Doch .vs.soch

[-APEX-]

hey so whats the advantages and dissadvantages to a doch and soch egnine like is one more powerful than the other one?:dunno:

[Blue Devil 2]

It's actually SOHC. And DOHC is more powerful.

[littledan]

DOHC - dual overhead cam
SOHC - single overhead cam

[5.9 R/T]

Originally posted by Blue Devil 2
And DOHC is more powerful.

Not it's not.

[-APEX-]

oh i see cause i always though in most cases SOHC engines were for automatics and DOHC was for standards

[hjr]

Originally posted by Blue Devil 2
It's actually SOHC. And DOHC is more powerful. Not nessisarily. It is more flexible/variable system, but not actually more powerful Just because its DOHC. What gives the power is the 4 to 5 valve per cylinder set-up. Dont quote me on this but for example, the early style subaru 2.5rs used DOHC 16v setup but that was dropped for a SOHC 16v set up.


Originally posted by -APEX-
oh i see cause i always though in most cases SOHC engines were for automatics and DOHC was for standards Not at all.

[-APEX-]

yea i was thinking theres some automatci talons and they have a SOHC engine with a twin cam

[2.2vtec]

Originally posted by 5.9 R/T


Not it's not.

Please explain why not?

[5.9 R/T]

Originally posted by 2.2vtec


Please explain why not?

There is no correct answer to the question.

[Blue Devil 2]

Originally posted by 5.9 R/T


There is no correct answer to the question.

Umm, ok. It's simple Dual Overhead Cam is more powerful than a Single cam.

[hjr]

Originally posted by hjr
Not nessisarily. It is more flexible/variable system, but not actually more powerful Just because its DOHC. What gives the power is the 4 to 5 valve per cylinder set-up. Dont quote me on this but for example, the early style subaru 2.5rs used DOHC 16v setup but that was dropped for a SOHC 16v set up.
semi-explained.

[hjr]

OK, Ok. In general with the technology found today, A DOHC set-up is "generally" more powerful with a 4 or 5 valve/cyl head.

[5.9 R/T]

Originally posted by Blue Devil 2


Umm, ok. It's simple Dual Overhead Cam is more powerful than a Single cam.

Too many variables. Question isn't specific enough.

Fords 4.6 SOHC makes more power then Honda's 2.0 DOHC.

[-APEX-]

yea cause my automatic neon had a dual overhead cam it also cost big bucks to fix so lets jus say the DOHC an SOHC are even in thier own ways and it all depends on how you supe up the engine and w/e else you do to it that makes it the better engine

[hjr]

close but not quite, but this thread should probably die anyways.

[davidI]

Originally posted by 5.9 R/T


Too many variables. Question isn't specific enough.

Fords 4.6 SOHC makes more power then Honda's 2.0 DOHC.

ugh, isn't that cause the ford is a 4.6 and the honda is a 2.0?

I know with first gen dodge neons the SOHC engine makes 132 HP and the DOHC makes 150 HP but the SOHC makes a smoother dyno curve and many prefer it to the DOHC as it can be faster with such a nice powerband.

From what I know a Dual Overhead Cam engine makes more power because when the rpm's get high enough and the second cam kicks in there is more valve lift etc. correct?

[hjr]

Originally posted by davidI


ugh, isn't that cause the ford is a 4.6 and the honda is a 2.0?
thats the point.

[DSMer4Life]

Originally posted by davidI
From what I know a Dual Overhead Cam engine makes more power because when the rpm's get high enough and the second cam kicks in there is more valve lift etc. correct?

No. In a dual cam setup, one cam controls the intake valves and the other controls the exhaust valves. Benefit? You can upgrade either the intake or exhaust cam separately, depending on your level of mods.

What you're thinking of is a second intake cam, such as with Honda's "VTEC" technology, where a secondary larger intake cam kicks in at higher rpms to let more air and fuel in.

[Akagi Redsuns]

Second cam kicks in? Getting confused with the V-TEC and VVTL-i...etc systems I think.

DOHC usually means that one cam is actuating the exhaust valves directly, another cam is actuating the intake valves directly. Hence double overhead cams...they are both working ALL the time, there is no cam that kicks in...unless it's a VTEC, VANOS, VarioCam, VVTL-i.....etc system.

