SOCH vs DOCH
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From: Sacramento/NAPA
01' C320
SOCH vs DOCH
Qust. i have a C320 01' and i see that it has a SOCH in it but now i see the new models have a DOCH so my qust. is what is the difference and those this make more hp. how do they both differ and is it worth it 
Thx
Thx
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From: Glendale, CA
2016 Mercedes S550
Originally Posted by white_w203
first of all to clear things up its
Single Over Head Cam SOHC
Double Over Head Cam DOHC
Single Over Head Cam SOHC
Double Over Head Cam DOHC
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From: Long Island, New York
'05 C230SS 6MT, 1966 Triumph TR4a IRS, Shelby Cobra 427 Supercharged
The switched to DOHC because the new engines are 4 valves per cylinder. It is very difficult to reliably put 4 valves on one cam shaft. It doesnt mean one is by default better, but 4 valves allows much better breathing, and can more effectively get rid of exhuast, and bring in fresh air, which can allow it to make more power, but it all depends on the tune.
And yes, having 4 valves instead of 2 or 3 will allow the engine to make more power at higer engine speeds because it can get rid of exhuast fumes out of the cylinder better, allowing you to have more fresh air to use in the combustion process. That is the whole idea behind "Vtech" and the likes. The have variable cam timing to change when the valves open and close because at higer RPMs opening at the same point as at lower RPMs is not efficient in expelling exhuast and replacing it with fresh air/fuel.
And yes, having 4 valves instead of 2 or 3 will allow the engine to make more power at higer engine speeds because it can get rid of exhuast fumes out of the cylinder better, allowing you to have more fresh air to use in the combustion process. That is the whole idea behind "Vtech" and the likes. The have variable cam timing to change when the valves open and close because at higer RPMs opening at the same point as at lower RPMs is not efficient in expelling exhuast and replacing it with fresh air/fuel.
Last edited by Capt Nemo o2; Apr 26, 2006 at 07:19 AM.
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From: Illinois, Indiana
2005 C230 Sedan 6spd
DOHC is design to make more HP
SOHC is design to make more Torque
DOHC engine usually has higher Redline compared to SOHC
DOHC engine cost more to make than SOHC
The only high revving SOHC engine that I know is probably the 3.2L VTEC engine in the Acura TL. Pretty amazing engine if you ask me.
Performance car usually have DOHC setup, while SOHC is cheaper to maintain and probably more reliable due to less moving components.
SOHC is design to make more Torque
DOHC engine usually has higher Redline compared to SOHC
DOHC engine cost more to make than SOHC
The only high revving SOHC engine that I know is probably the 3.2L VTEC engine in the Acura TL. Pretty amazing engine if you ask me.
Performance car usually have DOHC setup, while SOHC is cheaper to maintain and probably more reliable due to less moving components.
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From: The blue white rock, third out.
2002 C230 Coupe(M111)
Originally Posted by BabyBenz6spd
DOHC is design to make more HP
SOHC is design to make more Torque
DOHC engine usually has higher Redline compared to SOHC
DOHC engine cost more to make than SOHC
The only high revving SOHC engine that I know is probably the 3.2L VTEC engine in the Acura TL. Pretty amazing engine if you ask me.
Performance car usually have DOHC setup, while SOHC is cheaper to maintain and probably more reliable due to less moving components.
SOHC is design to make more Torque
DOHC engine usually has higher Redline compared to SOHC
DOHC engine cost more to make than SOHC
The only high revving SOHC engine that I know is probably the 3.2L VTEC engine in the Acura TL. Pretty amazing engine if you ask me.
Performance car usually have DOHC setup, while SOHC is cheaper to maintain and probably more reliable due to less moving components.
As for more torque from SOHC...not really. Torque is a function of stroke and displacement x number of cylinders. Big displacement, long stroke and 8 cylinders always means gobs of torque...regardless of how many cams an engine has. Where OHV and SOHC comes into the torque realm has to do with air flow. Steady flow, high velocity air intake from a two valve design tends to emphasize torque...but a lot of that is by design...because two valves flow poorly at high rpm- where you make all your HP...so the engineers try to enhance the torque if the engine can't spin high...and usually it can't spin because of the design favoring torque.
The most satisfying engines for daily driving all have lots of torque...torque is what gives you that grunt, that hard pull in gear accelleration.
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From: Long Island, New York
'05 C230SS 6MT, 1966 Triumph TR4a IRS, Shelby Cobra 427 Supercharged
For that... Drive the last gen Mustang GT and Mustang Mach1... The standard GT was SOHC where as the Mach1 was DOHC (Similar to the Cobra, but without the blower)...
Engine Specifications
4.6L 260 hp V8 - 4.6L 305 hp V8
Horsepower - 260 @ 5250 RPM - 305 @ 5800 RPM
Torque (lb-ft) - 302 @ 4000 RPM - 320 @ 4200 RPM
Valves/Valve Config - 16/SOHC - 32/DOHC
Displacement (cc) - 4605 - 4605
Bore X Stroke (in.) - 3.55 X 3.54 - 3.55 X 3.54
Compression Ratio - 9.4:1 - 10.1:1
Fuel Type/System - Gas/SEFI -- Gas/SEFI
Turbocharger - No - No
Supercharger - No - No
Its a decent real world comparo, since all is the same but the compression ratio, but thats not that huge of a difference... Its just to give you an idea...
