Back to the Future - the Pushrod Engine
#1
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Back to the Future - the Pushrod Engine
December 4, 2005
Engines Go Back to the Future
By CHERYL JENSEN
GERMAN automakers gave up pushrod engines long ago, in favor of more complex overhead-cam power plants. The Japanese have essentially quit making the old-design engines. Ford is down to just a couple.
But Chrysler, with seven, and especially General Motors, with about a dozen in 21 different forms, remain bastions of the pushrod engine, also known as an overhead-valve design.
Not only has G.M. continued to carry forward older engine designs, like the famous "small block V-8" in your grandfather's 1955 Bel Air (and your son's 2005 Corvette), it has been designing new ones. The Chevy Impala offers two pushrod V-6's that are new for 2006.
G.M. says the new engines share almost nothing with the old ones. The Impala's base engine, a 3.5-liter V-6, was actually developed from the more powerful 3.9 V-6; the two share more than 80 percent of their parts.
While the Impala's powertrains may seem caught in a piston-pushing time warp, the new-old engines were designed with innovations like variable valve timing, which provides a broader power range and produces lower emissions.
Further, G.M. and Chrysler say that pushrod engines lend themselves better than overhead-cam engines - the two companies make plenty of those, too - to another bit of fuel-saving technology that is becoming popular: deactivation of half the cylinders at cruising speed.
But money is a big factor in G.M.'s back-to-the-future powertrains. Brett Smith, director of product and technology forecasting for the Center for Automotive Research in Ann Arbor, Mich., said the company saved an estimated $800 a vehicle by sticking with pushrod motors, which cost less to make largely because they contain fewer parts. Dollars saved on the engines can be used to add other features to the cars.
Some enthusiasts defend pushrod engines, which usually have two valves per cylinder (rather than the three or more valves common among overhead-cam designs) for their strong low-end thrust.
A potentially bigger deficiency of the new Impala is its four-speed automatic transmission; competitors have five or six speeds. Additional gears can improve acceleration and fuel economy. G.M. is working on six-speed automatics for front- and all-wheel-drive cars, but they were not available in time for the 2006 Impala.
http://www.nytimes.com/2005/12/04/au...s/04CHEVY.html
Engines Go Back to the Future
By CHERYL JENSEN
GERMAN automakers gave up pushrod engines long ago, in favor of more complex overhead-cam power plants. The Japanese have essentially quit making the old-design engines. Ford is down to just a couple.
But Chrysler, with seven, and especially General Motors, with about a dozen in 21 different forms, remain bastions of the pushrod engine, also known as an overhead-valve design.
Not only has G.M. continued to carry forward older engine designs, like the famous "small block V-8" in your grandfather's 1955 Bel Air (and your son's 2005 Corvette), it has been designing new ones. The Chevy Impala offers two pushrod V-6's that are new for 2006.
G.M. says the new engines share almost nothing with the old ones. The Impala's base engine, a 3.5-liter V-6, was actually developed from the more powerful 3.9 V-6; the two share more than 80 percent of their parts.
While the Impala's powertrains may seem caught in a piston-pushing time warp, the new-old engines were designed with innovations like variable valve timing, which provides a broader power range and produces lower emissions.
Further, G.M. and Chrysler say that pushrod engines lend themselves better than overhead-cam engines - the two companies make plenty of those, too - to another bit of fuel-saving technology that is becoming popular: deactivation of half the cylinders at cruising speed.
But money is a big factor in G.M.'s back-to-the-future powertrains. Brett Smith, director of product and technology forecasting for the Center for Automotive Research in Ann Arbor, Mich., said the company saved an estimated $800 a vehicle by sticking with pushrod motors, which cost less to make largely because they contain fewer parts. Dollars saved on the engines can be used to add other features to the cars.
Some enthusiasts defend pushrod engines, which usually have two valves per cylinder (rather than the three or more valves common among overhead-cam designs) for their strong low-end thrust.
