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Saturday, October 11, 2008
7:59:08 AM EDT
Hearing 2460+277
Automatic Transmissions Rule
Not that many years ago, the automatic transmission was first replacing the "standard" transmission---but only as an option. Ahhh...how times have changed!! What was once felt to be a gasoline waster, performance robbing type of transmission has become the darling of today's manufacturers. Why? WEll, several reasons, as usual. Modern technology has produced very reliable, long lasting, and smooth shifting automatic transmissions. Thanks to electronics/computers, they are also considered fuel savers as they more efficiently and consistently select the proper up/downshift patterns.
Finally, in the modern era of turbocharged engines, the automatic transmission offers uninterrupted torque flow, thus keeping the blower "spooled up" for instant throttle response and acceleration. With constant throttle pressure, not only is performance enhanced. Emissions are reduced with such constant signals to the engine management system.
Drawbacks??
Written by outsider8413
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Friday, October 10, 2008
3:59:00 PM EDT
Hearing 2460+272
Those "Other" paths to performance
No question about it!! In their quest (or desperation) for more performance with fuel efficiency, European/Asian manufacturers (mfg's) have, for years, used smaller engines. To obtain the desired performance, howver, turbocharging and/or diesel designs have insinuated themselves into the lineups....more now than ever! Saab, at one time, offered no "non-turbo" engines; and, the turbo and diesels go together hand-in-hand, as evidenced by the later diesels from several mfg's.
But, what all has been done to "tame" these technologies to today's level? While both are very competitive "works in progress", a diesel or turbo engine of say, 3 years ago, is considerably out of sync with today's more fuel efficient and higher performance designs.
First the diesel: This design had a reputation for being noisy, sluggish (the '60s-'70s Mercedes diesels could barely keep up with a well tuned VW Beetle), smoky, and maintenance headaches. Fuel efficiency was impressive, however and, in money concious times and places, this drove residual values up on resale Mercs. So what if they were slow as molasses and noisy?
But, flash forward few decades and we see that all of the drawbacks have been engineered out, to the point that only say, initial cost, is an issue. In this day , when OUR fuel prices cause sticker shock, a diesel Merc might seem a good investment!
So, what's their secret? Well, lotta things, but principally, one might focus on a)enhanced turbocharger efficiency and b)direct fuel injection. All in all, the big 3....economy, performance AND emissions ....have been optimized in the latest diesels from several mfg's. Smooth, quiet, virtually smokeless performance results from decades of refinements.
Suffice to say that the Germans are in the forefront with diesel development. Another brand...related to the VW group...is Audi. In recent years they have launched one diesel model after another...and even entered endurance racing with their V12 diesel "very high tech" race specific model. Know what? They have won that race 2 years running!! Who ever said diesels are slow ??
Their sports utility models benefit greatly from diesel power, as do the other models in which diesel is available.
OKay...I keep mentioning the turbocharger as an integral part of diesel, and a growing part of gasoline engines, as well. What gives? Well, as with the diesel, "turbo" engines of yore had distinct drawbacks. Perhaps rushed to market back in the 60's, they were prone to "cook" their bearings as a result of considerable internal heat build-up. In addition, their torque curves and throttle response left much to be desired.
Multiple refinements in recent years have addressed turbocharged engines' shortcomings. The dreaded "turbo lag" ...or "waiting for boost" characteristic has all but disappeared, thanks to judicious selection of the turbo's size and A/R ratio, as well as the design advances of the turbo itself.
As an added plus for turbo-diesels, the advent of direct injection allows for higher boost pressures, inasmuch as DI has a cooling effect in the combustion chamber which mitigates pre-ignition. DI's better mixture homogenity and propagation also serve as big plusses for the engine's operational characteristics.
While both of the "boosting" systems herein described are large power boosters, another, less dramatic technology has become "de rigeur" of late in manifolding. In the mid-50's, an enterprising group of Chrysler Corp. engineers...the Ramchargers....began drag racing with their "ugly duckling" 1950 Plymouth. Among other experimental items, their obvious "high rise" stance made for a most awkward, if effective, appearance. The body was actually raised considerably, with the plan that higher center of gravity factors would enhance traction; forget aerodymanics!! LOL
But more important, perhaps, was their breakthrough experiment with what is properly termed "resonance tuning". A wild array of intake tubing....extending considerably above the hood....on which the carburetors were perched...plus a similarly bizarre group of exhaust header pipes on each side of the car....have come to be the accepted beginning of today's tuned manifolding. Virtually all brands' engines utilize intake tuning, some of the manifolds actually 2-stage, which complements the engine engineers' efforts to broaden the torque curves.
