Where 'oh where has the OHV gone..

[92saturnsl2]

... oh where oh where can it be? With its torque down low and its midrange pull, oh where oh where can it be?

Referring to pushrod engines obviously, as OHC can also be considered OHV. Anyone wonder why they have all but disappeared?

In my many years of driving, I've driven all sorts of different cars with all sorts of different engines. Call me crazy, in my driving experience, I would rather have an pushrod engine for several reasons.

a) Fuel economy seems better. My last car, a 3700lb. 2000 Bonneville with the 3.8L supercharged series II engine turned in a solid 27 mpg on the highway. My dad's 3.4L Monte Carlo (not a light car by any means) routinely gets in the low 30's on the highway. We have two similarly equipped minivans at work, an '03 Chevy Venture w/ 3.4L, and an '09 Kia Sedona w/ 3.5L DOHC, and the Chevy gets at least 2-3mpg better at nearly every fill-up.

Compared to the OHC crowd; my current car, a turbo 2.4L weighing 600 pounds less than my Bonneville, driven lightly, gets 28 mpg highway. Yes it's turbocharged so there's some lost efficiency with the exhaust restriction, but it's not unlike a supercharged engine whose turning a pair of rotors at high speeds. I think that's poor considering the Bonneville had more power (dynoed 240whp @ 5700rpm / 346 ft-lbs @ 2800rpm), two more cylinders, weighed more, and was an auto.

I had a VW Jetta VR6 (2.8L 12 valve SOHC) that would get 28-29mpg highway. Despite that being a manual, it's considerably less than the 30+ my dad gets in his Automatic Monte Carlo, which weighs more.

b) Packaging & Complexity

All OHV motors I've had under the hood were a breeze to work on, because there's simply more room in the engine bay. 4 cyl and SOHC designs do not suffer as much, but a lot of DOHC examples can be utter nightmares to work on. Take GM's 4.6L Northstar which is routinely stuffed transversely into less than ideal spaces. V6's aren't as bad because they're often 60 degrees, but 90 degree DOHC V6's, forget it.

C) Reliability

Ever hear of a timing belt on a pushrod motor? I'm not saying they don't exist, but they sure aren't common. Ever had a chain break? I haven't. Change the fluids, turn the key, keep driving. No expensive timing belts (labor) to replace or break, no unreliable chain designs that can stretch or whose tensioners wear out. I've seen LOTS of high mileage cars destined for the junkyard simply because the timing belt breaks and pistons meet valves, with a less than friendly introduction. Someone who buys a used car with no maintenance history is especially in danger, because few people will dish out several hundred to replace a timing belt without knowing it needs replaced until it's too late.

By no means am I suggesting that OHC designs are inferior or have no place in the market. They have greater horsepower potential, no doubt about it.

But look at the market and the needs of 90% of the people on the roads. Most drive very casually, never (or are afraid to) exceed 4,000rpm, thus would benefit from a wide torque curve, with peak torque at lower RPM's, typically what you get from an OHV design.

There was a day when OHV was king, and OHC was relegated to high performance applications like the GM Quad 4. I think this made perfect sense. But Japan had a tax based on displacement, so all the Japanese manufacturers went OHC, and brought those designs stateside. Since then, US automakers had to compete with the Japanese's higher "paper-power" by transitioning to overhead cam engines.

Even though an OHC engine will typically make more horsepower, that HP will often be available for a very short duration (*especially* before variable valve timing became widespread); I've always felt that when displacement is similar, the pushrod engine will exhibit smoother, more effortless power compared to OHC, making it feel more refined.

Am I the only one with this perspective, or do you think my examples and / or assertion is flawed?

Before some takes it personally, or this turns into a OHC vs pushrod war, I agree there are LOTS of great SOHC/DOHC examples out there that are nothing short of a marvel in engineering. Just saying that OHV engines have a lot of great attributes, and it's unfortunate that they're no longer widely available.

 

[OVERKILL]

Originally Posted By: 92saturnsl2
... oh where oh where can it be? With its torque down low and its midrange pull, oh where oh where can it be?

Referring to pushrod engines obviously, as OHC can also be considered OHV. Anyone wonder why they have all but disappeared?

