GM's new 4.2L DOHC twin turbo V-8 !!

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Re: GM's new 4.2L DOHC twin turbo V-8 !!

Post by Truckedup »

Are the engine blocks of the latest PU truck Diesel engine cast iron or aluminum?
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Re: GM's new 4.2L DOHC twin turbo V-8 !!

Post by Olds455 »

mekilljoydammit wrote: Fri Nov 30, 2018 10:28 am I'm just waiting for the Corvette version, followed shortly by GM fanboys claiming they were always for DOHC V8s and that they haven't been crapping on DOHC 4-valve engines for the last 20 years.

For places overseas where displacement is taxed more, this might have a better luxury car take-up than pushrod V8s did; god knows BMW seems to sell enough stuff using their turbo V8s. It is kind of a weird seeming thing to see released coming on the heels of mass layoffs though, but if they didn't think the business numbers made sense they wouldn't have done it.
Why would you be waiting for "fan Boys to blah blah blah..."


Who gives a shit what they said 5 years ago or even 20 years ago about DOHC engines? Why let it affect you that much? In the broad scope of things, it means literally nothing. Nothing.
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Re: GM's new 4.2L DOHC twin turbo V-8 !!

Post by Brian P »

Truckedup wrote: Sun Dec 02, 2018 11:55 am Are the engine blocks of the latest PU truck Diesel engine cast iron or aluminum?
A lot of modern diesel engine blocks are made of CGI ... which is a special variety of cast iron but is not plain ordinary grey cast iron.
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Re: GM's new 4.2L DOHC twin turbo V-8 !!

Post by peejay »

Brian P wrote: Sun Dec 02, 2018 11:48 am To my knowledge, Honda has NEVER built an engine with a cast iron block. Honda does have a reputation for building pretty good engines ...

They did. The carbureted 12v engines ("E" series?) used in the mid-80s in the Civic and Accord before they were replaced by the D and F engines respectively, were iron block.
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Re: GM's new 4.2L DOHC twin turbo V-8 !!

Post by peejay »

Truckedup wrote: Sun Dec 02, 2018 11:55 am Are the engine blocks of the latest PU truck Diesel engine cast iron or aluminum?
Neither. They use compacted graphite, which is technically "cast iron" in a broad sense, but is closer to steel or nodular iron in composition than the brittle cheeselike material that we think of as "cast iron".
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Re: GM's new 4.2L DOHC twin turbo V-8 !!

Post by mekilljoydammit »

Olds455 wrote: Sun Dec 02, 2018 11:57 am
mekilljoydammit wrote: Fri Nov 30, 2018 10:28 am I'm just waiting for the Corvette version, followed shortly by GM fanboys claiming they were always for DOHC V8s and that they haven't been crapping on DOHC 4-valve engines for the last 20 years.

For places overseas where displacement is taxed more, this might have a better luxury car take-up than pushrod V8s did; god knows BMW seems to sell enough stuff using their turbo V8s. It is kind of a weird seeming thing to see released coming on the heels of mass layoffs though, but if they didn't think the business numbers made sense they wouldn't have done it.
Why would you be waiting for "fan Boys to blah blah blah..."


Who gives a shit what they said 5 years ago or even 20 years ago about DOHC engines? Why let it affect you that much? In the broad scope of things, it means literally nothing. Nothing.
... because I find it funny? Other than watching people who are currently LS fanboys try to shift gears without looking foolish, none of this affects me at all; I'm not in the market for any performance car that will use either engine family.

I mean I build rotary engines, it's not like I'm actually heavily affected by what people think. ;)
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Re: GM's new 4.2L DOHC twin turbo V-8 !!

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peejay wrote: Sun Dec 02, 2018 12:31 pm
Truckedup wrote: Sun Dec 02, 2018 11:55 am Are the engine blocks of the latest PU truck Diesel engine cast iron or aluminum?
Neither. They use compacted graphite, which is technically "cast iron" in a broad sense, but is closer to steel or nodular iron in composition than the brittle cheeselike material that we think of as "cast iron".
Is this material used in any spark ignition engines?
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Re: GM's new 4.2L DOHC twin turbo V-8 !!

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Re: GM's new 4.2L DOHC twin turbo V-8 !!

