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Cooling system flow direction


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#1

rkmdogs

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Posted 17 September 2005 - 03:16 PM

When the Lt1 first came out, a big deal was made about the flow direction of the coolant, from the top, or heads on down, as an improvement in engine cooling system technology, and adding to the longevity of an engine. Now, I recently read that the LS1 & LS2 were reverted back to the old system, of coolant flow from the bottom of the engine up and out thru the heads. My question is, is this correct, and if so, why? What was the technical reasons for reverting back? The explanations for going to the heads first system made a lot of sense, and I have not heard anything about why this methodology was dropped, if in fact it was dropped. If it wasn't, then why is this significant difference not publicized as superior to the life of the new small-block engines, when compared to the competition?
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#2

daves87rs

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Posted 18 September 2005 - 12:04 PM

Now I want to know too....
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#3

rkmdogs

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Posted 18 September 2005 - 11:09 PM

O.K. Dave, I went back to my resources and found the magazine article that started me wondering. It was in the July,1997 issue of "Car Craft" magazine, in an article called,"Shoe-In", starting on page 41. It was written by Marlan Davis, a man who knows cars. This article is about transplanting a '97 Corvette LS1 V-8 into a '55 Chevy Del Ray 2 dr. shoebox. The transplant was being done as an experimental exercise by Scott Leon of the Chevy Raceshop at their Desert Proving grounds, to see what would be necessary to make this a successful transplant. On page 42 of the article,Davis quotes from Leon, "Unlike the late LT1 and its reverse-flow cooling system, LS1's use bottom-up cooling, albeit modified from conventional systems with a suction-side thermostat and weep lines coming off the rear of the heads."............. The article also has a list of the 24 stock Chevy parts that were used from other applications to make this transplant a success. I guess all things are possible when you have the entire GM parts bin to pick from! But nowhere in this or any other article is an explanation of why the cooling system was reversed -- again! As an aside to this is a comment that was made in another thread about the new Impala 9C1 & 9C3 police cars, not using the new V-8 because of idling cooling problems! Hm-m-m-m???
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#4

rkmdogs

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Posted 27 September 2005 - 11:41 PM

Now I went a-diggin' again from an inquiry made by one of our correspondents on another thread asking about LT1 specs. So this is straight from the General's archives. on the 1996 Caprice/Impala- Engines page on the Product Information Guide. "A reverse-flow cooling system circulates coolant through the cylinder heads before the engine block, improving heat transfer in the engine and radiator, and allowing a higher compression ratio for increased power" If it was so good in '96 that this feature was one of six features that was highlighted about the technical features of these cars............. WHY ARE THEY NOT STILL USING IT ? I'M still waiting for a responsible answer!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
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#5

rkmdogs

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Posted 11 October 2005 - 10:19 PM

Well Dave, I finally got the answer to my question....... but not from any of the "experts" on this forum! I just got the Dec.2005 issue of GMHIGHTECHPERFORMANCE magazine. They had a feature article on the LT1 vs the LS1 engines. In this article, on p.62 they quote GM engine-builder Ray Bohacz, when asked why the switch. He said," There seem to have been several reasons behind it. Apparently there were some problems with air pockets developing in the systems themselves. I'm also not sure that reverse-cooling reaped the benefits that GM thought it would. It allowed them to run a high compression ratio in the LT1(10.4:1), but high compression means a high output of oxides of nitrogen, and that raises emissions questions. As for the LS1, its' heads are so much better that they make more power without the emissions penalty." Now that's his quote, but I don't agree with some of the statements that he made as fact, i.e., high compression raises NO2 output. Other studies have concluded otherwise, but somebody got convinced at GM! <_<
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#6

daves87rs

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Posted 12 October 2005 - 06:09 PM

Very interesting.... :) I tried to hunt for a bit of info myself...but could find nothing...
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