Cooling situation

[RockinRobin]

I have never been able to get my drag car to maintain it's water temperature at high idle. I have it idling at 1500rpm for launch purposes since I footbrake. I have a quite large 3 row aluminum radiator and a big block Chevy electric pump rated at 35 GPM. The pump is brand new. There are also 2 12" puller fans on the radiator. I can bring the temperature down quickly in the pits by running the pump and fans. The top has a standard gooseneck with no restrictor in it and a 1 1/2" radiator hose. The bottom is a -16AN hose going into the water pump. . I'm wondering if the water flow is going through the radiator too fast to let it get cooled or if it is not going through fast enough. The temperature sender is on the inlet side, I've been thinking about putting a second water sensor on the bottom hose to see the difference.
I run it down the track at 160-165 degrees and it gains about 10 degrees going down the track. It will pick up another 10-15 degrees or so idling back to my trailer.
This is a 750hp GenIII Hemi motor.

 

[Dana67Dart]

Are the temps really an issue?

10 deg in 8 to 10 seconds.

Do you run the fans while on a run?


Can't push fluid fast enough through the rad.

Your lower hose is slightly less than 1 inch id

Big blocks got 1.75 lower hose
Small blocks got 1.5 lower hose.

You look to have a restriction in the lower hose.

35 gpm doesn't seem like a lot to me. For a run (10 seconds) it is only moving 5 gallons of fluid through the engine and rad. But if it is a commercially available pump I suppose that's normal.

 

[RockinRobin]

I guess I forgot to say that if I let it idle with pump and fan on the temperature Will never level off, just keeps slowly rising. Have to shut motor off to get it to stop.

 

[RustyRatRod]

Sounds like not enough air flow.

 

[Newbomb Turk]

35 gph might cool 450 honest horsepower. Maybe.

You are far better off with a mechanical water pump.

The power you lose isn’t half of what you’ll gain from keeping the coolant temperature at 160. Or 140 but that’s pretty hard to do.

 

[MOPARMAGA]

Judging by where you live you might want one of those NASCAR styled radiators with less fins per inch...gets the air through.
I imagine that hemi block will hold onto heat more than our old cast small and big blocks, they're some hefty pieces.
I notice things like that when im honing blocks at work, they take a few more minutes to shrink back then most others.

 

[Dana67Dart]

Judging by where you live you might want one of those NASCAR styled radiators with less fins per inch...gets the air through

You want more fins per inch the only heat transfer takes place at the fin tube contact.

Fewer contact points = less heat transfer.

NASCAR are running continuously at high speeds (unlimited airflow) and they run at very high pressures and temps compared to street and strip.



My money is the tiny return line to the pump / block is the issue

 

[MOPARMAGA]

You want more fins per inch the only heat transfer takes place at the fin tube contact.

Fewer contact points = less heat transfer.

NASCAR are running continuously at high speeds (unlimited airflow) and they run at very high pressures and temps compared to street and strip.



My money is the tiny return line to the pump / block is the issue

Less fins is open for extra air flow.
If the air is having trouble getting through the fins it's not helping cool. I think the difference was only 5 less per inch, they use them on hot tracks, drafting behind cars, little opening for radiator to contact air. & Keep low temps.
Edit, not NASCAR

 

[Dana67Dart]

NASCAR uses them on hot tracks, drafting behind cars, little opening for radiator to contact air. & Keep low temps

My info says 290 deg F is standard on NASCAR

There is certainly a point where more fins per inch lowers cooling efficiencies. But that would make the fins basically touching, air molecules are really small

US radiator has a great video on the subject.



Also the aluminum material has a lower ability to transfer heat than copper brass BUT the solder used at the copper brass fin to tube interface mostly negates that difference but it is still SLIGHTLY better

 

[MOPARMAGA]

My info says 290 deg F is standard on NASCAR

There is certainly a point where more fins per inch lowers cooling efficiencies. But that would make the fins basically touching, air molecules are really small

US radiator has a great video on the subject. I'll try to find it.

Also the aluminum material has a lower ability to transfer heat than copper brass BUT the solder used at the copper brass fin to tube interface mostly negates that difference but it is still SLIGHTLY better

I am incorrect in saying NASCAR.
It is a circle track type car and now I can't remember. You're right.

 

[Bewy]

Isn't the lower hose 2.5"?

 

[MOPARMAGA]

My info says 290 deg F is standard on NASCAR

There is certainly a point where more fins per inch lowers cooling efficiencies. But that would make the fins basically touching, air molecules are really small

US radiator has a great video on the subject.