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Reading though, there appears to be lots of conjecture supported by inaccurate narratives resulting in improbable projections of future results. I will wait to see what one of the worlds largest design engineering and manufacturing organization delivers. My expectation as a consumer is 300K-500K miles in standard use and trim with recommended maintenance. How will that not be delivering on reliability? I see a trend to single use components, meaning major parts are less suited to rebuild than in the past. It is indeed the result of optimizing manufacturing to reduce cost and increase reliability, but that comes with the already mentioned expected consumer life that was a pipe dream of in my youth.
A big thank you to William Edwards Deming and the disciplines that resulted from his advice to focus on statistical quality analysis. Continuous improvement, Total Quality Management, Total Productive Maintenance, The Toyota Production system and it's subparts like 5-S, Kaizen, Pull manufacturing, and Kanban signaling, Quick Response Manufacturing and POLCA (Paired overlapping cells with authorization) from the U. of Wisconsin at Madison and many other flavors not mentioned that deliver product quality and reduce cost to the manufacturer and consumer alike.
An extra big thank you to the Japanese manufacturers that pioneered and demonstrated the viability of the concepts before Americans could see the value.

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Re: GM's new 4.2L DOHC twin turbo V-8 !!

Post by Momus »

Truckedup wrote: Sun Dec 02, 2018 1:01 pm
peejay wrote: Sun Dec 02, 2018 12:31 pm
Truckedup wrote: Sun Dec 02, 2018 11:55 am Are the engine blocks of the latest PU truck Diesel engine cast iron or aluminum?
Neither. They use compacted graphite, which is technically "cast iron" in a broad sense, but is closer to steel or nodular iron in composition than the brittle cheeselike material that we think of as "cast iron".
Is this material used in any spark ignition engines?
The current NASCAR blocks are each CGI and Ford Motorsport were selling Windsor blocks made from the stuff last time I looked
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Re: GM's new 4.2L DOHC twin turbo V-8 !!

Post by peejay »

Truckedup wrote: Sun Dec 02, 2018 1:01 pm
peejay wrote: Sun Dec 02, 2018 12:31 pm
Truckedup wrote: Sun Dec 02, 2018 11:55 am Are the engine blocks of the latest PU truck Diesel engine cast iron or aluminum?
Neither. They use compacted graphite, which is technically "cast iron" in a broad sense, but is closer to steel or nodular iron in composition than the brittle cheeselike material that we think of as "cast iron".
Is this material used in any spark ignition engines?
Technically yes, in that some WRC engines use Diesel blocks to tolerate running 30psi of boost on a 2.0 or 1.6l engine with a stock-block rule. Air is restricted and the fuel is regulated, so power must be made by increasing the compression and running at the threshold of detonation all the time. I don't know what modern practice is but aluminum rods used to be common.
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Re: GM's new 4.2L DOHC twin turbo V-8 !!

Post by peejay »

Brian P wrote: Sun Dec 02, 2018 1:06 pm Ford 2.7 Ecoboost.

https://www.caranddriver.com/features/l ... 2015-f-150
Interestingly, Ford has gone back to a setup like a separate cylinder block and crankcase with the 2.7.

Alternatively, they put the pan rail up against the bottom of the water jacket and use a very, very deep structural aluminum oil pan.

The 2.7 does make more torque/displacement than this 4.2l V8, and it is a truck engine so it is expected to run at heavy power all the time, unlike a passenger car engine. Corvettes don't weigh 6000lb and get expected to tow 16' enclosed trailers. (Or maybe they do as part of the C8 product development, I don't get the press releases :D )

The 3.5 Ecoboost is all-aluminum.
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Re: GM's new 4.2L DOHC twin turbo V-8 !!

Post by Brian P »

Yeah, the 2.7 Ecoboost is a pretty interesting design. The structural load path is made of CGI and then it has a bolted-on external aluminum crankcase and oil pan (and the cylinder heads are aluminum). This is an engine in which the forced induction was designed in from day one. It may have parts that could loosely be described as "made of cast iron" but it is a thoroughly modern design with modern design features and construction methods.

