Probably shouldn't bring mpg into it, i could probably bet that most of those mpg numbers come from a very high over drive gear. Plus, GM states that the chevy tahoe is supposed to get in the range of high teens low 20's for gas mileage. My uncles 2004 tahoe is lucky to break 15...........
Anyhow, i didn't say there was anything wrong with pushrod, i'd imagine most of their research comes from their nascar team. However i highly doubt pushrod has as many advantages as you claim. After all last time i checked, IRL, WRC, F1, etc etc don't use pushrod engines. And GM is the only manufacterer that exclusively uses pushrod engines. But of course, them crazy engineers must not know that it's a much more reliable and efficient design then OHC'ed engines. I guess you guys have found the secret to the best designed race engines that only you and GM have figured out ;)

BTW, here's something else you might want to take a gander at.
http://www.detnews.com/2005/autosinsider/0511/11/A01-379282.htm

EPA for a Malibu V6: 22/30
EPA for a Camry V6: 20/28

I don't think the Malibu has a very tall overdrive. But when GM starts rolling out its line of 6-speed autos in 1-2 model years, I think that figure should increase nicely.

Great point, but I think that race leagues kind of make rules to please the engine builders. NASCAR sticks with pushrod tech because it's what the manufacturers are (maybe were) putting out. European makers tend to do things in a complex way, they use OHC, and the international race bodies reflect that.

Additionally, a pushrod engine has less valvetrain. There's less weight, less reciprocating mass, more compact, and the ability to lower the center of gravity. An LS1 fits inside an normal 944 bay, a 928 V8 doesn't.

I'm not arguing that pushrods are unequivocally better. I just sent my SOHC 944 to redline today. It sounds great, even if it's running out of breath at 5500. There are distinct advantages to OHC engines, like the ability to easily create a multi-valve engine.

On the other hand, pushrod engines aren't bad and aren't worthy of the heaps of criticism that people put on them. That's the point I want to advance. The "thrashy" GM engines come from 25-year-old designs. They aren't good enough, contrary to what the company says. They should rework the engines. Pushrod engines are fine for everyday use. The small block V8, with cheap and plentiful power, has shown us that.

Point taken, however, doesn't it feel a little odd to you to spend 65k on a car with a push rod v8.
And your right, there is nothing wrong with it, if your going to stick with 2 valves per cylinder it's actually not a bad idea. However, both diameler chrysler and ford have jumped on the variable valve timing wagon. This doesn't mean that GM doesn't have the tech, or ability to do the same for there mass production cars. What it means is that the general public is perfectly fine with the pushrod design. That is the sad part. BTW, i took a quick gander at the malibu in question, it's the 200 hp v6 that gets that claimed fuel mileage. I would assume based on it's power figures that it's an all torque low reving engine. But the motor i like is that 240hp 3.9, peak torque at 2800 with peak horsepower at 6k, now that is a torque curve. Unfortunately that motor does 26, gotta pay to play, no free lunch.

Who buys a $65K car based on how the valves are actuated? The Z06 has 505hp and outruns every other new $65K car. The early 90's ZR1 was a 32V four cam motor. Made 375-405hp from 5.7L. Very exotic motors, those LT5's. But the ZR1 package added $27-31K! They were $70K+ fifteen years ago! I'd rather have the Z06 and its extra 100 horsepower.

I'm not sure what makes that sad??? The public cares about how well the car works for them, not HOW it works. GM wouldn't sell one more car if they advertised 'all of our cars are OHC!' There are pluses and minuses for each technology.

Variable valve timing is utilized in several GM cars. In fact, GM says they will have 2.5 million powerplants with VVT by 2007.

The 'Ecotec' four cylinders (which are DOHC 4valves, BTW) are available in 2.4L (LE5) form with VVT that phase up to 50 degrees relative to the crank. The 2.4L makes 170-177hp @ 6000rpm, but more importantly makes 170 lb-ft from 2400 to 5600rpm. That's a wide torque curve for such a little motor. The 2.4L is currently available in the Chev Cobalt, Chev HHR, Pontiac Solstice, and Saturn ION, but will soon be available in the Saturn VUE, Saturn SKY, Chev Malibu, Pontiac G6, Pontiac Pursuit, and Saab 9-3. The ION and Cobalt with 2.4L automatics are rated at 24city /32hwy mpg.... same as their 2.2L 140hp counterparts. No fuel economy penalty for 30hp/ 30lb-ft!

