Radiator Hose Routing: Intake on Top or Bottom?

dperkins

Well-Known Member
#1
I am ready to route my radiator hoses and connect them to the radiator. I have done research on the best way to route it, but have not found anything more than a few posts. Lonny said to put the intake (drivers side) on the top of the rad to eliminate air pockets, which hampers the ability to cool efficiently. JSTAX disagrees and recommends have the intake on the bottom to reduce the chances of sucking in air and increase efficiency because heat rises, and the top of the rad is hotter than the bottom. Anyone done any tests or recommend one way or another for another reason?
 

ctuinstra

Well-Known Member
#2
I have yet to hear of any ill effects either way. Quite frankly what I have seen so far is these cars don't produce a lot of heat to begin with and the radiator seems to do a fine job so it works either way. The factory way is as JSTAX stated, but we are not using everything factory so it may no longer apply. I personally went with Lonny on this one because I could see how air could collect in the top. The entire radiator will cool regardless of the heat on the top of the bottom.
 

dperkins

Well-Known Member
#3
I am just a little more worried considering I will be making nearly twice the amount of power the stock turbo car is making at the crank. I want to maximize my cooling capability so nothing has to be changed or added in the future. Both ways seem to have upsides and downsides so I think for the moment I will stay with what Lonny says. If there are problems, Ill change it up I guess.
 

JSATX

Well-Known Member
#4
I’m not trying to tell anyone to do it one way or the other, I was just stating the reasons why I will keep mine the way it is.

I got out an IR thermometer and measured the top of the radiator vs the bottom and the top was over 80° hotter.
 

Briann1177

Well-Known Member
#6
Yes, with hot flowing into the top, the temperature will drop as it flows down and passes through the cores and releases its heat to the air.
 

DanPerryy

Well-Known Member
#7
The radiator will "trap" air at the top. Coolant "rising" or falling due to temperature is not like it is with a gas (compressible). Hot gases rise primarily due to the gas molecules expanding (decreased density) and thus the mass per volume decreases. Coolant is not compressible so it does not "flow" or move heat like a gas.

I think we need to suck coolant from the bottom of our radiators. I know some of us have done this backwards, me included, but I am preparing to change mine around. Every old car I have seen always has drawn coolant from the bottom. The inlet side of the radiator will always be hotter, just because the heat has not yet been extracted by the radiator.
 

Waterdriver

Well-Known Member
#8
I am just a little more worried considering I will be making nearly twice the amount of power the stock turbo car is making at the crank. I want to maximize my cooling capability so nothing has to be changed or added in the future. Both ways seem to have upsides and downsides so I think for the moment I will stay with what Lonny says. If there are problems, Ill change it up I guess.
I think of it this way, which end of the radiator are you guaranteed a water supply to your water pump intake. Bottom. You'd have to nearly completely lose all your coolant before starving that pump.

If there is any air buildup in the radiator and your in a long, high G load right hand corner, that top connection will not be picking up coolant consistantly.

Review and see how your other sports car's coolant hoses are routed. In fact, any liquid cooled engine.
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DanPerryy

Well-Known Member
#9
This ( the previous post) is right. A second good reason for doing this in the Goblin is that any air (a big top bubble in the radiator) would have to be pulled back down (in a large diameter hose) to the lower frame rail to get back to the water pump where the bubble could then escape to the expansion tank. I actually raised my expansion tank a bit on my car (an inch) so the coolant in the tank was above the highest point and trapped air would get to the tank and not get stuck in the top of the cylinder head.
 

dperkins

Well-Known Member
#11
Last night I switched my hoses around to be more like a regular liquid cooled car. I used the S bend hose from the drivers side hose to the passenger side rad inlet. Looking for a good hose with a 60 degree bend to mount the passengers side hose to the top of the radiator. I really don’t want air to be sucked in if I take a really hard turn when driving.
 

Waterdriver

Well-Known Member
#12
Last night I switched my hoses around to be more like a regular liquid cooled car. I used the S bend hose from the drivers side hose to the passenger side rad inlet. Looking for a good hose with a 60 degree bend to mount the passengers side hose to the top of the radiator. I really don’t want air to be sucked in if I take a really hard turn when driving.
Purchase another Dayco 71796 hose to use for the passenger side. I believe I had to trim it a little so as to have the hose in its naturally shaped state, as much as possible. So as to not put undue stress on the radiator connection.
 

Tony

Well-Known Member
#13
I just left AZ, and they didn't have Dayco 71796 (it showed up in their system as a power steering pressure hose). I walked back with the manager, and the rad hoses jumped from 71783 to 71800. I found 72311 that is similarly shaped. I'll report back on whether it works later.