månadsarkiv: juni 2015

Stålkolvar kommer nu på bred front

Trenden  går mot stålkolvar i nya motorer. Både för personbilar och tunga fordon. Detta är ett paradigmskifte som öppnar för mer CGI. Stålkolvar och aluminiumblock har för stor skillnad i expansionskoefficient. Aluminiumblocket utvidgar sig mer än stålkolven. Friktionen minskar men samtidigt ökar läckage och ljudnivå. Vanligt gjutjärn blir för tungt. Ett block i CGI passar perfekt tillsammans med stålkolvar.
Detta kan dramatiskt öka användningen av CGI. Både för bensin och diesel för såväl raka som V-motorer.
Lite nyttig läsning om stålkolvar
In diesel engines, steel pistons provide significant potential for reducing CO2 emissions in comparison with the aluminum pistons that have been typical up to now. After a long history of positive results in commercial vehicles, MAHLE has therefore developed steel pistons for passenger car diesel engines to the point of series production readiness. Significant advantages result from the frictional loss. Thermodynamic conditions additionally result in advantages in combustion that lead to a reduction in fuel consumption and emissions levels. The lower compression height of a steel piston can also be utilized to increase the swept volume or to decrease the height of the engine. The first series application of a MAHLE steel piston in a passenger car diesel engine is scheduled for 2014.
The slugs of aluminum inside your engine live in a fiery hell. At full throttle and 6000 rpm, a piston in a gasoline engine is subjected to nearly 10 tons of force every 0.02 second as repeated explosions heat the metal to more than 600 degrees Fahrenheit.
These days, that cylindrical Hades is hotter and more intense than ever, and it’s only likely to get worse for pistons. As automakers chase higher efficiency, piston manufacturers are preparing for a future in which the most-potent naturally aspirated gasoline engines produce 175 horsepower per liter, up from 130 today. With turbocharging and increased outputs come even tougher conditions. In the past decade, piston operating temperatures have climbed 120 degrees, while peak cylinder pressures have swollen from 1500 psi to 2200.
A piston tells a story about the engine in which it resides. The crown can reveal the bore, the number of valves, and whether or not the fuel is directly injected into the cylinder. Yet a piston’s design and technology can also say a lot about the wider trends and challenges facing the auto industry. To coin a maxim: As the automobile goes, so goes the engine; and as the engine goes, so goes the piston. In the quest for improved fuel economy and lower emissions, automakers are asking for lighter, lower-friction pistons with the stamina to endure tougher operating conditions. It is these three concerns—durability, friction, and mass—that consume the piston suppliers’ workdays.
In many ways, gasoline-engine development is following the path laid out by diesels 15 years ago. To compensate for the 50-percent increase in peak cylinder pressures, some aluminum pistons now have an iron or steel insert to support the top ring. The hottest gasoline engines will soon require a cooling gallery, or an enclosed channel on the underside of the crown that’s more efficient at removing heat than today’s method of simply spraying the piston’s underside with oil. The squirters shoot oil into a small opening on the bottom of the piston that feeds the gallery. The seemingly simple technology isn’t easy to manufacture, though. Creating a hollow passage means casting the piston as two pieces and joining them via friction or laser welding.
Pistons account for at least 60 percent of the engine’s friction, and improvements here have a direct impact on fuel consumption. Friction-reducing, graphite-impregnated resin patches screen-printed onto the skirt are now nearly universal. Piston supplier Federal-Mogul is experimenting with a tapered face on the oil ring that allows a reduction in the ring tension without increasing oil consumption. Lower ring friction can unlock as much as 0.15 horsepower per cylinder.
Automakers are also hungry for new friction-reducing finishes between parts that rub or rotate against each other. The hard and slippery diamond-like coating, or DLC, holds promise for cylinder liners, piston rings, and wrist pins, where it can elimi­nate the need for bearings between the pin and connecting rod. But it’s expensive and has few applications in today’s cars.
“The [manufacturers] are discussing DLC often, but whether or not they will make it into production cars is a question mark,” says Joachim Wagenblast, senior director of product development at Mahle, a German auto-parts supplier.
Increasingly sophisticated computer modeling and more-precise manufacturing methods also enable more-complex shapes. In addition to the bowls, domes, and valve indents needed for clearance and to achieve a particular compression ratio, asymmetric skirts feature a smaller, stiffer area on the thrust side of the piston to reduce friction and stress concentrations. Flip a piston over and you’ll see tapered walls scarcely more than 0.1 inch thick. Thinner walls require tighter control on tolerances that are already measured in microns, or thousandths of a millimeter.
Thinner walls also demand a better understanding of the thermal expansion of an object that sometimes has to warm from below freezing to several hundred degrees in a matter of seconds. The metal in your engine doesn’t expand uniformly as it heats up, so optimizing tolerances requires the design experience and precise machining capabilities to create slight eccentricities in the parts.
“Nothing we make is straight or round deliberately,” says Keri Westbrooke, director of engineering and technology at Federal-Mogul. “We’re always building in some compensation.”
Diesel-engine pistons are undergoing their own evolution as peak cylinder pressures rise toward 3600 psi. Mahle and Federal-Mogul are predicting a shift from cast aluminum to forged steel pistons. Steel is denser than aluminum but three times stronger, leading to a piston that is more resilient to higher pressures and temperatures with no increase in weight.
Steel enables a notable change in geometry by shortening the piston’s compression height, defined as the distance from the center of the wrist pin to the top of the crown. This area accounts for 80 percent of the piston’s weight, so shorter generally means lighter. Critically, a lower compression height doesn’t just shrink the pistons. It also allows for a shorter and lighter engine block as the deck height is reduced.
Mahle manufactures steel pistons for leading-edge turbo-diesel applications, such as the four-time Le Mans–winning Audi R18 TDI and Mazda’s LMP2 Sky­activ-D engine. The company will begin shipping its first steel pistons for a light-duty production diesel engine, a Renault 1.5-liter four-cylinder, later this year.
The internal-combustion engine’s lasting relevance is due to the continuous evolution of its components. Pistons are not sexy. They’re not as modish as a lithium-ion battery, as complex as a dual-clutch transmission, or as interesting as a torque-vectoring differential. Yet after more than a century of automotive progress, reciprocating pistons continue to produce most of the power that moves us.