A potentially bigger deficiency of the new Impala is its four-speed automatic transmission; competitors have five or six speeds. Additional gears can improve acceleration and fuel economy. G.M. is working on six-speed automatics for front- and all-wheel-drive cars, but they were not available in time for the 2006 Impala.
http://www.nytimes.com/2005/12/04/au...s/04CHEVY.html
#3
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Originally Posted by CGTSX2004
I understand that GM is into saving money and all, but seriously, when you produce a 3.5L engine that doesn't even come remotely close to stacking up against the competitions 3.5L engine in terms of output, then you've got yourself a problem.
#4
Senior Moderator
The pushrod motor is not GM's primary problem IMHO. Although I dont think pushrod motors are as refined as their DOHC counterparts, GM has done fairly well in developing that technology.
That said, I still wish GM would have further developed the LT5 motor (C4 ZR1); with its 405hp/385lb-ft 5.7L DOHC 32v V8, I would have liked to see what it could have become by now.
That said, I still wish GM would have further developed the LT5 motor (C4 ZR1); with its 405hp/385lb-ft 5.7L DOHC 32v V8, I would have liked to see what it could have become by now.
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Originally Posted by CGTSX2004
I understand that GM is into saving money and all, but seriously, when you produce a 3.5L engine that doesn't even come remotely close to stacking up against the competitions 3.5L engine in terms of output, then you've got yourself a problem.
And they have shown that they can make high HP pushrod engines when needed like the LS7 that makes as much HP as the V10 in the M5/6 for example, but gets significantly better fuel economy and makes much more torque.
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Originally Posted by biker
They may have saved $800 per engine doing that but one sure can't see where that money was spent elsewhere.
I thought the same thing!
It does well for what it is. It win in any HP per displacement measures, but it gets excellent torque, reasonable HP and excellent fuel economy. Lastly, the benefit is that it is cheap.
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#8
I can't say I dislike pushrod engines per se. They are simple and if properly designed can be extremely reliable. They do not produce the fuel economy (at least in current form) as most over head cam engines provide. It is easy to tout the LS7s fuel economy but in the Vette it is in a very light chassis with a slippery shape and uses a forced skip shift to get there. Bottom line old school can be fine since both designs have draw-backs.
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Originally Posted by F23A4
The pushrod motor is not GM's primary problem IMHO. Although I dont think pushrod motors are as refined as their DOHC counterparts, GM has done fairly well in developing that technology.
#10
Registered Abuser of VTEC
Originally Posted by M TYPE X
Much agreed. The Chevrolet Malibu/Pontiac G6 V6 3.5L unit has torque, but it's not as fun to drive as a DOHC unit.
And I test drove a G6 several months ago. They have grunt down low, but they run out of power up top.
#11
Pit Stop?
For all of you talking about comparing the LS7 to BMW's V10, I'd just like to point out the configuration of cylinders isn't really important. The BMW V10 is only 5.0L in displacement while the LS7 is, well, 7.0L while making the same horsepower. Similar in the way the Viper V10 is 8.3L, yet only develops 520bhp. American engineers just don't do enough with their engines to warrant their sizes.
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Originally Posted by Minch00
For all of you talking about comparing the LS7 to BMW's V10, I'd just like to point out the configuration of cylinders isn't really important. The BMW V10 is only 5.0L in displacement while the LS7 is, well, 7.0L while making the same horsepower. Similar in the way the Viper V10 is 8.3L, yet only develops 520bhp. American engineers just don't do enough with their engines to warrant their sizes.
Please enlighten me as to why displacement matters? What is the downside of the LS7, a 7.0L engine compared to the BMW 5.0L engine?
In the end, all that matters is what gets achieved, not how it is achieved. The results speak for themselves.
The Viper engine was never meant to be an engineering masterpiece. It is derived off a Truck engine, but again achieves the results it was set out to do. In the end, that is all that matters.
Last edited by cusdaddy; 12-04-2005 at 05:54 PM.
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Originally Posted by youngTL
My "problem" with pushrod engines is that the revving isn't as smooth, nor do they rev as high. Some people might see low revivng as an advantage, but I see it as a disadvantage, because I love to rev up to 7000RPM when I drive. I absolutely cannot stand to drive a vehicle with a redline lower than 6500.
And I test drove a G6 several months ago. They have grunt down low, but they run out of power up top.
