Cast iron block vs. Aluminum block

[yeasure]

Some people are new to mod motors and don't have a clue, i say let them be clueless and when they start going to the track and seeing the big boys run with their aluminum blocks maybe then they will start reading/watching/learning/try to understand.
If you read this whole post you'll see some just can't understand no matter how much you show them, just let them have their cast iron block and be done with it.
On most of the boards i surf, we call them noobies oke: :-D

 

[Silver2003Cobra]

I've probably already replied to this thread sometime in the past.. but who cares

the FORD aluminum blocks aren't anywhere near as strong as the Teksid aluminum blocks, which is why for the Terminators SVT choose to use the cast iron block from the Mustang GT, instead of their aluminum block.. Now if Ford was to use the same casting technology they used on the 5.4 DOHC Ford GT's block, then YES it would be as strong as the Teksid block.. but I don't see that happening, atleast not for awhile..

 

[jonas]

I've probably already replied to this thread sometime in the past.. but who cares

the FORD aluminum blocks aren't anywhere near as strong as the Teksid aluminum blocks, which is why for the Terminators SVT choose to use the cast iron block from the Mustang GT, instead of their aluminum block.. Now if Ford was to use the same casting technology they used on the 5.4 DOHC Ford GT's block, then YES it would be as strong as the Teksid block.. but I don't see that happening, atleast not for awhile..

I wanted to share some facts about the history of the 4.6 cobra motor. Just to explain why these older ford cobra 96-98 blocks are the best stronges and lightest mod blocks ever made. SVT wanted an aluminum block for the new mod cobra but didnt have the technoligy to do it. they outsourced the operation to a small company called teksid in italy http://www.teksid.com/home.htm which is the same company that makes aluminum blocks for pretty much all the exotics like ferrari. Their proccess yealds a very high quality aluminum block cast. Its not just the design alone, theor aluminum manufacturing makes a better product.

Ford eventually gained the capability to make these aluminum mod blocs themselves and in 99 switched to getting the blocks in house. Their proccess is nowhere near as refined as teksid and their blocks are therefore weaker. So the only decision that svt had (this part is speculation and not fact) was to use the relatively weak 99-up aluminum block or go with the stronger yet much heavier iron block. Now the decision makes a bit more sense. They just dont have the technoligy or budget to aquire the technoligy to make a strong aluminum block so thats the only 2 choices they had.

just my 2 cents

 

[HISSMAN]

What he said. And what I said earlier.

 

[fiveohhhstang]

I would prefer a cast iron block. You can make a car with a cast iron block go essentially as fast as you want it to. I know having an aluminum block makes your car lighter, but unless you're really looking to lose time on your quarter mile or something the cost just isn't worth it. Plus, aluminum can't handle the heat as well, and I don't trust that very much.

 

[HISSMAN]

I would prefer a cast iron block. You can make a car with a cast iron block go essentially as fast as you want it to. I know having an aluminum block makes your car lighter, but unless you're really looking to lose time on your quarter mile or something the cost just isn't worth it. Plus, aluminum can't handle the heat as well, and I don't trust that very much.

OK, you need to go back and read all of the posts..especially the one's that I made.

 

[05 Roush]

OK, you need to go back and read all of the posts..especially the one's that I made.

I've read all the posts. I will also say that the heat coefficient for iron is much higher than aluminum, meaning it will absorb more heat and handle more abuse.

Any blocks running 600+ RWHP should be iron. Plain and simple. Anything less that that should be running aluminum. If you want the block to handle 600+ HP safely, it should be forged, regardless of whether it's iron or aluminum.

 

[jonas]

I've read all the posts. I will also say that the heat coefficient for iron is much higher than aluminum, meaning it will absorb more heat and handle more abuse.

Any blocks running 600+ RWHP should be iron. Plain and simple. Anything less that that should be running aluminum. If you want the block to handle 600+ HP safely, it should be forged, regardless of whether it's iron or aluminum.

Wow a forged block? same store you pick up blinker fluid and muffler bearings?

ok im assuming you mean internals yea agreed, anything pushing more than 350 hp or more than 10psi boost should be forged, I agree.

As for the heat issue, you have it backwards. I recall back in my 5.0 days that you can run more compression/boost on an aluminum headed car because the aluminum heads reject heat better. look at a radiator. Its either copper or aluminum for the same reason.

 

[GTSpartan]

FWIW, a top fuel draster I believe uses an aluminum block and they produce 7500hp. Correct me if I'm wrong.