Also the aluminum material has a lower ability to transfer heat than copper brass BUT the solder used at the copper brass fin to tube interface mostly negates that difference but it is still SLIGHTLY better

Right around the 28 minute mark is the explanation

 

[Dana67Dart]

Isn't the lower hose 2.5"?

I goofed, the stock hoses are 1.5 for SB and 1.5 and 1.75 for BB.

I don't know what is stock on a Gen III Hemi.

I was just using the IDs for comparison to the tiny -16AN HOSE

the OPs -16AN lower hose is 0.875 ID to his pump

The top has a standard gooseneck with no restrictor in it and a 1 1/2" radiator hose. The bottom is a -16AN hose going into the water pump.

 

[TT5.9mag]

It only gains 10 degrees going down track because you have a massive amount of airflow. Your water flow is a constant and it’s cooling when you’re making and using horsepower. So the only variable changing is airflow. The two 12” fans are insufficient.

 

[RustyRatRod]

A high efficiency radiator core is 14-16 fins per inch. Any more than that and you start having airflow issues. I wouldda tried a high efficiency two row core with two 1.25" or 1.50" rows. I think you'd have better luck. Especially if you got more air flow from "some kinda" fan(s). If you really want a GOOD fan, I'd recommend something like this.

FANS

 

[RockinRobin]

I goofed, the stock hoses are 1.5 for SB and 1.5 and 1.75 for BB.

I don't know what is stock on a Gen III Hemi.

I was just using the IDs for comparison to the tiny -16AN HOSE

the OPs -16AN lower hose is 0.875 ID to his pump

I switched the bottom hose from 1.75 to -16AN because I see cars at the track with those hoses bottom and top all the time and I figured if it works for them with a lot more HP than I am running it should work for me. There has been no difference after the switch so I don't think that is the issue.

 

[Scody21]

What PSI cap are you running? If using a 15 it’s too low, you want over 20.

 

[RockinRobin]

What PSI cap are you running? If using a 15 it’s too low, you want over 20.

I think it's 18 psi. I should move to a higher one.

 

[B3422w5]

35 gph might cool 450 honest horsepower. Maybe.

You are far better off with a mechanical water pump.

The power you lose isn’t half of what you’ll gain from keeping the coolant temperature at 160. Or 140 but that’s pretty hard to do.

I have a 35 gph electric pump and it cools my 600 horse motor just fine.
His issue is not enough fan.
I have found if the fan doesn’t draw more than 20 amps the motor isn’t powerful enough, no matter what the sometimes bogus cfm ratings say. Been there, done that.

 

[Newbomb Turk]

I have a 35 gph electric pump and it cools my 600 horse motor just fine.
His issue is not enough fan.
I have found if the fan doesn’t draw more than 20 amps the motor isn’t powerful enough, no matter what the sometimes bogus cfm ratings say. Been there, done that.

How cool do you run the engine? How much does the temperature climb during a pass? Will the car idle and not gain temperature?

35 gph is not very much flow. And, it’s got the same issue ALL electric pumps have and the is it may flow 35 gph (probably not but I forget exactly how they are rated) but lets say it is 35 gph that means that even IF it is flowing that much, it’s not enough to cool the engine at idle.

As more power is made, more coolant flow is required and that electric pump is already tapped out. When pump flow should be going up, the electric pump is what it is.

The OP says that.

That tells me that at WOT during the run the pump certainly can’t keep up.

I’m not saying the OP doesn’t have a fan issue. I’m not a fan of electric fans (no pun intended) on bracket cars.

I’m also not a fan of electric water pumps on bracket cars for this very reason.

It’s just not worth it for the little bit of power saved if you can’t control the temperature, especially at idle. That’s crazy.

I get the idea of cooling the engine after the pass, but I’d you can’t control the temperature during the pass that’s crazy.

I get that 10 degrees doesn’t sound like a big gain, but for a WOT 9 second pass that’s a bunch to me.

Also, I don’t think the OP mentioned ambient temperature and humidity and how well the cooling system does on 90 degree plus days.

I’ll say it again. I try to discourage anyone with a bracket car from using an electric pump for these reasons.

 

[B3422w5]

How cool do you run the engine? How much does the temperature climb during a pass? Will the car idle and not gain temperature?

35 gph is not very much flow. And, it’s got the same issue ALL electric pumps have and the is it may flow 35 gph (probably not but I forget exactly how they are rated) but lets say it is 35 gph that means that even IF it is flowing that much, it’s not enough to cool the engine at idle.

As more power is made, more coolant flow is required and that electric pump is already tapped out. When pump flow should be going up, the electric pump is what it is.

The OP says that.

That tells me that at WOT during the run the pump certainly can’t keep up.

I’m not saying the OP doesn’t have a fan issue. I’m not a fan of electric fans (no pun intended) on bracket cars.

