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Practical limits to closed cooling?

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Old 09-25-2007, 09:52 PM
  #11
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I have stock 502 efi. Closed system including the SM exhaust manifolds. never goes past 175.
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Old 09-26-2007, 08:37 AM
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checkmate454mag, your avatar looks like you have a really neat setup for your closed cooling. Could you post some pics. I need to dress my setup some.

Tom
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Old 09-26-2007, 12:58 PM
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There really are no limits to the cooling ability of a heat exchanger. It simply needs to be matched correctly to your application. A good friend upgraded to a 5" H/E after he Whippled his 496. Temp stays right where it should be, and that is in 90 degree water. A five inch H/E should fit the 500-550 HP range well.



Darrell.
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Old 01-09-2009, 09:57 AM
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Hey.

I have a 502 with 625 hp that I put closed cooling on. I have some problems with overheating. I use standard mercury circulation pump and I had a 140 degree thermostat in it. take the thermostat out and it will be alright?
Thanks!

Andree
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Old 01-09-2009, 10:23 AM
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hi guys, i've been running closed cooling on a set of 750 hp NA motors and able to maintain 190 engine temp. the engines like a little temp for better performance. we've actually done dyno testing running the motor at 100 to 110 which would be the same as a raw water setup compared to 180 degrees and lost quite a bit of HP. same goes for oil temp which might be even more important.

i'm using standard heat exchanger - 5" x 24" 4 pass

champ products - http://www.champproducts.com/

arty there has been really helpful. these guys make most of the exchangers for some of the other marine engine manufatures.

also don't forget to look at the raw water pumps. i've found the all the "billet" raw water pumps that use the stock merc style impeller are right on the edge of suppling enough volume of water and pressure. also watch out i had alot of problems with the original rigger setting up the pumps with the incorrect pulleys and ending up spinning the pumps to fast causing the rubber impeller to be damaged after about 3 races.

as for needing more passes, 2112, you are probably not flowing enough water thru the exchanger to cool the egine water. same as not having enough air flow thru a radiator. some time more passes can hurt you rather than help.
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Old 01-09-2009, 11:37 AM
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Most closed cooling systems for BBC engines in that horsepower range are more than adequate in size and type to keep your engines at the proper operating temperature of about 160 degrees. I suspect that either the cooler itself has clog or flow issues or that the raw water sytem or closed system have flow and circulation issues that are keeping the exchanger from doing its cooling properly.
Do not remove a thermostat unless its bad ( you can check in a pan of hot water with a thermometer to check opening) and in almost all cases removing the thermostat entirely will cause the block coolant to pass through the exchanger to fast and the cooler will not be able to transfer the heat to the cool raw water side of the exchanger.
Check you raw water pressure and flow, you will probably find the problem on that side of the system. good Luck!

Best Regards,
Ray @ Raylar
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Old 01-09-2009, 01:42 PM
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Quote:
Originally Posted by skaterdave View Post
hi guys, i've been running closed cooling on a set of 750 hp NA motors and able to maintain 190 engine temp. the engines like a little temp for better performance. we've actually done dyno testing running the motor at 100 to 110 which would be the same as a raw water setup compared to 180 degrees and lost quite a bit of HP. same goes for oil temp which might be even more important.

i'm using standard heat exchanger - 5" x 24" 4 pass

champ products - http://www.champproducts.com/

arty there has been really helpful. these guys make most of the exchangers for some of the other marine engine manufatures.

also don't forget to look at the raw water pumps. i've found the all the "billet" raw water pumps that use the stock merc style impeller are right on the edge of suppling enough volume of water and pressure. also watch out i had alot of problems with the original rigger setting up the pumps with the incorrect pulleys and ending up spinning the pumps to fast causing the rubber impeller to be damaged after about 3 races.

as for needing more passes, 2112, you are probably not flowing enough water thru the exchanger to cool the egine water. same as not having enough air flow thru a radiator. some time more passes can hurt you rather than help.
Dave what raw water pump/impellers do you use? I often wondered how the impellers hold up to what we are running, rpm wise we spin 74-7600. Not sure what Ed runs but no failures so far.

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Old 01-09-2009, 02:04 PM
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i was running hardin marine with jabsco impellers. max volume is 37 gal/mn at 2350 rpm. i was replacing them about every 3 races. you could see visible damage to the impeller. small pieces missing at the rolled lip area and the rubber vains themselves had cracks in the actual rubber. after looking into the pulley ratio on the pump and crank snout i was spinning the pumps at 5300 rpms if the motor was spinning 7600. jabsco impeller is only rated to 2350. and in talking with jabsco after you reach max rpm you are airating the water causing more damage along with hurting the water flow.

i'm current going with an 1 1/4 npt size jabsco pump that puts out 62 gal/mn and with the help from jones pulley and their HTD pulley setup i can slow the pump down to 2350 @ 7600 rpm on the crank
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