Is it "free horsepower".....well, yeah, since there is no parasitic effect as there is in turbo / super charging. Of course, the gains from resonance tuning are nowhere near as great as from "boosting", but, after all, such manifolding designs are just good sense now.
Written by outsider8413
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Saturday, October 4, 2008
11:00:54 AM EDT
Hearing 2460+266
Some Updates
Ok so you thought the tristar company was reaching a point of "pause" in their product lineup!! No Way!!
Whether considering one of their "family" priced sedans, crossover vehicles or high-end performers, one must marvel at Mercedes' ever-upward technical achievements.
One example...the newest SL...is sure to light a fire under any enthusiast's seat. The SL65AMG (those last 3 letters say it all!) ..in its latest iteration the "Black Series"...is quite simply a no holds barred, very close facsimile to an European "spec racer".
Six liters of V12 power, dual turbocharged and optimized for acceleration and top speed boasts of 670BHP, and a monsterous 738 lb-ft of torque. And get this!!! That is with very conservative boost limiting; unlimited, it is said to have an even more prodigious 886 lb ft!!!! How in heck can drivetrain engineers design transmissions, and other components to cope with all that!!
"Only" a five speed tranny is used, inasmuch as the torque curve is so broad, with monsterous output thruout the rpm range!! Turbochargers are good for that! Complementing the powertrain is an updated , fully adjustable suspension specifically engineered by AMG, and a "wide-body" stance with flared front and rear fenders matching huge tires/wheels. Plenty of GRIP!!
The two-door body style is no longer a folding hardtop. In stead, a fixed, carbon-fiber roof offers lower weight and enhances body rigidity.
Written by outsider8413
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Wednesday, October 1, 2008
9:26:52 PM EDT
Hearing 2460+250
"Birds of a Feather"
For decades, American car companies have used various strategies to expand their product lines, while keeping costs down. It's no secret that, in fact, say...GM...doesn't really make 5 unique versions of its full sized cars. While each brand presents a special appearance and has particular features, there is much sharing of parts.
The term "cookie cutter cars" was aimed at GM for its interdivisional sharing of body shells/platforms throughout the years. That said, GM was the best of the Big 3 when it came to "stylizing" each division's version of the "B", "C" or other base body shell. Even when the era of "tack on" rear fenders was past, rear quarter panel uniqueness, along with the usual front end sheet metal styling strategies made for easily identifiable appearances for each individual brand within GM
In the 60's, GM introduced its first "new" size cars...the intermediates...which among four of the divisions shared one body shell. Again, front/rear styling motifs, greenhouse designs, and, of course GM's unique to each brand interiors, accessories, engines and even suspension designs gave each division its personality. Pontiac was the most individual, with its "slant-four" engine, solid "bar" driveshaft and unique transaxle, among other features. Oh yes..the "Tempest" also sported a swing axle independent rear suspension. GM typically used one division's products in any product line for experimenting, and Pontiac claimed that title for the newly introduced "A" bodies.
Buick and Oldsmobile had their own experiment...an aluminum V8 engine which had its own set of problems. Cost was one...and the characteristics of aluminum were new for the Corporation. While light and peppy, the engines manifested issues with coolant leakage at gasket interfaces.
At any rate, these "A" bodies exemplified the strategy of further body sharing among allied brands. They did maintain their particular frame and suspension designs, along with interior appointments. Ironic, as "intermediates" with 115" wheelbases, these cars were the same size as the 55-57 Chevrolets!
So successful was that strategy that...after the "A" body programs, GM eventually entered the front wheel drive arena with their "X" body program. Ultimately, all divisions had their versions, all sharing the same platform , drivetrains, and body architectures.
Stretching their lineup in the early 80's, GM evolved the "X" platforms into their "all new" "A" body cars. Looking closely, one could see that these were merely "enhanced" "X" bodies....same wheelbase and track....same interior room...only bigger trunks!! But, that's the auto industry, for ya. The Buick Century and Pontiac 6000 became big sellers during the economic downturns of the 80's.
