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#879113 - 04/12/07 08:47 AM Aluminum Block /Cast Iron Blocks ;heat conduction?
smokey1 Offline


Registered: 04/05/07
Posts: 1626
Loc: usa
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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#879114 - 04/12/07 09:44 AM Re: Aluminum Block /Cast Iron Blocks ;heat conduct [Re: smokey1]
lars11 Offline


Registered: 12/16/06
Posts: 916
Loc: Sweden
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

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#879115 - 04/12/07 11:07 AM Re: Aluminum Block /Cast Iron Blocks ;heat conduct [Re: lars11]
smokey1 Offline


Registered: 04/05/07
Posts: 1626
Loc: usa
it's a engine coolant issue . Thanks . Will keep monitoring this topic .

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#879116 - 04/12/07 01:13 PM Re: Aluminum Block /Cast Iron Blocks ;heat conduction? [Re: smokey1]
Merkava_4 Offline


Registered: 01/30/07
Posts: 15118
Loc: Clovis, CA
Aluminium conducts heat easier than iron, but also dissipates heat easier too.

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#879117 - 04/12/07 08:45 PM Re: Aluminum Block /Cast Iron Blocks ;heat conduction? [Re: Merkava_4]
smokey1 Offline


Registered: 04/05/07
Posts: 1626
Loc: usa
So , if quicker than cast iron, that would mean faster heat transfer to the coolant making the engine run cooler , no ?

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#879118 - 04/12/07 09:06 PM Re: Aluminum Block /Cast Iron Blocks ;heat conduction? [Re: smokey1]
punisher Offline


Registered: 09/11/04
Posts: 2339
Loc: snowblind in TX
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.

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#879119 - 04/12/07 09:08 PM Re: Aluminum Block /Cast Iron Blocks ;heat conduct [Re: smokey1]
1 FMF Offline


Registered: 08/12/02
Posts: 1680
Loc: CT
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.

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#879120 - 04/12/07 11:03 PM Re: Aluminum Block /Cast Iron Blocks ;heat conduct [Re: 1 FMF]
mechtech2 Offline


Registered: 09/05/06
Posts: 19479
Loc: Chicago Area
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.

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#879121 - 04/12/07 11:56 PM Re: Aluminum Block /Cast Iron Blocks ;heat conduct [Re: mechtech2]
smokey1 Offline


Registered: 04/05/07
Posts: 1626
Loc: usa
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 ?

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#879122 - 04/13/07 01:46 AM Re: Aluminum Block /Cast Iron Blocks ;heat conduct [Re: smokey1]
1 FMF Offline


Registered: 08/12/02
Posts: 1680
Loc: CT
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?

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#879123 - 04/13/07 03:57 AM Re: Aluminum Block /Cast Iron Blocks ;heat conduct [Re: 1 FMF]
smokey1 Offline


Registered: 04/05/07
Posts: 1626
Loc: usa
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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#879124 - 04/13/07 04:00 AM Re: Aluminum Block /Cast Iron Blocks ;heat conduct [Re: smokey1]
smokey1 Offline


Registered: 04/05/07
Posts: 1626
Loc: usa
ah yeh , in a technical and roundabout way .

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#879125 - 04/13/07 06:25 PM Re: Aluminum Block /Cast Iron Blocks ;heat conduct [Re: smokey1]
carock Offline


Registered: 03/05/06
Posts: 537
Loc: California
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.

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#879126 - 04/13/07 09:03 PM Re: Aluminum Block /Cast Iron Blocks ;heat conduct [Re: carock]
TexasHonda Offline


Registered: 01/22/05
Posts: 110
Loc: Katy, TX
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
_________________________
See you down the ROW.

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#879127 - 04/14/07 09:11 PM Re: Aluminum Block /Cast Iron Blocks ;heat conduct [Re: carock]
PT1 Offline


Registered: 02/06/07
Posts: 5746
Loc: near the mistake
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...
_________________________
Oils well that ends well...

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