Engine Specifications
4.6L 260 hp V8 - 4.6L 305 hp V8
Horsepower - 260 @ 5250 RPM - 305 @ 5800 RPM
Torque (lb-ft) - 302 @ 4000 RPM - 320 @ 4200 RPM
Valves/Valve Config - 16/SOHC - 32/DOHC
Displacement (cc) - 4605 - 4605
Bore X Stroke (in.) - 3.55 X 3.54 - 3.55 X 3.54
Compression Ratio - 9.4:1 - 10.1:1
Fuel Type/System - Gas/SEFI -- Gas/SEFI
Turbocharger - No - No
Supercharger - No - No
Its a decent real world comparo, since all is the same but the compression ratio, but thats not that huge of a difference... Its just to give you an idea...
Last edited by Capt Nemo o2; Apr 27, 2006 at 08:41 AM.
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From: asdfasdf
One with 4 wheels
Originally Posted by Outland
Its cost. DOHC is for most applications the better solution. SOHC, and OHV(cam is in the block) are much cheaper designs. Less machining, fewer components, less cost.
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From: York, PA
2003 C230K Sport Coupe, 1986 190E 2.3
Originally Posted by TA-9FF
When were OHV engine's popular??? I've never even heard of OHV's...
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From: The blue white rock, third out.
2002 C230 Coupe(M111)
Originally Posted by TA-9FF
When were OHV engine's popular??? I've never even heard of OHV's...
BTW, OHC, and DOHC designs are nothing new. They date all the way back to the 1920's, perhaps even earlier. Complexity and Cost kept them a niche technology until the late 70's and early 80's.
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From: SF Bay Area, CA
2006 E55 and 2002 E320
Having both a SOHC car and a DOHC car in the garage, it's difficult to say which one is better.
I will say that I think that SOHC cars on average get better fuel economy. I could be wrong.
DOHC cars are definitely higher revving and more inclined to rev than SOHC cars.
Many people are wondering why their expensive cars have SOHC and think it's a compromise to DOHC, personally I can't really tell the difference.
We should have a poll, which do you prefer?
SOHC?
DOHC?
Either?
I will say that I think that SOHC cars on average get better fuel economy. I could be wrong.
DOHC cars are definitely higher revving and more inclined to rev than SOHC cars.
Many people are wondering why their expensive cars have SOHC and think it's a compromise to DOHC, personally I can't really tell the difference.
We should have a poll, which do you prefer?
SOHC?
DOHC?
Either?
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From: Illinois, Indiana
2005 C230 Sedan 6spd
I prefer DOHC over both just because is more "advance" and all the race car uses this setup (JGTC, DTM, Formula One, etc..), allows higher ravving.
P.S. I'll take Rotary engine over all of the above~
P.S. I'll take Rotary engine over all of the above~
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From: OC
a quarter mile at a time
Originally Posted by BabyBenz6spd
I prefer DOHC over both just because is more "advance" and all the race car uses this setup (JGTC, DTM, Formula One, etc..), allows higher ravving.
P.S. I'll take Rotary engine over all of the above~
P.S. I'll take Rotary engine over all of the above~
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From: Eastern Ontario
2001 ML320 E, 2003 C230K Sport Sedan
DOHC allows better control of the the Variable valve timing. Variable valve timing does not work as well on a SOHC, since you change the intake and exhaust togeather, when what you really want to do is advance the intake timing, and retard the exhaust timing....or something like that.
Ed.
Ed.
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From: The blue white rock, third out.
2002 C230 Coupe(M111)
Originally Posted by m-benzw203
i was looking at the MB web site and most of the AMG models have SOCH even the SLR i think
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From: Eastern Ontario
2001 ML320 E, 2003 C230K Sport Sedan
Originally Posted by Outland
Yep. MB is el-cheapo. MB's outgoing family of V8 and V6 motors are all spawned from the same architecture. The three valve SOHC design was a compromise...to save money, yet get some improvement in breathing.
Thus is why BMW engines had it over Merc Engines. Using their Double Vanos, BMW could keep the low end torque & efficiency, while still reving to get the HP.
Now that Merc has a decent platform, the score should be much more equal.
Note from 2002 the 230 was a dohc, with independant Variable Valve timing on intake & exhaust. I think Merc saw they had to play catch-up back in 2000, and the 1.8 was the development mule for the head.
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From: Eastern Ontario
2001 ML320 E, 2003 C230K Sport Sedan
Originally Posted by bwco
Wow, there's lots of misinformation in this thread ! Beware ! 
You posess some knowledge you would like to share????.......or you just like to comment about other's?
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From: The blue white rock, third out.
2002 C230 Coupe(M111)
Originally Posted by fasteddie
I agree;
Thus is why BMW engines had it over Merc Engines. Using their Double Vanos, BMW could keep the low end torque & efficiency, while still reving to get the HP.
.
Note from 2002 the 230 was a dohc, with independant Variable Valve timing on intake & exhaust. I think Merc saw they had to play catch-up back in 2000, and the 1.8 was the development mule for the head.
Thus is why BMW engines had it over Merc Engines. Using their Double Vanos, BMW could keep the low end torque & efficiency, while still reving to get the HP.
.
BMW has thus far employed more technology on the engine side for sure.
.
.
The M271 had it on exhaust and intake. I don't really see the M271 as anything but a long overdue replacment for the M111. I prefer the M111(m271 didn't deliver on the performance), but standards for things like fuel economy, NVH, and emmisions always are marching forward.