In my many years of driving, I've driven all sorts of different cars with all sorts of different engines. Call me crazy, in my driving experience, I would rather have an pushrod engine for several reasons.

a) Fuel economy seems better. My last car, a 3700lb. 2000 Bonneville with the 3.8L supercharged series II engine turned in a solid 27 mpg on the highway. My dad's 3.4L Monte Carlo (not a light car by any means) routinely gets in the low 30's on the highway. We have two similarly equipped minivans at work, an '03 Chevy Venture w/ 3.4L, and an '09 Kia Sedona w/ 3.5L DOHC, and the Chevy gets at least 2-3mpg better at nearly every fill-up.

Compared to the OHC crowd; my current car, a turbo 2.4L weighing 600 pounds less than my Bonneville, driven lightly, gets 28 mpg highway. Yes it's turbocharged so there's some lost efficiency with the exhaust restriction, but it's not unlike a supercharged engine whose turning a pair of rotors at high speeds. I think that's poor considering the Bonneville had more power (dynoed 240whp @ 5700rpm / 346 ft-lbs @ 2800rpm), two more cylinders, weighed more, and was an auto.

I had a VW Jetta VR6 (2.8L 12 valve SOHC) that would get 28-29mpg highway. Despite that being a manual, it's considerably less than the 30+ my dad gets in his Automatic Monte Carlo, which weighs more.

b) Packaging & Complexity

All OHV motors I've had under the hood were a breeze to work on, because there's simply more room in the engine bay. 4 cyl and SOHC designs do not suffer as much, but a lot of DOHC examples can be utter nightmares to work on. Take GM's 4.6L Northstar which is routinely stuffed transversely into less than ideal spaces. V6's aren't as bad because they're often 60 degrees, but 90 degree DOHC V6's, forget it.

C) Reliability

Ever hear of a timing belt on a pushrod motor? I'm not saying they don't exist, but they sure aren't common. Ever had a chain break? I haven't. Change the fluids, turn the key, keep driving. No expensive timing belts (labor) to replace or break, no unreliable chain designs that can stretch or whose tensioners wear out. I've seen LOTS of high mileage cars destined for the junkyard simply because the timing belt breaks and pistons meet valves, with a less than friendly introduction. Someone who buys a used car with no maintenance history is especially in danger, because few people will dish out several hundred to replace a timing belt without knowing it needs replaced until it's too late.

By no means am I suggesting that OHC designs are inferior or have no place in the market. They have greater horsepower potential, no doubt about it.

But look at the market and the needs of 90% of the people on the roads. Most drive very casually, never (or are afraid to) exceed 4,000rpm, thus would benefit from a wide torque curve, with peak torque at lower RPM's, typically what you get from an OHV design.

There was a day when OHV was king, and OHC was relegated to high performance applications like the GM Quad 4. I think this made perfect sense. But Japan had a tax based on displacement, so all the Japanese manufacturers went OHC, and brought those designs stateside. Since then, US automakers had to compete with the Japanese's higher "paper-power" by transitioning to overhead cam engines.

Even though an OHC engine will typically make more horsepower, that HP will often be available for a very short duration (*especially* before variable valve timing became widespread); I've always felt that when displacement is similar, the pushrod engine will exhibit smoother, more effortless power compared to OHC, making it feel more refined.

Am I the only one with this perspective, or do you think my examples and / or assertion is flawed?

Before some takes it personally, or this turns into a OHC vs pushrod war, I agree there are LOTS of great SOHC/DOHC examples out there that are nothing short of a marvel in engineering. Just saying that OHV engines have a lot of great attributes, and it's unfortunate that they're no longer widely available.


Bone stock E39 M5 dyno (this engine is DOHC):

It makes a stump pulling 330lb-ft of torque (this is REAR WHEEL) at just over 2,000RPM. And the curve looks like something out of a diesel.

This is a tiny 5.0L V8, naturally aspirated.

It also gets 28Mpg in a car that I'm sure weighs just as much as your Bonneville.

It is a myth that all OHC engines only make power up top. Ford's SOHC Modular engines made plenty of bottom end grunt and didn't wind to the moon.

And with VCT on modern DOHC setups providing the ability to advance and retard the cam timing on both the intake and exhaust valves independently means that you have more power EVERYWHERE over a comparable pushrod engine.

And of course a million feet of timing chain doesn't mean it won't be reliable. A huge pile of P71's in LEO and Taxi duty can attest to that.

