ENGINE BLOCKS: Aluminum vs. Iron

what is up engine heads welcome to another episode of d4 race engine bootcamp and in today's episode we're talking about the backbone of every internal combustion engine the engine block of course and in today's episode we're going to cover the differences between iron and aluminum engine blocks in relation to their strength performance reliability durability heat conductivity and more but we're also going to be talking about engine blocks in general and why they point such a key role in every engine so sit back and get ready to absorb some knowledge the engine block is the backbone of every internal combustion engine if engines were humans I guess the engine block would be their skeleton and a human without a skeleton would be just a blob of meat so to an engine without an engine block would be just a mess of parts on the floor the engine block is the single largest and most intricate piece of metal on any internal combustion engine all the big stuff gets bolted to the engine block the cylinder head the oil pan and even the transmission everything gets bolted to the engine block the engine block is as old as the internal combustion engine itself it was there from day one and it will be there until the end now the first ever aircraft engine to fly the one in the 1903 Wright Flyer had an aluminum engine block obviously for weight saving purposes however aluminum engine blocks were rare throughout most of the internal combustion engines history where iron engine blocks dominated for a pretty long time but already in the sixties and the seventies you could find a woman on engine blocks in mass-produced passenger cars however 12 the 60s and the 70s aluminum engine blocks held around 1% of the market share of all newly produced internal combustion engines however as time moved on this percentage increased and by the way tonight these aluminum engine blacks accounted to almost 1/3 of all new produced engine blacks but beyond this point ever tighter emissions and fuel consumption regulations pushed manufacturers to try and find ways of making ever lighter and ever more efficient engines and vehicles and this is what tipped the scales in favor of aluminum engine blacks because aluminum is lighter it takes less fuel to move it around so by 2005 aluminum engine blocks were present in as much as half of all mooing manufactured internal combustion engines today in 2020 aluminum engine blocks are present in more than two-thirds of all newly manufactured internal combustion engines pretty much every new petrol engine now comes with an aluminum engine block and the woman dimension blocks are even taking over when it comes to turbo diesel passenger cars stationary engines and commercial diesel engines seem to be the last real strongholds of the iron engine black but newly manufactured engines aside the iron engine black definitely isn't dead the remanufacturing industry definitely still loves their iron engine blocks and you will still find many enthusiasts racers and tuners sticking to the good old iron engine block they re machining and rebuilding these engine blocks into some very serious and capable engines now simply saying aluminum or aluminium if you will and iron is a bit misleading and a bit inaccurate and this is because within the term aluminium we have hundreds of different alloys and within the term great cast iron the iron typically used to cast inch blocks we have dozens of different grades and classes so to be more accurate let's see what kind of Oh minim and what kind of iron is actually used to make engine blocks now as I said engine blocks the iron ones are typically cast using great cast iron this is one of the cheapest possible castings you can have and everything from manhole covers and hammers to gears and valve bodies and engine blocks and cylinder heads is made from gray cast iron now the classes of great cast iron that are typically used to make engine blocks are class 20 and 25 and these have a typical tensile strength rating of anywhere from twenty to twenty-five thousand psi now something else that is pretty rapidly emerging when it comes to cast iron engine blocks it's called CGI no not this kind of CGI in this case actually CGI stands for compacted graphite iron and it has a tensile strength rating that is one and a half to two times greater than that of great cast iron however it is still it is in most cases reserved for high-pressure fuel injection commercial diesel engines as seen in trucks and agricultural vehicles and it's almost never employed in passenger vehicles which is why in this video when I say cast iron engine box I'm referring to the classes of grey cast iron typically used to cast passenger vehicle engine blocks now when it comes to aluminum aluminum engine blocks are typically made from the 319 or the a three five six or the a three five seven hours and here you can see what these hours are made from other than aluminum now all these hours receive either 85 or t6 heat treatment before the blocks are machined without heat treatment of these hours would be very very weak and unsuitable for engine blocks not a typical tensile strength rating off these hours is between 10 and around 14,000 psi now there's another only I called 6061 and this one's a lot stronger it has a tensile strength of around 60 to 70 thousand psi but it's only used in billet aluminum engine blocks this is an aftermarket only type of engine block that is machined and reserved for the highest levels of extreme Motorsports and it's almost never seen outside those spheres and in this video when I say aluminum engine blocks and referring to these three hours which is what you're going to see in a William engine box and I'm not talking about 6061 because these three hours is what most of us actually have access to now both aluminum and iron engine blocks are cast this means that you melt the metal and pour it into some sort of mold and while iron isn't particularly sensitive