Some details of the 2AZ-FE engine
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From: C. E. White on 15 Jul 2008 07:47 "Hachiroku ハチロク" <Trueno(a)e86.GTS> wrote in message news:pan.2008.07.15.14.41.47.208604(a)e86.GTS... > On Mon, 14 Jul 2008 20:08:50 -0700, Built_Well wrote: > >> The cylinder head cover (not to be confused with the cylinder >> head) is made of magnesium alloy for lighter weight. I think >> cylinder head cover is synonymous with "valve cover," but the >> Camry manual refers to it as the "cylinder head cover." > > Yeah, that's the valve cover... >> >> Since the manual doesn't mention what the cylinder head, itself, >> is made of, I will assume iron, but just an assumption. > > Toyotas have been using aluminum heads for as long as I can > remember. My > first Corolla, a '74, had an iron block and aluminum heads, which > worked > well for them, but was a fatal combination for certain Chevy (VEGA) > models... Actually Vegas had aluminum blocks and cast iron heads! One of the stangest combinations ever. The original Vega block was the linerless aluminum type and was die case with an open top deck. The aluminum alloy had a lot of silicon in it .The theory was that the aluminunm would wear away slightly, exposing the silicon surface, which would prevent (or at least slow down) further bore wear. The block was very light and not particulalry stiff which is why they used a cast iron cylinder head to provide the stiffness absent from the block. I suppose the test engines all worked well. Unfortunately, in the real world, things did not work so well. The whimpy blocks couldn't take any "normal" abuse. The slightest overheating would lead to rapid bore wear and significant oil consumption. Hard driving would cause block distortions which also led to rapid bore wear and significant oil consumption. Poor maintenance practices led to rapid bore wear and significant oil consumption. Etc. Essentially driving the car led to rapid bore wear and significant oil consumption. But it often was not much of a problem since rust usually ate the body away before oil consumption was too bad. Body rustwas not a problem restricted to Vegas by the way. Toyotas of the era were at least as prone to rusting away. BTW, Porsche and Mercedes use the linerless aluminum blocks that GM tried on he Vega. But even today, you don't want to overheat an engine using that technology. Ed
From: Built_Well on 15 Jul 2008 08:53 JoeSpareBedroom wrote: > Built_Well wrote > > > > > Gonna write this stuff down and post it so I don't lose it. > > ============= > > Of course, you could've just written it down in a text document and saved it > rather than posted it, assuming the actual purpose was to not lose it. ================= Joey, you should take a hint from Jeff Strickland. He's much more polite and together than you.
From: N8N on 15 Jul 2008 09:04 On Jul 15, 10:41 am, Hachiroku $B%O%A%m%/(B <Tru...(a)e86.GTS> wrote: > On Mon, 14 Jul 2008 20:08:50 -0700, Built_Well wrote: > > The cylinder head cover (not to be confused with the cylinder > > head) is made of magnesium alloy for lighter weight. I think > > cylinder head cover is synonymous with "valve cover," but the > > Camry manual refers to it as the "cylinder head cover." > > Yeah, that's the valve cover... > > > > > Since the manual doesn't mention what the cylinder head, itself, > > is made of, I will assume iron, but just an assumption. > > Toyotas have been using aluminum heads for as long as I can remember. My > first Corolla, a '74, had an iron block and aluminum heads, which worked > well for them, but was a fatal combination for certain Chevy (VEGA) models... IIRC it was backwards... the Vega had an aluminum block with an iron head. This was back in the day before the Nikasil and similar processes were perfected, and I am guessing that simple piston/bore wear was the cause of most of the mosquito fogging action that the Vegas were famous for. I remember when I was a kid the neighbors across the street had one and it would lay one heck of a smokescreen. Was an attractively styled little car but the engines were definitely a weak link. I believe that John DeLorean addressed some of the engineering mishaps in the Vega's development in his book, but it's been years since I read it so I'm a little furry on the details. nate
