A case for the Pushrod Engine:

[Z-06]

Case of OHV vs. OHC is like that of value investment vs. speculation.

No matter how much you validly convince that the value investment is better, majority of people will still speculate because it invokes the perception of better due to having fanciness of trend following, beating the market, using high end computer software, and complex equations to tell you when to sell.

[dwightlooi]

Case of OHV vs. OHC is like that of value investment vs. speculation.

No matter how much you validly convince that the value investment is better, majority of people will still speculate because it invokes the perception of better due to having fanciness of trend following, beating the market, using high end computer software, and complex equations to tell you when to sell.

Berkshire Hathaway is an obsolete organization that knows nothing about modern investments...

[riviera74]

Is GM really better off ditching pushrods for DOHC in their cars? I know that the 3.6v6 DOHC is in every car that is not equipped with a 4cyl DOHC engineered by Opel. Why are pushrods being relegated to trucks, Camaro, and Corvette only?

I will always swear by the Buick 3800 Series II/III engine as fabulously torquey and just great all-around. While my '99 Park Avenue Ultra was getting its transmission rebuilt, the DOHC 4cyl in the 2012 LaCrosse with eAssist was a smooth if peaky 4cyl with little useful torque. The engine in that LaCrosse sounded a lot like a Honda engine in a Civic. I am sure that the 3.6v6 in a LaCrosse or an CTS/SRX/XTS will sound better in city driving, but I am unconvinced that pushrods are necessarily bad, especially from a torque perspective.

[Drew Dowdell]

Pushrods aren't bad at all except to the HP/Liter crowd. the 3900 in the Lucerne was as smooth as anything out there and just a bit deficient on power. Nothing that couldn't be helped with more liters and a 6-speed.

[G. David Felt]

In case you are still wondering why it is possible for a 6.2 liter pushrod engine to be smaller and lighter than a 4.0 liter DOHC V8, here are the two engines side-by-side. Notice the amount of room and extra material needed by the DOHC heads, quad cams, their sprockets and gears?

BMW S65 4.0 liter DOHC V8 (Left), GM LS3 6.2 liter Push-rod V8 (Right)

So would it be safe to say you could if you did not know your engines say that BMW DOHC engine is the NorthStar DOHC engine?

Based on this, while the North-star was a solid engine, it still was not capable of doing what the push-rod version could do.

[dwightlooi]

So would it be safe to say you could if you did not know your engines say that BMW DOHC engine is the NorthStar DOHC engine?

Based on this, while the North-star was a solid engine, it still was not capable of doing what the push-rod version could do.

The Northstar was introduced in 1993. It made 300 hp / 295 lb-ft out of 4.6 liters at the time.

The Northstar ended its production run in 2010 making 320 hp / 315 lb-ft owing mostly to an increased (10.5:1) compression and the addition of Varaible Cam Phasing. The LH2 Northstar weighed 195 kg and it delivered 15/24 mpg out of a 3900 lbs Cadillac STS.

The LT1 engine (Gen III) was its pushrod contemporary engine at the time (introduced on the 1992 Corvette). The LT1 made 300hp / 330 lb-ft out of 5.7 liters.

The 6.2 liter LS3 engine (Gen IV) in 2010 made 436 hp / 428 lb-ft out of 6.2 liters. The LS3 weighed 183 kg and it delivered 16/24 mpg out of a 3850 lbs Camaro SS or 16/26 mpg out of a 3300 lbs Corvette.

Between 1993 and 2000, the Pushrod engine has seen more significant developments than the DOHC Northstar. Amongst the greatest change is the adoption of an Aluminum block with the LS1 (Gen IV) engine in 1997. The Northstar was a relatively light DOHC engine for its time and has always been an aluminum engine. At 195 kg the Northstar is actually lighter than today's 201 kg Ford 5.0 DOHC (Coyote) V8, although its output of 69.5 hp/liter has always been on the lower end of the DOHC V8 spectrum.

I report, you decide.

Edited August 16, 2012 by dwightlooi

[aldw]

Given that Bentley is giving up the Pushrod for DOHC for future engines, my take is that GM will sooner rather than later be forced to used DOHC for V8s or face market oblivion.

