Radiators- single pass vs double pass

[ace1]

Is it recomended or necessery to run a double pass radiator in a lm. I have only run modifieds and used single pass with no issues.

[TheJet-09]

Recommended? I'd say yes. Necessary? I'd say "not necessarily." Were you running alcohol in the Modified? I think most everyone (at least up by me) is on gas now in Late Models. Seems like we always needed to slow the coolant down some in the old days, I think the double pass radiators help do that and increase the radiators ability to actually reduce coolant temps. I suppose the only real test would be to race with a single pass then switch to a double and note any changes. But now these triple pass radiators? I'm not convinced that if two of something is good then three is even better.

[TheJet-09]

I think how you plumb your system has a great effect on cooling too. I have water from the waterpump going to the outside/center of the heads, and I pull water off the heads in the center (inside/intake side) and the very back, all going back to the waterneck.

[Matt49]

If you trust the folks at Stewart Components, there is no real advantage to a double pass.
See this for some good reading:
http://stewartcomponents.com/index.p...ormation_id=13

At the top of that page there is a Tech Tips link that has a bunch of links to other very informative stuff.

[ace1]

I think how you plumb your system has a great effect on cooling too. I have water from the waterpump going to the outside/center of the heads, and I pull water off the heads in the center (inside/intake side) and the very back, all going back to the waterneck.

That was actually another question. I have seen lines run from different locations and wondered if it help and when/where to use them. I have steel heads and on gas.

[Lizardracing]

The laws of thermal dynamics apply here. It's not about staying in the block or radiator longer because it's a closed loop system. There's always water touching the water or block.

You want the water speed high enough to create a turbulence. Tumbling water will allow all the water(more molecules) to touch the metal so heat transfers to and away. Slow smooth flowing water creates an insulated boundary barrier(stacked molecules) between the metal and the inner portions of the water. That's why thinner tubes with very fast moving water work better and the reason two pass radiators need faster moving water to create that turbulence. Stewart explains is better than me. I'd say if you do everything Stewart says to do on their tech tips page than all your problems will go away.

[ace1]

I have only had a issue once on a modified and change to 1-1 pulleys, I think that's what they were, its been a few years, and fixed it. At the time I guess I was like some and thought the water had to be slowed down for the radiator to cool it. But after changing pulleys I started thinking the other way, move it so it can cool the engine. I'm needing a radiator for a lm and wondered others opinions on single or double

[Dirtmod13]

I think how you plumb your system has a great effect on cooling too. I have water from the waterpump going to the outside/center of the heads, and I pull water off the heads in the center (inside/intake side) and the very back, all going back to the waterneck.

I haven't seen the lines to the center of the heads before. Do u have a pic?

[Bubstr]

Taking it down to basics, The weak spot of the cooling system is the transfer of heat from water to air, in the radiator, provided you have complete flow of coolant threw out the engine. (no steam pockets). Allowing or forcing air flow threw the radiator is more important than increased or decreased water flow. If you don't think so, look at when your engine gets hot. Not at wide open, with 100 mph air going threw the radiator, at the time it is making the most heat, but when you slow down and reduce the air flow. The thicker the radiator, the harder it is to flow air. The closer the fins are, the harder it is to flow air. More fins are good, as long as it doesn't choke air off. A fan too close to the radiator can hurt air flow.

[TheJet-09]

@Dirtmod13, I can attempt to take a pic and load it, but my browser is not 4M friendly or something (hence why I can never directly reply to someone). But either way, the locations I'm speaking of are just stock/basic for most Brodix heads, nothing I came up with on my own. For everyone, while on the topic of airflow/speeds/etc., I've wondered a couple things as far as cooling....1) I've seen radiators leaned back some on asphalt cars, yet dirt cars are pretty much straight up and down. Any advantage/disadvantage either way? 2) Has anyone ever run an electric fan on a dirt car? With 16V systems I think we'd have enough juice, but would there be any advantage HP wise of not having a fan hanging on the front of the motor, especially if the need for "forced" airflow is greatest at slow speeds (like under caution)?

[Lizardracing]

Thinner tubes add restriction to the system and make the water move slower, stay in the engine longer. I've been there done that also, tried to save a few bucks on a discount radiator and ended up over heating 3 engines and freshening them.

Turbulence isn't the issue in engines, its pressure to push the water against the block so it can absorb heat.

Nope....your wrong SCD.
Think surface area.....Thinner and WIDER tubes are the way to go to maintain surface area and reduce the cross section area to prevent the boundary layer.

I'd recommend you go read what Stewart's web site has to say. They are smarter about these things than either one of us. Especially you hahaha!

[MasterSbilt_Racer]

@Dirtmod13, I can attempt to take a pic and load it, but my browser is not 4M friendly or something (hence why I can never directly reply to someone). But either way, the locations I'm speaking of are just stock/basic for most Brodix heads, nothing I came up with on my own. For everyone, while on the topic of airflow/speeds/etc., I've wondered a couple things as far as cooling....1) I've seen radiators leaned back some on asphalt cars, yet dirt cars are pretty much straight up and down. Any advantage/disadvantage either way? 2) Has anyone ever run an electric fan on a dirt car? With 16V systems I think we'd have enough juice, but would there be any advantage HP wise of not having a fan hanging on the front of the motor, especially if the need for "forced" airflow is greatest at slow speeds (like under caution)?

I have successfully used an electric fan on a 358 inch engine burning methanol. I would not try it on gas.

[Lizardracing]

yeah haha, your babbling about something you've read and Im posting with factual information learned from my 22 years of racing experience in 7 different classes.

Go buy a Chinese radiator with .078 thick tubes and one with .089 tubes and see how it works out for you. or just call stewart about the cheap import radiators. All the alum radiators have the tubes the same width front to back.

I forget you know everything already....Sorry about that.

[FlatTire]

Yeah lizard come on, stock car man is pure racing genius.

[Matt49]

SCD, am I understanding you correctly? Are you implying that water/coolant turbulence is a non-issue in engine cooling?

[Matt49]

It isn't a moot tiny detail when it demonstrates your lack of understanding in a discussion on this topic. Turbulence means everything in our cooling systems and you can certainly build something into the system to increase it: namely a radiator with smaller tubes to increase velocity which increases turbulence.
My point is this: Just because you used a radiator with thicker tubing and got opposite results, doesn't mean that the thicker tubes caused better cooling. It means there was another variable you're not taking into account between the two radiators. Your real world experience doesn't really trump the scientific facts yet you talk down to those of us that don't choose to accept it. It's truly baffling.

And yeah...
Number of times I've tried to sell something in the tech forum = 0
Number of times you've tried to sell something in the tech forum = stopped counting a long time ago

[fastford]

Single pass cool better.

If you slow the water down with a double pass it is also slowed down in the engine absorbing more heat since it takes longer for the water to get from the inlet to the outlet of the radiator.

another dumb azz post by no it all, stay down there in them street stock section..BOYYYYYYYY......

[Lizardracing]

SCD is like a Chihuahua and a top.....Has a lot of attitude but it doesn't mean anything and if you get him going you can sit back and watch it go! It's pretty fun actually.

[cjsracing]

From my experience with my late model the Double pass reduced my water temp 20 degrees. It takes a really heavy track and a hot night to get it above 210 degrees, usually right around 180 to 190 degrees.

[fastford]

a double pass is good , but down here in the height of summer when its 95 degrees at start of hot laps, a triple pass is even better.