[dv657172]

I sure hope I am not wearing you guys out with all my questions....really appreciate all the help & advice

Engine temperature is increasing 20-25 degrees from staging lane to the end of an 1/8th mile run. I wouldn't think it should heat up that much?

Car temp seems stable but elevated after a run at around 210 degrees as I go back to the pits. It typically is 180-190 degrees in the staging lane but does creep higher with any notable wait time.

Typical outside temperature is 70-80 degrees, 70-80% humidity

1965 GTO dedicated drag car with a 1968 400 (462") and 68 #16 heads
Griffin Universal Radiator - 2 rows of 1" tubes with shroud and SPAL electric fan
Meziere Electric Water Pump - Heavy Duty, 42 GPM
Moroso coolant restrictor in place of a thermostat but I dont know what size the opening is off hand
Car has a SPAL temp sending unit (185/175) in case I dont remember to turn on my manual override switch for the fan and water pump
Have only ever used 100% distilled water + Water Wetter in the car

New personal best Friday night (7.577, 89.64 in 1/8th) so car seems to run ok but has always seemed to get hot pretty easily once it initially builds up some heat

Is it possible to push water through the radiator too fast? WP appears to definitely be working well when I look in the radiator

Thanks
DV

[Dragncar]

Its normal.
I stop and start my car in the lanes. No reason for extra heat. By the time you do the burnout you are warm enough.
I run a 160 deg thermostat.

[chiefbigb]

I try to be around 160 in the water. The hotter the engine gets seems to slow it down a bit. Bracket racing always try to keep the temps consistent. Remember how the car reacts to different engine temps and adjust if you can't control it later in the race

[dv657172]

Thanks guys, I have a lot of work to do on improving my starting line consistency for sure (burnouts, engine temp control, etc).

Thanks for the feedback

[Sirrotica]

To answer your question about water going too fast through a radiator, no you cannot go faster than coolant can reject heat. Coolant rejects water at the same rate of the speed of electricity, so it cannot happen.

One thing that can happen is adding a restrictor, or themostat, will raise the pressure of coolant in the block. This can eliminate steam pockets by increased pressure making the coolant more efficient. I believe this is why the "coolant traveling too fast through the radiator" myth persists. Adding a restrictor removes the steam pockets, giving the coolant more area in the coolant jackets to absorb more engine heat. Raising the pressure in the block does make the coolant more efficient in absorbing heat in areas that would have a gas bubble at lower coolant pressures. Gas doesn't absorb heat nearly as well as liquid.

Keeping the coolant restricted, and raising the pressure internally in the system has the same symtom of slowing flow, but is actually connected to the myth of how fast/slow liquid coolant can absorb/reject heat.

It's important to have good coolant pressure to raise coolant efficiency, so there should be a restrictor, or thermostat in the system to raise pressure to keep steam and gas pockets at a minimum, not to slow coolant so heat has a chance to transfer to the coolant.

Hopefully this dispells some of the myth of coolant traveling "too fast" through the radiator, because if there was any truth to the myth, it wouldn't pickup the heat from the engine to begin with............

It's pretty easy to see how the coolant getting restricted, showing a higher pressure in the block raises efficiency, showing a cooler system is misinterpretted as coolant passing too fast through the radiator to reject heat appears, but it's not a fact that bears out through physics.

Remember, Pontiac engineers actually used smaller pulleys on the A/C, H/D cooling options to speed up the waterpump RPM.

[Elarson]

Sirrotica is exactly correct. Higher water speed gives higher heat transfer and higher pressure avoids boiling pockets.

Eric

[Elarson]

Originally Posted by dv657172

I sure hope I am not wearing you guys out with all my questions....really appreciate all the help & advice

Engine temperature is increasing 20-25 degrees from staging lane to the end of an 1/8th mile run. I wouldn't think it should heat up that much?

Car temp seems stable but elevated after a run at around 210 degrees as I go back to the pits. It typically is 180-190 degrees in the staging lane but does creep higher with any notable wait time.

Typical outside temperature is 70-80 degrees, 70-80% humidity

1965 GTO dedicated drag car with a 1968 400 (462") and 68 #16 heads
Griffin Universal Radiator - 2 rows of 1" tubes with shroud and SPAL electric fan
Meziere Electric Water Pump - Heavy Duty, 42 GPM
Moroso coolant restrictor in place of a thermostat but I dont know what size the opening is off hand
Car has a SPAL temp sending unit (185/175) in case I dont remember to turn on my manual override switch for the fan and water pump
Have only ever used 100% distilled water + Water Wetter in the car

New personal best Friday night (7.577, 89.64 in 1/8th) so car seems to run ok but has always seemed to get hot pretty easily once it initially builds up some heat

Is it possible to push water through the radiator too fast? WP appears to definitely be working well when I look in the radiator

Thanks
DV

Your car may only need 30-50 horsepower at cruise. So going down track, you may be processing 10x as much energy; so a temp increase is very normal. If the temp comes back down during your cruise back to the pits, your cooling system is working fine.

