Reverse flow cooling question
Thread Starter
Instructor
Joined: Sep 2002
Posts: 159
Likes: 1
From: Denver CO
Reverse flow cooling question
Is the LS1 motor cooled in the so called "reverse" fashion? Im just curious about GMs design history here.
Someone I know locally said that the LS1 went back to the conventional coolant flow direction. That didn't make sense to me. It seems like the reverse flow cooling has advantages by cooling the heads first and staving off detonation in higher compression motors. I beleive it is one of the contributing factors, along with combustion chamber design, and electronic engine management, that has allowed the newer motors to run higher static compression ratios and make such good power on pump gas.
Thanks,
Ken
Someone I know locally said that the LS1 went back to the conventional coolant flow direction. That didn't make sense to me. It seems like the reverse flow cooling has advantages by cooling the heads first and staving off detonation in higher compression motors. I beleive it is one of the contributing factors, along with combustion chamber design, and electronic engine management, that has allowed the newer motors to run higher static compression ratios and make such good power on pump gas.
Thanks,
Ken
Race Director
Joined: May 2001
Posts: 14,165
Likes: 9
Re: Reverse flow cooling question (Ken Lanham)
You're right, the reverse flow cooling system has some very nice benefits with very few drawbacks. To be honest with you though I'm not sure about the LS1. I know it has a more efficient combustion chamber design, part of the reason why it will make more power than an LT1 out of the same cam profile and CFM airflow.
I too would think it strange for the LS1 to go back to conventional cooling.
I too would think it strange for the LS1 to go back to conventional cooling.
Drifting
Joined: Mar 1999
Posts: 1,250
Likes: 1
From: Greensboro NC
Re: Reverse flow cooling question (Ken Lanham)
The LS1 went back to the conventional flow of coolant. The LT1/4 engines are the only ones with th reverse flow configuration. Similarities are that the thermostats for both, the LT and LS engines are on the colant intake site. Normally the thermostat is on the hot coolant outflow side of the cooling system and coolant gets circulated throught the heater and bypass circle (which also warms up the thermostat) until the engine is hot enough and the thermostat opens. On the LS and LT engines the thermostat is still ebing warmed by the bypass coolant circle, but is positioned at the coolant inflow side coming from the radiator.
Is the LS1 motor cooled in the so called "reverse" fashion? Im just curious about GMs design history here.
Someone I know locally said that the LS1 went back to the conventional coolant flow direction. That didn't make sense to me. It seems like the reverse flow cooling has advantages by cooling the heads first and staving off detonation in higher compression motors. I beleive it is one of the contributing factors, along with combustion chamber design, and electronic engine management, that has allowed the newer motors to run higher static compression ratios and make such good power on pump gas.
Thanks,
Ken
Someone I know locally said that the LS1 went back to the conventional coolant flow direction. That didn't make sense to me. It seems like the reverse flow cooling has advantages by cooling the heads first and staving off detonation in higher compression motors. I beleive it is one of the contributing factors, along with combustion chamber design, and electronic engine management, that has allowed the newer motors to run higher static compression ratios and make such good power on pump gas.
Thanks,
Ken
Safety Car
Joined: Feb 1999
Posts: 3,504
Likes: 4
From: Mexico Beach FL
Re: Reverse flow cooling question (Ken Lanham)
It's been awhile, but I've posted this link before: http://www.theherd.com/articles/lt1_cool.html
Tom Piper
Tom Piper
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Joined: Jan 2002
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From: O'Fallon Missouri
Re: Reverse flow cooling question (Tom Piper)
[QUOTE]It's been awhile, but I've posted this link before: http://www.theherd.com/articles/lt1_cool.html QUOTE]
Nice article, although I question the 100,000 mile life expectancy of the Lt1 water pump. My water pump lasted 12,000 miles.
Nice article, although I question the 100,000 mile life expectancy of the Lt1 water pump. My water pump lasted 12,000 miles.
Elite Torch Red Member
Joined: Sep 1999
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From: Exit 89 GSP,Lakewood,NJ The Land Of Mojo
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Re: Reverse flow cooling question (STL94LT1)
It's been awhile, but I've posted this link before: http://www.theherd.com/articles/lt1_cool.html QUOTE]
Nice article, although I question the 100,000 mile life expectancy of the Lt1 water pump. My water pump lasted 12,000 miles.
Nice article, although I question the 100,000 mile life expectancy of the Lt1 water pump. My water pump lasted 12,000 miles.
Le Mans Master
Joined: Dec 1999
Posts: 8,540
Likes: 1
From: And on the fifth day, subpoenas were served to Obama senior staff
Re: Reverse flow cooling question (95wht6spd)
The following are only personal thoughts, so check on validity.
LT1 block is cast iron, while the heads are aluminum like the later L98.
No particular advantage to aluminum, it is much lighter. Iron head actually disapates heat better. Aluminum heads excell due to superior shaping, similar shape in iron should get more heat out. Weight advantage is significant with aluminum.
Reverse flow cooling turned out to yeild about 1*C advantage over normal cooling, so it is not a huge advantage. There were some downsides that I can't recall to reverse coolant flow, which is why it no longer is used. Although I would think it would be good to get even 1*C if you could.
Pete
LT1 block is cast iron, while the heads are aluminum like the later L98.
No particular advantage to aluminum, it is much lighter. Iron head actually disapates heat better. Aluminum heads excell due to superior shaping, similar shape in iron should get more heat out. Weight advantage is significant with aluminum.
Reverse flow cooling turned out to yeild about 1*C advantage over normal cooling, so it is not a huge advantage. There were some downsides that I can't recall to reverse coolant flow, which is why it no longer is used. Although I would think it would be good to get even 1*C if you could.
Pete
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Michael S. Palmer
Racer
Joined: Oct 2000
Posts: 476
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From: Socorro New Mexico
Re: Reverse flow cooling question (PeteL)
Quote:
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Iron head actually disapates heat better
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No, iron heads do not dissapate heat better than the aluminum heads. Smoky Yunik and Grumpy Jenkins used to coat the water passages in the aluminum heads with waterglass in order to help keep heat in the combustion chamber better.
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Iron head actually disapates heat better
----------------------------------------------
No, iron heads do not dissapate heat better than the aluminum heads. Smoky Yunik and Grumpy Jenkins used to coat the water passages in the aluminum heads with waterglass in order to help keep heat in the combustion chamber better.
Le Mans Master
Joined: Jul 2000
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From: Greenville SC
Re: Reverse flow cooling question (Rynda)
:yesnod: Aluminum conducts heat better than iron, that is why you can run higher CR in an LT5 and LS1. Iron heads will make more power on low compression engines than alum. because it holds the heat, but as the CR rises aluminum is better because it will dissapate the heat faster and reduce the chance of detination.