[dwightlooi]

Given that Bentley is giving up the Pushrod for DOHC for future engines, my take is that GM will sooner rather than later be forced to used DOHC for V8s or face market oblivion.

Actually they did use the DOHC configuration for V8 engines. Twice actually. Once in form of the DOHC 5.7 liter V8 in the Corvette ZR1 and once more in form of the Northstar 4.6. They were discontinued because they were generally inferior to the Pushrod alternatives.

As far as "faith" based takes go, one can just as easily assert that "sooner rather than later, the superior performance and economics of Pushrod V8s will force BMW, M-B and everyone else to develop a pushrod engine or face market oblivion.

[dwightlooi]

A comparison of contemporary V8 engines

I report, you decide.

[aldw]

Given that Bentley is giving up the Pushrod for DOHC for future engines, my take is that GM will sooner rather than later be forced to used DOHC for V8s or face market oblivion.

Actually they did use the DOHC configuration for V8 engines. Twice actually. Once in form of the DOHC 5.7 liter V8 in the Corvette ZR1 and once more in form of the Northstar 4.6. They were discontinued because they were generally inferior to the Pushrod alternatives.

As far as "faith" based takes go, one can just as easily assert that "sooner rather than later, the superior performance and economics of Pushrod V8s will force BMW, M-B and everyone else to develop a pushrod engine or face market oblivion.

However, given that they are all using DOHC configurations rather than pushrods and continuing to develop such, empirically DOHC is winning the marketing war far more clearly than pushrods.

[dwightlooi]

However, given that they are all using DOHC configurations rather than pushrods and continuing to develop such, empirically DOHC is winning the marketing war far more clearly than pushrods.

Or, it could simply be that overwhelming majority engines sold are DOHC designs simply because the majority of makers do not know how to build a pushrod engine!

Again, look at this table and tell us how the DOHC designs are better? Can you?

Red = Best in category. In fact, the Pushrods hold the crown in 4 out of 5 categories and is a very close 2nd on the 5th.

Edited August 18, 2012 by dwightlooi

[Z-06]

How do the rate of carbon dioxide emission for these engines compare?

[dado]

Dwightlooi do you really think Mercedes, Porsche, BMW etc can't make engine with cam in block if they want to?

I bet they can. Same way GM could make very good DOHC V8, V10, V12 or any other configuration if they want to. To my understanding cam in block engine is cheaper to make, cost less so GM can put engine in cheaper cars (chevrolet ) and can be shared with less expensive trucks etc.

Yes both design have their advantages and disadvantages .

Also why haven't you put M159 engine instead of M156...or McLaren M838T engine..or V8 engine from ferrari italia? Yes a cam in block V8 engine is more simple design, more compact design, cheaper, etc etc. But it is still loosing battle against DOHC V8 in market around world. Not because one is better or worse. Was bentley 6.75 OHV v8 bad engine? Not to my knowledge.

But rumors are GM is still considering special V8 for cadillac flagship..something in the line of engines not being shared with truck .Maybe even DOHC. Also why did GM build Northstar engine if they could use chevrolet small block engine instead, in STS, XLR.? And Ultra V8 DOHC was in plans until crisis hit GM. I don't hear any rumors about Mercedes, Jaguar, BMW, Lexus etc. trying to build cam in block V8, V10 engine? And i also don't think buyers would be to happy if Ferrari put CIB v8 in their cars.

And i am betting that you will sooner see Cadillac having DOHC v8 engine in future cars than Mercedes,BMW, Audi having CIB V8 engine in theirs. Yes, let GM built CIB engine for chevrolet, truck etc. But for expensive, luxurie cars... I'm not so sure it is a best choice. Not because it is a bad engine or anything like that. It is more of a image small block from GM have.

I do appreciate GM small block engine design..but this is turning in threads like the ones you can read on BMW forums: "My car (engine in this case) is best car (engine) in world. All others don't know how to build proper car (engine).They all suck" etc.

[dwightlooi]

Dwightlooi do you really think Mercedes, Porsche, BMW etc can't make engine with cam in block if they want to?

I bet they can. Same way GM could make very good DOHC V8, V10, V12 or any other configuration if they want to. To my understanding cam in block engine is cheaper to make, cost less so GM can put engine in cheaper cars (chevrolet ) and can be shared with less expensive trucks etc.