From: N8N on 15 Jul 2008 09:16 On Jul 15, 7:47 am, "C. E. White" <cewhi...(a)removemindspring.com> wrote: > "Hachiroku $B%O%A%m%/(B" <Tru...(a)e86.GTS> wrote in message > > news:pan.2008.07.15.14.41.47.208604(a)e86.GTS... > > > > > > > On Mon, 14 Jul 2008 20:08:50 -0700, Built_Well wrote: > > >> The cylinder head cover (not to be confused with the cylinder > >> head) is made of magnesium alloy for lighter weight. I think > >> cylinder head cover is synonymous with "valve cover," but the > >> Camry manual refers to it as the "cylinder head cover." > > > Yeah, that's the valve cover... > > >> Since the manual doesn't mention what the cylinder head, itself, > >> is made of, I will assume iron, but just an assumption. > > > Toyotas have been using aluminum heads for as long as I can > > remember. My > > first Corolla, a '74, had an iron block and aluminum heads, which > > worked > > well for them, but was a fatal combination for certain Chevy (VEGA) > > models... > > Actually Vegas had aluminum blocks and cast iron heads! One of the > stangest combinations ever. The original Vega block was the linerless > aluminum type and was die case with an open top deck. The aluminum > alloy had a lot of silicon in it .The theory was that the aluminunm > would wear away slightly, exposing the silicon surface, which would > prevent (or at least slow down) further bore wear. The block was very > light and not particulalry stiff which is why they used a cast iron > cylinder head to provide the stiffness absent from the block. I > suppose the test engines all worked well. Unfortunately, in the real > world, things did not work so well. The whimpy blocks couldn't take > any "normal" abuse. The slightest overheating would lead to rapid bore > wear and significant oil consumption. Hard driving would cause block > distortions which also led to rapid bore wear and significant oil > consumption. Poor maintenance practices led to rapid bore wear and > significant oil consumption. Etc. Essentially driving the car led to > rapid bore wear and significant oil consumption. But it often was not > much of a problem since rust usually ate the body away before oil > consumption was too bad. Body rustwas not a problem restricted to > Vegas by the way. Toyotas of the era were at least as prone to rusting > away. > > BTW, Porsche and Mercedes use the linerless aluminum blocks that GM > tried on he Vega. But even today, you don't want to overheat an engine > using that technology. > > Ed Thanks for confirming that my memory isn't completely shot :) FWIW the all-aluminum engine in my 944 leaks more oil than it burns AFAICT. I seem to have a penchant for attracting vehicles that aren't known for gasket integrity :( Rust seems to be a common theme with cars from the mid-70s and older. The same neighbors that had the Vega also had a Volare wagon, the front fenders were rusted through in only a couple of years. My dad's Oldsmobile fared a little better, but it still had rusty fenders, possibly because of some collision repair early in its life (was sideswiped in a snowstorm on a windy country road by another driver who lost control of her car) Once the Germans started using galvanized body panels and that waxy undercoating the problems pretty much went away (my mom's Golf lasted almost 20 years in semi-rural PA before any significant corrosion showed up) I don't know about newer American cars but I would assume that they've taken similar measures. nate
From: N8N on 15 Jul 2008 09:18
On Jul 15, 1:54 am, "Ray O" <rokigawaATtristarassociatesDOTcom> wrote: > "Steve W." <csr684...(a)yahoo.com> wrote in message > > news:g5hcd3$lmc$1(a)aioe.org... > > > Built_Well wrote: > >> Ray O wrote: > >>> Some older Toyota engines (and current domestic engines) have > >>> a single overhead cam, or SOHC. > >> ======== > > >> Single overhead cam (SOHC)!!!! Well, I guess that's better > >> than using pushrods and rollers. > > > WHY? > > Push rod engines have been around a LONG time. Toyota even agrees as they > > built more than a few. (take a look under the Tundra V8s hood) > > > -- > > Steve W. > > The production Tundra's 4.7 and 5.7 liter V8's are both DOHC designs. The > NASCAR Craftsman Series "Tundras" use pushrod engines ;-) > > AFAIK, Toyota does not sell any pushrod engines in North America any more.. > > People have probably spent millions of hours debating the benefits of > pushrods vs OHC engines, and IMHO, each style has benefits over the other in > certain applications. The main advantage to a pushrod engine is packaging. I believe that was one of the reasons given for GM for sticking with a pushrod design for their newest small-block V-8s; they needed them to fit under the low hoodline of a Corvette. nate |