And I test drove a G6 several months ago. They have grunt down low, but they run out of power up top.
My Z on the other hand has the power available when I most use it. I don't need to feel like I'm killing the engine to get any performance.
Each has it's + and -'s but after my experience with the Z, I'd prefer a torque monster over revs for my next car.
#14
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Originally Posted by cusdaddy
Why does the displacement matter? Doesn't the LS7, even though 2.0L more displacement get significantly better fuel economy? Doesn't it produce more HP and significantly more Torque? Isn't it significantly cheaper to produce?
Please enlighten me as to why displacement matters? What is the downside of the LS7, a 7.0L engine compared to the BMW 5.0L engine?
In the end, all that matters is what gets achieved, not how it is achieved. The results speak for themselves.
The Viper engine was never meant to be an engineering masterpiece. It is derived off a Truck engine, but again achieves the results it was set out to do. In the end, that is all that matters.
Please enlighten me as to why displacement matters? What is the downside of the LS7, a 7.0L engine compared to the BMW 5.0L engine?
In the end, all that matters is what gets achieved, not how it is achieved. The results speak for themselves.
The Viper engine was never meant to be an engineering masterpiece. It is derived off a Truck engine, but again achieves the results it was set out to do. In the end, that is all that matters.
All I'm saying is, 500hp out of a 7.0L engine doesn't impress me as much as 500hp from a 5.0L engine. Much like the K20 in the S2000 making 240hp, while a 2.0L from, say, GM, makes only 160ish hp. American engineers have the mentality of making it bigger equals the same percentage in horsepower gains. They don't refine the technology, just put more of it under the hood. Just seems lazy to me, that's all.
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GM has devloped pushrods very welll. I have no problems with the use of the engines, the continue to save fuel, and remain very reliable. IMO, most family buyer's don't have a lead foot. They're more interested in what gas costs, and how often the engine will have to be fixed. The 3800 has been around forever, and will finally retire soon, but the damn thing's bullitproof, and easy to work on. Paring these engines with a 5sp tranny (at the least) is a must, though.
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Originally Posted by Minch00
All I'm saying is, 500hp out of a 7.0L engine doesn't impress me as much as 500hp from a 5.0L engine. Much like the K20 in the S2000 making 240hp, while a 2.0L from, say, GM, makes only 160ish hp. American engineers have the mentality of making it bigger equals the same percentage in horsepower gains. They don't refine the technology, just put more of it under the hood. Just seems lazy to me, that's all.
Yes, it is impressive that an engine with small displacement can produce high-hp, but why is it better than a more simple engine that has more displacement but is lighter, produces more HP/Torque and gets better fuel economy? Isn't the benefit of small displacement supposed to be better fuel economy? All you are doing in that case is adding cost, complexity, reduced engine life without achieving the end results.
Right now, there is no engine out there in the market today that can beat the LS7 on all 3 counts of HP, Torque, and Fuel Economy. To me, that is mightily impressive.
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I agree with cusdaddy. These engines get great mileage in any car they are put in. GM's limiting factor right now is their transmissions.
As far as the big 3 with their smaller engines....we got a long way to go, baby.
I think that the different philosphies over engine types has developed partially because of the difference in driving conditions in america vs. europe vs. asia. We have big gargantuan road vs. the rest of the world. Torque starts to matter a lot more.
As far as the big 3 with their smaller engines....we got a long way to go, baby.
I think that the different philosphies over engine types has developed partially because of the difference in driving conditions in america vs. europe vs. asia. We have big gargantuan road vs. the rest of the world. Torque starts to matter a lot more.
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Originally Posted by Minch00
All I'm saying is, 500hp out of a 7.0L engine doesn't impress me as much as 500hp from a 5.0L engine. Much like the K20 in the S2000 making 240hp, while a 2.0L from, say, GM, makes only 160ish hp. American engineers have the mentality of making it bigger equals the same percentage in horsepower gains. They don't refine the technology, just put more of it under the hood. Just seems lazy to me, that's all.
