3 Valves per Cylinder. How does it work? - Mercedes-Benz Forum

Reply
 
LinkBack Thread Tools Display Modes
post #1 of 12 (permalink) Old 07-14-2006, 09:25 AM Thread Starter
BenzWorld Elite
 
lnguyenh's Avatar
 
Date registered: Jan 2004
Vehicle: SL500, CL55, E350, E320
Location: Northern VA, USA
Posts: 3,209
Mentioned: 0 Post(s)
Quoted: 4 Post(s)
(Thread Starter)
3 Valves per Cylinder. How does it work?

I know how 4-valve works (2 intakes, 2 exhausts) but how does 3-valve work? Will there be 2 intakes and 1 exhaust? Thanks.
lnguyenh is offline  
Sponsored Links
Advertisement
 
post #2 of 12 (permalink) Old 07-14-2006, 09:44 AM
BenzWorld Elite
 
Kajtek1's Avatar
 
Date registered: Dec 2005
Vehicle: W211 E320 Bluetec R129 SL500 - $1300 car ........ Ford F350 6l
Location: CA Bay Area
Posts: 31,769
Mentioned: 9 Post(s)
Quoted: 1123 Post(s)
I think it is 2 intakes, but than over the years I've seen lot of whining about efficiency of MB engines with 2 spark plugs, however never have seen any serious drawing with explanation.
Kajtek1 is online now  
post #3 of 12 (permalink) Old 07-14-2006, 08:48 PM
Lifetime Premium Member
 
Musikmann's Avatar
 
Date registered: May 2006
Vehicle: 2001 E320 - Brilliant Silver/Ash: 107,000+
Location: West Virginia, USA
Posts: 17,193
Mentioned: 0 Post(s)
Quoted: 6 Post(s)
Lifetime Premium Member
Question Inguyenh

Quote:
Originally Posted by lnguyenh
I know how 4-valve works (2 intakes, 2 exhausts) but how does 3-valve work? Will there be 2 intakes and 1 exhaust? Thanks.
I was informed on one of these forums that the MBs using 3 valves per cylinder have 2 intake valves and one (larger than the intakes) exhaust valve.

Someone also said that it requires a DOHC to operate 4 valves/cylinder vs. SOHC to operate 3, so that it is easier and less costly I suppose.

Also, it seems that MB used 4 valves/cylinder earlier, then went to 3 valves, and that they are using 4 valves again in some of the newest engines.

I'm sorry if this seems a little vague, but I asked the same question elsewhere, and received what seemed like similar conflicting answers.

Mercedes Benz - Das beste oder nichts!

Last edited by Musikmann; 07-14-2006 at 08:51 PM.
Musikmann is offline  
post #4 of 12 (permalink) Old 07-14-2006, 10:11 PM Thread Starter
BenzWorld Elite
 
lnguyenh's Avatar
 
Date registered: Jan 2004
Vehicle: SL500, CL55, E350, E320
Location: Northern VA, USA
Posts: 3,209
Mentioned: 0 Post(s)
Quoted: 4 Post(s)
(Thread Starter)
Thanks for the answers. I sounds about right to me (2 intakes, 1 exhaust). I still cannot picture how a Single Cam (SOHC) works with 3 valves though. MB claimed to save on costs but a DOHC engine would have worked less and produced more TQs --> more HPs. Anyways, I am just curious because I used to have 2 SL500's of which one of them was DOHC and one of them was SOHC. The SOHC (5 speed tranny) has 13 HPs less than the DOHC (4 speed tranny) but ran faster! (Me and my friend raced it side by side).
lnguyenh is offline  
post #5 of 12 (permalink) Old 07-16-2006, 01:07 PM
Lifetime Premium Member
 
Musikmann's Avatar
 
Date registered: May 2006
Vehicle: 2001 E320 - Brilliant Silver/Ash: 107,000+
Location: West Virginia, USA
Posts: 17,193
Mentioned: 0 Post(s)
Quoted: 6 Post(s)
Lifetime Premium Member
Arrow Inguyenh

Quote:
Originally Posted by lnguyenh
Thanks for the answers. I sounds about right to me (2 intakes, 1 exhaust). I still cannot picture how a Single Cam (SOHC) works with 3 valves though. MB claimed to save on costs but a DOHC engine would have worked less and produced more TQs --> more HPs. Anyways, I am just curious because I used to have 2 SL500's of which one of them was DOHC and one of them was SOHC. The SOHC (5 speed tranny) has 13 HPs less than the DOHC (4 speed tranny) but ran faster! (Me and my friend raced it side by side).
You are very welcome.

