Engine construction
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From: Seattle
Engine construction
I was talking to a buddy of mine about the way that engines have changed over time. Neither one of us could come up with a good reason for doing what the auto manufacturers have done/did with their engines.
Why did the manufacturers start using aluminum heads on the cast iron blocks? That was always a source of grief - the head would inevitably warp and ruin the engine. Seems like it they stuck with cast iron it would have been
a) Cheaper (cast iron is cheap)
b) Would eliminate head warp due to having 2 metals in contact with each other
c) Only be about 50 lbs heavier.
Why did they decide to go this route? Or put another way, if they decided to change the head, why not the rest of the engine?
Why did the manufacturers start using aluminum heads on the cast iron blocks? That was always a source of grief - the head would inevitably warp and ruin the engine. Seems like it they stuck with cast iron it would have been
a) Cheaper (cast iron is cheap)
b) Would eliminate head warp due to having 2 metals in contact with each other
c) Only be about 50 lbs heavier.
Why did they decide to go this route? Or put another way, if they decided to change the head, why not the rest of the engine?
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From: So Cal
There are a lot of engines with aluminum heads and or engine blocks. Reliability all depends on how they design the cooling paths.
Many of the high perfromance cars have at least aluminum heads. Due to better cooling they can give a bit higher compression and more power. Also every hundred pounds of weight is about 1/10th in the quarter miles.
I used to be on a Chebby Impala site and there was a lot of discussion about the aluminum engines and heads used in the Camaros and Corvettes, the Imp had all cast iron. There are tens of thousands or even millions of aluminum head and engine blocks out there. Maybe the engineering has improved a lot. There was no worry about aluminum reliability and many SS owners decided to do engine swaps or at least head swaps for the benefits mentioned.
I think the bigger problem with Aluminum and iron engines is that the dissimilar metals can have worse corrosion. So you have to keep up on the antifreeze and I am guessing there may be some design features to help minimize this.
About the only common aluminum part you probably don't want is aluminum rods. I have read that these pound themselves to death in a street engine. Better to use iron or steel rods.
Just my opinions, based upon reading and owning a couple Aluminum block and or head engines over time, never had a problem due to aluminum.
Jim Henderson
Many of the high perfromance cars have at least aluminum heads. Due to better cooling they can give a bit higher compression and more power. Also every hundred pounds of weight is about 1/10th in the quarter miles.
I used to be on a Chebby Impala site and there was a lot of discussion about the aluminum engines and heads used in the Camaros and Corvettes, the Imp had all cast iron. There are tens of thousands or even millions of aluminum head and engine blocks out there. Maybe the engineering has improved a lot. There was no worry about aluminum reliability and many SS owners decided to do engine swaps or at least head swaps for the benefits mentioned.
I think the bigger problem with Aluminum and iron engines is that the dissimilar metals can have worse corrosion. So you have to keep up on the antifreeze and I am guessing there may be some design features to help minimize this.
About the only common aluminum part you probably don't want is aluminum rods. I have read that these pound themselves to death in a street engine. Better to use iron or steel rods.
Just my opinions, based upon reading and owning a couple Aluminum block and or head engines over time, never had a problem due to aluminum.
Jim Henderson
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From: Marengo, Iowa
The 50 pounds makes a difference in fuel efficiency, the heat dissipation quality of aluminum makes a difference as well, and actually, cracking is more of a problem than warping typically. Dissimilar metals can be a bit of an issue due to different rate of expansion, and the corrosion angle, but that is why the stretch torque head bolts became so popular. As mentioned, many performance heads are also aluminum.
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Hmm, okay. So really its a matter of heat dissipation improvements and maybe some weight saved - although I have a hard time believing a commuter car benefits from the weight savings.
What about ceramic engines. Has anyone ever taken a look at something like that? Seems like a ceramic engine would have benefits above and beyond metal for a commuter or passenger vehicle. Despite opinions to the contrary, engines are much more efficient when they can operate at higher tempretures.
What about ceramic engines. Has anyone ever taken a look at something like that? Seems like a ceramic engine would have benefits above and beyond metal for a commuter or passenger vehicle. Despite opinions to the contrary, engines are much more efficient when they can operate at higher tempretures.
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From: The Big, Oregon
Aluminum heads are less prone to detonation with higher compression ratios due to their heat conductivity. Most aluminum heads are also later designs, and have better flow to begin with. Aluminum really doesn't have more of a warpage problem than iron, it's more a flaw in the attachment system, and like has been said before, cracking is a much bigger issue.
Head gasket shear hasn't been a problem since the early 90's, modern hg's have a lubricating layer on them to prevent shear issues.
Aluminum head have been used since the 30's, maybe even before, on many different brands of vehicles with a decent track record. Ford even put them on the flathead v8s from 33-38 (and before anyone says they must have been aftermarket, look it up. I had one here with Ford cast into the heads)
Head gasket shear hasn't been a problem since the early 90's, modern hg's have a lubricating layer on them to prevent shear issues.
Aluminum head have been used since the 30's, maybe even before, on many different brands of vehicles with a decent track record. Ford even put them on the flathead v8s from 33-38 (and before anyone says they must have been aftermarket, look it up. I had one here with Ford cast into the heads)
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Originally Posted by eigenvector
Hmm, okay. So really its a matter of heat dissipation improvements and maybe some weight saved - although I have a hard time believing a commuter car benefits from the weight savings.
What about ceramic engines. Has anyone ever taken a look at something like that? Seems like a ceramic engine would have benefits above and beyond metal for a commuter or passenger vehicle. Despite opinions to the contrary, engines are much more efficient when they can operate at higher tempretures.
What about ceramic engines. Has anyone ever taken a look at something like that? Seems like a ceramic engine would have benefits above and beyond metal for a commuter or passenger vehicle. Despite opinions to the contrary, engines are much more efficient when they can operate at higher tempretures.
The turd on a stick idea I recall was stamped steel engines....made up blocks with liners. And I think it was Ford working on it!!!
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From: The Big, Oregon
Originally Posted by 85e150six4mtod
The turd on a stick idea I recall was stamped steel engines....made up blocks with liners. And I think it was Ford working on it!!!
Fleet Mechanic
Joined: Jul 2004
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From: Travelers Rest SC
Actually, Crosley made a stamped steel engine for a number of years. Never heard a Crosley referred to as 'durable', though. As far as weight savings goes, engineers constantly look at the whole car to trim weight. Many car components have been put on diets over the years. Then they go and put more and more powerful engines in 'em. Go figure!
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