heat factor questions

grumpyvette

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Staff member
69 chevy said:
It might be time for a new mouse. And since the price isn't much different I was thinking going the 400ci route, ala 4.125" bore Dart shp block and 3.75 stroke. But no bigger; no 427 or 434.

All else being equal, and I'm talking street driving here, will increasing the displacement from 350 to 400 tax my OEM stacked plate aluminum radiator? No extra heat produced by a slushbox trans, I have a manual gearbox. No A/C either.

Will switching from the OEM cast iron heads to aluminum help decrease any extra heat?

And on that note, will painting the cast aluminum parts (water pump, intake and heads) Chevy Orange help or hinder the heat dissipation?

A larger displace engine built in a similar configuration to the original engine, and operated at similar rpm and loads will always tend to build more heat simply because its larger displacement, as it allows a greater volume of fuel/air mix to be burn during the same time frame, and that engine, at least in theory be able to produce more power as the larger displacement should increase torque and its larger bore and/or stroke will generate more friction during its operation, thus generating more heat.
Nearly 70% of the heat an engine generates is coming from the valve train components like rockers and valve springs,and upper bore and cylinder head areas, its generated in the upper 2" of the cylinders due to combustion and friction, the cam, lifters and bearings while being a big contributor don,t come close to the combustion and valve train friction
yes aluminum is significantly more efficient at heat transfer , so aluminum cylinder heads will transfer heat in the combustion chambers to the coolant faster, this does not necessarily make the engine run cooler but it will tend to reduce combustion chamber temps slightly, thus reducing the tendency toward detonation, a larger and more efficient radiator with proper fans , providing adequate air flow rats,and duct work will be required,
your current radiator may or may not have the ability to effectively transfer the increase in coolant , transported or transferred (heat) to the outside airflow .
most cooling systems in good working order will require 1.5-to-1.7 square inches of fined cooling tube area with unrestricted air low per cubic inch of displacement, there are obviously other factors like the rate of air flow,thru the radiator, effectiveness of duct work, fan efficiency, outside temps, use of an additional oil cooler or larger baffled oil pan, average operational rpms and loads , type of coolant etc. yes you can deduct or reduce some percentage of the heat load on the cooling system by adding powered fan equipped oil coolers and a larger capacity baffled oil pan, and remote mounted oil filters
400 blocks with the larger bore normally have SIAMESE cylinder bore walls this reduces the coolant contact surface area and can slightly increase the coolant temps.
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yes theres a huge difference in radiator capacity, quality and sizes available
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if your cars got an automatic transmission and a higher stall speed converter its a damn good idea to install an auxiliary trans fluid cooler with an electric fan,
OK FIRST LOOK UP THE TRANSMISSIONS FLUID CAPACITY
HERES A LINK


http://fluidcapacity.com/
http://www.cartechbooks.com/techtips/autotransfluid

keep in mind most performance cars with an auto transmission and a higher rpm stall converter, will need an auxiliary trans fluid cooler, Id strongly suggest you find one with an electric fan and 1/2" or AN#8 line size as you'll want to allow a minimum of 2 gallons a minute trans fluid flow rate

its CRITICAL to keep the trans fluid clean and ideally changed about every 70K miles and use of a auxiliary cooler that keeps the fluid temp under about 170F is going to extend service life a good deal longer
Ive helped do at least 7 of these big block engine swaps now for other people and obviously results vary with the components being used but most of the swaps required a trans cooler and Ive installed 2 now in the rear tire carrier area, 200f -230f temps on trans fluid are very common on stock transmissions, with stock original engines when your beating the hell out of the trans racing, but 190f-210f on the street while cruising is more common using the stock radiator trans cooler in the lower radiator trans fluid cooler.
I had a larger than original capacity aluminum aftermarket radiator most of the time , in my corvette even with the current 383 sbc, and if I ran a 180f T-stat both the coolant and trans fluid tended to run about 190f UNTIL I swapped to a 3200 stall converter , where the temps jumped noticeably by about 20f higher, if I pushed the car ,but those temps dropped rapidly if I was just cruising in O.D. but I felt I needed a better system, to cool the trans fluid, adding the additional rear mount aux cooler drops temps to 150f-160f with the fan on and about 170f=180f with it off even if Im pushing the car so I wired a switch to the fan, and a sensor that turns the fan on at 175F

http://www.summitracing.com/parts/der-16759

http://static.summitracing.com/global/i ... -16759.pdf
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internal cross sectional area of the fluid transfer lines matters, anything less than 1/2" or AN#8 can be restrictive to flow
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read the links
http://garage.grumpysperformance.co...-octane-for-compression-ratio.2718/#post-7057

viewtopic.php?f=57&t=853

viewtopic.php?f=57&t=2991

viewtopic.php?f=57&t=9880

viewtopic.php?f=57&t=7774&p=45162&hilit=shroud+fans#p45162

viewtopic.php?f=57&t=4230

viewtopic.php?f=57&t=1540

viewtopic.php?f=57&t=5607

viewtopic.php?f=57&t=348
 
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Kinda Sux they don't provide Engineering data sheets with aftermarket radiators.
A Performance cooling curves as you have shown above.
 
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Ive found that if you select a decent quality radiator , like the 3 or four tube high fin count designs,equipped with a matching fan and fan shroud,
your generally fine with a 1.7-2 square inch of frontal surface area per horsepower,but I see places state you only need about 1 square inch of radiator surface area per cubic inch of displacement, which may be fine on a stock engine but wholly inadequate for a performance application. if you had a 700 hp engine this will rather obviously pose a problem,as a bit of quick math will obviously show theres not nearly enough surface area for ideal engine cooling, as most muscle car radiators are in the 400-500 square inches of surface area range (18"-19"tall and 24"-30" wide), so adding oil coolers, transmission fluid coolers and very effective fans that increase the cooling capacity are generally required.
adding high efficiency fans and shrouds boosts heat transfer rates,but youll rapidly find just a radiator won,t tend to be adequate in heavy traffic and low speed driving on hot days,unless your very careful with a multi level cooling system design, the stock radiator would rapidly prove it was inadequate.
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larger capacity oil and trans fluid coolers with power fans can remove a good deal of the heat load an engines cooling system would otherwise be burdened with.
having a large capacity oil and transmission fluid cooler separate from the engine coolant radiator, increases the surface area the air flow through the additional fan equipped fluid coolers , ideally mounted around the car rather than stacked in front of the cars radiator has the desired and more effective use of that air flow to transfer that heat with.
remember your oil and lube system are used to absorb and transfer a great deal of the engines heat from moving parts before the coolant comes into play, so constantly cooling the engines internal lubricating oil flow pays off in reduced engine temps.

http://garage.grumpysperformance.co...sion-and-oil-cooler-increases-durability.176/

http://garage.grumpysperformance.co...ing-system-flow-rates-and-heat-transfer.9880/

http://garage.grumpysperformance.co...er-and-remote-filter-require-a-new-pump.3144/
 
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We Don't ever talk much about Cost factor Grumpy.
I agree methods shown above are Best.
On top of my head , about $2,000.00 to do it.
 
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