Nothing will ever replace the CGT in my eyes, but for argument's sake, the Z06 starts to make a lot of sense if you think of it as a cut rate CGT. You'll start to wonder why the Porsche costs so damn much.
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GM's 6 and 8 cylinder motors are worthy of high praise. Their 4 cylinders are from mediocre to junk. The 4 speed hydramatic tranny is the weak spot IMO.
As stated by Cusdaddy, the fact that a 7 liter engine can achieve performance AND frugality should be noted.
As stated by Cusdaddy, the fact that a 7 liter engine can achieve performance AND frugality should be noted.
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Originally Posted by Ken1997TL
GM's 6 and 8 cylinder motors are worthy of high praise. Their 4 cylinders are from mediocre to junk.
#22
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I agree that the only metrics by which an engine should be judged ought to be cost, reliability, smoothness, and power or responsiveness at cruising speeds. On these counts GM's engines do well. Plus it's not as if the 3.3L engine in Camry makes that much more hp than the one in an Impala.
IMO hp/liter is a red herring. It confers bragging rights but does little for the average driver.
IMO hp/liter is a red herring. It confers bragging rights but does little for the average driver.
#23
Originally Posted by youngTL
My "problem" with pushrod engines is that the revving isn't as smooth, nor do they rev as high. Some people might see low revivng as an advantage, but I see it as a disadvantage, because I love to rev up to 7000RPM when I drive. I absolutely cannot stand to drive a vehicle with a redline lower than 6500.
And I test drove a G6 several months ago. They have grunt down low, but they run out of power up top.
And I test drove a G6 several months ago. They have grunt down low, but they run out of power up top.
#24
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Originally Posted by SJ Silver Type-S
Dude sorry to be a dick, but can you change your avatar? That sh*t is seriously gay....
This is your ONE and only warning. DO NOT post like this again it's inappropriate and just completely uneccessary. And do not follow-up on this post either, I don't want to hear it.
Grow up and get over your homophobia kid.
#25
Pit Stop?
I agree with everything stated in this thread, I love the Z06 and the LS7 engine, all I'm saying is personally I love small engines that produce massive amounts of horsepower naturally aspirated. Everyone loves the "big, American V8" (myself included), but I also love engines like the 3.6 in the Ferrari 360 Modena pushing 400HP while the 6.0L in the C6 Vette creates the same amount. I love both, but find the Ferrari to be more impressive. My opinion only.
I commend GM on their LS7, but they need to work on everything else in their line-up.
I commend GM on their LS7, but they need to work on everything else in their line-up.
#27
'Big Daddy Diggler'
The funny thing about the pushrods is that yopu can take a 3.4 liter Grand Am motor with only 175 hp, drop intake, headers, exhaust on it and jump make about 240 horses. They respond great to mods. Also, GM pushrods are bulletproof. Ive seen 200k on some of those old 3.8's. Also, there are 12 second GTP's with pulley's, exhaust, headers, intake and tunes. No internals, no supercharger upgrades, and these cars run strong.
#28
Registered Abuser of VTEC
Originally Posted by F23A4
So it seems to be so far.
While the Ecotec is a marked improvement over previous I4 DOHC motors out of GM's shop, it has a little ways to go in approaching the refinement of a K24A.
While the Ecotec is a marked improvement over previous I4 DOHC motors out of GM's shop, it has a little ways to go in approaching the refinement of a K24A.
#29
I'm more interested in the bottom line- how the engine performs/holds up than I'm am about whether an ohc/ohv/rotary are being used. At least for GM, Nascar racing technology is actually beneficial in building better engines for prodcution models.
#31
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Originally Posted by Minch00
I agree with everything stated in this thread, I love the Z06 and the LS7 engine, all I'm saying is personally I love small engines that produce massive amounts of horsepower naturally aspirated. Everyone loves the "big, American V8" (myself included), but I also love engines like the 3.6 in the Ferrari 360 Modena pushing 400HP while the 6.0L in the C6 Vette creates the same amount. I love both, but find the Ferrari to be more impressive. My opinion only.
I commend GM on their LS7, but they need to work on everything else in their line-up.
I commend GM on their LS7, but they need to work on everything else in their line-up.