Could it be that the gearing ratios were different enough to skew the torque curve in whatever direction that your lower HP SL500 was faster than the higher one?

Just curious: Did this happen from 0-60, 0-100, or at the top speed?

Mercedes Benz - Das beste oder nichts!
Musikmann is offline  
post #6 of 12 (permalink) Old 07-16-2006, 03:14 PM
BenzWorld Elite
 
MarcusF's Avatar
 
Date registered: Apr 2005
Vehicle: 2002 CLK430
Location: Southern California
Posts: 1,681
Mentioned: 2 Post(s)
Quoted: 3 Post(s)
Quote:
Originally Posted by lnguyenh
Thanks for the answers. I sounds about right to me (2 intakes, 1 exhaust). I still cannot picture how a Single Cam (SOHC) works with 3 valves though. MB claimed to save on costs but a DOHC engine would have worked less and produced more TQs --> more HPs. Anyways, I am just curious because I used to have 2 SL500's of which one of them was DOHC and one of them was SOHC. The SOHC (5 speed tranny) has 13 HPs less than the DOHC (4 speed tranny) but ran faster! (Me and my friend raced it side by side).


A SOHC can control 3 valves per cylinder with rocker arms. The photo on the right is of an M113 head. You can see that the cam runs down the center of the head and the rockers ride on that cam. Using rockers, a SOHC can control 4 valves per cylinders.

If you’re just looking at peak HP numbers, it’s easy to be confused about why one car is slower than another. The M119 design had 4 valves per cylinders. The M119 was replaced by the M113, which was a 3 valves per cylinder design. The initial 4.3 liter M113 had 275 HP, the same peak number as the 4.2 liter M119. The difference between the two is the M113 produced more HP over a wider rev range. It’s easy to compare the two engines – look at the 1997 E420 and the 1998 E430. Aside from the engine, those two are the same car. According to Mercedes-Benz, the zero to sixty times decreased from 6.7 to 6.4 with the M113 design. Initially, one might think the extra 100cc of engine made the difference, but the fuel economy increased as well. According to Mercedes-Benz, the M113 design gets 13% better fuel economy. Due to heat transfer, a three valve design also produces fewer emissions. Also, a 3 valve design has less mass, which translates to less drag.

This isn’t to say every three valve design is superior. In some cases, a particular three valve design can be better than a particular four valve design. There is a page at my website that discusses the M113 design.
MarcusF is offline  
post #7 of 12 (permalink) Old 07-16-2006, 03:24 PM Thread Starter
BenzWorld Elite
 
lnguyenh's Avatar
 
Date registered: Jan 2004
Vehicle: SL500, CL55, E350, E320
Location: Northern VA, USA
Posts: 3,209
Mentioned: 0 Post(s)
Quoted: 4 Post(s)
(Thread Starter)
Quote:
Originally Posted by Musikmann
You are very welcome.

Could it be that the gearing ratios were different enough to skew the torque curve in whatever direction that your lower HP SL500 was faster than the higher one?

Just curious: Did this happen from 0-60, 0-100, or at the top speed?
We didn't max it out. We've only tried from 0-60.
lnguyenh is offline  
post #8 of 12 (permalink) Old 07-16-2006, 03:40 PM Thread Starter
BenzWorld Elite
 
lnguyenh's Avatar
 
Date registered: Jan 2004
Vehicle: SL500, CL55, E350, E320
Location: Northern VA, USA
Posts: 3,209
Mentioned: 0 Post(s)
Quoted: 4 Post(s)
(Thread Starter)
Quote:
Originally Posted by MarcusF


A SOHC can control 3 valves per cylinder with rocker arms. The photo on the right is of an M113 head. You can see that the cam runs down the center of the head and the rockers ride on that cam. Using rockers, a SOHC can control 4 valves per cylinders.

