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Cooling System Improvement Suggestions

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  • Cooling System Improvement Suggestions

    I have a 350CI 400 HP engine in my car. Its a tight fit and I have always has some cooling issues. I'm revamping the system to try and improve cooling.. The engine is lower than the rad so I have a filler block on top of the intake above the thermostat to make this the primary fill point and the high point in the system. It has a 16lb cap and overflows to a remote recover tank. The rad has a 24 -26 lb cap so it will not open before the 16lb cap. I replaced my old custom brass and copper rad with a new 3 row, .75 tube Champion aluminum rad. and improved the upper and lower rad hoses. I replaced a 160 degree stainless thermostat with 3/16 holes drilled around the perimeter with a virgin undisturbed 180 degree high flow thermostat ..not sure which was a better use for the system. Space is tight and there is no room for a mechanical or electrical puller fan in front of the engine. I have a 17" pusher fan mounted in front of the rad with about 1 1/2 inch air gap. Its shrouded but I plan to improve the current shroud and ducting on the front of the car. It has a 175 degree auto switch. I'm looking for suggestions on any mistakes o might have made or thing I might improve. Attached is a picture Click image for larger version

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  • #2
    All the air in front of the car needs to be directed or funneled to go thru the radiator and slowed down. form a series of scoops in front to direct air, then use a shroud on the backside(engine side) to slow the air and funnel it coming thru the radiator. The other thing you need to do is learn to make 1 change at a time, that way you can tell what's helping, hurting, or in different to your problems

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    • #3
      ^agreed.
      a shroud is most useful when the fan is mounted on the back of the rad as a puller to give the on-coming air no choice but to draw past the entire rad.. im not sure you will see the same benefits with a shroud on a pusher fan. in fact i would venture to say it would be worse than having no shroud at all. if the front of the rad is shrouded at all, remove it and go with JUST the fan mounted on the front, and perhaps a piece or 2 of screen (like screen door screen) on the back side of the rad to slow the air once its in the rad like suggested above.
      as for thermostat, i would try a 190* as well as an unmolested 160* and see how they fair VS. your 180*. often times if coolant is pushed through the rad TOO fast, it doesn't allow enough time for heat dissipation and it will run hot. also i would have your fan switch set to turn on lower... like set it to come on around 150* (if its the type you can dial in and set). in theory, by the time its hitting 175* and the fan is coming on to control things, the coolant may only be leaving the radiator at 140*, and by the time its coming back around, its just getting hotter and hotter and the fan has come on too late to keep up. try getting the fan to come on earlier, or see how it does with the fan on constantly or put it on a manual switch even. i usually run all my fans constant, but also have them on a switch in the dash.
      again, be sure your rad cap AND YOUR OVERFLOW POINT is the highest point in the system. air will always come to the very top and if that air cant get out, it will cause things to boil. looks like you have 2 rad caps. which ever one is LOWER, try putting a higher PSI rad cap on it. this way your 16psi cap is the functioning bubble/release point for air and overflow.
      also be sure your overflow tank is large enough. as the coolant expands under heat, the excess is bled off at 16psi (cap pressure) into the overflow. then as it cools after running, the system creates a vacuum and draws back the same amount that was lost, from the overflow tank. this being the case, your overflow tank needs a hose running from the caps bleed off/overflow point, right to the bottom of the overflow tank so that vacuum created, can draw back the coolant it needs. otherwise on the first heat cycle, it will dump the excess expanded coolant, but not be able to recover it, and it will then draw air back in instead every time it cools.
      my dad had a firebird with no overflow tank that would always run hot. i told him to add a tank like this and it ran perfect ever after. it was basically running with not enough coolant in it, causing hot spots and air in the system.
      all the best.

      edit: looking at your picture closely, i would definitely put a higher PSI cap on the radiator (which looks to be lower) making this cap essentially non-functioning, and plug the radiators overflow port. let the block mounted cap be your functioning 16psi cap and bleed tube. its tube is set up nicely coming from the bottom of your tank. i wonder if your tank is large enough. i have a 1.3L mazda rotary engine in one hot rod and it can fill and drain a tank that size in a heat cycle NO problem.... and it has 1/3 the volume of expanding coolant you have in that small blocks system. i would try a larger tank. or to test its size... fill your overflow right up to the top when things are cool, and then on the heat cycle, just let it piss out as much as it doesn't want, (maybe put a tube on its drain to the ground so it doesn't mess up your nice engine bay) and then once its cool again, check to see if there is anything left in the tank, or if it has drained itself ALL back into the system. if the tank is EMPTY, then you know you need a bigger thank and likely have air in the system every time it cools.
      Last edited by turbominivan; 11-15-2016, 07:10 PM.

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