Yes both design have their advantages and disadvantages .

Also why haven't you put M159 engine instead of M156...or McLaren M838T engine..or V8 engine from ferrari italia? Yes a cam in block V8 engine is more simple design, more compact design, cheaper, etc etc. But it is still loosing battle against DOHC V8 in market around world. Not because one is better or worse. Was bentley 6.75 OHV v8 bad engine? Not to my knowledge.

But rumors are GM is still considering special V8 for cadillac flagship..something in the line of engines not being shared with truck .Maybe even DOHC. Also why did GM build Northstar engine if they could use chevrolet small block engine instead, in STS, XLR.? And Ultra V8 DOHC was in plans until crisis hit GM. I don't hear any rumors about Mercedes, Jaguar, BMW, Lexus etc. trying to build cam in block V8, V10 engine? And i also don't think buyers would be to happy if Ferrari put CIB v8 in their cars.

And i am betting that you will sooner see Cadillac having DOHC v8 engine in future cars than Mercedes,BMW, Audi having CIB V8 engine in theirs. Yes, let GM built CIB engine for chevrolet, truck etc. But for expensive, luxurie cars... I'm not so sure it is a best choice. Not because it is a bad engine or anything like that. It is more of a image small block from GM have.

I do appreciate GM small block engine design..but this is turning in threads like the ones you can read on BMW forums: "My car (engine in this case) is best car (engine) in world. All others don't know how to build proper car (engine).They all suck" etc.

I am sure they can, but it'll mean starting over and doing something they haven't done before. It'll take longer and cost more money. And it may not be very good the first time they tried it. It'll be like GM doing the Quad Four back in the 80s. It took GM four engine generations to get from that to where they are today. It'll take BMW and M-B at least two product cycles or about 12 years to catch up to GM. There is also the inherent risk of such a departure. They will continue down the path they are currently on -- which is delivering year over year mpg and performance improvement anyway. And, if it means being unnecessarily expensive -- like going to bi-turbo DOHC V8s to compete -- well, their market segments can afford it.

[aldw]

Benz has built pushrod engines before, in fact one of their engines was used to win the Indy 500 back in the 90's before it was promptly banned, so it isn't a lack of ability for them to build CIB engines. In the end however, marketing muscle will overpower mere technical ability, from the 1930's to today (just look at Marmon, Duesenburg or Doble for example).

Edited August 19, 2012 by aldw

[dado]

Benz has built pushrod engines before, in fact one of their engines was used to win the Indy 500 back in the 90's before it was promptly banned, so it isn't a lack of ability for them to build CIB engines. In the end however, marketing muscle will overpower mere technical ability, from the 1930's to today (just look at Marmon, Duesenburg or Doble for example).

Well mercedes 500l(actually it was designed by Ilmor and penske before mercedes took over) was build only so they can use some loophole in the engine rules. There were also one engine which was planned for racing .Brayton V8 LINK

And i agree on marketing muscle overpowering mere technicall ability.

[G. David Felt]

Marketing can make or break a company.

GM needs to wake up and brag about their engineering finesse and show the world that they build world class products in more than a niche ZR1 or some other specialty product.

[Drew Dowdell]

Marketing the pushrod would be easy.

[riviera74]

Marketing the pushrod would be easy.

I am not sure about that, given the near-worship of DOHC in the last 30 years or so.

[Drew Dowdell]

Marketing the pushrod would be easy.

I am not sure about that, given the near-worship of DOHC in the last 30 years or so.

As with anything, point out the benefits over the alternatives..... I really should have been a marketing major....

[G. David Felt]

Marketing the pushrod would be easy.

I am not sure about that, given the near-worship of DOHC in the last 30 years or so.

As with anything, point out the benefits over the alternatives..... I really should have been a marketing major....

This is far easier than most people realize, yes you will have the die hard lovers that will not even look at anything but DOHC, but then you just smack them upside the head with facts that leaves them dazed but allows the rest of the world to understand the benefits of American V8's.

You do not even have to mention that it is a push rod. Just stick to simple facts of horsepower, torque, etc and point out how it helps the end user accomplish their needs.

