I stole these specs from Fresh Alloy

Engine and Driveline· Standard Nissan Endurance 5.6-liter DOHC V8 producing over 300 horsepower and more than 375 lb-ft of torque· Aluminum block with cast iron cylinder liners , forged steel crankshaft, microfinished crankshaft and camshaft, molybdenum-coated pistons, 6-bolt main bearing caps, Super Silent single-stage timing chain· Standard 5-speed electronically controlled automatic transmission with manual shift and tow/haul modes for enhanced fuel economy and towing capacity · Available Vehicle Dynamic Control (VDC) with Brake Activated Limited Slip Traction Control (includes deactivation switch)· Standard Dana 44 front and rear axles· Tire Pressure Monitor System

Does anyone know why they're using an aluminum block with cast iron cylinder liners? This came up in a conversation during the Raiders/Titans game last night and we came up with a lot of interesting theories, but no good reason...

Heath

Because once you exceed 4.0-4.6 liters you are deviating away from the ideal bore size; single stage chain [may mean no VVT] so the truck engine is more American in design [lower cost]......kind of a 343 Chevy with 4 valves per cylinder.I'm being too critical, probably better than a Chevy! But we can guess what a Mississippi made engine will be like in the first year of production?

Ring sealing in larger bores is a well established science with iron or iron liners vs very very few large bore aluminum blocks have been successful with horrible US high Sulfur gasoline.

A 5.6 liter should deliver 400-410 lb/ft with VVT if built as the early Q was but I'm not sure if the 3 rings would be enough to control piston rocking?

In a truck application cast iron liners extra 2-3 pounds vs saving $300 for exotic coatings favors adding the weight:http://www.instmat.co.uk/iom/d...3.htmh ... /5140r.htm

"Switching engine blocks from cast iron to aluminum is not quite a no-brainer, though. In 1996, BMW ran into problems in the U.S. when it began to convert iron-blocked I-6 and V-8 engines to aluminum. Because BMW wanted to enjoy the full weight-saving benefits of aluminum-block construction, it spurned the commonly accepted - but rather lowbrow, by BMW standards - practice of fitting cast-iron cylinder liners in the aluminum blocks to enhance durability.

Instead, BMW engineers opted for Nikasil, a fancy process in which a high-silicon-content cylinder-bore "insert" is placed in the block casting mold; when the aluminum is injected into the mold, the insert melts, but leaves a high-silicon surface right where you want it: on the cylinder bores.

BMW hadn't factored-in high-sulfur U.S. gasoline, though. The Nikasil coating didn't hold up to the effects of heavily sulfured gasoline - and quite a few BMW production engines gave their lives in the prove-out. For the I-6s in the 3- and 5-Series, the Bavarians briefly switched back to iron. This year, aluminum returns - but with the more pedestrian cast-iron liners.

There are alternatives to Nikasil that are more sulfur-resistant, including Alusil and Lokasil (both aluminum/silicon processes); Porsche AG uses Lokasil for its all-aluminum engines. But BMW 3-Series director and product line manager Wolfgang Zeibart admits all these processes are expensive - thus the move to iron liners for the new, '99 3-Series aluminum 6-cyl. engines.

The liner/surface-coating camps each make good points. Makers of higher-priced, premium vehicles tend to prefer the higher-tech, cylinder-coating approach. Yet for smaller engines, using iron liners often negates a goodly portion of the weight saved in the switch to an all-aluminum block. This aspect was underscored when General Motors Corp. converted the block of the old LT1/LT4 V-8 to aluminum in creating the new LS1 V-8. Engineers kept iron cylinder liners.

John Juriga, the lead GM Powertrain engineer for the LS1, summed it up in an interview in '97: "We've seen some problems others have had with Nikasil and other coatings," he said. "The cast-in liners are a good, reliable method; the weight penalty really isn't that great """"

How do the engineers compensate for the differences in expansion rates between the aluminum block and the iron liners? It seems they would work themselves apart after a while.