By the way, the new 2006 Honda Civic Si makes 197hp @ 7800 rpm, but peaks at only 139 lb-ft @ 6200 rpm. It's rated at 22/31 with the 6 spd. And it needs 91 octane premium. The 2.4L manual Cobalt or ION makes more horsepower all the way to its 6000rpm peak, and up to 40lb-ft more torque at any rpm from idle to redline. The Civic only makes more its 27 additional horsepower after the GM's redline. The manual ION gets 4mpg better hwy (35) than the Civic, and makes do with 87 octane.

The 3.6L V6 (LY7) that powers the base Cadillac CTS, STS, and SRX; Buick Rendevous and LaCrosse; and upcoming Buick Allure and Saturn Aura are DOHC 4 valve VVT motors. They make 240-255 hp @ 6000-6500 rpm, and 225-255 lb-ft from 2000-5200 rpm. 27mpg freeway from the LaCrosse (Camry is 1 mpg better but smaller and down 45 horsepower).

You mentioned the 3.9L (LZ9) in the Malibu. It has VVT that phases up to 40 degrees, even though it is a 'cam-in-block' pushrod motor. The 3.9L makes 240hp @ 6000rpm and makes 241lb-ft from 2800 to 5400 rpm. The 3.9L is currently available in the Malibu, Impala, Monte Carlo, G6, and all the GM minivans. The 3.9L shares bore, piston, and valve / head specs with the LSx V8s. They also feature 'DOD' displacement-on-demand to run as 3 bangers when cruising.

Variable valve timing is planned for other 'cam-in-block' GM pushrod motors. The Corvette, SSR, CTS-V, and GTO will have LS2's with 425-430hp without changing FE ratings (Vette 6spd 28mpg hwy). More importantly to GM, the Silverado and Suburban/Tahoe (and all variants, ie Escalade) will get DOD and VVT for better fuel economy and better performance. And all this with old-tech pushrod motors.

The EPA rating for the Malibu 3.5L V6 sedan is 22/32 (you quoted the Maxx weird-wagon-thingy)

The high-tech 3.0L DOHC 4valve VVT Toyota Camry V6 makes 190hp @ 5800rpm and 197lb-ft @ 4400rpm, and gets 28mpg hwy.

The old-tech 3.5L iron-block 2valve pushrod Malibu V6 makes 201hp @ 5600rpm and 221lb-ft @ 3200rpm, and gets 32mpg hwy.

Yeah, pushrods must suck.

GM doesn't 'exclusively' use pushrod engines. See above.
IRL, Indycars have used pushrod motors on and off for decades. The 3.8L Buick-based turbocharged cars were wickedly fast. John Menard had lots of success with them. Rule changes decide what engine technology.

WRC and F1 are european. Even the French are invited. Enough said.

There are plenty of pushrod motors in the SCCA, IMSA, FIA, ALMS, and other racing organizations. Again, I remind you that Corvettes and Vipers have won LeMans and FIA GT world championships with pushrod motors.

In other US-based forms of motorsports you are hard-pressed to find anything but pushrods. NASCAR, monster trucks, NHRA drag racing, sprint cars, off-shore race boats, off-road baja trucks, etc., etc..

NHRA Top Fuel drag cars run old-tech 500 cu in (8.1L) pushrod V8s. They make over 5000 horsepower and have 9500 rpm redlines. The fastest 1/4 mile passes are in the 4.4 second range at 335mph. They average over 4G's(!) acceleration over the entire 1320 feet. They launch at close to 8G's.

Think about this: You are in your new Porsche Carrera GT at an honest 200mph. You come up on a Top Fuel drag car sitting still in the next lane. The instant your nose is even with his, he nails the throttle. Within 2.5 seconds (roughly 500 ft, 30 car lengths) the Top Fuel dragster has caught you and passed you, from a standing start. And less than 2 seconds later, when he crosses the finish line a quarter mile from where he started, he will be 30 car lengths ahead and travelling 145mph faster than you.

With a pushrod motor.