Americans want to know how they can save money while still playing and getting their desires done. Focus on this and how they have JD Powers and Assoc blessing and you will win.

[Z-06]

Marketing the pushrod would be easy.

I am not sure about that, given the near-worship of DOHC in the last 30 years or so.

As with anything, point out the benefits over the alternatives..... I really should have been a marketing major....

But then you would not be thinking logically.

[Drew Dowdell]

I already have the idea for the commercials in my head....

[Robert Hall]

They need to come up w/ a catchy name for marketing it so the masses will find it appealing..something like 'EcoPush technology' ...

[G. David Felt]

They need to come up w/ a catchy name for marketing it so the masses will find it appealing..something like 'EcoPush technology' ...

I like this idea:

EcoPush V8

Makes way more sense and communicates more to you in just that phrase than the confusing skyactive which I still have no idea of what Mazda is trying to sell other than small cars.

[Drew Dowdell]

buy the name "Simplicity"

[Z-06]

I already have the idea for the commercials in my head....

I was saying it sarcastically. Given how marketing operations are performed in the world

[Robert Hall]

buy the name "Simplicity"

That used to be a lawn mower brand, I think

[Drew Dowdell]

Yes it was.

[G. David Felt]

Yes it was.

Good thing we do not have many people who remember that. No need to confuse poor lemming buyers.

[Robert Hall]

Looks like Simplicity is still around...

http://www.simplicitymfg.com/

[balthazar]

I still prefer 'InBlockCam' (as the alternative denominator to 'DoubleOverHeadCam'), but I don't believe either has any resonance with the mass market consumer.

Edited August 20, 2012 by balthazar

[Robert Hall]

I still prefer 'InBlockCam' (as the alternative denominator to 'DoubleOverHeadCam'), but I don't believe either has any resonance with the mass market consumer.

IBC like the root beer.. Problem is, the mass market consumer has no idea what a 'block' or 'cam' is.

[balthazar]

I know; we agree here. I don't think marketing a IBC motor on that principal is the way to go, even if it is the catalyst to a list of improved characteristics.

It should be marketed on the advantages, not on the cam location.

[Robert Hall]

I know; we agree here. I don't think marketing a IBC motor on that principal is the way to go, even if it is the catalyst to a list of improved characteristics.

It should be marketed on the advantages, not on the cam location.

Yes..something nebulous like Mazda's 'Skyactiv' could work...tout the efficiency and power of the engines without getting into technical specifics. 'Greenpower'.

[dwightlooi]

How about "Shared Unified Cam" -- SUCK? LOL

Really, I don;t the the moniker matters. At the end of the day, if the Horspower, Torque and MPG numbers are superior that is good enough for gear heads. For non-gear heads probably just the MPG numbers and the test drive experience.

[Drew Dowdell]

"Integrated cam" - "Unlike our competitors, our engines feature an integrated cam system, this allows us to give you more engine with lower weight, better fuel economy, and better reliability without sacrificing (cue video of Camaro, CTS-V, or Corvette pealing out and driving off).... any performance."

[Robert Hall]

"Integrated cam" - "Unlike our competitors, our engines feature an integrated cam system, this allows us to give you more engine with lower weight, better fuel economy, and better reliability without sacrificing (cue video of Camaro, CTS-V, or Corvette pealing out and driving off).... any performance."

Sounds good....i-Cam Technology FTW!

[Drew Dowdell]

Use clips from this video:

"Some auto makers like to use all sorts of complicated tricks to try and squeeze extra power out of their little engines. With our integrated cam system, you get more engine, better fuel economy, and better reliability with out all of the (cue clip of some V6 blowing a timing belt) .... fuss. Integrated Cam, just part of the Simplicity System by General Motors."

[Drew Dowdell]

"Some of our competitors try to hide their small engines by adding extra complexity like DOHC and turbo chargers.... Our integrated cam system gives you more fuel economy, better performance, with lower weight all in a bigger engine... because of course... (cue a Silverado ripping out a stump or something).... size matters. Integrated Cam, just part of the Simplicity System by General Motors"

[Robert Hall]

"Integrated Cam engines--Bigger on the inside, smaller on the outside and lighter than our competitors V8s.."