to the way it's being cast aluminum is different and is a bit of a disadvantage here because aluminum forms a layer of oxide on surface almost immediately after being exposed to air this property aluminum is even more prominent when aluminum is in a liquefied State and this is why in the past parts cast from aluminum would usually contain within themselves layers of oxide these were most often invisible but were a serious compromise to the structural integrity of the parts and very common fracture points but casting has come a long way from the simple melting and pouring of metals and this is right today you are going to hear fancy terms like squeezed casting in poor packaged systems in sand casting as well as advanced vacuuming and mold feeding techniques and all of this is part of a extremely accurate computer-controlled process which has resulted in giant leaps when it comes to the quality of aluminum engine blocks but a woman who is expensive typically three to four times more expensive than iron depending on the alloy and these advanced casting technologies are expensive as well so manufacturers of course try to save money and advanced casting technology hasn't really spread to all engine segments and even today you are still going to find aluminum engine blocks in economy engines made from simple primitive casting methods resulting in weaker in the lesser quality engines but in general aluminum engine blocks have come a long way and are much much stronger and much much better compared to their ancestors from the 80s and early 90s wait is aluminum's biggest advantage over iron and you want your vehicle components to be as light as possible because the less weight means better fuel economy OS weight means better acceleration and aluminum is more than twice as light as iron here we have specific weight of aluminum and here we have a specific weight of iron by being twice as like this I don't you would expect that an aluminum engine block is more than twice as light than iron engine block but in practice in reality that is almost never true and this is because a woman 'm is weaker than iron as we have seen a woman um has a lower tensile strength when compared to iron so the walls of aluminum engine blocks need to be made thicker to compensate for this difference in strength and while modern casting techniques are increasing the weight gap between aluminium and iron engine blocks on average in general aluminum engine block still haven't managed to be twice as light as their parent counterparts and here we have the average weight of homonym engine blocks in inline-four engines v6 and v8 engines here we have the average weight of iron engine blocks in a nine force v6 and v8 as you can see they aren't twice as light when it comes to a woman um but the differences still are significant and aluminum engine blocks are noticeably lighter you might think that fifteen kilograms isn't much but it is in the engine block alone constitutes around one and a half to two percent of the entire weight of a vehicle and over a long period of time the fuel savings from this difference in weight becomes significant and the acceleration types that are improved because of this are also pretty important as well as we already know Iren is stronger than a woman 'm it resists all forms of deformation better than aluminum it is stiffer than aluminum and this is why a woman imagine blacks need to employ a more intricate design with numerous reinforcement rips and other tricks up their sleeve to compensate for this difference in strength an example of this are main bearing collateral frames you are often going to find main bearing the latter frames that further reinforce the structure of the aluminum engine block in many performance oriented engines with aluminum engine blocks on the other hand you are almost never going to find a ladder frames in iron engine blocks even engine blocks such as the famous 2jz which is capable of sustaining around 800 horsepower in bone stock form doesn't employ a main bearing go out of frame it simply isn't necessary the iron material the block itself even with a pretty simplistic casting is simply that strong and that stiff and this is also the reason why you are something sometimes not going to find a main bearing the latter frames but cast iron main bearing caps inside aluminum engine blocks they're there to help reinforce this important structural element of the engine block now strength is just one part of the equation the other part is where iron has significantly better wear resistance than aluminum and this is why onnum engine blocks are almost never made entirely from aluminum many aluminum engine box employ cylinder liners which are so Eve's that are inserted into the aluminum engine block there are either dress fit or inserted during the casting process and the block is gassed around and the material of choice for these sleeves in aluminum engine blocks is in many case you guessed it ayran ayran is just that good when it comes to wear resistance how there are also liner or less so aluminum blocks without any sleeves instead the boards of these blocks have special coatings known as Nick a cell or a cell or MMC or a bunch of different names and they aren't press-fit or installed there they're either plasma sprayed or etched onto the bores and while this has been a failure in some engines in others it has performed very well without any issues so it's sort of a mixed bag when it comes to my nervous homonym engine blocks a big ol fat and heavy iron engine block is great for doing two things absorbing noise and absorbing vibrations again aluminum tries to compensate with more complex and intricate castings but in general and iron engine black is gonna vibrate to us and you're gonna hear a less of its internals aluminum engine box experience greater heat expansion than iron engine box in fact by the time it reaches operating temperature and a woman in black will have expanded usually twice as much