Kombinationen stålkolvar och CGI-block finns redan i en flygmotor där men speciellt trycker på den goda termiska likheten mellan CGI-blocket och kolvarna


Compacted Graphite Iron (CGI) Cylinder Block

Steel Pistons

Again, the Graflight V-8 takes advantage of stronger materials in its pistons, employing steel instead of aluminum, which is prone to melting failures. Strong, fatigue-resistant steel allows shorter pistons, reducing overall engine weight. And since steel pistons have almost the same thermal expansion coefficient as the CGI block, engine warm-up damage is minimized. Friction and wear are also reduced compared to aluminum pistons, and cold weather starts are not a problem. Taken together, the CGI block and the steel pistons allow for a target TBO of 3,000 hours, compared with 1,500-2,000 hours for other diesel piston engines.


Blocket i denna kommer från Gainger & Worrall, med Sintercast

Taken together, the CGI block and the steel pistons allow for a target TBO of 3,000 hours, compared with 1,500-2,000 hours for other diesel piston engines.

I den nya Duramax 6600 kommer de också med stålkolvar.


We have not been able to confirm whether or not the new engine will feature an aluminum block or CGI (Compacted Graphite Iron). The aluminum block is unlikely if they opt for steel pistons.

Det nuvarande är i gråjärn och då är valet självklart CGI. Annars hade den större motorn inte fått plats…………


Navistar har redan stålkolvar i sina CGI-motorer. Detta har jag missat.

