Coolent Temp for Bracket Racing

[cgmach1]

Jay or anyone else here that bracket races, what temp do you guys like to stage the car at?  160, 180?  I've been staging at around 160 but I'm not sure if that is the best temp horsepower wise and for engine longevity.  Also, what do you use for temp control?  Stat or just restrict the flow some?

[jayb]

I always use a 160 degree thermostat.  I will often stage the car with a low coolant temp, because it will usually go faster that way.  I guess I don't like to stage over 180, because the temp can rise too much during the burnout and on the starting line.   150-160 is real typical for me.  If I'm below the thermostat opening temperature when I stage, by the time I hit the line the temp has come up to 160 and everything is good.

[Rory428]

I like to be pretty cool as well. I don`t run a thermostat on either car, and ideally, I`d like to be about 145F at the starting line, but thats kinda tough to do in real life, especially in the warm summer temps. Realistically, I am usually about 140-145 in the burnout box, and 160ish on the starting line. With driving up the returm road, getting the ET slip, and driving back to the pits, I`m usually up to 185-190, sometimes closer to 200 if traffic is heavy in the pits. Since I don`t have a generator to charge the battery between rounds, I perfer not to run the water pump any more than neccasary. After a run, I usually spray down the rad with water in a garden sprayer, and run the water pump for a few minites to get the temp down to 140, then turn off the pump, and spray the rad again. If its a good day, and I`m going some rounds, I will often flush the rad in the water cool down area in  a hot lap situation. My Fairmont has a V6 Firebird aluminum rad, the Mustang uses a stock 5.9 rad, both have Moroso electric water pump drives, although a CSR, Mezirere, (or maybe a Jay Brown/CVR ) electric pump are on the wish list. The Fairmont has a fiberglass FlexALite fan on the Edelbrock water pump, the Mustang uses a stock aluminum reverse rotation 5.0 pump, and a single cheapo electric rad fan. Both cars have a single battery and stock alternator, and have no trouble going thru a 2 day weekend without any re charging, although if a buddy next to me has his generator handy, I may borrow it for 1/2 hour if I feel it is a good idea on a hectic hot lap day, or if its getting dark, and I need to use the headlights.

[cgmach1]

Thanks for the replies guys.  It seems I'm doing something similar to both of you in trying to hit the line at around 160.  I've been just cutting the center of the stat out to restrict the flow a little and it seems to keep work in the same way you both are doing.  Jay might remember from an earlier post of mine that I've had a problem cracking #1 cylinder a couple of times and just wanted to make sure I'm not screwing something up that is easy to change.  Thanks again.

[Faron]

Rounds or ET's ?, Having been in Many 6-9 final round finals , consistency is the key , not necessarily low temps , you will go faster , BUT if you cant maintain that temp after say 3rd round , your going to be guessing your dial in , My mustang runs a 10th faster the first time run ( no heat soak ) after that it settles down to 1-3 hundredths max variance , I like to be at 160 at burnout time and at that temp its easy to stay at 180 or less , BIG radiator , Alt, Elec , water pump , NO Thermostat !! in 90 degree weather trying to run the car at 140 is almost pointless ( unless you run Alcohol ) a portable generator , and a garden Sprayer ( to mist the radiator ) on the Hottest days , get in a routine and stick with it

[fe66comet]

So actually what would be the most efficient target temperature all around? I would think at a certain point itemization becomes an issue and low combustion temps would give you incomplete burn, especially wit alcohol?

[Qikbbstang]

I understand NASCAR teams run their motors scalding hot. Obviously the less cooling required the smaller the air-flow into and through the grille and the better the aero package = part of the advantages of the Ford FR9 race motor. But still the teams run high water and coolent temps over 200F.  It's no secret that low coolent temps accelerate cylinder wear and my own logic says if there is wear its costing power.  Then again a cold engine I guess can be tuned run with more compression then a hot engine FWTW.

[jayb]

Basic thermodynamics says that the cooler the intake charge, the more power will be produced from combustion.  So ideally you would like to have the air/fuel mix entering the cylinders at the lowest temperature possible.  Obviously there are limits to how cold you can go, but drag racers running turbos or superchargers with air to water intercoolers will pack the intercooler box with ice to get the inlet air temp as low as possible.

Running the coolant hot is fundamentally a different issue, except that with a higher coolant temperature the air/fuel mixture will tend to rise in temperature as it travels through the intake tract and into the cylinder, just due to heat transfer from the engine castings.  All the NASCAR teams make use of thermal barrier coatings to try to prevent as much heat transfer to the air/fuel mixture as possible, and of course they all run a fresh air package and an air gap style intake manifold.  My guess would be that the NASCAR guys have found the best tradeoff for racetrack performance.  Just as a guess, maybe they could pick up horsepower by running the coolant temps lower, but they would lose aerodynamic efficiency, and thus would go slower overall.

[fe66comet]

So I.would say 160 would.be a good target temp for my 445 FE?

[Qikbbstang]

Try to imagine how much heat can be imparted into a Fuel:Mixture when it's passing through an air cleaner, carb, intake manifold and intake port at 6,000+ rpm
--------By my math that over 50 intake pulses a second------that's not much time to heat up anything.

[fe66comet]

I do have an air gap intake and was planning on a valley pan if it will clear my roller lifters. With the 19/30 two row aluminum radiator I have and a aluminum 1000 CFM oil cooler I think keeping the engine warm is more of a concern. OH yeah and your 55 gph water pump too.

[jayb]

Try to comprehend how much heat can be imparted into a Fuel:Mixture when it's passing through an air cleaner, carb, intake manifold and intake port at 6,000+ rpm
--------By my math that over 50 pulses a second on intake pulses------mm

The way that works is that the air molecules in contact with the walls take on the heat of the walls pretty much instantly, and as you go farther away from the walls, it takes longer and longer for the air molecules to heat up.  So the air running down the middle of the intake tract probably won't heat up at all, but the air at the periphery of the intake tract will, even with 50 pulses a second.  So, some charge temperature increase, on average, will occur.

[fe66comet]

OK might have to get the thesaurus out but I catch what you mean.

[Qikbbstang]

traveling through from air cleaner to intake valve in 1/50th of a second?....You have to remember that the heat in the metal surface of the intake tracht is being subjected to thousands of pulses per minute - it's not like one pulse fire through a heated tube.
  Like Jay said it would only be the outer boundry of the charge, and it would average out, but what a degree?...two degrees?... five degrees? ..... of heat gain on the intake charge.   Of course there's also the “chilling” effect of the rapidly evaporating fuel being introduced into the air stream that likely produces a significant change and that's cooling.
   

[Faron]

Remember the post was about BRACKET Racing , the goal is consistency , not The Most HP , at least that was my take

[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.