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Old 08-12-2015, 11:56 PM
 
Location: New Orleans, LA
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Old 08-13-2015, 12:20 AM
 
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cast iron = heavy engines, stiff blocks, long wearing cylinders.

aluminum = lighter weight, flexible blocks, requires steel sleeves for long wear.

in the end it depends on what you are wanting from the engine and the car. for instance if i were to build a race car, i would use an aluminum block if the rules allowed. mostly because i would want the lighter weight so i could put the lost weight where ever i needed it to balance the race car. an aluminum V8 is about 200lbs less than an cast iron V8 of similar design, and that means i could put that 200lbs on the right rear to aid traction coming off the corners, or distribute that weight on the left side to help eliminate body roll to the right on a circle track car.

in the end neither engine is better than the other, because you have to take into account the application.
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Old 08-13-2015, 01:07 AM
 
Location: NWA/SWMO
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Aluminum. NOONE has gone from Aluminum to cast iron. Aluminum engines manage heat better, weigh less, and are even more durable because plasma cylinder walls or steel inserts are more durable than cast iron ever was. They also don't have the ungodly expansion differentials that cast iron engines have, with aluminum heads. And NOONE is running cast iron heads anymore who is anywhere NEAR cutting edge.
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Old 08-13-2015, 06:12 AM
 
447 posts, read 729,269 times
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Quote:
Originally Posted by JWG223 View Post
Aluminum. NOONE has gone from Aluminum to cast iron. Aluminum engines manage heat better, weigh less, and are even more durable because plasma cylinder walls or steel inserts are more durable than cast iron ever was. They also don't have the ungodly expansion differentials that cast iron engines have, with aluminum heads. And NO ONE is running cast iron heads anymore who is anywhere NEAR cutting edge.

Another reason is the aluminum is much lighter and helps get better fuel economy. You can make as much or more HP with cast iron heads but they are heavier so most performance heads are aluminum. But if I would accidently overheat my eng I would want cast iron. I remember when a belt came of my old cast iron 273 V/8 eng and it hit like 250 degrees. But the eng and all was ok and had no problems at all. I know if that had been an aluminum eng I would have had problems.

But I should have also been watching my temp gauge closer. I was younger and dumber when that happened. But I agree aluminum if the future as thats what everyone seems to be going with. Ron
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Old 08-13-2015, 07:07 AM
 
Location: Miami, FL
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MOPAR Hemi blocks still cast iron.
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Old 08-13-2015, 08:03 AM
PDD
 
Location: The Sand Hills of NC
8,773 posts, read 18,292,121 times
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Quote:
Originally Posted by rbohm View Post
cast iron = heavy engines, stiff blocks, long wearing cylinders.

aluminum = lighter weight, flexible blocks, requires steel sleeves for long wear.

in the end it depends on what you are wanting from the engine and the car. for instance if i were to build a race car, i would use an aluminum block if the rules allowed. mostly because i would want the lighter weight so i could put the lost weight where ever i needed it to balance the race car. an aluminum V8 is about 200lbs less than an cast iron V8 of similar design, and that means i could put that 200lbs on the right rear to aid traction coming off the corners, or distribute that weight on the left side to help eliminate body roll to the right on a circle track car.

in the end neither engine is better than the other, because you have to take into account the application.
You forgot Compacted Graphite blocks which that little 2.7 liter F150 engine is using to outperform the V-8's That is the same material that is used in Fords diesel engines.

I will probably be the basis for all high stress engines in the future.


Leave the Iron On: Ford Buries New-Age Iron in Its Aluminum-Intensive 2015 F-150 - Tech Dept. - Car and Driver

Last edited by PDD; 08-13-2015 at 08:20 AM..
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Old 08-13-2015, 12:08 PM
 
Location: By the sea, by the sea, by the beautiful sea
68,271 posts, read 53,985,563 times
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Quote:
Originally Posted by rbohm View Post
cast iron = heavy engines, stiff blocks, long wearing cylinders.

aluminum = lighter weight, flexible blocks, requires steel sleeves for long wear.
Audi's very successful endurance racing diesels have aluminum blocks, likely as difficult a test of blocks as you're likely to find, no steel liners either.
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Old 08-13-2015, 01:09 PM
 
Location: Eastern Washington
17,106 posts, read 56,712,890 times
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Quote:
Originally Posted by burdell View Post
Audi's very successful endurance racing diesels have aluminum blocks, likely as difficult a test of blocks as you're likely to find, no steel liners either.
928 Porsche as well. These get a "Nicasil" or "Alusil" treatment, makes them wear better than iron. Almost impossible to wear them out in honest use, even if driven quite hard.

An iron block with an aluminum head gives some of the best of both worlds, at a lower price point than an all-aluminum engine can.

The one way to ********** up is to have an aluminum block with an iron head - I had forgot that GM did this on some 70's cars.
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Old 08-13-2015, 01:20 PM
 
33,387 posts, read 34,617,896 times
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Quote:
Originally Posted by burdell View Post
Audi's very successful endurance racing diesels have aluminum blocks, likely as difficult a test of blocks as you're likely to find, no steel liners either.
very true, but those engines are rebuilt after every race. an aluminum block with no liners in the cylinder bores will not go 100,000 miles, as those that owned a vega can attest.

and i made no assertions as to which one was better anyway, i merely pointed out the advantages and disadvantages of each material, and which one i would prefer if i were building a race car, or other vehicle, and if the rules allowed it.
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Old 08-13-2015, 01:31 PM
 
Location: We_tside PNW (Columbia Gorge) / CO / SA TX / Thailand
34,548 posts, read 57,460,499 times
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C.I. vs Al, very application dependent...
CI has dimensional stability across a WIDE heat range and would be considered more robust / forgiving / longevity.

I have seen Al brought to catastrophic failure due to HIGH temps in a turbo fed combustion chamber (and why I do not plan on buying a Dura Max for HD truck application (tho they seem to be holding up... there are aftermarket replacements for Dura Max Al Heads for some reason...)


Quote:
Originally Posted by burdell View Post
Audi's very successful endurance racing diesels have aluminum blocks, likely as difficult a test of blocks as you're likely to find, no steel liners either.
but... audi has an unlimited supply of these lightweight diesels and the time / money / labor to change them between each race. Glad they are paying for the research on this!

regretfully, I spend plenty of time 'fixing' / deal with the burden of Al heads on Cast Iron blocks. Not a pretty solution (differential Thermal expansion).

Physics is Physics... some things will not change (thermal expansion can only slightly be mitigated by alloys).

Flexible (stretch) bolts (torque to yield) have helped, but stuff is STILL moving between every heat cycle, that stuff will eventually leak (highly probable).

General heavy service, I will stick with CI. (dozers / trucks / work horses) but... I appreciate AL engines on my racing motorcycles!
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