 

[05 Roush]

Wow a forged block? same store you pick up blinker fluid and muffler bearings?

ok im assuming you mean internals yea agreed, anything pushing more than 350 hp or more than 10psi boost should be forged, I agree.

As for the heat issue, you have it backwards. I recall back in my 5.0 days that you can run more compression/boost on an aluminum headed car because the aluminum heads reject heat better. look at a radiator. Its either copper or aluminum for the same reason.

No, forged aluminum block. You won't get 8500 HP out of a standard aluminum one.

http://www.sme.org/cgi-bin/get-mag.pl?&&02fem072&000007&2002/02fem072&ARTME&SME&

Aluminum absorbs more heat, not rejects it. You are correct. It has a higher coefficient of heat, but it also has a higher coefficient of heat expansion, making it harder to maintain tolerances in higher temp applications.

 

[jonas]

No, forged aluminum block. You won't get 8500 HP out of a standard aluminum one.

http://www.sme.org/cgi-bin/get-mag.pl?&&02fem072&000007&2002/02fem072&ARTME&SME&

Aluminum absorbs more heat, not rejects it. You are correct. It has a higher coefficient of heat, but it also has a higher coefficient of heat expansion, making it harder to maintain tolerances in higher temp applications.

Ok this is stuff from college physics that I barely recall since its been almost 10 years and im now a "computer guy" by trade. The specific heat of an object doesnt change whether its being heated or cooled. It takes a certain amount of energy to go up a deg per amount of material. aluminums ability to accept heat easily, its good conduction of heat also lets it cool just as fast. Im fairly certain i am right, I can do web research and link formulas but that would be a waiste of both of our times. If you feel im wrong, please link me to proof. also in the computer industry, heatsinks are also made out of aluminum and copper for the same reason.

 

[05 Roush]

Ok this is stuff from college physics that I barely recall since its been almost 10 years and im now a "computer guy" by trade. The specific heat of an object doesnt change whether its being heated or cooled. It takes a certain amount of energy to go up a deg per amount of material. aluminums ability to accept heat easily, its good conduction of heat also lets it cool just as fast. Im fairly certain i am right, I can do web research and link formulas but that would be a waiste of both of our times. If you feel im wrong, please link me to proof. also in the computer industry, heatsinks are also made out of aluminum and copper for the same reason.

You are correct to a point. Aluminum does transfer heat better in air. But, remember that an engine block is typically water cooled, not air cooled. The convection film heat transfer coefficient is more important than the thermal conductivity of aluminum (do a search on the Fourier heat transfer equation). Both blocks will cool off about the same.

However, because of the larger coefficient of heat expansion of aluminum, there is a better chance of tolerance and cracking issues in high temperature, high stress applications. Plus, iron retains more cylinder heat (convection), which in many cases is better for combustion. When you forge the metal, however, that's a different story.

As for radiators, the main reason why aluminum ones are used is corrosion. That and they're lighter and cheaper to make than copper radiators. The heat dissapation is dependent more on the coolant than the metal.

Hope this makes sense.

 

[yeasure]

Why can't people understand people like SHM, Big John, Dave King(others) have tested these engines/blocks time after time since 1996 and they will tell you the aluminum blocks are the strongest period.
You still have people say otherwise.
I say this, you show me proof that fords cast iron blocks(mod motors) are stronger then it's older aluminum blocks and this will all end.
Problem is you're not going to because it is fact fords pre aluminum blocks are the strongest period.
I don't give a rats ass about other blocks that nascar/top fuel/gokarts are using, we are talking about "FORDS" mod motor blocks "ONLY".
Btw for the record, SHM says the 99 block is the strongest, then 96-98.....99 beening the last year they were bought/used from Italy.

 

[jonas]

Why can't people understand people like SHM, Big John, Dave King(others) have tested these engines/blocks time after time since 1996 and they will tell you the aluminum blocks are the strongest period.
You still have people say otherwise.
I say this, you show me proof that fords cast iron blocks(mod motors) are stronger then it's older aluminum blocks and this will all end.
Problem is you're not going to because it is fact fords pre aluminum blocks are the strongest period.
I don't give a rats ass about other blocks that nascar/top fuel/gokarts are using, we are talking about "FORDS" mod motor blocks "ONLY".
Btw for the record, SHM says the 99 block is the strongest, then 96-98.....99 beening the last year they were bought/used from Italy.