SOHC usually means that one cam is actuating both the exhaust and intake vavles directly.

Most car manufactures that have the same engine but SOHC and DOHC heads, it seems that the SOHC has better low end power and the DOHC has better top end, like the Neon and the older Saturn 1.9L in the SL1/SL2, SC1/SC2. Dunno if its because of tuning or perhaps the engine has to work harder to move all the camshafts? Shouldn't hurt it that much really.

[-APEX-]

oh i c

[Weapon_R]

Originally posted by 5.9 R/T


Too many variables. Question isn't specific enough.

Fords 4.6 SOHC makes more power then Honda's 2.0 DOHC.

For simplicity, what if Ford made a 4.6L DOHC...wouldn't the DOHC make more power than the 4l.6L SOHC?

[benyl]

Originally posted by -APEX-
yea i was thinking theres some automatci talons and they have a SOHC engine with a twin cam

That doesn't make sense.

Twin cam = DOHC

[5.9 R/T]

Originally posted by Weapon_R


For simplicity, what if Ford made a 4.6L DOHC...wouldn't the DOHC make more power than the 4l.6L SOHC?

Possibly, but what kind of power are you talking about horsepower or torque? Where do you want the power to be made? Are you refering to area under the curve or total numbers? etc. etc.

But again there are two many variables to compare then just size. what about I/E valve size? Compression? Flow capacities and characteristics of the head? Weight?

[-APEX-]

yea i thought a dual cam gave you more torque hont more hp

[alloroc]

Originally posted by 5.9 R/T


Too many variables. Question isn't specific enough.

Fords 4.6 SOHC makes more power then Honda's 2.0 DOHC.
Your wrong on both counts.

Honda's 2.0 litre DOHC has a streetable HP/Litre output that ford can only dream of.

The S2000 2.0 has 240 HP that is 120 HP / litre.

Has ford built a Normally aspirated 4.6 litre 552HP engine that runs on pump gas and passes all emmisions lately?
Didn't think so. Fords current 4.6L high output engine (it is DOHC by the way) only makes 65HP / Litre. That, by today's standards, is pathetic.

For those interested, the SOHC prodiction 4.6L HO runs 303HP
For those interested, the DOHC prodiction 4.6L HO runs 330HP

Doh did I say 4.6L DOHC makes more than the SOHC? Hey look I did. The DOHC is available in the MACH1 mustang.

Go figure

It is not just about the cams. It is about airflow and the combustion chamber design. You can't build a hemispherical, crossflow, 4 valve, swirl patterned, high compression cylinder head with just one overhead cam.

[Double0Civic]

I didnt even know that domestics used an Over head cam setup I thought they used a pushrod setup with the cam under the head. oh well...
wish I had a DOHC...*sniff

[benyl]

Originally posted by Double0Civic
I didnt even know that domestics used an Over head cam setup I thought they used a pushrod setup with the cam under the head. oh well...
wish I had a DOHC...*sniff

The only pushrods left are V8s.

I think most, if not all domestic V6s are OHC.

I think that I4 domestics have been OHC for almost 20 years.

[LUDELVR]

Originally posted by alloroc

Your wrong on both counts.

Honda's 2.0 litre DOHC has a streetable HP/Litre output that ford can only dream of.

The S2000 2.0 has 240 HP that is 120 HP / litre.

Has ford built a Normally aspirated 4.6 litre 552HP engine that runs on pump gas and passes all emmisions lately?
Didn't think so. Fords current 4.6L high output engine (it is DOHC by the way) only makes 65HP / Litre. That, by today's standards, is pathetic.

For those interested, the SOHC prodiction 4.6L HO runs 303HP
For those interested, the DOHC prodiction 4.6L HO runs 330HP

Doh did I say 4.6L DOHC makes more than the SOHC? Hey look I did. The DOHC is available in the MACH1 mustang.

Go figure

It is not just about the cams. It is about airflow and the combustion chamber design. You can't build a hemispherical, crossflow, 4 valve, swirl patterned, high compression cylinder head with just one overhead cam.

