Aluminum Block /Cast Iron Blocks ;heat conduction?

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Does aluminum conduct heat less than cast iron ? I know one reason for aluminum is the weight , = better mileage . Will possibly post another topic depending on the outcome .
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no, actually aluminum conducts heat better. Why do you ask? Heat conduction in the engine is not really an issue if its not a air cooled thing. Other engineering properties are more important
 
it's a engine coolant issue . Thanks . Will keep monitoring this topic .
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So , if quicker than cast iron, that would mean faster heat transfer to the coolant making the engine run cooler , no ?
 
Well, an aluminum head transfers heat away from the combustion chamber faster than iron so you can get away with a slight compression ratio boost, advanced timing or a leaner mix. The combustion chamber will run cooler, but the total heat output of the engine is the same despite the head material.
 
not sure what you're looking for, but in the grand scheme of things it depends on the path the heat flows into the coolant, and the basic design of the engine.
In the case of aluminum blocks, for a traditional V-8, they have iron cylinder liners so you really don't figure heat transfer based on aluminum, at least from the cylinder into the block. I don't remember where the majority of the heat comes from and how it flows out of the engine, there was a good article either somewhere here on this site or out in the internet cloud about it.
In the case of cylinder heads, not sure if the majority of heat from the cylinder enters the coolant here, but they plays a big part in engine performance and the ability of the heads to manage the heat is very important! In most all cases iron block motors with aluminum heads outperform iron heads. Not sure where you're going with this, but, you might want to consider cylinder heads in addition to the block when considering heat transfer.
 
Aluminum cylinder heads cool faster than cast iron heads. This allows more ignition advance and higher compression to be used, with power and gas economy gains. Also, the light weight helps a little.
 
so , let's say if you use an syn-oil such as MOBIL 1 in the aluminum engine , could it perhaps help lower the cooling of the block , which in return lower coolant temp. , then possibly affecting the temp. gage needle to lower a bit and taking needle a little longer to reach that point ?
 
I would say no because, from memory of article i was referring to and some common sense, the source of all the heat in a motor is from combustion within the cylinders. The amount of heat caused by moving (lubricated) parts, provided they are properly lubricated, is insignificant compared to heat generated within the cylinders.
If you want to make an argument such that running less oil in the oil pan or using the wrong viscosity oil can increase heat in the engine, then I could see some validity in that. Since you mentioned using a synthetic oil, I get the impression you're looking to find out if a "synthetic" oil is reducing friction generated heat enough to where you are seeing that affect on your coolant temp gauge and by how long it takes the gauge to get to operating temp?
 
Yes , but the pistons do travel a ways in the cylinders generating heat over fairly good amount cylinder walls . Also , I would assume some heat is dispersed out the manifold . This is very mind boggling .
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Oil picks up heat directly from the engine. Redline synthetic oil has a heat transfer capability that is about 25% better than dino oils, so your engine will run cooler. The effect is noticable with smaller engines that work hard, like Fiats.
 
Warmup time might be affected slightly by cast iron vs. aluminum but remember you have a thermostat to maintain constant operating temperature. Overheating is only issue if something is not transferring heat as designed (electric fan inop, radiator blockage, low coolant, etc).

Increased heat transfer has no value except in design, where a designer might be able to reduce cooling system weight (coolant capacity, radiator size) and fan air flow rate (smaller fans).

Some aluminum blocks (honda) have cast iron sleeves for better wear performance. Hard to argue w/ durability of Honda engines. I'm pretty sure the reason is weight and heat transfer impact is probably negligible.

regards
 
Quote:


Oil picks up heat directly from the engine. Redline synthetic oil has a heat transfer capability that is about 25% better than dino oils, so your engine will run cooler. The effect is noticable with smaller engines that work hard, like Fiats.




Very noticable with air cooled motorcycle engines although there are "experts" on this forum who disagree based on some mumbo jumbo lingo they have developed to intimidate non-chemists. If you have any technical data/facts on this please post it. I would love to copy it and paste it on my cubicle wall at work so I can commit it to memory...
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"for a traditional V-8, they have iron cylinder liners so you really don't figure heat transfer based on aluminum"


do all aluminum blocks employ steel sleeves? my mazda is the first aluminum block ive owned.
 
smokey1 the rings are not produceing any heat they are helping to carry heat away. The rings should not be toaching anyting other then oil film unless the engine has mechanical issuses. The heat is all a byproduct of combustion if all of those part inside the engine were rubbing metal on metal all of the time they would wear away in no time flat. The amount of heat generated from direct friction from metal onmetal rubbing is minimal.
 
No all aluminium blcoks do not contain an iron or steel sleve. Some use a high slicone content or nickle and silicon content in the area of the bores. When they machine it it leaves a hard very even surface. I am not a fan of nickle-sel(sp) technology at all. I also do not like the other compostite coating that are sprayed on either. You basicly end up with an engine that is horably heat sensitive and can not be rebuilt. Usualy Aluminum blocks with cast in sleves tend to be much more durable then engine with press in sleeves or no sleeves at all!!!
 
chevy vega engines had aluminum blocks but either no sleeves or very lousy ones. They cylinders got ovaled during warranty and they burned tons of oil and went to the junk heap quickly.

At any given thermostat temperature they want a consistent cylinder temp without any hot spots that can cause detonation. But they want it warm enough for good emissions. They're always tweaking the water jacket and flow characteristics to get this right, and I'm sure metallurgy/conductivity plays a part that they consider.
 
so what's the outcome ?????

you said this was a coolant issue,
and still not sure what you're looking for regarding how oil (lubrication) factors into things but here are the numbers I was thinking of:
sum oil vs coolant temps in technical & white papers
http://theoildrop.server101.com/forums/s...ge=0#Post721468

at 2000 rpms:
piston undercrown = 76% to 72% heat into the oil from 2000 rpms vs 4000 rpms;
main bearings = 13% @ 2000 rpms and 19% @ 4k rpms
oil pump = 8% heat into oil
 
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