HOME  |  NEWS  |  BLOGS  |  MESSAGES  |  FEATURES  |  VIDEOS  |  WEBINARS  |  INDUSTRIES  |  FOCUS ON FUNDAMENTALS
  |  REGISTER  |  LOGIN  |  HELP
Page 1/2  >  >>
Ockham
User Rank
Gold
Re: what's the big deal?
Ockham   10/11/2012 9:37:01 PM
NO RATINGS
Hi David, Thanks for the article. Makes sense re: racing my turbo BBC. Nope, I drove it on the street - for almost three years. Street racing is illegal! :-)

Dave Palmer
User Rank
Platinum
Re: what's the big deal?
Dave Palmer   10/11/2012 7:43:34 PM
NO RATINGS
@Ockham: Here is an article that describes in more detail why these pistons are a big deal.  Was your 7L V8 turbodiesel for racing? If so, you probably didn't need to worry too much about thermal fatigue.  Also, two decades ago, you probably didn't need to worry about emissions too much.

Aluminum pistons are obviously nothing new, but in order to reduce diesel emissions, it's desirable to get piston bowl temperatures as high as possible.  Unfortunately, if you get them too high, the aluminum will melt. (Also, at temperatures near the melting point, the fatigue strength of the aluminum is greatly reduced).

Interestingly enough, when the aluminum melts and resolidifies, its mechanical properties are greatly improved.  This is the idea behind Federal-Mogul's Durabowl process.  I have no idea how they got the idea, but I wouldn't be surprised if it occurred to someone while looking at a failed piston.

Ockham
User Rank
Gold
what's the big deal?
Ockham   10/11/2012 4:56:39 PM
NO RATINGS
Don't quite get the point of this article.

Aluminum pistons, cast, hypereutectic and forged have been standard fare for piston technology for decades, some of them in very high stress applications.

They're talking about 93kW per liter. O.K. that's a 250 hp 3 liter diesel. Great. I was getting over 600 kw out of a turbosupercharged 7 liter V8 over two decades ago, and it had typical OEM forged aluminum pistons. They seemed to hold up just fine, even with over 20 inches of turbo boost...and I did all that design with a piece of paper and a slide rule and OEM components! :-)

Aluminum blocks? So? That's no big shakes either...and long before the Vega, too. They've have been around in various GM products since the early 1960's (Buick 215, Corvair flat six, etc.)

The much maligned Vega used aluminum block and cylinder with a spray coated cylinder wall which failed rather miserably in the Vega. But (like so many other technologies prototypd on the Vega, such as the HEI ignition system) very similar technologies eventually made their way into the GM product line, like the LS1.

Pardoning the pun, why are we suddenly so gassed about an aluminum pistoned turbo diesel?

 

 

RICKZ28
User Rank
Platinum
Re: Is aluminum strong enough?
RICKZ28   7/25/2012 3:07:00 PM
NO RATINGS
I believe the GM "LS" series V8 engines used in rear-drive cars since 1997-1998 is an all-aluminum block (no iron cylinder liners).  It was first used in the 1997 Corvette.  The LS engines are used in the current Corvette and Camaro high-performance cars.

http://en.wikipedia.org/wiki/GM_LS_engine

http://www.gmhightechperformance.com/tech/0901gmhtp_ls1_ls6_ls2_ls3_l99_ls4_ls7_ls9_lsa_engine_history/viewall.html

 

Personally, I own a 1998 Chevrolet Camaro Z28 that is factory equipped with the LS1 5.7 liter V8 with aluminum block and heads (and 6-speed manual transmission).  I have 135,000 miles on the car, and it still runs like new...brutal power and acceleration by normal car standards.


For most GM truck applications, the LS engine blocks are cast iron.

During the late 1970's, I had a 1973 Chevrolet Vega with the aluminum block.  It drank about one quart of oil for every 100 miles, due to the aluminum cylinder wear.

Dave Palmer
User Rank
Platinum
Re: Is aluminum strong enough?
Dave Palmer   7/16/2012 5:42:08 PM
NO RATINGS
@Chuck: Yes, Mercury used their proprietary Mercosil low-copper hypereutectic alloy, along with a nickel-based piston coating, for some 15-25 HP engines in the late '90s.  As far as I know, they never used it outside of that horsepower range.  I'm not quite sure why it hasn't been more widely used, since it does seem to have offered a number of benefits.

Mercury's decision to keep most of their casting in-house and to develop it as a core competency has paid off; the Mercosil alloy is sold commercially, along with a series of die-casting alloys, called Mercalloy, which Mercury developed.  Mercury casts these alloys for outside customers, and also licenses the alloys to foundries.

While Evinrude closed its die-casting division prior to the OMC bankruptcy, they have held on to their lost-foam casting facility; in fact, they recently won Best-In-Class in the AFS Casting of the Year competition.  Like Mercury, they also do work for outside customers.