Then came the famous trio "cum quartet" of "J" cars....smaller than the X/A, and basically four cylinder rides, with V6 options later on. Again, this program was initially slated for the economy divisions, but Buick/Olds, and, eventually, Cadillac wanted their piece of the pie, as well. MOre platform sharing!! When Cadillac debuted its gussied up version of the "J", nee Cimmaron, much ridicule flooded the press, and it has always been a standing joke illustrating American tendency to up-content or chrome up an economy car and charge more for it.
OK that's a history of GM's early years in platform sharing; let's look at a contemporary example. Toyota....imposing as their lineup is....has 3 distinct models sharing one platform. The Camry and its Lexus first cousin...the E-series....along with the Avalon...all are the same under the skin. With a considerable diversity of prices, these three models maximize the usage of one very well developed platform.
VW uses this strategy with its "New Beetle", Golf and other models. Not only platform sharing, but sharing previously EPA certified drivetrains enhance the profitability of expanded model lineups.
In fact, many foreign and domestic companies have endorsed mutual platforms for their various models ...more now than ever. Thing is, also more than ever ...stylists and engineers are skillful at disguising the similarities!!
Written by outsider8413
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Thursday, September 25, 2008
5:08:26 PM EDT
Hearing 2460+249
Automatic Driving
"Necessity Is The Mother Of Invention"
A perfect summary of American product evolution, it is particularly pertinent in today's automotive industry. Driven by the need for higher efficiencies which yield more fuel mileage and better performance, along with lower emissions, the engineering community
is ever evolving the drivetrains of today's vehicles.
One article's lead summarized it well: "more gear ratios, reduced internal friction, lower inertia, and smarter use of electronic controls" all combine for big efficiency gains.
Seemingly moving in multiple directions, the transmission design community has several approaches to their future configuration: a)stepped gear, multi ratio planetary automatic b)automated manual transmission --AMT c) constantly variable transmission --CVT d)dual clutch transmission --DCT
Following the lead of ZF and Lexus, GM is going all out with its development of a proprietary 8-speed automatic ...planetary gears, torque convertor and all. AS with the Euro/ASian designs, GM's focuses on aggressive torque convertor lock-up strategies, minimal internal efficiency losses to friction and parasitic drag and inertia, increasing ratio spread and enhancing shift sequence accuracy with respect to speed, load and throttle movement.
When operating such multi-ratio automatics, the onboard computer and actuators have greater responsibility to ensure that , a) the proper gear is automatically selected for the accelerator position/vehicle speed, b) upshifts and downshifts are logically programmed, c)some degree of "gear anticipation" prevents the dreaded "hunting" between gears and d) shift quality and speed are appropriate for the conditions. No small task, to be sure. One has only to listen to trucks being driven around town to realize that frequent shifts are necessary, and the proper gear is advantageous to acceleration.
Another major architecture...the DCT....is making gains in market penetration. Where once the Audi TT had exclusive rights on its use, the DCT is becoming the transmission of choice for the "high end" torque automatics with several brands. In lieu of the efficiency robbing torque convertor, the DCT is essentially two transmisions in one, each controlled by its own clutch. Uninterrupted torque transmission, automatic operation and excellent acceleration are some of the salient plusses for the DCT. Complexity, weight/size, and cost are drawbacks to their being used on moderate priced brands.
Porsche used its version many years ago in their fastest race cars, making headlines as Porsche does often with their technical innovation. Their current production transmission, nee PDK, is a seven ratio direct descendant of that racing debut and is said to be flawless in operation.
Now, the ever-ambitious Chinese have developed their own version of the DCT. This one's uniqueness lies in that its two sets of gears share one common mainshaft....lessening bulk and mass of the transmission. This is accomplished by using a chain drive actuating two clutches on parallel shafts, instead of concentric clutches as in most DCT designs.
Testing has shown as 13% fuel efficiency gain using the DCT compared with automatics...much of it as a result of torque convertor elimination.
The third design technology...the CVT....finds its "home" with smaller displacement, lower torque rating engines. A nearly 50 year old design pioneered by the Dutch company DAF, the CVT is gradually insinuating itself into various brands. While several have offered the CVT with initial introductions, many of those have been withdrawn as a result of poor sales.