I think the point was overlooked here. Yes Honda's s2k engine is a more effecient engine as most of the engines in Honda's family are. The fact that honda makes a more effecient engine is not part of the argument here. We're talking simply about power and not really power /lieter, and as you just state:


Originally posted by alloroc

For those interested, the SOHC prodiction 4.6L HO runs 303HP
For those interested, the DOHC prodiction 4.6L HO runs 330HP



So really, the engine in question (the sohc engine by ford) does in fact have more power than the DOHC engine.

[rice_eater]

Originally posted by alloroc

Your wrong on both counts.

Honda's 2.0 litre DOHC has a streetable HP/Litre output that ford can only dream of.

The S2000 2.0 has 240 HP that is 120 HP / litre.

Has ford built a Normally aspirated 4.6 litre 552HP engine that runs on pump gas and passes all emmisions lately?
Didn't think so. Fords current 4.6L high output engine (it is DOHC by the way) only makes 65HP / Litre. That, by today's standards, is pathetic.

For those interested, the SOHC prodiction 4.6L HO runs 303HP
For those interested, the DOHC prodiction 4.6L HO runs 330HP

Doh did I say 4.6L DOHC makes more than the SOHC? Hey look I did. The DOHC is available in the MACH1 mustang.

Go figure

It is not just about the cams. It is about airflow and the combustion chamber design. You can't build a hemispherical, crossflow, 4 valve, swirl patterned, high compression cylinder head with just one overhead cam.

your flame is uncalled for...no one asked/cared about how much hp/litre honda makes. WHO CARES! But by flaming him you proved his point! His point was that there are soo many things to take into consideration, not just whether it has one cam or two. And you said yourself in your last paragraph. Lets not argue over unrelated stuff and keep to the topic (like your last paragraph). So...i've done a lot of wrench turning on my peeon but i'm slowly learning the actual physics of it all. PLease explain your last statement. From it i can assume right away that for low compression applications (turbos) having a SOHC will indeed be better. :whipped:

[DSMer4Life]

Fyi, Ford was the first domestic car company to utilize OHC technology. Don't quote me on this, but I believe it was introduced in the 4.6L.

[alloroc]

That was not a flame that was a response that included some information. Instead of assumptions.

What do you want me to do reply with something like

"Is too"

Wait

Me: "Is too"
Him "is not"
Me "Is too"

That's funny.


Originally posted by rice_eater


no one asked/cared about how much hp/litre honda makes. WHO CARES!

He brought it up with his comment "Fords 4.6 SOHC makes more power then Honda's 2.0 DOHC."

I don't drive a Honda but that is a pretty silly statement to make when comparing valve trains.


Originally posted by rice_eater


His point was that there are soo many things to take into consideration, not just whether it has one cam or two.

I thought the thread topic was SOHC vs DOHC, sorry I must have been mistaken.


Originally posted by rice_eater


PLease explain your last statement. From it i can assume right away that for low compression applications (turbos) having a SOHC will indeed be better. :whipped:

Last statement was to say that actual HP is determined my many things. True.

However,
I also said airflow and combustion chamber design are very important. The most efficient, ergo, BEST, setup is with a dual cam.

I did say "high Compression head"

You can build the arrangement that I mentioned with pushrods and lifters but like I said earlier I think the thread topic was about DOHC and SOHC heads.

You can also build a crossflow hemi head if you angle the valves outward from the centerline on a SOHC arrangement but you can't tune the valve timings separatley without buying a new cam.
Yes forced inducion engine can gain more HP with more lower compression. Where did I say Turbo?

I have been lurking on these boards for quite some time and normally find your responses lucid so I am probably crossing the line. After I make a few more responses you won't hear from me again. For a while.

Sorry if I offended you 5.9R/T

[alloroc]

Originally posted by DSMer4Life
Fyi, Ford was the first domestic car company to utilize OHC technology. Don't quote me on this, but I believe it was introduced in the 4.6L.

Chev although they didn't develop it the had used the Toyota 4age in the Chevy prism starting in 1985

They were also the the first domestic to build vvt OHC engines as they had overhead cam variable valve timing on the regal grand national.

[alloroc]

Originally posted by LUDELVR


So really, the engine in question (the sohc engine by ford) does in fact have more power than the DOHC engine.