Charles Murray
User Rank
Blogger
Re: Is aluminum strong enough?
Charles Murray   7/16/2012 4:18:59 PM
NO RATINGS
Thanks, Dave, for stirring my memory a bit. I do recall the outboard engine industry using aluminum alloy blocks. I looked back at an old article (from the '90s) and found that Mercury Marine was using (and maybe still uses) a hypereutectic aluminum-silicon block alloy known as Mercosil. Those engines went into production in '94. The silicon in the block was supposed to enhance wear resistance. Later, they used a nickel phosphorous/boron nitride piston coating with no cylinder liner, but I don't know how that turned out, or whether they still use it.

Dave Palmer
User Rank
Platinum
Re: Is aluminum strong enough?
Dave Palmer   7/16/2012 1:20:20 PM
NO RATINGS
@Chuck: I can't speak for the auto industry, but in the outboard engine industry, the status quo is a block made out of a lost-foam cast or die-cast alumium alloy (typically A356), a cast iron cylinder sleeve, and a hypereutectic aluminum alloy piston.  However, Yamaha has started to use plasma-sprayed cylinder liners instead of cast iron sleeves.  I believe the technology they use was developed by Ford and Flame-Spray Industries.  Sulzer Metco has a different plasma-sprayed cylinder liner technology.  One of the advantages of the plasma-sprayed liners is that they save weight compared to a cast iron sleeve.  The properties of the coating be tailored to get additional benefits.

Ann R. Thryft
User Rank
Blogger
Re: Is aluminum strong enough?
Ann R. Thryft   7/16/2012 11:53:57 AM
NO RATINGS
Chuck, trying to get details on the piston construction proved very difficult. This company makes both aluminum and steel pistons, and their liners are made of several materials including cast iron.

bob from maine
User Rank
Platinum
Re: Is aluminum strong enough?
bob from maine   7/16/2012 9:44:33 AM
NO RATINGS
BMW Motorcycles ran an all aluminum block with no cast iron liners with great success. I've seen them run over 100,000 miles with no loss of compression. I don't think the problem is purely aluminum but the overall design of the combustion process. The normal diesel "crack" that occurs at the time of ignition created enormous stresses in all the metal in the combustion chamber, not just the piston; spreading this explosion out over time would go a long way toward reducing stress. I'd guess that BMW has adopted more than just a triple turbocharger and an aluminum piston to make this engine meet their performance goals. Using aluminum pistons and reducing reciprocating mass is a significant step toward increased performance and durability.

naperlou
User Rank
Blogger
Re: Is aluminum strong enough?
naperlou   7/16/2012 9:15:17 AM
NO RATINGS
Rich, ceramics are finding use in the turbine blades in aircraft engines.  If that works out, can applications in automobile engines be far behind?

Page 1/2  >  >>


Partner Zone
Latest Analysis
Released on September 19, 2014, this 5.5 inch screen iPhone is the larger version of the iPhone 6, whose teardown follows tomorrow.
A Design News course on field programmable gate arrays (FPGAs) should help engineers who are considering the technology for their upcoming designs.
In many engineering workplaces, there’s a generational conflict between recent engineering graduates and older, more experienced engineers. However, a recent study published in the psychology journal Cognition suggests that both may have something to learn from another group: 4 year olds.
CTC releases EtherCAT Master module for high-performance control of networked servos, stepping motors, and I/O devices.
Conventional wisdom holds that MIT, Cal Tech, and Stanford are three of the country’s best undergraduate engineering schools. Unfortunately, when conventional wisdom visits the topic of best engineering schools, it too often leaves out some of the most distinguished programs that don’t happen to offer PhD-level degrees.
More:Blogs|News
Design News Webinar Series
9/10/2014 11:00 a.m. California / 2:00 p.m. New York
7/23/2014 11:00 a.m. California / 2:00 p.m. New York
7/17/2014 11:00 a.m. California / 2:00 p.m. New York
9/25/2014 11:00 a.m. California / 2:00 p.m. New York
Quick Poll
The Continuing Education Center offers engineers an entirely new way to get the education they need to formulate next-generation solutions.
Sep 22 - 26, MCU Software Development – A Step-by-Step Guide (Using a Real Eval Board)
SEMESTERS: 1  |  2  |  3  |  4  |  5  |  6


Focus on Fundamentals consists of 45-minute on-line classes that cover a host of technologies. You learn without leaving the comfort of your desk. All classes are taught by subject-matter experts and all are archived. So if you can't attend live, attend at your convenience.
Next Class: September 30 - October 2
Sponsored by Altera
Learn More   |   Login   |   Archived Classes
Twitter Feed
Design News Twitter Feed
Like Us on Facebook

Sponsored Content

Technology Marketplace

Copyright © 2014 UBM Canon, A UBM company, All rights reserved. Privacy Policy | Terms of Service