|
Multi-Displacement V8 - No Mercedes V8 has this technology!
MDS - Multi Displacement System is coming on the 2005 Chrysler 300C and Dodge Magnum R/T with the 5.7 Liter Hemi V8 engine. The V8 saves fuel by running on 4 cylinders. Only the Mercedes V12 does that - runs on 6 cylinders. The cars go on sale in April and May 2004.
This released by Daimler-Chrysler on 5 Jan 2004: "Chrysler Group Multi-Displacement System will be First Cylinder Deactivation Sold in North America on Modern, Large-Volume Vehicles 2005 Chrysler 300C and Dodge Magnum RT Will Feature HEMI® Power with Maximum Fuel Economy Up to 20-Percent Improvement in Fuel Economy Standard Equipment on Chrysler 300C and Dodge Magnum RT Uncompromised HEMI® Power Smoothly Transitions from Eight Cylinders to Four in Just 40 Milliseconds" Additionally: "The system deactivates the valve lifters. This keeps the valves in four cylinders closed, and there is no combustion. In addition to stopping combustion, energy is not lost by pumping air through these cylinders. Customers will experience estimated fuel economy gains of up to 20 percent under various driving conditions, and a projected 10 percent aggregate improvement. Improved fuel economy is realized without any change in customer experience—drivers will receive the benefit without changing their driving habits and without compromising style, comfort or convenience." |
Re: Multi-Displacement V8 - No Mercedes V8 has this technology!
Originally posted by E55 KEV Only the Mercedes V12 does that - runs on 6 cylinders. |
Yes, as of 2003, the V12 Mercedes engines no longer have the 6 cylinder cut off.
I know the 2001 - 2002 Mercedes V12's had the cylinder cut out. |
Dude, last time when DC tried this, they ran into problems. The 2001-2002 S/CL600's were plagued with problems because of this "feature".. and to top it off, the mileage STILL sucked
|
How does keeping the valves closed work? Wouldn't the piston moving down the cylinder create a ton of suction? Wouldn't this creat drag? Could this suction be great enough to unseat the valve?
No manufacturer has had any luck with this idea. GM spent $$ settling the lawsuit the owners of the 8-6-4 engines brought and MB drops it after only 2 years. I'll pass. Thanks. |
"How does keeping the valves closed work? Wouldn't the piston moving down the cylinder create a ton of suction? Wouldn't this creat drag? Could this suction be great enough to unseat the valve? "
That's exactly what I was thinking. Have you ever tried to pull a suction against a wall? It doesn't work very well and with the valves closed the engine would in effect be sucking against a wall. |
EXACTLY!
Much easier when you remove the spark plugs from an engine and turn it over. If they opened the intake valves however, they'd have to open the exhaust valves EARLY to avoid compression friction. That is pretty hard to do on a gas engine with a mechanical camshaft and valve system. |
Arg, schemes like this make me cringe.
There's no way you can assure me that you don't loose peak performance by running half the engine when lightly loaded (i.e., most of the time). The only multi-displacement technology that ever made sense to me was on Caddy's Northstar system, which disabled half the cylinders only when all the coolant leaked out to give you a safe driving window to get to a service station! Lets hope this scheme fails terribly, or at the very least, that the consumer can hack together some sort of all-cylinders-on switch. |
Actually it's not true..... W220 S-Class does have cylinder cut-out on both S500 and S600... However, only European S500 can be had w/cylinder cut-out....
|
Originally posted by AKRY Actually it's not true..... W220 S-Class does have cylinder cut-out on both S500 and S600... However, only European S500 can be had w/cylinder cut-out.... |
Originally posted by E55AMG99 Not sure where you got your info but V-8's never had it anywhere and V-12 dropped it in 2003 everywhere when they added turbos. http://www.findarticles.com/cf_dls/m.../article.jhtml Mercedes springs a cylinder cut-out system for its new 5.OL V-8, while Honda debuts a VTEC for engines with bucket-type tappets. MERCEDES' CYLINDER CUT-OUT Nearly 20 years after Cadillac shattered its own reputation with its infamous V8-6-4 variable-displacement V-8, Mercedes-Benz becomes the first European automaker to offer a cylinder cut-out system. It's aimed at boosting fuel economy on the company's new 5.0L sohc, 24-valve V-8. Optional on the 1999 S-Class (a 4,139-pound sedan) the system shuts off four cylinders by deactivating their valves. The system retains the base engine's double-rockershaft design but replaces its one-piece rockers with a pair of unique arms. One arm follows the cam lobe for valve opening/closing, the other controls the valves' deactivation. In full V-8 mode, hydraulic pressure forces a tiny piston to lock both arms together. In deactivated 4-cylinder mode, electromagnetic shift valves force the locking pistons against return springs, shutting the valves (both intake and exhaust side) and thus the cylinder. Based on an engine load map, the ECU staggers cylinder deactivation in each cylinder bank -- number two and three on the right, five and eight on the left. It works automatically between 1,000 rpm and 3,500 rpm in third through fifth gears. Valve reactivation happens when the hydraulic pressure releases the little pistons, which locks up both arms again. To keep the walls of the deactivated cylinders warm during cut-out, the system closes the exhaust valves immediately after the power stroke. They open first during reactivation. The system apparently robs the base V-8 of about seven horsepower -- 299 hp versus 306 hp. But fuel efficiency (on the new European driving cycle) is claimed to increase 7%. And at a steady 56 mph, it's improved by 15%. Sport-utility vehicle planners, take note. http://autozine.kyul.net/html/Mercedes4.htm CCS cylinder cutoff for 5.0 V8 : to save fuel when the engine is running at light load, 4 of the cylinders will be cut off, others' ignition and injection timing will be adjusted to keep the engine running. Claimed to save 7-15% fuel. This is not a new concept, GM and Mitsubishi had tried it in before. After all, is it really important ? You pay the price of a V8 for a 4-cylinder ? |
Thanks for the info. I didn't know they had it as an option on the V-8. I wonder how many they sold.
|
More neat info from Kev. This is the kind of technology I wouldn't touch until it's perfected, but I've gotten enough fill ups under my belt for my thirsty beast to appreciate what they're going for.
|
Originally Posted by E55AMG99
(Post 572743)
Not sure where you got your info but V-8's never had it anywhere and V-12 dropped it in 2003 everywhere when they added turbos.
|
15+ year old bump. Bravo!
|
Originally Posted by BlownV8
(Post 7783395)
15+ year old bump. Bravo!
|
That wasn't an insult. Just never seen a 15+ year bump on this forum. Kind of impressed actually.
|
| All times are GMT -4. The time now is 02:11 PM. |
© 2024 MH Sub I, LLC dba Internet Brands