No, if done properly, the block is cast around the liners, so in effect the liners are shrunk-in and immovable. ALFA has been doing it on mass production since the early fifties. I am sure it was done before that by them (and others) on a smaller scale since the thirties, at least.

It is tricky to find the correct balance between cold and operating temperature and full power temperature for clearances: the rings must be pretty special.

Like they are on Q to get 250,000 miles.

Actually the cast iron liners and the cast alloy pistons have very little expansion from cold to the proper heat range. It is the steel rings on the iron liners (protected by a thin film of lubrication) taking the brunt of the load and wear. They are both relatively thermally stable in their operating range, especially compared to forged pistons, which aren't that bad.

I'd like to remind the folks that MBZ has been succesfully running 'aluminum alloy' cylinders (no iron liners) in their engines since 1980. Problems are extremely rare, and almost always due to slight water/glycol coolant leaks . The glycol wets the cylinder and lifts the oil layer of--leading to scuffing and destruction.

GM had the same problem with their infamous Chevy Vega engine -- which Cosworth proved was near indestructable with an alloy cylinder head, but which often self destructed due to seepage through a cheap fiber gasket between the alloy block and heavy cast iron cylinder head on the standard models. 'Bean counters' decision to go to CI head trashed the car line.

BMW's problem was not 'high sulfur fuel' , but poor manufacturing quality control.

The acid etched/lapped high silicon content aluminum alloy results in a near perfect cylinder wall, but other 'treatments' have not proven so robust. The process is not costly (the GM Vega engine was very low cost)

When the word cast iron is used most don't understand that it just means the perponderance [more than 50%] is iron and it's cast..........nothing used is pure this or that..........even copper wire is usually not 99.5% pure copper............all aluminums used today are alloys [there are 1,000 of them each different] as is iron due to intentional impurities!

Just like gasoline is a mixture of hundreds of chemicals plus isomers and the ratios vary from batch to batch.

A little off subject here but the talk of trucks and Germans related to an article I read today about a new Dodge truck alleged to be the fasted production truck ever. It has a modified Viper V-10. The head of the division (Woldfgang something or other) stated, "There is no replacement for displacement." Gotta love it! Just as Nissan is ramping up on size, looks like the current contenders will up the stakes. Also, Toyota announced that the Tundra will be supersized for the 2006 model to be built in the new San Antonio plant. I bet it will have a bigger V-8 than the current 4.6(?).

The is no replacement for the gasoline used at idle or cruise in a big displacement engine. A 5.5 liter will use 22% more gasoline than a 4.5 liter engine less any correction for lower cruise rpm [the fact that it might cruise at 1800 instead of 2,000 rpm...............might reduce the 22% to 10-13%] acting like a 4.95 liter maybe ...........but the idle use would still be 22% more

Q45tech wrote:The is no replacement for the gasoline used at idle or cruise in a big displacement engine. A 5.5 liter will use 22% more gasoline than a 4.5 liter engine less any correction for lower cruise rpm [the fact that it might cruise at 1800 instead of 2,000 rpm...............might reduce the 22% to 10-13%] acting like a 4.95 liter maybe ...........but the idle use would still be 22% more

Which prompts a question about the various cylinder disabling schemes. I don't recall any of these working at idle, only under light load. Some cars did have engines that shut down on stopping and restarted on using the accelerator. Must have had large battery power reserve for the accessories when stopped.

i dont believe i herd any 1 mention that cast iron liners to alumin pistions have less friction than alum block or liners to alumin pistons link http://autozine.kyul.net/techn...liner

Advanced Engine Material"Using alloy pistons is not very costly, what prevent most mass production all-alloy engines from using them is the friction generated between pistons and cylinder walls. It is commonly known that the contact between two aluminium surfaces results in high friction - much higher than between cast-iron and aluminium. Therefore many engines with aluminium block have to employ cast iron pistons. "