as an errand one but iron box expands so with all that expanding twice as much still isn't a lot at all and under normal operating conditions these expansions of aluminum engine blocks aren't noticeable measurable or even relevant in almost all daily driven engines but what if the engine overheats well this is when the aluminum engine block is at a disadvantage because in overheating scenarios and aluminum engine block is more likely to work this is going to cause a permanent change to its shape which is going to require major engine servicing and overhauling to be repaired in the worst-case scenario the damage is going to be irreparable and the aluminum block is going to be destined for the scrap heap but a woman imagine blacks also have an advantage when it comes to heat and that's that they're better conductors of heat compared to iron blocks this means that a woman imagine blocks typically reach operating engine temperatures faster than iron and your box it also means that a woman on blocks are capable of transferring more of their heat away onto their coolant when compared to piling blocks this is also by iron box typically run hotter than aluminum engine blocks but most importantly aluminum engine blocks are capable of pulling away more heat from the combustion chambers and this is really important because it enables engineers to specify higher compression ratios for the engine and higher compression ratios are great for both performance and fuel economy by having a lower temperatures in your combustion chambers you reduce the risk of hot spots and engine damaging detonation besides weight this is the other key reason why aluminum engine blocks are taking over it's also the reason why performance flagship engines of many of the world leading car manufacturers have switched from island to aluminum engine blocks and why the newer engines almost always have a higher compression ratio compared to their predecessors both Iran and the woman imagine blocks can crack and while this doesn't happen very often when it does a woman Amanda blocks are easier to repair then iron once when old man Jabbar cracks the crack can be ground away and then filled in using a TIG welder if an iron engine bar cracks it can be repaired but it's pretty difficult it requires great skill a furnace welder and the success rate is a lower when compared to aluminum engine blocks what about rebuilding well in general iron engine blocks are easier to rebuild than aluminum ones iron engine box are simple when over boring them you're basically machining the board itself there aren't any liners or so leaves and even a poorly equipped machine shop can deal with a basic iron engine block also iron engine blocks are less likely to be distorted during the rebuilding process and while the sleeves of some aluminum engine box can be machined just like the bores of iron blocks typically aluminum blocks are more limited in the number of times you can do this plus Reese leaving an aluminum engine block is often more tricky and requires more skill and experience when compared to the receiving process often iron engine block when it comes to ly nervous aluminum engine blocks often it isn't possible to rebuild these blocks at all because reapplying the special coatings on their boards is often impossible or it simply doesn't make any financial sense and this is why line Arles box are usually thrown away once they reach the end of their lifespan and you have to buy a new block from the manufacturer which is almost always a lot more expensive than a rebuild and this is why iron engine blocks make great choices for cheap and easy boosted power because they're strong and stiff they can typically take more boost than an aluminum engine block and because they're easy and cheap to rebuild they make a great choice great combinations for enthusiasts working for quick and easy boosted power so here I have made a score table for iron and aluminum blocks and as you can see they score an equal total number of points and this is just my opinion but in reality both of these types of box have significant advantages and to say that one is absolutely better than the other would be wrong which one is better depends on the scenario and the application and which one is better should be considered at a case-by-case basis for example if you're just gonna daily drive your engine you're gonna benefit more from the increased efficiency and the water weight aluminum engine blocks but if you're looking to two and rebuild something and have fun with boost on the cheap then an iron engine block might be a better choice for you also it's wrong to assume that an engine block is gonna be strong and heavy just because it's made of iron and then an engine block is gonna be light and weak just because it's made from aluminum there are many iron engine blocks that are poorly made and that are gonna crack under the slightest amount of boost and there are many aluminum engine blocks that are really strong and that are capable of handling a lot of boost and abuse so again information is power and consider everything on a case-by-case basis but in general these are the differences between the two types of engine blocks so I hope you found this useful and informative as always thanks so much for watching and I'll be seeing you soon with more stuff on the beforeI engine boot camp

Channel: driving 4 answers

Views: 995,806

Keywords: aluminum engine block, aluminum crankcase, aluminum cylinder block, aluminum vs iron engine blocks, cast iron engine block, aluminum block vs iron block for boost, iron block vs aluminum block ls, aluminum engine block history, 5 3 aluminum block vs iron, ls cast iron block vs aluminum, cars with cast iron engine blocks, cast iron vs aluminum strength, 2jz, 2jz gte, 4g63, 4b11, k20, rb26, rb26det, b58, supra engine, aluminum, cast iron, vr38, vr38dett, aluminum alloy engine blocks, cnc

Id: dIjtap8GLF8

Length: 20min 9sec (1209 seconds)

Published: Sun Apr 19 2020