Now, pushrod engines are certainly far more compact! And I definitely enjoy working on them a lot more. But OHC engines have replaced them for a reason.

 

[sciphi]

Agreed, OHV V6 engines were great every-day motors. GM especially knew how to make a decently-performing OHV V6 (moronic bean-counter-driven engineering choices set aside). I had a Buick LeSabre that consistently averaged 30-31 mpg in rural highway type driving. The engine was smooth in that car, too.

GM's still using pushrods in their LS engines. The next Corvette engine is pushrod, and still is a nice engine.

Engineers pushing for further "efficiency" gains will invariably see the lifter and pushrod as more potential energy loss points, and do away with them. Less un-necessary moving mass theoretically equals more energy available to apply to the road.

 

[Dakota1820]

overkill everything you said is true. but in my own personal experience i will say the useful power band in a small car is important. my saturn if in 2 high a gear and a slight hill and it will buck slightly basically because it does not have the balls where it needs it . where as my old cavalier 2.2ohv wouldnt do that because it performed better at low rpm. but the saturn loves above 3,000 rpm where as the cavalier hated it. i would say for little econo boxes the ohv is smoother but the ohv makes you feel faster.

 

[OVERKILL]

Originally Posted By: sciphi
Agreed, OHV V6 engines were great every-day motors. GM especially knew how to make a decently-performing OHV V6 (moronic bean-counter-driven engineering choices set aside). I had a Buick LeSabre that consistently averaged 30-31 mpg in rural highway type driving. The engine was smooth in that car, too.

GM's still using pushrods in their LS engines. The next Corvette engine is pushrod, and still is a nice engine.

Engineers pushing for further "efficiency" gains will invariably see the lifter and pushrod as more potential energy loss points, and do away with them. Less un-necessary moving mass theoretically equals more energy available to apply to the road.


Not only that, but fewer valvetrain components to keep in check means lighter valve springs (and 4-valve heads can run lighter valves, which again, don't need as much spring pressure) and the ability to have engines that can rev higher while still being reliable.

 

[MinamiKotaro]

No pushrod I4 is going to do what a DOHC one can. The 2.2 Ecotec in my Saturn sure doesn't have a low-end torque problem compared to the crime against humanity that was the GM 2.2, pushrod I4.

Changing the spark plugs is much easier on a DOHC I4. They're right there in the middle of the valve cover.

I do not own, never have owned, and never will own a V8 or V6 so I can't speak to those applications.

 

[morris]

my 2001 dodge dakota V-6 239 ci. i still want more low end torque.

 

[92saturnsl2]

Originally Posted By: OVERK1LL
It also gets 28Mpg in a car that I'm sure weighs just as much as your Bonneville.

It is a myth that all OHC engines only make power up top. Ford's SOHC Modular engines made plenty of bottom end grunt and didn't wind to the moon.


Apples and oranges comparison. Further, I couldn't find any evidence that real world mileage is anywhere near the 28mpg in your example.

http://www.fuelly.com/car/bmw/m5/gas v8

You're putting words in my mouth that were never shared in my post. Nowhere did I suggest that all OHC engines make power up top. There's a million different variables that allow the engineer to make peak power at wherever they decide to.

Clearly this touched a nerve, and your intentions are exactly what I wished to avoid. This is not a [censored] contest, nor is is it a OHV vs. OHC battle of which is better. I'm simply sharing some observations that I have, you seem to have somehow twisted them into a declaration that OHV engines are somehow better. I never made that claim nor wish to.

 

[Spazdog]

I wonder if someone lamented the demise of flathead engines at one time?

Out of the fullsize trucks, GM and Ram still have "cam in block" engines. GM is exclusively OHV (until 2014 when it allegedly gets the 3.6). Ram is just the Hemi. But that is still 2 out of 5 brands of fullsize trucks

In the '70s, OHV engines were common in Japanese cars. If a Toyota didn't have an R-series engine, it was OHV. If a Nissan didn't have an L-series, it was probably OHV. Subaru held out with OHV until about '84. Mitsubishi and Isuzu didn't sell OHV vehicles here but then again in the '70s, you could only buy Mitsubishi and Isuzu rebadged as Chrysler and GM products. The Mazda engine everyone focused on did not have any heads or valves.