E

The engine is coming apart during the 1/4 run. The spark plugs are gone at the 1/8 mile mark and the engine continues to run via dieseling from the red hot cylinder heads. So, after the 1/4 mile race with the CGT the CGT will drive home and the dragster will be towed to the pits for a rebuild. I prefer an engine that doesn't need a rebuild every 20 seconds. j/k

Kaisen - I am impressed with all your knowledge of cars in general, either you are a hell of a google searcher or you really are into cars. Or, you do this for a living, which is it?

There is no denying that GM has a good formula with their pushrod V-8 and the Corvette. If it aint broke don't fix it!! Theres nothing wrong with that.

Hahaha! Google searcher! I got that drag racing email that he is quoting 2 years ago, lol.

Jim-

All of the above

ZLP-

Yes and no. The data is everywhere to find. some of it I know off the top of my head, other data I'd better check up on so as not to get flamed.

E

Copy and paste some more knowledge. :)

By the way, my grandfather once told me the same analogy of the drag car. Except he was talking about the Mercedes Benz Silver Arrow and a car that was doing 100mph. The distances and times weren't as impressive, but the Silver Arrow amazed him. He was a big Duesenberg fan. Still with us at 91 years young, and driving daily.

E

What if theres a turn at the end of the quater mile?

Wasn't refering to the drag racing quote alone, I got the same e-mail.

I was refering to his knowledge of the Audi line up, the entire GM line up and other cars in general.


Kaisen - Any publications I know?

Right now I only have Autoweek coming to my house, somehow my subscription to Racer expired. Gotta fix that.

You are screwed I think ;)

What would you like to know?

If you can find in any of my posts that I have truly cut and paste copied ANY source, other than quoted or a phrase, I'll sell belly button lint here on Pelican

E

Not even sure what that means? Guess you googled the wrong thing.:rolleyes:

Good logic there…

Do you feel odd having a Porsche with SOHCs? On top of that your 911 only has two valves per cylinder. You know, even a Miata runs dual cams, and four valves. Why did you pay so much for a car with an inferior valvetrain?

The beauty of the new GM LS Small block is that the push rods do not intrude with the ports. The ports are as clean and clear as if the car had SOHC, DOHC, or pneumatically operated valves. Yet the valve train is simple, light, and easy to manufacture. This is a real engineering feat, not a detraction.

Now let me lend a personal observation. There was a new C6 Z06 at the track this past weekend. I didn’t ride in it. I didn’t drive it. But I can tell you the car was wicked fast. Even in the turns. ;)

Terry-

You are screwed if you are in a Top Fuel dragster running 335mph toward a curve. Sorry I didn't articulate. Took me a few hours to Google your request. 'Small member' took me on a google tangent I'd rather forget.

E

I do actually, that's part of what makes certain cars neat. If everyone kept doing what worked, and followed the phrase don't fix it if it ain't broken all the time, we'd still be wearing animal skin for warmth and clubbing eachother in the head for food ;)

Actually i don't, because it represented a good amount of technology at the time. Plus it's technologically unfare when comparing to a watercooled motor since they allow for other better designs. However, it was and still is some of the best designs for air cooled engines there is (and sometimes quite amazing).

I'm not sure what's up with all of the pushrod technology biggotry.

Yes, overhead cams are amazing, but it's hard to deny that a SBC is an amazing motor. It must not be too bad or it wouldn't be as prolific as it is.

Not to mention. The comparison between F1 and it's overhead cam technology (are they camless yet?) and a SBC engine is kind of weird. Street cars (what we are really talking about here) have a certain range of compromises to make, and F1 cars or most other racing cars have a very, very different range of compromises to make. A 15000 or 18000 rpm street motor (that's not a wankel) would probably not be a good street motor. A 6000rpm SBC would probably not be a good match for an F1 car. Which engine would you rather have in your corvette or Chevy Suburban that you drive daily?

There are much worse cars that you could pay $65k for.

Hehehe....He said Wankel...

FYI - Being a Rotorhead, most of your wankels do not go past 10,000 RPM unless you have lots of money or a death wish. Some crazy bridgeported motors will rev to 12-14K RPM's but them your buying special flywheels and clutch assemblies and that is big money. Not to mention havign the entire rotating assembly balanced. If you are not then you can risk the loss of your feet or life from failure due to vibration.

My Rev limiter is set to 9300 RPM and I have told to lower it by my engine builder. (Pettit Racing) I have been told 8700 RPM is plenty.