The driving experience is unfamiliar or strange, with the sensation being one of "slippage" as a result of non-stepped ratio change. If one holds constant pressure on the accelerator, the engine reaches a certain RPM, and holds it while the transmission smoothly transitions through its ratio range.
Torque limitation is a primary factor, as well. Strides have been made to increase this with aggressive "belt" redesigns, as well as torque member changes. Parasitic losses from the oil pump, belt and pulley losses, oil-friction and agitation losses, losses in bearings bushings and clutches are efficiency issues which are being addressed.
Automated manual transmissions AMT, are complex and expensive. They are used in high-end sports/gt cars and come under close scrutiny for those preferring conventional manuals. Ferrari has done much in the area of AMT development (they are also called SMT's '
(sequential manual transmissions). Computer actuated clutches and gear changes are salient features of the AMT.
In overview, one can see that the possibilities are wide open to the drivetrain engineer. With the parameters at his/her hand, many decisions must be made to optimize the design. Of course such issues as cost and packaging are major considerations.
Point is...no one design is best for all applications, stay tuned.
Written by outsider8413
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Tuesday, September 23, 2008
6:22:48 PM EDT
Hearing 2460+244
Lotus Evora
Finally a real name for Lotus' venture into the 2+2 market!! EVORA...another "E" car...is Toyota V6 powered(Lotus' other models use inline 4's from Toyota), with all the high tech features which one would expect!
According to Lotus, the output will be about 280bhp, and enable sub-five second 0-60 times with a top speed of 160mph.
It may be a four seater, but true to Lotus' mantra, it is a real lightweight. Granted, the rear seats are of the "kiddie" variety, but still...they're included. The 3.5 liter engine, Toyota sourced, has dual VVT controlling the valvetrain, producing 276 bhp...not too shabby for such a lightweight. Lotus' estimates of performance are "sub-5 second 0-60" and "160mph top speed". Pretty heady wouldn't you say?
Written by outsider8413
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3:47:52 PM EDT
Hearing 2460+241
Audi Gets Sexy;Cadillac's Sport Wagon
Typically Audi evolves its various series (much the same way that Porsche does), first introducing a base model, then an "uplevel" performance version, and then a "near competition" hot rod.
The genesis goes like ....A4, S4, RS4.....or in this case, RS 5. A swoopy coupe...see below...its front facia is considerably modified for greater air flow.m
Mechanical/technical details are yet to be released, but , rest assured, there will be no disappointments!! As soon as they are available, this blog will feature all the particulars.
****
Now...Cadillac has shown its successor to the successful SRX "crossover". The CTS SportWagon broke cover at the Pebble Beach Concours...and is visually an obvious first cousin to the CTS sedan which has been so well received.
Written by outsider8413
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Monday, September 22, 2008
11:23:09 AM EDT
Hearing 2460+233
Porsche Update
A recent article in an engineering publication had a most succinct title:
"DFI and PDK for 911"
While that headlines the most salient changes in the "997-2" for 2009, it by no means covers this unusually extensive "mid-generation" update for such a conservative brand.
DFI (direct fuel injection) has not been at the top of Porsche's "to-do" list for long. Other brands have ensconced the technology over the last few years, having considered its advantages and disadvantages. Well, with the 2 new engines in the "997's" for '09, both are DFI ...and the results are impressive. Very evident is the change in specifications...horsepower and torque; not so evident are the improvements in fuel efficiency and emissions. Talk about a win-win!!
The other , higher profile advance for '09 is the production availability of Porsche's dual clutch transmission (PDK), featuring dual, concentric clutches to operate the seven(!) forward gears with "urging" from the computer, of course! The source company for this wonder is ZF....a well renowned provider of drivetrain componentry. (another prestigious example of ZF's expertise is their 8-speed automatic)
The technical aspects of the PDK are staggering, in order to juggle the torque path between gearsets, provide uninterrupted acceleration, and cope with daily driving situations. The electrohydraulic control unit "readies" the next gear in sequence, and provides the appropriate shift timing etc.
The PDK uses wet clutches, an unusual feature, and the hydraulic control system alternates power flow thru the two parallel gear trains for reportedly uninterrupted acceleration.
Besides automatic operation, there is "paddle shift", driver actuation available at all times. In such operation, reported shift times (from one gear to the other) are said to be 60% quicker than an automatic's.
