Mazda Skyactiv-D Diesel

[Doozer]

So does the old "Banana in the tail pipe" trick.

--Doozer

[Willy]

Having the exhaust manifold integral with the head certainly goes against what I consider conventional wisdom.
But I also realize that modern engine designers do have a very broad set of goals to meet.
Certainly manufacturing simplicity and associated costs involved is one that cannot be ignored. But fuel economy requirements and ever tightening emission regs are also primary goals.

Metallurgy, machining technology, and lubricants have evolved into what would have almost been science fiction to the tools an engineer of 30 years ago had at his disposal.
Remember when it was considered something to brag about when an automotive engine had accumulated 100-150 thousand miles? With a little TLC it is not unusual now to see 500-700 thousand today.

The SIDI Gm V-6 was conceived as a basis for a world engine in 2003.
GM used the talents of some of it's most talented engine designers from Australia, North America, and Germany in order to design this engine.
323 HP from a 3.6 L engine while meeting mileage and emission goals is nothing to sneeze at. Something an old 5.7 design, as good as it is, would be hard pressed to equal.

I have to ask myself, do these engineers perhaps have a sightly better handle on the subject than us?
I would like to think that perhaps they do.
Time will be the final arbitrator as to engine's longevity.

Here is GM's take on the integral exhaust head, the page also has a short video embedded from one of GM's engineers.

http://www.caradvice.com.au/119730/v...ld-for-new-v6/

[oldtiffie]

The Mazda CX-5 diesel is now available in Australia. This forum, starting at post #4, has a user's report on the driving experience. http://www.mazdas247.com/forum/showt...-Photos-Videos

http://www.google.com.au/#hl=en&rlz=...w=1280&bih=523

[crusty]

The video in Willy's post says it all.

To quote Boomer's signature

"If you always do what you've always done,
You'll always get what you've always gotten."

[A.K. Boomer]

Having the exhaust manifold integral with the head certainly goes against what I consider conventional wisdom.
But I also realize that modern engine designers do have a very broad set of goals to meet.
Certainly manufacturing simplicity and associated costs involved is one that cannot be ignored. But fuel economy requirements and ever tightening emission regs are also primary goals.

Right - so why in the hell would you build something heavier that also has a lower power output ?

Metallurgy, machining technology, and lubricants have evolved into what would have almost been science fiction to the tools an engineer of 30 years ago had at his disposal.
Remember when it was considered something to brag about when an automotive engine had accumulated 100-150 thousand miles? With a little TLC it is not unusual now to see 500-700 thousand today.

u are totally dreaming if you think your going to get those kinds of longevity numbers out of an engine that's cooking itself to death.

The SIDI Gm V-6 was conceived as a basis for a world engine in 2003.
GM used the talents of some of it's most talented engine designers from Australia, North America, and Germany in order to design this engine.
323 HP from a 3.6 L engine while meeting mileage and emission goals is nothing to sneeze at. Something an old 5.7 design, as good as it is, would be hard pressed to equal.

Nothing to sneeze at? Reality check, u do realize that they are still falling short by over 10% of what honda was achieving TWO DECADES AGO!

I have to ask myself, do these engineers perhaps have a sightly better handle on the subject than us?
I would like to think that perhaps they do.

Maybe not "Us" ,,, but what I can tell you honesty is that "most" of them have a better understanding than you do, and im one of them that is from that particular crowd in this particular matter...

Time will be the final arbitrator as to engine's longevity.

Time is just one of the things stacked against it - it's a bad idea in so many ways I could write a book about it...


But what I think amazes me the most is just how many "sheeple" there are in the world - and all it takes is some guy to blow a little smoke - and have the credentials of "chief engineer" and boy howdy my god lets not question that one --------------- well ------------ lets

First off - lets cut through the crap about better flow - the flow is junk - it's why their falling short of what was going on two decades ago --- the flow improvement he was talking about was due to larger valves and has nothing to due with the restrictive internal exhaust ports - so they threw bigger valves into their old heads that should have had them in the first place - big deal - don't try to sell that as the integral exhaust porting fiasco...