I already said it. The production 96-98 blocks are better than the iron 03. i base it on what I see in modular drag racing as well as these blocks are produced by arguably the best aluminum automotive block manufacturer on the planet. as for longevity Its been proven over and over with almost every new car these days sporting aluminum blocks. That arguement is between you and platnum, not me. If I had the money yea id do it but Im quite happy with what ford gave me and cant justify getting a new block unless I toasted this one and I honestly believe it wont happenen unless I somehow get into the 800rwhp range. Im quite happy with 600rwhp on 91 octane and the 03-04 blocks Have seen up to 900rwhp that I know of with no probs.

 

[jonas]

You are correct to a point. Aluminum does transfer heat better in air. But, remember that an engine block is typically water cooled, not air cooled. The convection film heat transfer coefficient is more important than the thermal conductivity of aluminum (do a search on the Fourier heat transfer equation). Both blocks will cool off about the same.

However, because of the larger coefficient of heat expansion of aluminum, there is a better chance of tolerance and cracking issues in high temperature, high stress applications. Plus, iron retains more cylinder heat (convection), which in many cases is better for combustion. When you forge the metal, however, that's a different story.

As for radiators, the main reason why aluminum ones are used is corrosion. That and they're lighter and cheaper to make than copper radiators. The heat dissapation is dependent more on the coolant than the metal.

Hope this makes sense.

Ok first paragraph. I vaugly recall issues with film contact with aluminum and needing special coolant that broke down surface tension of water to "wet" the aluminum better for aluminum engines/radiators (now all modern coolants run fine with aluminum engines/radiators)

The 2nd paragraph I agree and disagree at the same time because it depends on application. On an N/A 5.0 at stock 9.0 compression you would get less hp out of an aluminum head than an Iron head if the casting was exactly the same. For a blown/turbo/nos/highcomp car you want to get rid of as much heat as possible because you are now making loads of it. This is from my old school 5.0 days. We ran Iron blocs and aluminum cylinder heads. (remember the twisted wedge rage? oh I miss those days ) Ford gave us aluminum cylinder heads for that reason.


3rd paragraph. They dont make copper radiatiors, they make them copper/brass allow because copper alone is too soft (copper is one of the components in the brass alloy). aluminum is actually worse than brass for radiator material but its not much different but its weight savings over brass is something like 3 to 1 (just an educated guess I didnt look it up but its a huge diff) and automobile manufacturers have pretty much gone all aluminum for weight savings for fuel economy. the copper/Brass alloy is also MUCH less corrosive than aluminum. This is probably the only thing i have to 180 disagree with you on. I do agree that copper by itself is highly reactive and will oxidize much more easily that aluminum. One of the reasons you must check and verify at least back in the day of your coolant was compatible with aluminum radiators/blocks for additives that protect aluminum and lower water surface tension to allow proper thermal conduction between the aluminum and the coolant.

 

[jonas]

Correct me if im wrong but Ive never heard of a forged block being offered in any production automobile. With the exception of some ultra exotics and racing apps, all production blocks including the teksid are cast right? Anyone fill me in on this, I'd like to know.

 

[mike79]

Ok I just read this thread, AGAIN. I still cant beleive the same points are being said over and over again. Yeasure, I feel your pain

 

[05 Roush]

Correct me if im wrong but Ive never heard of a forged block being offered in any production automobile. With the exception of some ultra exotics and racing apps, all production blocks including the teksid are cast right? Anyone fill me in on this, I'd like to know.

Correct, and you are correct in the previous post. It does depend on the application.

Aluminum is less resistant to corrosion than copper/brass. However, it's not the metal that fails in radiators, it's the joints. Newer aluminum radiators use epoxy or aluminum brazing to weld joints together, whereas brass/copper ones use solder brazing. This is why manufacturers have changed to aluminum.

Coprobraze technology may sway manufacturers to return back to copper, but we'll just have to wait and see.

 

[yeasure]

I'm not a SHM fan boy for the record, honestly i've bought one thing from SHM.....his book.
If you own a mod motor, you should already have this book, nothing but great info you should know about the mod motors you own.
I've heard bad things about SHM but even if they are true i still have to give them 100% respect for what they've done.

 

[05 Roush]

I'm not a SHM fan boy for the record, honestly i've bought one thing from SHM.....his book.
If you own a mod motor, you should already have this book, nothing but great info you should know about the mod motors you own.
I've heard bad things about SHM but even if they are true i still have to give them 100% respect for what they've done.

I may have to grab me a copy. :beer: