Debating fan shroud/electric fan options, intake manifold/filter tubing routing, rad hose routing and want help with my 70 1/2ton LS swapped lm7.
Pros/ cons of a cross flow rad vs a downflow rad.
The original 307 had a cross flow, the lm7 has a crossflow, but it would sure simplify my life if I could use a downflow radiator to help route all the above tubing/ hosing.
Would a downflow cool a warmed over lm7?
1970 Chevrolet C10 Grandpa's -- My first truck -- In progress to shiny Follow the build in the Project Journal 1950 Chevrolet 1-Ton Dually "Ole Red Girl" In the Stovebolt Gallery More pictures here 1951 GMC 9430 1 ton dually--Shiny! | 1972 Chevrolet C20- Rusty- the puzzle box lid for the C10 | 1962 AMC Rambler American- my wife's Parts trucks- 1951 GMC 9300 | 1951-GMC 9430 | 1951- Chevrolet 1300
A radiator is simply a heat exchanger- - - -energy released by burning fuel goes three directions, through the transmission and drivetrain to move the vehicle, out the exhaust, and dissipated by the cooling system. Ideally, if we could capture and use all the thermal energy burning the fuel releases, we could get three times the gas mileage. The problem is, the energy is released much faster than it can be trapped and applied to the powertrain. That's one reason turbocharged vehicles make lots of power with tiny engines- - - -at least some of the thermal energy that would normally get wasted out the tailpipe gets recycled back into the engine in the form of higher manifold pressure created by the spinning turbine- - - -driven by exhaust energy.
The cooling system is tasked with getting rid of enough energy to prevent the engine from overheating and destroying itself. This can be done directly by making the cylinder walls thin, adding fins, and blowing lots of air over them, or indirectly by absorbing the heat with a liquid, piping it to a heat exchanger (AKA "radiator") and blowing air over the radiator. It doesn't matter if the coolant flows up, down, sideways, or backwards as long as there's enough area for the liquid/air heat transfer to happen. Cross flow radiators are more a function of the body style the engine is installed in, rather than the direction the coolant flows. Long, low vehicles with wedge-shaped hoods can use a wide, angled cross flow radiator to good advantage while something tall and big like a Peterbilt tractor will have a fairly narrow downflow cooling system. Bottom line- - - -it's more about the volume of coolant, how fast it flows through the heat exchanger, and how many square inches of area there is for the air to contact. Blowing lots of high speed air over a relatively small radiator might keep a big, powerful engine cool, but in general, bigger is better where radiators are concerned, no matter what direction the coolant flows. Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
To condense Jerry's very detailed answer: Use whatever you like. It won't make a measurable difference, assuming the same area and tube count.
Kevin 1951 Chevy 3100 work truck Follow this saga in Project Journal Photos 1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car) Busting rust since the mid-60's If you're smart enough to take it apart, you darn well better be smart enough to put it back together.
klhansen Agree with your take,made my first 3100 cross flow in about 77 always cooled my 283 2x4 sorry it was in 67. Those brass radiators were easy to work on !! Learned to use brass shim stock too close holes then cut new ones where you needed them.
I have a '64 C10 that originally had a 292 6 cyln. I converted the truck to a '97 Z71 chassis with a 5.7 Vortec V8 and a 4L60 trans and a GM 10 bolt w/373 gear ratio. I used a cross-flow Speedway Racing aluminum radiator with a custom fabricated shroud.. I had a '65 C20 that I had for 18 years. It was a V8 AT w/AC.. The original cooling system was very marginal, tried everything to keep the truck from overheating during summer driving in desert/mountainous areas. Never had that problem with later model vehicles w/ cross-flow radiators. Wm
if you do not have a sealed system, meaning the radiator is always full the crossflow will still function when the coolant level is low. If the coolant level is low with vertical tubes you will be sucking air, lots of bubbles, poor heat exchange internally in the engine, and overheating.
However, with either, if you keep it properly serviced there is no problem.
Off-roaders prefer the crossflow because sometimes we run a fan into the radiator and we want to creep out of the backcountry rather than walk out.