I'm sure the external aluminum crankcase design was selected to minimize the amount of CGI that the engine is made of. The crankcase just needs to keep the oil inside and perhaps give someplace to attach the engine mounts.
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Re: GM's new 4.2L DOHC twin turbo V-8 !!

Post by Bazman »

Great to see the GM release. I think the motor will be pretty epic for a mass production engine. I've owned 3 AMG 6.2's and can honestly say of all V8's I've ever owned, nothing topped them for all round reliability, usability, and power band. They'd pull from 1000rpm as well (or better) than any OHV that could rpm past 6.5k but these would flatten off and make the same power from 6500 to 7500rpm. Did over 200,000km on one and it was still running perfect.

It's laughable to bash all aluminum motors today. Yes - in an all out pump gas effort, there's 20+hp between a good alloy block and a good cast block... but that deficit can be reduced or near eliminated via careful reinforcing/redesign... and trust me, NASCAR run cast graphite blocks because they HAVE TO run iron. If they had the chance to take 60lb off the front of their cars they would or lose to those that did!

Only those that don't care about corners want cast iron in anything designed as a performance road car. I actively track and road race a twin turbo LS3 and have the turbos about mid-car (where the back seats used to be). For a front engine car it turns in pretty good. Thank you GM for the light 6.2...

Yessir - big hats off to GM for taking that weight off the front 20 years ago. That and decent heads were the greatest step forward in the Chev evolution IMO. Anyone says the LS platform is unreliable has rocks in their head. For everyone that had reliability issues (out of 5 million they're be some) there are hundreds and thousands that had none. A normal LS1 is so tight at 100,000 miles you can still add power adders and it'll be happy to take it and shift to 6500rpm daily (for a while).

The old SBC were iron, and their castings were complete crap in many cases, as were most Ford V8's, Mopar were better as they used more nickle - but still responded well to blue printing. The only reason the older motors lasted 200,000 miles was because they seldom saw over 5000rpm. Tolerances were all over the place... which was why you had good ones and bad ones, and why blueprinting the older Chev's was (is) a massive thing... all the old motors need blueprinting and better parts to make a decent performance engine. An LS is a decent performance motor (for street and weekend fun)
by anything from a simple tune to bolt ons, unless you want to get serious.

So.... relax guys that are worried - this GM engine will be a beauty IMO.

I am sad about the displacement drop - but they may have left some meat in there like they did with the LS - it went from 4.8 to 7.... though I doubt for emissions reasons they will ever make another 7L... leaving the aftermarket to do it, if feasible. Having said that I've experienced the new AMG twin turbo V8, and at only 4L it's friggin epic. Was ridiculous around a track for an OEM that could be daily driven.

These are good times - better than the old muscle car days
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Re: GM's new 4.2L DOHC twin turbo V-8 !!

Post by iadr »

Bazman, I don't even know where to start-

200,000 km is half what we expect from a modern car here in Canada (and the US I'd assume). I don't know where you live, Holland maybe? But you just don't get the need in other parts of the world, for durability.

We who are critical, are not talking faults in an evolutionary design like the LS, but the complete crap like the "High Feature" 3.6L engine in GM SUV's.
Recently, I was tasked- I work in the service industry- with finding a good used replacement motor. Through all searches, the nearest one that was worth buying was 3,100km away. And even then, with 101,000km on it the dealer parts guy strongly recommended doing a "front end rebuild" (his words) with revised components, re-engineered after approx 1.5 million of these motors had been foisted on the customers.
Because of demand, the motors are worth more than the 5-6yo vehicles they are found in.

That is the GM we speak of- a company so badly managed as to lose market share year after year, take 11.2billion dollars net government funds, and produce vehicles with half the life expectancy they rightly should have.

Go on Bob is the oil guy and read the hundred+ post mortems of these V6 motors. Buy one yourself, and you will see our point. You and Newold are consumers. Armchair observers, honestly. Don't arrogate your expertise to think it on the level of those of us on this board who do service work for a living.
And yep, I worked for an MB dealer and have replaced 6.3 and 5.0 V8's for failures.

Currently, I work for Mazda, and if their 2.3 DI turbo from back in 2007 is what the industry is facing, I will be forced to leave said industry. Daily calls of failure. We'd rather the clients gave up and junked the CX7's.
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