Eric

[dv657172]

Thks Sirrotica and Elarson

I will definitely keep a better eye on it going back to the pits. I think its stays elevated on the way back to the pits but I know it doesnt go any higher. Its a short drive back but will watch it more closely and let it idle a bit afterwards and see if improves.

If not would you try reducing the restrictor hole size to see if that helps any?

[Sirrotica]

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.

[dv657172]

Sirrotica

Thats some interesting info on circle tracks cars, we have a couple dirt tracks around here that I go to occasionally to spectate.

I am running a Meziere Electric Water Pump - Heavy Duty, 42 GPM so I think I should be good there along with an electric SPAL fan which is hopefully adequate

DV

[Sirrotica]

I'm no fan of electric fans, that being said my 05 GTO has one that's never given me any trouble in 18 years, and 148,000 miles, but that's also an aluminum block LS2 steet car.

Stratostreak engines are notoriously harder to cool, and many times benefit from engine driven fans over electric, I would never try to run any of my race cars with one, but we're talking a completely different type of racing, apples, and oranges.

Just by looking at the fan picture I posted, you can see it's very aggressive as far as air flow, even at idle it moves a ton of air.

With the guidance of an old time radiator shop owner, I scienced out my dirt track cars cooling system problems, and got the whole system performing very well, as well as reliable.

[Tim Corcoran]

For a dedicated drag car electric water pump is the best option. You put the fan and water pump on a thermal switch and when you get back to the pits the fan and water pump runs until it gets back down to the correct temperature of your thermal switch and shuts off automatically. Mine is set at 160

[dv657172]

Tim

What thermal switch are you running?

I manually switch on/off my electric WP/fan but also have a SPAL temp sending unit (185/175) hooked up to turn on the WP/fan in case I forget to turn on my manual override switch

[Tim Corcoran]

I put that system in over twenty years ago so I don't remember. The switch is installed in the water cross over on the front of the intake manifold and controls both the fan and water pump. This way I don't have to worry about wearing my battery down if I forget to turn off the fan and water pump. I have it on a three position switch, off, on and auto. Before I roll into the water box I set it to auto and have the temp at 160. After the run it never gets over 185 max. even on hot days. I attribute the cool running partially to the partially filled engine with hardblock. This was with my 455/473 engine I would turn my fan/water pump on and off in the staging lanes to go into the water at 160.

[Half-Inch Stud]

Heads get much hotter, so could be a quart or 2 low on coolant.

[dv657172]

Just curious, what pressure rating radiator cap are you guys running?

[Sirrotica]

I run 16 Lb. cap, each Lb. of pressure increases boiling point by 3 degrees F. With 16 lbs you're near 260 degrees for a boiling point. Once the coolant boils, it's all downhill as far as recovering without shutting down, cooling down, and adding more coolant.

Steam inside the system compromises cooling to the extent that you'll have to shut it off. No steam internally, and no coolant loss makes much better chances for a recovery without shutdown.

One other advantage is, the higher the pressure the less room for steam pockets throughout the system, making for more coolant contact with hot metal, and heat transfer is improved.

[Probird]

On alcohol it should gain 10 degrees on a pass. So I’m guessing on gas 20 degrees is a good indication of normal. I would bring you water temp down to about 160 going into the water box. 190 is too much and when it gains 20-25 degrees on the pass it takes a while to get it back down from there.

[dv657172]

Thanks guys, very helpful!

DV

[dv657172]

Revisiting this issue...sort of

While it sounds like a 20-25 degree temp increase is normal on a run, I am still bothered by how fast the temp increases at idle even when its just idling in my shop or in the staging lanes. Temperature also doesnt begin to cool down until I get back to my pit after a run and shut it off leaving the fan and WP running.

What size CFM fan should I be running?
Current electric fan is a SPAL 16" rated at 1,918 True CFM which I bought from Griffin along with radiator & shroud (see pic) many years ago. A couple websites I read recommend 3,000+ CFM for 400+ engines.

Car has 461", 16 heads, Meziere Heavy Duty Electric WP, and I use a 5/8" water restrictor in place of a thermostat. Have only ever run distilled water and car is dedicated drag car.
Car also has a seperate B&M SuperCooler Trans cooler in front of radiator.