 

[92saturnsl2]

Originally Posted By: OVERK1LL
Not only that, but fewer valvetrain components to keep in check means lighter valve springs (and 4-valve heads can run lighter valves, which again, don't need as much spring pressure) and the ability to have engines that can rev higher while still being reliable.


Excellent point. On that same token, it stands to reason that with half the valves, there is less overall spring pressure to overcome. I've read somewhere that some 30% of an engine's specific output goes to opening valves; that's a substantially amount of energy that increases with the number of valves that need to open.

There's no arguing that valvetrain mass is one of OHV's greatest drawbacks, and the reason you don't often see redlines much past 5,500 - 6,000 rpm, except performance applications.

 

[OVERKILL]

Originally Posted By: chevyboy14
overkill everything you said is true. but in my own personal experience i will say the useful power band in a small car is important. my saturn if in 2 high a gear and a slight hill and it will buck slightly basically because it does not have the balls where it needs it . where as my old cavalier 2.2ohv wouldnt do that because it performed better at low rpm. but the saturn loves above 3,000 rpm where as the cavalier hated it. i would say for little econo boxes the ohv is smoother but the ohv makes you feel faster.


But the Cavalier engine is bigger, your Saturn has a 1.9L engine; one that is 15% smaller than the engine in the Cavalier

But GM DID design the Saturn DOHC engine to rev higher because they wanted the HP numbers to be on par or close to what the Japanese were offering (a point made by the OP and one I agree with).

There are only so many ways to extract power out of a given amount of displacement. Better breathing means it can rev higher and make more HP. But this is often at the expense of low end torque (no longer as much of an issue with variable cam timing setups as shown by the BMW graph I posted earlier). This applies to both pushrod AND OHC engines.

The "traditional" long runner intake pushrod engines, that had poorly breathing heads and baby cams would make all their power down low. But they made very little HP.

But then the same could be said for the 1st gen SOHC Modular, which also had a long runner intake, poorly breathing heads and baby cams. And it also made all its power down low and very little HP.

You take a 302 Ford, put a set of high flow heads on it and a longer duration, higher lift cam to increase the HP and you move the power band UP. It means low RPM manners and performance suffer at the expense of the increase in overall HP.

Now of course you can also put a baby cam in a heavy breathing engine and while not coming close to maximizing the potential of the parts, still allows you to make lots of power and retain excellent manners. This has been GM's technique with the LSx engines. Big heads, small (relatively) cams and cubes. This allows them to work within the constraints of the pushrod architecture while being able to compensate for its shortcomings through displacement.

The opposite of that technique is that leveraged by Ford, Toyota, Hyundai, Nissan and the German marques. Smaller displacement V8's with four cams, heavy breathing and variable cam timing. They've decided to throw technology at it instead of cubes.

Two different ways of dealing with the same "problem". The OHC engines should in theory be better on fuel. But in practice the difference isn't much, if anything. Adoptions of technologies like cylinder deactivation have gone to help the pushrod engines gain even greater grounds in fuel economy. Though it is interesting to note that Ford seems to have shown no interest in adopting this technology (on their OHC engines of course).

While the OHC engines benefit from the ability to have better (wider, less peaky) power curves, the obvious advantage of the pushrod engine in this instance (using GM's latest LSx offerings) is that they have huge heads and plenty of displacement and are simply cammed small to behave appropriately in their application. They have the potential to make a LOT more power than they come out the door with if one is willing to sacrifice the manner of the stock cam to do it.

 

[OVERKILL]

Originally Posted By: 92saturnsl2
Originally Posted By: OVERK1LL
It also gets 28Mpg in a car that I'm sure weighs just as much as your Bonneville.

It is a myth that all OHC engines only make power up top. Ford's SOHC Modular engines made plenty of bottom end grunt and didn't wind to the moon.


Apples and oranges comparison. Further, I couldn't find any evidence that real world mileage is anywhere near the 28mpg in your example.

http://www.fuelly.com/car/bmw/m5/gas v8

You're putting words in my mouth that were never shared in my post. Nowhere did I suggest that all OHC engines make power up top. There's a million different variables that allow the engineer to make peak power at wherever they decide to.

Clearly this touched a nerve, and your intentions are exactly what I wished to avoid. This is not a [censored] contest, nor is is it a OHV vs. OHC battle of which is better. I'm simply sharing some observations that I have, you seem to have somehow twisted them into a declaration that OHV engines are somehow better. I never made that claim nor wish to.


