Hello all.
Any radiator experts out there? In my race car (The lotus 7 replica) I am contemplating changing the direction of the flow of coolant through the radiator.
Is there any problem with this? Seems like It should not matter which direction it flows to me but.....does it?

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

Yes it will the water pump circulates the coolant through the engine ,.And as it comes in to the top of the radiator , and as it falls to the bottom then it gets cooled down by the fan or fans if you have 2 of them .

Hmmmm, also seems like sometimes the inlet and outlet are not the same sizes...outlet smaller for coolant shrunken by cooling...?

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

If two different sizes are used, there needs to be a larger hose on the suction side than the pressure side. Since the suction side may be under a negative pressure, a larger hose (less restriction) is needed for proper flow. As the coolant leaves the engine at a higher velocity, it doesn't need as large a return hose.

The more practical reason you can't suck coolant from the top of the radiator is, what happens if your coolant is half an inch low... You'll suck air and it won't work.

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1984 300TD -- summer daily driver
Many others that aren't Mercedes...

That makes sense.

Thanks!

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

Flowing backwards (i.e. from the bottom up) is also counter to natural convective flow through the system...coolant heats up and expands, becomes less dense, rises to the top of the engine. Then travels over to the radiator, cools, becomes more dense, falls to the bottom of the radiator. The water pump is set up to assist this natural flow.

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The OM 642/722.9 powered family
Still going strong
2014 ML350 Bluetec (wife's DD)
2013 E350 Bluetec (my DD)

both my kids cars went to junkyard in 2023
2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles)
2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles)

1998 E300DT sold to TimFreeh
1987 300TD sold to vstech

Yes. Thanks Jaybob!

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

Is this a crossflow or downflow radiator?

The core is indiffernt to flow direction, but:

1 The inlet should be placed higher than the outlet, to get the benefit of convection.

2 On most radiators, the outlet will be LARGER than the inlet in order to raise pressure at the pump. This helps reduce pump cavitation.

It appears to be a downflow.

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

Were you thinking a complete reverse flow system?

I don't think so. I was thinking about it because the hoses cross under the engine and I'd like it better if they didn't.

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

How about relocating the inlet/outlet? They should be in opposite corners, but that still leaves two choices.

Oh that's not necessary. I'll just live with it as it is.

Thanks for the thoughts!

(Also, its an all aluminum radiator so relocating the nipples would be tricky.)

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

Assuming you could take care of the other items mentioned here (flow direction, cooling of water and density etc...)

.... I think it is more important that you do not send the cooled water into the head.

Not that that is what you stated, but typically, that is how these items line up in a car.

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Isn't that exactly where it goes?

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.