200° head temp, just above the block as the car is moving into the staging lights. And advised those of you that were not getting anywhere close to those numbers to lean the BV [ and readjust the idle]. Bob McKray shoots for the same temps on his non-RR SBC, 7.20's running car.
Now the 180-200 temps are for water in the heads/blocks combo's. Dry blocks shoot for 150° to 160°
OK, here's "the rest of the story" or at least my 2 cents. 1'st the most important reason to run water, of course it keeps the engine temps more even, especialy in the middle cylinders of a SBC with the exhaust valves next to each other. Case in point if you have ever noticed black marks,streaks in the bore, that means it's been RED HOT there. Running water in the block helps support the cylinders, which helps better ring seal. Bob McKray sometimes gets hired to "tune" at a dyno test. One time he was hired, the customer was happy with the HP it was running, and he said " OK, now dump the water because we race dry" Next run-up it lost 20hp, can't be, so put the water back in, 20hp increase. Holy Crap, how can that be ? Well Bob and I figure the water supports/dampens the harmonics in the cylinder walls, and so you end-up with better ring seal = more power. Our theory was backed-up by Rick Watters, who builds most of the winning Comp elim motors [ he will be glad to build you a complete, top to bottom JrFuel motor for 60-70k], when I talked to him at this years Vegas National event, when he said running with-out water your cylinder walls ring like a bell with harmonics, no way you can get good ring seal with the cylinders vibrating.
As some of you may know, besides having a motor in Bud Hammer's Heritage JrFuel car, I've also had a motor in Dean Carter's B/ND for a couple of years, 2008, 2009, and I crew on his car at the West Coast NHRA Comp events. At 2011 Div 7 race in Vegas [I wasn't there] they cracked a head, either too hot or too much porting, so they couldn't run water. When I was taking engine temps at the Vegas National he was staging at over 200° dry, it ran pretty good with the last qualifing at 7.05, 188mph at 4500'DA. But when I checked the engine temp at the turn-off, it was 235° to 238° for that run. When I check under the valve cover I noticed a pushrod not where it should be, turned-out the # 3 cylinder exhaust valve was stuck in the guide. So they were done racing for the event.
So lesson learned, 235° is way too hot for a dry block, and I think too hot for water too.
Now you know the limits 200° for wet blocks and 170° for dry, and if you're looking for cheap 20hp and you're running dry, run water.
Yes, I know Parks doesn't run or believe in running water, mostly because they lost a round because of a water leak, and of course they consider the weight of the water, and some of their heads are soo large they can't run water.
OH ya we also put a blanket over the motor after we warm it up in the pits before we go to the staging lanes to keep the heat in the motor. Another thing is we plug in our freeze plug heaters [ one on each side], and oil pan heater when we warm-up the motor for the 1'st time of the day.
I know of some bracket racers that change their engine temps to run their index/dial-in. 10° makes a difference.
I hope this helps.
Jon