Edited August 20, 2012 by Cubical-aka-Moltar

[Guest Dewey Vicknair]

QUOTE(91z4me @ Feb 16 2007, 01:25 PM) 252289[/snapback]

You do know that there are 4 valve OHV engines in produciton, right? The Duramax is probably the best example.

The Duramax head is not particularly good for airflow (the intake and exhaust ports run into one valve first then the other since the valves are tandem not side by side). Also, it is also possible only in a diesel because the Diesel engine uses a a completely flat combustion chamber roof and all four valves are parallel. The approach -- using one rocker to push down on two parallel valves connected by a bridge is not feasible for a gasoline engine.

The Honda CX500 engine used 4 valves per cylinder and a pushrod-and-rocker valvetrain. It also revved safely to 13,000 rpm.

[dwightlooi]

Well, it is "easier" to make a OHC engine rev to stratospheric RPMs compared to a pushrod engine. The elimination of the rod mass and the individually smaller valves which are lighter run into valve float at greater opening and closing speeds given the same spring tension. The CX500 also has 250cc cylinders (roughly comaprable to what you'll find in a 1.0 liter 4-cylinder engine. Smaller cylinders mean smaller valves and also generally lower piston speeds (they tend to have shorter strokes as well as smaller bores).

Still, the point is that the kind of engine speeds above which DOHC 4-valve heads really shine are not really employed in many, if not most, of today's DOHC powerplants. You really need to get to about 6000 rpm before you see any tangible benefits, 7000 rpm before it is significant and 8000 rpm before it is really worth it. With a few exceptions -- Such as Honda's B-series or F-series, Toyota's 2ZZ-GE, GM's LF1/LFX, BMW's S65, etc. -- most of today's DOHC 4-valve engines are DOHC 4-valve for no good reason!

For example, Toyota's 2.5L DOHC I-4 used in anything from Camrys to Scions makes 178 bhp @ 6000 rpm and 170 lb-ft @ 4100 rpm. That's 71.2 bhp/L. Their mainstream 3.5 V6 makes 268 bhp @ 6200 rpm and 248 lb-ft @ 4700 rpm. That's 76.6 hp/L. You can achieve that kind of numbers with Pushrod or SOHC heads, along with 2-valve per cylinder. The LT1 V8 is at 460 bhp @ 6000 rpm with 465 lb-ft @ 4,600 rpm. That's 74.2 bhp/L. Even the Ecotec³ 6.2L pushrod V8 used in Silverado trucks makes 420 bhp @ 5600 rpm with 460 lb-ft @ 4100 rpm. That's a not so shabby 67.7 bhp/L.

If you implement a DOHC 4-valve setup, it should at least rev to 7000 rpm and make it's peak power at close to 7000 rpm (like GM's 90 bhp/L LFX V6) or preferrably do what Honda did 22 years ago with the B16A 1.6L which makes 160 bhp @ 7600 rpm with 111 lb-ft @ 7000 rpm and a 8200 rpm rev limit. Anything less and a DOHC valvetrain is simply not worth the weight, the bulk, the cost, the complexity and -- if you don't care about any of the above -- the extra parasitic drag and fuel economy penalty. The problem with all the extra high revving designs is that they have emissions, tractability and/or efficiency issues down low which really takes a cam switching valve train to properly address. Over the years manufacturers had, instead, simply watered down their DOHC mills by reducing passage sizes, valve lift, valve overlap, etc. to make them civil and efficient at typical driving conditions. In doing so, they had also made the entire design choice moot. But, by now, they are so used to it that they carried on the tradition anyhow.

Edited January 19, 2014 by dwightlooi

[dwightlooi]

Use clips from this video:

"Some auto makers like to use all sorts of complicated tricks to try and squeeze extra power out of their little engines. With our integrated cam system, you get more engine, better fuel economy, and better reliability with out all of the (cue clip of some V6 blowing a timing belt) .... fuss. Integrated Cam, just part of the Simplicity System by General Motors."

How about...

Vrrrrmmmmhhhhh.... (Corvette Stingray Cut Scene)

0-60 mph 3.8 secs.

30 mpg (EPA Hwy MPG)

Single Integrated Cam

Because simple is simply better

Edited January 19, 2014 by dwightlooi