No, read it again.

SOHC 303
DOHC 330

Same ford engine.

Dual cam better.

[rage2]

This is one of the most pointless newbie debates ever, with very laughable "facts" that's been posted :). There's so many factors involved, the argument is totally irrelevant. But, to add my lame ass 2cents, if everything was exactly the same (head design, # of valves, etc), and the only difference was the # of cams (single vs dual), then dual would make less power because it takes more energy to drive 2 cams than 1... higher energy loss, lower total output.

The ford engine obviously has other factors that makes it achieve higher output. Higher compression? Better head design? More valves? Who knows, way too many factors.

[2000impreza]

Originally posted by alloroc



For those interested, the SOHC prodiction 4.6L HO runs 303HP
For those interested, the DOHC prodiction 4.6L HO runs 330HP



i don't agree that dohc means better. dohc and sohc both have their advantages. the hp numbers listed above doesn't prove anything because the heads could have different flow rates, lifts, valves,....etc. like someone siad already, there is no correct answer to this question.

[Heep]

Originally posted by alloroc
He brought it up with his comment "Fords 4.6 SOHC makes more power then Honda's 2.0 DOHC."


Exactly. 303 hp is indeed more than 240 hp. He did not say Ford's engine makes more power per litre, he simply said it makes more power, which was his point and is true.

A DOHC engine almost always has more power, but it's not simply because it has two cams instead of one. "DOHC has more power than SOHC" isn't a valid statement...it's usually true, but not set in stone.

An SOHC engine usually has only 2 valves per cylinder, while a DOHC engine always has 4 or more valves per cylinder. Those extra valves are what make the difference. "Why?", you ask? Draw a big circle on a piece of paper. Now make 2 smaller circles side by side inside the big circle, with each smaller circle touching one side, and the two small circles touching in the middle of the big circle. That is a very basic 2 valve per cylinder layout. See all that wasted space above and below the 2 smaller "valve" circles? That's just that...wasted space.

Now, draw another big "cylinder" circle. Draw 4 equal sized circles inside the the cylinder circle, using up as much space as you can. This is a very basic 4 valve per cylinder layout. Yes, the valves in the 4v/c layout are smaller than those of the 2v/c layout, but they cover more of the cylinder area with less wasted space. If you'd like, draw another one with 5 equal sized circles, and you have a basic 5 valve per cylinder layout, with even less wasted space.

That extra opening area allows more air to enter the cylinder and more to be expelled, improving efficiency, and, in most cases, improving power.

However, SOHC 4 valve per cylinder layouts exist...even Honda used them. An SOHC 4 valve per cylinder layout has just as little wasted space as a DOHC 4 valve per cylinder layout, and therefore has the same or similar volumetric efficiency.

So the statement "DOHC makes more power than SOHC" or "DOHC is more efficient than SOHC" is completely invalid since the number of camshafts is irrelevant...it's the number of valves that makes the difference.

[alloroc]

Is not.

[GTS Jeff]

Originally posted by rage2
This is one of the most pointless newbie debates ever, with very laughable "facts" that's been posted :). There's so many factors involved, the argument is totally irrelevant. But, to add my lame ass 2cents, if everything was exactly the same (head design, # of valves, etc), and the only difference was the # of cams (single vs dual), then dual would make less power because it takes more energy to drive 2 cams than 1... higher energy loss, lower total output.

The ford engine obviously has other factors that makes it achieve higher output. Higher compression? Better head design? More valves? Who knows, way too many factors. haahaha this is the only post in here so far that is actually correct.

sohc or dohc would make no difference in power output if the cam profile and phasing are kept the same!

[rage2]

Originally posted by GTS Jeff
haahaha this is the only post in here so far that is actually correct.
Heep seems to know what he's talking about too hehe.

[GTS Jeff]

Originally posted by rage2

Heep seems to know what he's talking about too hehe. hmm your post was the only SHORT and correct post i guess.

[alloroc]

Originally posted by Heep


An SOHC engine usually has only 2 valves per cylinder, while a DOHC engine always has 4

Do not.

[rage2]

Since alloroc is acting like a 4 year old...