SpeedyV6

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

CGTSX2004

iTrader: (1)

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.

charliemike

I don't think that's technology limitation though. Look at the LS7 ... That thing is amazing and BMW/VW use V10s to get that kind of output.

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.

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.

cusdaddy

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.

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.

biker

They may have saved $800 per engine doing that but one sure can't see where that money was spent elsewhere.

Loseit

iTrader: (1)

I thought the same thing!

I agree...and these engines are extremely reliable. So, why fuck with it. Technology for technologies sake does not make it better.

ilitig8

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.

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.

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.

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.

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.

cusdaddy

I actually prefer lower reving more Torque engines. I had a CL-S with I/H, and while fun, I rarely got to experience the high revs so for most of my driving, the car felt no faster than a common car on the road. It is fun at times to rev the heck out of the engine, but most of the time it gave me a headache and killed my gas mileage.

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.

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.

titan

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.

cusdaddy

But what is the use of creating a high tech engine for only the sake of having a high tech engine without showing the benefits that should go along with technology?

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.

Loseit

iTrader: (1)

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.

goldmemberer

With all due respect, any engine that reliably and cheaply produces 500hp/485lb. ft. and manages stellar fuel economy is worthy of praise, regardless of displacement, cylinder configuration, etc.

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.

Ken1997TL

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.

titan

The 2.4L Ecotec's a very good 4 cylinder.

Maximized

Great Another HP/Liter arguement. HP/Liter doesn't mean shit. Engines that have high HP/Liter ratios are peaky and have to be revved high.

SpeedyV6

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.

SJ Silver Type-S

Dude sorry to be a dick, but can you change your avatar? That sh*t is seriously gay....

SiGGy

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.

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.

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.

bigman

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.

youngTL

That's where they always lose out, refinement.

heyitsme

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.

kansaiwalker1

What next, will GM brag about using test tubes instead of microchips next?


Oh, they are so bulletproof and cheap! Blah blah Blah!

Ashburner

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???

Time For Sleeep

I fail to see the point of this post.

titan

That's what the consumer wants. Most of the american public doesn't have a lead foot, and aren't enthusiasts. Most people I know like cars that are quick off the line, reliable, and affordable. Pushrods are great option in that department.

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.

cusdaddy

Actually, aluminum pushrod engines are actually lighter than many equivalent DOHC engines due to their less complicated nature. The Z06 engine is quite light for example and I'm almost sure it is lighter than the V10 in the M5/6 for example.

titan

Not necessarily. The LS7 (the best pushrod made to date) is only 50lbs. heavier than GM's own 2.4L DOHC Ecotec.

bigman

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.

Xpditor

Union super-benefits. If you work for GM and are layed off, you continue to get 70% of your pay when you are no longer working.

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.

Ken1997TL

I think he meant Vacuum tubes rather than test tubes

kansaiwalker1

Sorry, I did mean vacuum tubes instead. I guess it really is time for sleep!