If you’re just looking at peak HP numbers, it’s easy to be confused about why one car is slower than another. The M119 design had 4 valves per cylinders. The M119 was replaced by the M113, which was a 3 valves per cylinder design. The initial 4.3 liter M113 had 275 HP, the same peak number as the 4.2 liter M119. The difference between the two is the M113 produced more HP over a wider rev range. It’s easy to compare the two engines – look at the 1997 E420 and the 1998 E430. Aside from the engine, those two are the same car. According to Mercedes-Benz, the zero to sixty times decreased from 6.7 to 6.4 with the M113 design. Initially, one might think the extra 100cc of engine made the difference, but the fuel economy increased as well. According to Mercedes-Benz, the M113 design gets 13% better fuel economy. Due to heat transfer, a three valve design also produces fewer emissions. Also, a 3 valve design has less mass, which translates to less drag.

This isn’t to say every three valve design is superior. In some cases, a particular three valve design can be better than a particular four valve design. There is a page at my website that discusses the M113 design.
Very educated page. Thanks. My question remains why Mercedes moves toward the 4-valve design now?
lnguyenh is offline  
post #9 of 12 (permalink) Old 07-16-2006, 06:06 PM
BenzWorld Elite
 
MarcusF's Avatar
 
Date registered: Apr 2005
Vehicle: 2002 CLK430
Location: Southern California
Posts: 1,681
Mentioned: 2 Post(s)
Quoted: 3 Post(s)
Quote:
Originally Posted by lnguyenh
Very educated page. Thanks. My question remains why Mercedes moves toward the 4-valve design now?
The newest generation of Mercedes-Benz V8s is internally called the M273. Mercedes-Benz went in this direction because “this” four valve per cylinder design is better than the three valve per cylinder M113 it replaces. In the same way the M113 V8 surpassed the M119, the M273 V8 is more powerful, has better fuel economy, and produces lower emissions. The M273 based 550 produces 26% more HP and 15% more torque than the five liter M113 it replaces. Sticking with the theme of looking at numbers over a range, my M113 based 430 produces 295 lb-ft of torque between 3000 and 4400 RPM. This new M273 based 550 has over 290 lb-ft of torque available at 1000 RPM.

The “best” engine design is a moving target. Fortunately, the engineers at Mercedes Benz are chasing that target.
MarcusF is offline  
post #10 of 12 (permalink) Old 07-16-2006, 06:32 PM
Lifetime Premium Member
 
Musikmann's Avatar
 
Date registered: May 2006
Vehicle: 2001 E320 - Brilliant Silver/Ash: 107,000+
Location: West Virginia, USA
Posts: 17,193
Mentioned: 0 Post(s)
Quoted: 6 Post(s)
Lifetime Premium Member
Arrow MarcusF - your website?

Thank you for the very informed response.

Could you please tell us how we can find your website?

Thanks,

M

Mercedes Benz - Das beste oder nichts!
Musikmann is offline  
Sponsored Links
Advertisement
 
Reply

  Mercedes-Benz Forum > General Mercedes-Benz Forums > General Mercedes-Benz

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Mercedes-Benz Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in











  • Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
     
    Thread Tools
    Show Printable Version Show Printable Version
    Email this Page Email this Page
    Display Modes
    Linear Mode Linear Mode



    Posting Rules  
    You may post new threads
    You may post replies
    You may not post attachments
    You may not edit your posts

    BB code is On
    Smilies are On
    [IMG] code is On
    HTML code is Off
    Trackbacks are On
    Pingbacks are On
    Refbacks are On

     

    Title goes here

    close
    video goes here
    description goes here. Read Full Story
    For the best viewing experience please update your browser to Google Chrome