Likaså DAF med sin


steel pistons

Cylinder pressures have increased considerably during the past years, i.e. up to the level that cast iron has difficulties to cope with the stress levels. Compacted graphite iron (CGI) has similar mechanical properties as steel but is easier to cast. CGI is frequently used in many new heavy-duty engines and in some passenger car diesel engine blocks. For pistons, however, forged steel is preferred over cast material due to the very small wall thicknesses. Nevertheless, CGI engine block and steel pistons go hand in hand




One way to make more fuel-efficient engines is to design them to run hotter. To function well at certain, higher temperatures, this may require steel pistons – one of the upgrades GM’s engineers have reportedly been considering. Duramax aficionados are also waiting to find out whether the new model’s engine blocks will be made of aluminum – to reduce weight for improved fuel economy – or compacted graphite iron (CGI). According to automotive engineers, engines equipped with steel pistons would require CGI engine blocks, for durability purposes.

You might also think about reading about the remote tools; continue reading to find out more.


läs även detta nya från dec 2016



GM med CGI i sin stora Duramax 6600 ?

Det verkar vara dags

Först kom denna hint om att de satsade på en ny motor

6 February 2014

DMAX Ltd.—a GM-Isuzu joint venture—will invest $60 million in the Ohio-based Duramax diesel engine plant to make design changes that meet future emission requirements.

Established in 1998, DMAX has produced almost 1.6 million engines since opening in 2000. GM owns 60% and Isuzu owns 40% of the venture that makes the Duramax diesel for heavy-duty trucks. The investment retains approximately 500 jobs at the engine plant.





Den nuvarande Duramax 6600 behöver bytas ut


Engine: 6.6L Duramax LML, 90 degree V8 diesel
Assembly Location: DMAX assembly plant in Moraine, Ohio
Years Produced: 2011 – current
VIN Code: 8 (8th digit of VIN)
Displacement: 403 cubic inches, 6.6 liters
Head/Block Material: Aluminum cylinder heads, cast iron engine block
Compression Ratio: 16.0 : 1
Firing Order: 1-2-7-8-4-5-6-3
Bore: 4.06″ (103 mm)
Stroke: 3.90″ (99 mm)
Aspiration: Turbocharged & intercooled – Garrett variable vane (VVT), variable geometry turbocharger (VGT) with air-to-air intercooler
Injection: Direct injection, 2000 bar (~30,000 psi) Bosch high pressure common rail w/ CP4 injection pump and piezo injectors
Valvetrain: OHV (overhead valve), 4 valves per cylinder, mechanical roller lifters
Oil Capacity: 10 quarts w/ filter (9.5 liters)
Fuel Compatibility: Ultra low sulfur diesel (ULSD) or max B20 biodiesel blend
Max Shift RPM: 3,000 rpm
Peak Horsepower: 397 hp @ 3,000 rpm
Peak Torque: 765 lb-ft @ 1,600 rpm

 Jämfört med de två huvudkonkurrenterna Ford och Cummins
Duramax 6600   397 hkr    765 lb/ft
Cummins 6,7      385 hkr    850 lb/ft ( de har nu aviserat en uppgradering som har 900 lb/ft)
Ford V8 6,7          440 hkr    850 lb/ft
Nytt i juli 2016
Nya Ford  6.7-liter diesel rated at 925 pounds-feet
Nu verkar det vara en replik från GM på gång………


Can the next generation of the V8 Duramax get to the 900 lb-ft torque output?
Knappast om de fortsätter med gjutjän i blocket. Den nuvarande har ett vrid på 765 lb/tf .
Det innebär att de siktar på en höjning med 17 %
Det verkar som CGI är enda alternativet.
Den nya var extremt tyst när reportern lyssnade. Detta tyder också också på CGI.
We have not been able to confirm whether or not the new engine will feature an aluminum
block or CGI (Compacted Graphite Iron).
De går inte från ett gjutjärnsblock till ett i aluminium om de skall lyckas höja effekten så
avsevärt. Höjningen från 765-900 lb/ft tyder på et materialbyte.
Även uttrycket:
A few years ago, when we first learned about the project, it appears that GM was entertaining
the “best of the best” type of parts
tyder på CGI
One thing has been consistent through the spy shots we’ve seen: each prototype wears a familiar raised scoop on the hood. This points to greater air flow into the engine via this new air duct, which allows us to deduce more power is headed to the Duramax diesel engine. Currently, GM’s 6.6-liter Duramax diesel sits at 765 lb-ft of torque, but its domestic competitors outdo the engine by over 100 lb-ft of torque.
Den skall försöka nå en effekt på 900 lb/ft för att överträffa Ford och RAM.  GM ligger f n ca
100 lb/ft efter sina resp motståndare.

