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Author Topic: 4905 6V92 & V730 Reman w/Pix  (Read 3316 times)
JohnEd
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« Reply #15 on: September 15, 2007, 10:13:01 AM »

Tom,

As I understand it you have 1,100 sq inches with 6 rows of serpentine in copper and you are adequate for your 375 HP engine.  That is a start on a rule of thumb but I think there is a spec for how many BTU's of heat that rad can "reject"(?) as well as how many btu's any engine creates in developing one HP.  If the engine is approaching typical efficiency.

It is often said that the MCI split rads don't cool adequately.  I could never argue that our people have problems keeping cool..the anecdotal evidence is overwhelming.  Some smart people "designed and made" these puppies and they sold their math and system tests to very smart people that would not purchase a defective design or manufacture's execution of it.  The 9 was an alltime best seller.  It seems to me that its system of cooling is much more complicated and that would lead to increased fauilures.  But it is still a rad and airflow and those can be maintained.  Somehow this isn't happening for a lot of people.

If I were to put a bus on a dyno and establish the rear wheel HP I could add the known drivetrain losses  and come up with the engine crank HP..rudamentry.  Now, if I have a 350HP 6V92 and the crank HP shows 300HP I can assume that 50 HP may be being converted to heat that i did not anticipate in the design.  I know there is the possibility that my throttle is not fully open but if I have a heat problem that isn't the case or cause.  What other ways are there to generate extra heat AND reduce HP other than restricting the exhaust, ala heat riser.  If you go from a 300HP 8V71 to a 300HP 6V92 I think the stock cooling system should work.  I think that if you went from 300HP to a 350Hp engine you could still go up any hill at the sustained "old" speed without overheating.

Whew!

John

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TomC
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« Reply #16 on: September 16, 2007, 01:07:19 AM »

John- your right in that horsepower rating and heat rejection is directly related.  If you go from a 8V-71N 300hp to a 6V-92TA 300hp, the 6V-92 will probably have a lower heat rejection since some of the extra heat is being absorbed by the turbo-especially at higher altitudes where a non turbo engine effectively gets richer burning with the less oxygen level-translated runs hotter.  If you have a 350hp engine and it puts out 300hp at the wheels, that loss is through the transmission, rear end and tire friction.  The 350hp rating already has the heat rejection built into it.
About the only way to directly correlate the horsepower heat rejection to the correct size of radiator, is to have the same type of radiator, with the same amount of cooling tube rows, with the same fan that pulls the same-it is very hard to figure out since there are so many variables.  In a truck, the radiators are the same design and they rely on front ram air-of which a bus doesn't have.  Good Luck, TomC
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Tom & Donna Christman. '77 AMGeneral 10240B; 8V-71TATAIC V730.
johnjem
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« Reply #17 on: September 19, 2007, 03:13:31 PM »

hey chris did u run into a problem with the rear bottom  ears on the cradel? i have different stlye i am preety sure i can use the 1s from the cradel i am puting in the bus the doner cradel,be much easer to swap the ears then 2 swap the cradel?? any ideas
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