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Reduce heater hose size

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Old Aug 26, 2024 | 07:54 PM
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Default Reduce heater hose size

I've read a few times about to much water going to the heater core rather than the radiator (race course use). I was thinking of reducing the lines to 1/2" or even 3/8". I still want to retain a heater core for this project. Any downsides to this????
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Old Aug 27, 2024 | 03:27 PM
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Originally Posted by Aardwolf
I've read a few times about to much water going to the heater core rather than the radiator (race course use). I was thinking of reducing the lines to 1/2" or even 3/8". I still want to retain a heater core for this project. Any downsides to this????
I wouldn't do that. If you're concerned about engine temp, keep in mind that the heater core acts as a radiator & the extra area of the heater cooling fins adds to the overall cooling capacity of the radiator. Old school hack....if you lose a belt & engine temp start to rise, turn on the heater to take advantage of the cooling fins in the heater core.
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Old Sep 2, 2024 | 11:17 AM
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I doubt if it would do much, but:
You can just goto the plumbing store and get barbed fittings and reduce it, then back to original to do a flow restricter in it, that would be pretty quick and easy.
Can also put the heater on max and high to drop temps a little and get that full race car feeling
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Old Sep 2, 2024 | 06:05 PM
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I was once told that the LS (Only LS) engines actually run hotter when the heater is on. IDK how that's possible, but was told it's due to the way the coolant flow is done on these engines.
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Old Sep 2, 2024 | 06:34 PM
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I have some reducing barb fittings I'll try. I don't have a cool suit so adding more heat on track would be bad. Car and driver both in a battle against heat lol
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Old Sep 12, 2024 | 06:55 AM
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I'm curious how water gets from the engine output side hot to the heater core without going thru the radiator?
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Old Sep 12, 2024 | 03:19 PM
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I run a restrictor in my heater core loop, just a slug of aluminum with a small hole drilled in it. I don't have a heater core, but the C6 setup can allow too much water to flow through the heater core, bypassing the radiator completely (I have thermal camera proof)

There are 3 loops in the LS water pump, the radiator, the thermostat, and the heater. Obviously you want most of the water going through the radiator. Plenty of water returns from the top of the radiator to the resevoir

Nothing balances the 3 loops other than the size of the holes. Somehow the balance was better in the C5 since the reservoir was part of the loop and on the passenger side, the dead-end setup with the C6 has created problems for many track cars that I personally know of.



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Old Sep 12, 2024 | 07:00 PM
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Thank you for the data and picture.

David would you think the hose to the reservoir should be increased so as to have better balance like the C5? Any other tips and tricks?
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Old Sep 13, 2024 | 09:02 AM
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The resevoir is just there as a backup in case you have a leak. Cars didn't have resevoirs for decades. However my return line from the radiator sends plenty of flow back to the resevoir to purge any air bubbles, AND it's on the hot side so no bypassing



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Old Sep 13, 2024 | 09:11 AM
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It is also there to help reduce boil over situations. Works much like a hot water heating system for homes, in that it operates as an expansion tank. In the old days, even if your cap was working as designed, if the car got hot enough, the coolant would surpass the rated pressure of the cap and deposit hot coolant onto the roadway/driveway. The recovery tank helps prevent this.....
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