Second radiator

I have a 1947 chev , 427 motor with a B&M 250 blower. Because of the small front grill and large motor I am limited to small radiator. I have the thinnest and biggest pull fan I could get, not much clearance. I have a custom cowling in the grill to catch as much air as posable. Still over heating so I installed a second radiator/heater core under the rear of the car. I Installed a custom cowling and a pull fan also, still over heating.

I believe that the rear radiator does not have enough GPM flowing because it is piped of off the heater hose and it is between 6 to 8 feet to the rear of the car. I what to add a electric water booster pump in the heater line. Im not sure how much GPM in need to make the rear radiator flow correctly. Has any one ever hade this problem?

I would work on figuring out why a single radiator isn't able to keep the engine cool.  

When does it overheat?  Idling?  On the highway?  In traffic?

So you're pulling as much air as possible into the engine bay, but how easily can the hot air get out again?

Try running it with the hood off, just as an experiment to see if it overheats.  If not, then you know you can work on venting the hood and/or fenders.

In reply to Cooter :

Mostly if I get on the throttle. The area for the radiator to fit is very narrow so there is not enough water volume for the large motor. Adding rear radiator/heater core gives me plenty of volume. Because of the distance from the front to the rear of the car and using 3/4 inch heater tubing. the original mechanical water pump is not made to pull that much and that far thru a 3/4 inch pipe.

Have you got a fan shroud?

Fans, electric or engine driven tend to do SFA without a proper shroud.

In reply to Floating Doc (Forum Supporter) :

The grill cowling that I made directs and keeps all the air it can and forces it into the radiator. The engine bay finder wells do have exit vents, but maybe I could add more. The bottom is wide open but I do have another issue that needs fixed. My left side header collector is modified  to accommodate my steering column. So my exhaust on the left side probably is restricted and in order to fix it I will haft to make custom exhaust. 

In reply to ShawnG :

yes the electric fan is inside of its own shroud.

Could you run the radiators in series to increase the amount of flow through the rear unit? It wouldn't be ideal to get the most out of the system but it will be better than 3/4" hoses.  To get the most you want the highest temperature differential between air and water temps in each radiator so parallel is better.

I think the small line to the rear radiator is a problem.  I would run all the coolant from the front radiator to the rear radiator using the normal size hose (not sure what size that is but more like 1.5").  Well, actually I would probably use some aluminum tube for the straight runs and put radiator hose on the ends but you get the point.  It's a long run so I would also install an electric water pump to help push the water from the rear radiator back to the engine.  I have used Davies Craig electric water pumps in a couple of applications and have not had any issues with them.  

In reply to Kubotai :

what GPH of pump should I use?

In reply to Kubotai :

what GPH of pump should I use? I don"t think a larger hose would work.

It's a lot to digest, but there's good information here: http://www.billavista.com/tech/Articles/Cooling_Bible/index.html

Particularly the parts about modern cross-flow vs. down-flow radiators and radiator cap location. If your current radiator is a down-flow style, it might be part of the problem.

How many rows does your current rad have? If it's only 2 then maybe a 3 or 4 row rad might help.

I think you just need a better front radiator. There's Anglias making big BHP that manage with a tiny grill area.

In reply to philboy :

I run much smaller bore engines than you so I don't have first hand experience sizing for your engine.  The biggest Davies Craig makes is 150 l/min (about 40 gpm) and they claim it is OK for "race engines".  It is set up to take a 1 1/2" hose.  You are adding this to the existing water pump so I would think it would be OK.  

I'm not sure what you mean by your comment on the larger hose.  I'm talking about putting the second radiator in series with the first and connecting them with the same size hose that goes to/from the existing radiator.  I would not try to use the heater line.

In reply to philboy :

Ford uses an inline electric water pump to supplement pressure in its boosted trucks. ( read cheapish ). Also, 3/4" hose seems like using brake line as fuel line (starvation).

My2c's