Other mid-generation upgrades include the latest Active Suspension Management, improved tire pressure monitoring, and advances in external lighting systems.
Rarely is an article written when a new "911" descendant is created that reference isn't made to its forebears. With over 40 years lineage, it certainly has one of the longest "bloodlines" in the industry!! This latest article put it this way: "It is ..a long long way from that 901 of 1963, but the basic conception of the 911 remains in place". NUFF SAID!
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Sunday, September 21, 2008
11:30:04 AM EDT
Hearing 2460+228
Four Dour "Sports Cars"
The very title of this entry seems an oxymoron, doesn't it? Well....I guess the "modern" term is "sports sedans"....but whatever the moniker, it represents what is arguably one of the first real "crossover" segments. Combining ample passenger space and comfort and features with capable road manners when "pushed", these cars are true family pleasers.
If BMW is the "parent" of modern sports sedans (Jaguar might lay claim to that title way back in the 50's), the Bavarians have been increasingly imitated and envied. Mercedes has forgone all the stodginess of yore with its sports sedans versions; Audi, Lexus and a few US brands fill the segment.
But wait...this list is incomplete. One of the earlier sports sedans from Japan was from Nissan. The unassuming looking Maxima hit the scene in the mid80's...by today's standards a "boxy fourdoor" aka Stanza. The difference lay beneath the skin....suspension, drivetrain and ...well...performance!! Its perky 3.0 liter V6 and five speed transmission yielded acceleration way beyond the Maxima's pricetag.
Several generations of Maximas later, the 2009 update is still a class leader.
The Maxima now brings 3.5 liters of 290bhp to the table, and, while no lightweight at 3600 lbs, its balance and tuning still make it a real performance sedan. Detractors will point to the fact that it's still a front wheel drive car, and well...the bad news...only available(for now) with a CVT drivetrain. A major focus during the design phase of the new Maxima was the “Super Cockpit Interior,” which Nissan says (you guessed it) feels like a cockpit while still being spacious. You’ll find that the excellent front seats are built for the long haul (particularly when equipped with the optional thigh extension), and the 9.3 GB Music Box means your favorite tunes are just a pushbutton or two away.
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Saturday, September 20, 2008
3:03:04 PM EDT
Hearing 2460-217
New Product Updates
Interestingly, it is some of the more conservative automobile brands which are ...shall we say....reinventing themselves. Previously blogged is Honda's "departure" with the "edgy" Accord. Within the journalist community, the Accord has pretty much been a love/hate relationship...with not much in between.
Two German brands are not letting any grass grow beneath their "wheels", either. Since 2001, BMW has made marked departures from the norm in virtually every way...forging new paths in its segment. The latest "7" Series trio...for '09....is as follows:
torque 0-60 top sp mpg
730d 245 398 7.2 152 39
740 twin turbo 326bhp 332 lb ft 5.9sec 155 28.5
750 " " 407 342 5.2 155 24.8
Continuing its "uber tech" features, the "7" features, among others:
Four stage , computer controlled dampers, dynamic stability control, variable electronic throttle, variable shift programs, variable electronic power steering, electronic disconnect of alternator, a/c etc at wide open throttle. Whew....
Mercedes Benz, as usual, continues to update its various series. Talk about overkill!
SL65AMG Black: 670 738 3.7(!) 198
With over 550lbs shaved from the "stock" SL65, and 66added ponies..over even the SL65AMG, this is your luxury rocket ship!!
One more amazement ride..the now well documented Ferrari Scuderia. 2970 lb 503 347 3.5(60),11.6/125 1/4, 198mph!
Another Ferrari..the California: Hardtop Convertible, 7 speed dual clutch transmission, a comfortable 454bhp from its 4.3 liter V8. With its 180 degree "flat" crank, direct injection, it hustles its 3700 or so lbs way fast!!
BMW...continues its "M" cars with the latest M5: twin turbos on this baby, 4.4 liters ...536 bhp!!
How bout a Porsche / Mercedes cmparo?
Merc SLK 3.5 lit/301bhp 3190lb 5.5sec-60 155 (lim) 1:31.1 lap
Porsche RS60 3.4lit/299bhp 2970 5.4 170 1:28.1
"997" CarreraS 3.8 380bhp 4.3 188 (7 speed PDK)
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