My example is my own vehicle, just like your example was your own vehicle

Touched a nerve? hardly.

The myth that OHC engines make all their power up top was touched on in your post and is one that has been around for ages. I mentioned it because of that fact, not as some sort of attack on you or your topic.

I'm certainly not putting words in your mouth, but you definitely do appear to be taking what I've posted in a way that it was not intended to be taken. I was partaking in the DISCUSSION on the topic, which is something you appeared to encourage. Or is it only encouraged if one's ideals and examples align with your own?

My observations are different from yours. I've wrenched, been involved in and have built a significant number of pushrod engines. I'm far from green on this topic. I've posted many of my efforts on this board with Ford 302 engines, which I still actively work on.

I've owned both an upgraded pushrod 5.0L V8 and the "techno marvel" that is the S62 BMW 5.0L V8 and as much as I absolutely LOVE the Ford 302, the DOHC 5.0L does everything better. It makes more torque, it gets better gas mileage, and is FAR less peaky making the same amount of power.

Also, I don't see how my OHC dyno graph example is apples and oranges? You cited a supercharged OHV engine as your example, with a roots-type blower, which is known to make a TON of bottom end power by design. Had we been comparing an N/A 3.8L, the abundance of bottom end power and the plateau-flat torque curve of the VCT DOHC engine would have been even more starkly in contrast to many people's observations as to how an OHC engine is "supposed" to behave.



************************
My posts in this thread are intended to be taken as good natured discussion. I am not attacking you or your observations, I am simply indicating that they do not necessarily align with my own. That's what the whole idea of a DISCUSSION is about. I am trying to be civil and SPEAK to you while expressing this fact. I humbly expect nothing more than that same courtesy in return.

 

[Dakota1820]

the 2.2 is bigger but the hp numbers and torque are close. my point was if going up a slight hill in 4th at 35mph the cavi would chug up the hill the saturn will but will feel it slowing and struggling. but overall the saturn is faster. above 3,000rpm the cavi sounded and felt like a obese whale being strangled. i prefer ohv for its simplicity reliability and such but the ohc is more fun and has more valves. i do think people who dont take care of their cars should buy pushrod engine cars, they seem to take more [censored] and keep on running.

 

[OVERKILL]

Originally Posted By: 92saturnsl2
Originally Posted By: OVERK1LL
Not only that, but fewer valvetrain components to keep in check means lighter valve springs (and 4-valve heads can run lighter valves, which again, don't need as much spring pressure) and the ability to have engines that can rev higher while still being reliable.


Excellent point. On that same token, it stands to reason that with half the valves, there is less overall spring pressure to overcome. I've read somewhere that some 30% of an engine's specific output goes to opening valves; that's a substantially amount of energy that increases with the number of valves that need to open.

There's no arguing that valvetrain mass is one of OHV's greatest drawbacks, and the reason you don't often see redlines much past 5,500 - 6,000 rpm, except performance applications.


Exactly.

Now another interesting comparison to make here is the difference between the spring pressure required on an SOHC modular vs a pushrod Windsor. To wind the Windsor as high as you wind the Modular, even though both are 2V heads, you need much heavier springs to compensate for the added weight of the rocker, pushrod, lifter....etc.

Now heavier springs aren't a problem if you are into building a performance engine. They are a "par for the course" upgrade on any built pushrod engine expected to be spun higher than stock. But an OEM who is planning to have an engine last for a long period of time, spring pressure and life are certainly factors. GM went to a lot of effort to lighten the valvetrain on the LSx engines. The LS7 was pretty much the epitome of that effort with plenty of titanium components, sodium filled valves...etc.

Yet a quick glance at Coyote and its 4V heads, high redline (even higher in BOSS 302 trim), not to mention the efforts put forth by Honda over the years with all their high RPM, yet extremely long lived examples certainly appear to indicate to me at least that the absence of all these extra (pushrod) components and the ability to run much, MUCH lighter springs on much smaller valves while still having heavy breathing heads gives the OEM that much more freedom with total safe engine RPM with a lot less to worry about than with a pushrod engine.

An example that I think perhaps indicates both your point and mine is a comparison of the LS3 and the Coyote:

LS3:

Coyote:

Both engines make similar power, yet the Coyote is wound 1,500RPM higher. The GM engine is 1.2L larger. But GM has chosen to "cam it down" to keep the RPM's at a reasonable level for longevity and driveability purposes.