I’m also not a fan of electric water pumps on bracket cars for this very reason.

It’s just not worth it for the little bit of power saved if you can’t control the temperature, especially at idle. That’s crazy.

I get the idea of cooling the engine after the pass, but I’d you can’t control the temperature during the pass that’s crazy.

I get that 10 degrees doesn’t sound like a big gain, but for a WOT 9 second pass that’s a bunch to me.

Also, I don’t think the OP mentioned ambient temperature and humidity and how well the cooling system does on 90 degree plus days.

I’ll say it again. I try to discourage anyone with a bracket car from using an electric pump for these reasons.

It’s actually foolish not to use an electric fan and water pump at the track. You can adjust your starting line temp to make it completely repeatable, otherwise you can’t.
I know of no remotely serious bracket racer, etc who doesn’t run electric water pump and fan(s).
I street drive mine, it never gets above about 185 or so.

Regards temp creeping up at idle, duh, yea, you have no airflow across the radiator, the water is going to get warmer

 

[Newbomb Turk]

It’s actually foolish not to use an electric fan and water pump at the track. You can adjust your starting line temp to make it completely repeatable, otherwise you can’t.
I know of no remotely serious bracket racer, etc who doesn’t run electric water pump and fan(s).
I street drive mine, it never gets above about 185 or so.

Regards temp creeping up at idle, duh, yea, you have no airflow across the radiator, the water is going to get warmer

Certainly a dragster or similar would be hard pressed to use an engine mounted pump. Especially if they tow it to the line and tow it back.

But a door car?

I don’t consider 180 or more acceptable for a race car. 160 is the max.

Just because everyone does something doesn’t mean it’s the best option.

 

[Demonx2]

I agree with RRR...sounds like an airflow issue if you can't control temps at idle. Pull the cap with the engine warmed up/stat open and see if you have a "river" of coolant going through the rad. I know the OP is plenty experienced to know what a "proper amount looks like - or at least what a too low amount woukd look like. If you've got the water flow at idle and temps keep rising, well then it's an airflow issue! Also, regardless of the engine's max hp, at idle, no engine uses much power to maintain speed. A new-Gen hemi is likely much more efficient at idle anyway but the difference is so small it really doesn't matter.

My avatar (408 engine) has a mechanical pump, 160 hi-flow stat, 2 puller electric fans and a Champion rad. I typically leave the line in the 160-170 range (I leave one fan on during the run) and cross the 1/4 mile stripe close to 10 degrees hotter. I flip on the 2nd fan and by the time I'm back at my trailer, I'm back in the 160 range. (Trans has its own Derale cooler - stripes about 170-180F, flip its fan on, and back to 150-160 at the trailer.) This setup also cools just fine on the streets in 90+ degree ambients here in Florida. I've posted this before but here's my fan/shroud setup. It's a Jegs brand fan set...well really a Maradyne branded as a Jegs.

I mention all this simply to say what the OP is trying to do CAN be done. Need to see his fan/shroud setup but he's no rookie and it's likely pretty good.

 

[9secRR]

when i had my black R/T, the engine was an X block that was half filled, 13.5 compression, W2 heads. moroso electric motor to spin the water pump. i bought the flex a lite extreme electric fan that pumps out 3300 cfm. factory 1979 rad. i tried one day to see how hot it would get at idle.....i let it idle for 45 minutes and 180 is all it would do. i set the thermostat control nob to 175. fan cfm is very important.

with the blue car, i had a small tiny rad with a little electric fan, maybe 9''. i used the moroso electric motor to spin the edelbrock water pump. i leave the line at 150-155, at the top end it's 160-165, drive back to pits it's usually 170. half filled 340 block. i drive back on gas to get some heat in the engine to burn off the moisture from the methanol. i let the car get to 180-190 before i shut it off in the pits.

now i have a remote meizure water pump with aluminum rad and small 10'' electric fan. no idea what will happen yet but will soon find out.

 

[B3422w5]

Certainly a dragster or similar would be hard pressed to use an engine mounted pump. Especially if they tow it to the line and tow it back.

But a door car?

I don’t consider 180 or more acceptable for a race car. 160 is the max.

Just because everyone does something doesn’t mean it’s the best option.

I was saying 180 street driving it. That is plenty fine.
I try to hit the water box at about 135-140 at the track. Usually by the ET shack getting my time slip it’s approaching the 180 mark
The key is staging the car at a consistent temp, running the electric water pump and fan allows me to dial the temp in to where it’s consistent, without the motor running.
Do you actually race? I know of virtually no race cars that don’t use basically the same procedure I mentioned above, at least if running gas.