And last but not least --- the huge emphasis on weight savings --- what a joke and totally stacked deck --- first off he's comparing it to a cast iron header, sorry, you don't get to do that anymore - most performance engines that are also geared to keeping the economy in check are already using tuned pipes, so take all the effort they took to create this abortion and throw it at a good set of tubes, so guess what happens to the "13 lb weight savings" yeah you got it - it's down to around 6 now, want some more reality ?

now look at that "obstruction" on the one side of the cylinder head that the exhaust is on - you can see it very nicely at the end of the sales pitch, it's got to be at least 3 pounds of aluminum per head ----- oooops,,, Pooof - there goes the weight savings,

Keep reading - it gets allot worse guys, Now - any idea what kind of extra cooling system capacity it would take if you tried to run coolant around your exhaust header and keep it as cool as your head?
it's unreal -------- there is so much heat there, it's like having another cylinder head to contend with, - each port is a literal "blow torch"

So the reality of the situation would be to show the conventional Lighter cylinder head with it's lightweight tuned pipe header next to it.

Then --- here's what you have on the other bench --- A heavier head to start with, a larger heavier radiator with more cooling capacity in the form of more cores and feed and return jackets, larger diameter feed and return hoses resulting in weight gain - larger diameter horsepower eating water pump impeller resulting in more weight and parasitic drag,
approximately 1/2 gallon more of coolant @ close to 4 more additions pounds.

Larger and heavier horsepower eating fan/clutch and fan or larger and heavier higher amp horsepower eating electric fan motor and fan that I might add has to run more...

So - all that extra weight and parasitic drag --- how's your integral exhaust ports looking now sheeple? u know - the ones that are going to cost u more fuel - give u less power - and drastically lower the longevity of your engine ? how's that working out for u ?

lets throw in one more little variable to look forward to --- remember when the Wifey ran the engine low on coolant that one time but luckily caught it in time cuz she seen the temp gauge gradually climbing up -------- yeah - you can forget about that anymore ---- you run this little baby low and it skyrockets, so try not to blink - ever,,, and because the hillbillies that built this hand-grenade attached it to an aluminum block u just bought the entire engine --- now how's things looking???? what a great idea huh

[A.K. Boomer]

The video in Willy's post says it all.

To quote Boomer's signature

"If you always do what you've always done,
You'll always get what you've always gotten."

To put a little perspective on one of my signature posts - sometimes you use this philosophy so you can predict results, anotherwords If you always do what youv always done on a ladder and you never fell off then by all means keep doing what you did...

welcome to reality Crusty, welcome to my world...

Can I ask u one question? and im really trying to be sincere --- what was your mindset when u watched that video? what impressed u about it? did he use a few "big words" or something -- or was it the computer image of the integral pipes with the changing colors?

[saltmine]

Just remember.....the majority of the car industry's "engineers" are nothing more than a bunch of drunken "frat boys", who boozed and doped their way through college on Mom & Dad's dime, and never worked a day in their lives.

I've worked closely with a few of them. And learned that what works on paper or in a test cell in a lab, don't necessarily work out on the street.

One really good engineer once told me, "Computers are great design tools, but they can't see around corners."

Of course, they have to try innovations...if for no other reason but to justify their fancy-pants job and high pay. If we didn't innovate once in a while, everybody would be driving around in four cylinder, side-valve, Model "T"'s and cooking in the fireplace.

Sometimes "taking a chance" fails miserably....sometimes it don't.

During WW2, Ford engineers designed a dual-overhead cam, 12 cylinder aircraft engine. It was a dismal failure. But, they took it back to the lab, sawed four cylinders off of it and discovered they had created a very successful tank engine.

Ed Cole, a GM engineer, wanted to design a "baby Cadillac" engine for the new model Chevrolet that was due to come out in 1955. What he came up with was the "small-block Chevy V-8" which is still going strong today.
The outstanding thing about Cole's design was the fact that Ed Cole actually drafted the plans, made the molds, poured the castings, and did all of the machine work on the prototype engine....HIMSELF. When he took the proposal for the new engine to GM, he had a working prototype, driving around in his own 1953 Chevy sedan. In my estimation, Ed Cole was a real engineer.