 

[OVERKILL]

Originally Posted By: chevyboy14
the 2.2 is bigger but the hp numbers and torque are close. my point was if going up a slight hill in 4th at 35mph the cavi would chug up the hill the saturn will but will feel it slowing and struggling. but overall the saturn is faster. above 3,000rpm the cavi sounded and felt like a obese whale being strangled. i prefer ohv for its simplicity reliability and such but the ohc is more fun and has more valves. i do think people who dont take care of their cars should buy pushrod engine cars, they seem to take more [censored] and keep on running.


But you are making my point for me

The engine that is 15% larger but making the same power, is going to make that power lower in the power band, allowing the person to experience exactly what you are experiencing. If the Saturn engine was OHV but breathed the same, and was cammed the same, the experience would be the same

The reason the 1.9L made the same power as the 2.2L was to compete in the "HP/L" wars that were/are taking place with the Japanese marques. Peak HP was increased (and makes the car drive like you describe) to give a better HP/L number on paper.

 

[92saturnsl2]

Quote:
Also, I don't see how my OHC dyno graph example is apples and oranges?


I guess I just don't see where I made the statement that OHC engines only produce power up top. Again, you're reading between the lines something that's not there.

I never included low end torque as any of the three primary reasons I like pushrod motors. The reason for that is that it's not an advantage-- If you want an OHC engine with gobs of low RPM torque, they're out there. It's all in the design.

My last truck, an Supercharged Nissan Frontier made 248 ft-lbs @ 2000-2800rpm, yet had no power up top. This completely contradicts your inference that I believe OHC engines are high-strung and only make peak power at high RPM.

The fact that an internet myth exists is wonderful but irrelevant. I wouldn't be posting on this forum if I didn't welcome discussion on the topic. Frankly I don't care whether or not you agree with me. We're both aware how quickly these types of topics turn into a mud slinging contest. When the first post out of the gate intends to discredit and prove me wrong, it's easy to view it in a hostile light.

The BMW example you gave is a poor one for this purpose. You're comparing a state of the art, high-compression V8 with dual variable valve timing, individual throttle bodies, and a host of other advancements to run-of-the-mill pushrod motors where one of the primary considerations is cost.

That's about as productive as comparing GM's best pushrod motor to Ford's 4.0L SOHC V6 and using that as the basis for pointing out the pros and cons of each.

Ultimately, I'm not even sure why you are so stuck on proving that OHC engines make power down low, as this was never a point that was argued, and as such is an exercise in futility.

 

[TallPaul]

When it comes to low rpm grunt, there is no replacement for displacement. I like push rod engines and my son just got a 2001 S10 2.2L 4-banger that is pushrod. Power seems good all across the rpm range, but his truck is geared about 8% lower than my Ranger in 1st and 2nd gears. My Ranger has the 2.3L DOHC and though I am a push rod guy, I kind of like that DOHC but for a slight weakness at the low end, which could be cured by slight adjustment of tire size to give it a bit more gear for take off.

 

[92saturnsl2]

You'll never hear me say that a OHV makes more power, and those that do are wrong.

But the OHV is still a well rounded engine that can be a win-win in a lot of applications where peak power for a given displacement is not a primary concern.

That's why I'm sad to see them go, not because they are a better engine; each have their own strengths and weaknesses.

 

[MinamiKotaro]

Originally Posted By: 92saturnsl2
I never included low end torque as any of the three primary reasons I like pushrod motors.


From the initial post:

Originally Posted By: 92saturnsl2
With its torque down low

Originally Posted By: 92saturnsl2
with peak torque at lower RPM's, typically what you get from an OHV design


You may not have meant it, but you said it. Twice.

 

[92saturnsl2]

Originally Posted By: MinamiKotaro
You may not have meant it, but you said it. Twice.


Nice try.

Originally Posted By: 92saturnsl2
a) Fuel economy seems better


Originally Posted By: 92saturnsl2
b) Packaging & Complexity


Originally Posted By: 92saturnsl2
C) Reliability


Even put the "three primary reasons" in list form separated by sequential lettering and you still missed them. Yikes.

And low end torque is typically what you get out of them. That doesn't make them any better or worse than an OHC motor in that regard.

Tired of beating the dead horse yet?