Coolent Temp for Bracket Racing

[fe66comet]

Well in order to gain consistency it is handy to understand the physics behind the question and answer. No solution can be understood if the answer is a mysterious variable.

[Faron]

Not really a variable , you pick a temp you can maintain , late in the rounds , takes some time , that's all , now if your looking to go as fast as possible , that is where all the variables come in , IMHO

[mmason]

Isn't the intake manifold heat crossover made to warm the incoming air to make the engine run better on cold days?

[jayb]

Yes, but I'm not sure if that is primarily for fuel atomization purposes, or if that is due to limitations of carburetors of the day, or what.  Modern EFI engines don't use a heat crossover as far as I know.  The fact remains that if you can cool the A/F charge, you can make more power.

[mmason]

I guess I should have given some more thought on that one before I posted. The point I was trying to make was that it seems to me that a large volume of air can change temperature quickly when passing over a heated or cooled surface as in a hot air furnace, radiator or airconditioner.

[fe66comet]

Also relative to how much area and the speed of the charge, like when you are pulling your lowest volume during shifts down the track or pulling into the staging area it will gain more heat than at full throttle.

[cgmach1]

Thanks for all the posts.  In my case I was more interested in durability of parts because of my cracking cylinder.  I have been able to be very consistant at getting to the line at around 160 and my ET's are good.  Mostly wondering if hitting the beams at a higher temp would help with my block problem.

[fe66comet]

Do you have a stat in there? Another factor could be flash when cold water meets hot iron or an air pocket that is not getting coolant flow till you get up to rpm then flashes? A overflow can might help if you do not have one?

[cgmach1]

No stat, just the outside ring of a stat with the center cut out for a little restriction.  Seems to control the heat well.  I do have an overflow can on it and an electric pump.

[fe66comet]

It sounds like you are getting a dry spot for some reason. I assume you got a good pressure cap and no leaks to introduce air into the system but you might try pressure testing it to verify. Cracked heads and blocks are usually a sign of overheating. I seriously doubt you are not draining the cooling system and letting water freeze in it which would be another cause.

[cgmach1]

The problem has beeen with #1 cylinder.  First cracking the cylinder wall without a sleeve and then 25 runs later cracking it again in the same spot in the sleeve.  I have re-sleeved it again, this time with a thick sleeve and planned on filling the block to the water pump holes with Hard Block.  This engine had issues that I found after it broke the first time with a new engine builder.  Bob weights off by 35 grams, piston clearance at 9.5 thou etc.  Wasn't good. I don't really trust this block too much anymore, so this is it's last chance and was trying to make sure I wasn't doing this by running it cooler than 180.  Cap and the rest of the system are good and stays in a heated garage all winter.  The garage doesn't help with the freezing much when the engine is broken and in parts all around the garage though!

[fe66comet]

Hard to say then if is maybe an off center drilled block, bad porous cast or something like that. Or something in the original high performance build. One thing I omitted was block torque which Buicks have issues with, the twisting force along with heavy compression snaps the block in the weirdest manners.

[manofmerc]

At one time whenever bracket racing my comet I went to great effort to cool my engine between rounds .Spraying the radiator until cool running the engine to circulate the cooer water throught the radiator etc. Bt the time it was my turn in the burnout box my temps were 185-190 .Now I just go to the line and run whatever my temps are normally 185-190 .Being consistent is what matters in bracket racing Wheather your temps are 160 or 190 every time is what matters .Most cars will be a bit quicker with cool temps but sometimes it is hard to maintain cooler temps whenever you go rounds .In Ga. in the summer sometimes it will be 95 at the track you have to do a lot of radiator spraying to maintain 160 in a big block powered car here .My comet (460 powered ) on the hottest days will be 190 whenever I am in the burnout box .My times never vary more than .002.004 .Normal it runs 7.12-7.15 in the eigth mile.Try running it at whatever temp it is without a lot of cooling effort just to see what it will run .You might be surprised . 8)Doug

[69Cobra]

With my old bracket motor (al. heads, intake and radiator) I could get the temp down to with in 20* of ambient pretty easy. Even tho I run an alternator I stick the charger on it and keep the water pump and electric fans on for about 5-10 minutes while spraying down the radiator at the same time. During the heat of the day you typically have a good hour or two between rounds and at night when rounds get closer its typically a lot cooler out. I try to stage the car as cold as possible (140 or below). I was also concerned wondering if you could be too cold. In the past I've spent some time with Billy Glidden and I asked him what he thought and while I was asking him it dawned on me that he tows his car to the lanes and doesn't fire it up until he is pulling in the burnout box. Then he's spraying it with -300* N20 and he shuts it down when he goes through the traps. Tows it back and puts a external cooler on it that pumps then water through ice water. So then I asked him about oil temps and he doesn't preheat the oil either. He said that by the time he's done with the burnout the oil is good. I didn't ask what weight oil but I'm pretty sure its some thin light weight stuff. Also, some of the NMRA N/A heads up guys run the external engine coolers and I've heard of them getting the engine down to 37* before making a pass. In a heads up world rumor its worth a tenth in the quarter mile.

Now, with that being said. I would guess the ones who are benefiting the most from this set internal clearances at these temps.