We have not been able to confirm whether or not the new engine will feature an aluminum block or CGI (Compacted Graphite Iron). The aluminum block is unlikely if they opt for steel pistons.

Duramax aficionados are also waiting to find out whether the new model’s engine blocks will be made of aluminum – to reduce weight for improved fuel economy – or compacted graphite iron (CGI). According to automotive engineers, engines equipped with steel pistons would require CGI engine blocks, for durability purposes.

se   http://www.wian.se/2015/06/stalkolvar-kommer-nu-pa-bred-front/

Just stålkolvar jämnar vägen för en bred övergång till CGI även i bensinare. CGI passar mycket bättre rent termiskt med stålkolvar.

New_Dmax1From what we have learned from a recent oil presentation from Shell, is that new engines are going to be running hotter in hopes of yeilding better economy. The increased heat, would probably be why DMAX is interested in steel pistons




Chevrolet Silverado

Rumor has it that GM has a significant update in the works for the Duramax to debut soon, so stay tuned, as it is doubtful GM will remain content with being third best.

Read more: http://www.trucktrend.com/truck-reviews/1501-2015-chevrolet-silverado-2500hd-duramax-and-vortec-gas-vs-diesel/#ixzz3dbvjN3C9




The big news for the HD models is an updated Duramax diesel engine. The current LML Duramax makes 397 hp and 765 lb-ft of torque. Respectable numbers in their own right but significantly lower than the current power leader, Ford’s 6.7L Power Stroke with 440 hp and 860 lb-ft of torque. The revised Duramax, which is expected to retain its 6.6L displacement, is rumored to produce as much as 450 hp and 850 lb-ft of torque. (nu är det 397 hp och 765 lb/ft)

Read more: http://www.trucktrend.com/future-trucks/1506-spied-2016-2017-chevrolet-gmc-1500-hd-trucks/#ixzz3dby5v5Ql


Jag har fått grundtipset ifrån en läsare av mina mailutskick som mailat mig. Själv har jag inte den riktiga glöden och tiden för närvarande att sitta så mycket vid datorn. Det går i omgångar.
Ju mer jag analyserade grundtipset. ju mer övertygad blev jag dock om att de som skrev om ett materialbyte kunde ha rätt. Ifrån att Duramax 6600 kom 2001 har den genomgått fem större uppgraderingar och gått ifrån 235-397 hkr och ifrån 500-765 lb/ft med samma gråjärnsblock. De står antagligen vid ”världs ände” materialmässigt sett.
Då kan man inte plötsligen höja vridet med ca 20 % utan att ha ett CGI-block att luta sig emot.

De talar ju också om att ” GM has a significant update”  in the works for the Duramax …..


Tänk om vi även hade fått en återintroduktion av den redan klara Duramax 4500 med block i CGI som togs bort och lades på, hyllan 2008. Detta är en färsk spekulation om att den återkommer


The “original” Duramax small-block V-8 was touted as having aluminum heads and integrated exhaust manifolds to keep its size the same as that of the then 5.7L gas V-8.

The 2017 variant, if there is one, would most likely feature the new diesel-era composite graphite block (CGI) and aluminum heads, a variable-vane turbo with direct-injection, along with other technology that’s evolved with it’s 6.6L big brother.



Redan vid en övergång till CGI-block i Duramax 6600 tror jag vi har en nätt liten produktion på 300-400.000 ekv  eller 15-20.000 ton per år. Det kommer att bli ett gott tillskott om ca ett år. Kommer även den lilla V8an på 4,5 liter  kan vi tala om lika mycket till.

NYTT den 30 juni




General Motors Believed Ready to Announce Commercial-Truck Venture With Navistar


Detta kan innebära  att Duramax 6600  kommer i ännu fler lastbilar.