So you don't like the LS2? Personally, I have one and I love it. Sure it may be 6.0L... who cares. It will easily do 150K+ miles and then a rebuilt (if needed) will only cost a few grand.
As far as the Ferrari goes- I would love to see that engine last 150K miles. Let alone the reliability is even half of the LS2. Let's not forget the $300 per oil change. Sure it's a technological marvel- but is it really worth it???
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Originally Posted by kansaiwalker1
What next, will GM brag about using test tubes instead of microchips next?
Oh, they are so bulletproof and cheap! Blah blah Blah!
Oh, they are so bulletproof and cheap! Blah blah Blah!
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Originally Posted by kansaiwalker1
What next, will GM brag about using test tubes instead of microchips next?
Oh, they are so bulletproof and cheap! Blah blah Blah!
Oh, they are so bulletproof and cheap! Blah blah Blah!
#34
I'm the Firestarter
If the pushrod engines offer just as good in all aspects as the DOHC engines, there's nothing wrong with them.
But there is a downside I can see to displacement which no one has mentioned yet, and that's size/weight. A bigger engine likely weighs more so it affects the handling of the car and obviously impacts the performance and fuel economy indirectly. It's easier to make a smaller good-handling car with a smaller engine than having to shove a huge one under the hood. In all my years of reading C&D I have rarely ran across GM cars that handle on par with the BMWs and Hondas in the same class, and I bet the heavier engines contribute to this. I'm sure this is not a problem in 2-seaters like the Vette and Viper where you have lots of room to put a big engine.
But there is a downside I can see to displacement which no one has mentioned yet, and that's size/weight. A bigger engine likely weighs more so it affects the handling of the car and obviously impacts the performance and fuel economy indirectly. It's easier to make a smaller good-handling car with a smaller engine than having to shove a huge one under the hood. In all my years of reading C&D I have rarely ran across GM cars that handle on par with the BMWs and Hondas in the same class, and I bet the heavier engines contribute to this. I'm sure this is not a problem in 2-seaters like the Vette and Viper where you have lots of room to put a big engine.
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Originally Posted by Belzebutt
If the pushrod engines offer just as good in all aspects as the DOHC engines, there's nothing wrong with them.
But there is a downside I can see to displacement which no one has mentioned yet, and that's size/weight. A bigger engine likely weighs more so it affects the handling of the car and obviously impacts the performance and fuel economy indirectly. It's easier to make a smaller good-handling car with a smaller engine than having to shove a huge one under the hood. In all my years of reading C&D I have rarely ran across GM cars that handle on par with the BMWs and Hondas in the same class, and I bet the heavier engines contribute to this. I'm sure this is not a problem in 2-seaters like the Vette and Viper where you have lots of room to put a big engine.
But there is a downside I can see to displacement which no one has mentioned yet, and that's size/weight. A bigger engine likely weighs more so it affects the handling of the car and obviously impacts the performance and fuel economy indirectly. It's easier to make a smaller good-handling car with a smaller engine than having to shove a huge one under the hood. In all my years of reading C&D I have rarely ran across GM cars that handle on par with the BMWs and Hondas in the same class, and I bet the heavier engines contribute to this. I'm sure this is not a problem in 2-seaters like the Vette and Viper where you have lots of room to put a big engine.
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Originally Posted by Belzebutt
If the pushrod engines offer just as good in all aspects as the DOHC engines, there's nothing wrong with them.
But there is a downside I can see to displacement which no one has mentioned yet, and that's size/weight.
But there is a downside I can see to displacement which no one has mentioned yet, and that's size/weight.
#37
'Big Daddy Diggler'
Gm Uses aluminum in a lot of their small blocks. The only time you see an iron block is when the motor will be used in a truck that will see some load.
#38
Senior Moderator
Originally Posted by biker
They may have saved $800 per engine doing that but one sure can't see where that money was spent elsewhere.
GM chose that instead of participating in state unemployment insurance. They thought it would be cheaper. It was when they didn't have layoffs.
Now, they're between a rock and a hard place. They need to shut down plants but they don't save much in doing so.
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Originally Posted by Time For Sleeep
I fail to see the point of this post.