Another pushrod engine dead?

[ToniCipriani]

Now that the '08 Malibu ditched the LZ4, there aren't many cars left with it.

G6, Aura, Impala, that's pretty much it. And by the sound of things, the next iteration of these cars will use the 3.6L as well.

So the family is dead, basically?

EDIT: Changed the title to reduce flames.

Edited January 17, 2007 by ToniCipriani

[ehaase]

So the family is dead, basically?

Yes, it is being phased out in favor of the HF V6 family on the high end and the 2.4L Ecotec on the low end. Edited January 6, 2007 by ehaase

[balthazar]

Can we please get literal with the terminology on this one? ALL engines are OHV; OHV is OverHead Valves- all DOHC are also OHV.

What would be far more accurate is to call the configuration in question In Block Cam --IBC--, which is a completely appropriate comparitive term to OverHead Cam, but I can't seem to get this term in regular use, tho I've seen a reference to it with the 3.9L with it's "dual in-block cams". Hopefully it'll take off so the descriptive disparity disappears.

[ehaase]

Can we please get literal with the terminology on this one?

No, we'll keep saying OHV, OHC, and DOHC, just as used in the automotive press for the last 50 years or more.

[Robert Hall]

Can we please get literal with the terminology on this one? ALL engines are OHV; OHV is OverHead Valves- all DOHC are also OHV.

What would be far more accurate is to call the configuration in question In Block Cam --IBC--, which is a completely appropriate comparitive term to OverHead Cam, but I can't seem to get this term in regular use, tho I've seen a reference to it with the 3.9L with it's "dual in-block cams". Hopefully it'll take off so the descriptive disparity disappears.

Chill out...'OHV' has been the standard term used by the media and in regular use for decades for pushrod engines. IBC is a brand of root beer.

[Croc]

Chill out...'OHV' has been the standard term used by the media and in regular use for decades for pushrod engines. IBC is a brand of root beer.

Excellent post...and now I am off to the store to buy some IBC root beer! I don't think I've had any in years...

[Satty]

IBC cream soda is quite tasty as well.

[thegriffon]

Can we please get literal with the terminology on this one? ALL engines are OHV; OHV is OverHead Valves- all DOHC are also OHV.

What would be far more accurate is to call the configuration in question In Block Cam --IBC--, which is a completely appropriate comparitive term to OverHead Cam, but I can't seem to get this term in regular use, tho I've seen a reference to it with the 3.9L with it's "dual in-block cams". Hopefully it'll take off so the descriptive disparity disappears.

The 3.9 doesn't have dual in block cams. You must be thinking of the 4.3 L XV8

[thegriffon]

The irony is that DOHC engines are far older than the OHV in-block cam. Before GM's OHV design, most engines in the US market used some type of side valve desig—flat-head, T-head, F-head, L-head etc. The OHV pushrod design gave the compactness, low-cost and the preferred OHV combustion-chamber design all in one package. Given the operating efficiencies of 2V engines at low speeds the OHV in-block cam continues to survive.It could that what the 3.6 needs to improve efficiency is a swirl-control valve commonly used in diesel engines and mercedes' 3.5 L, or the port deactivation system as used by GM in the family 1 and family 0 4-cylinders, and by PSA-Ford in the 2.7 V6 diesel, which has a similar function.

[balthazar]

As long as you sticks-in-the-mud understand that a DOHC is ALSO a OHV, therefore the OHV cannot die.

God, I can't even read "OHV" without thinking 'overhead valve'.

I have first-hand experience with flatheads, so the OHV moniker means something literal to me, not a blanket generalization for anything not OHC.

[dwightlooi]

Well, CIB or IBC, is more accurate. But the acronym OHV has stuck and is more commonly understood. In anycase, it is not incorrect. Pushrodders are OHV nothing more. SOHC and DOHC add single or dual overhead camshafts.

In anycase, if the LZ4 is dying... good riddance! Nobody wants a pushrod engine. It is perceived as unrefined (true), inefficient (true), low tech (not always but usually also true), heavy (not true but people think so anyway) and unreliable (true for domestic stuff of the 80s and 90s).

In fact, I think GM should drastically cut their engine lineup and do what Nissan does. Build ONE great engine and use it everywhere. There is just way too many engine models in GM's lineup. about 1/5th or 1/6th of the current numbers should be ample.

As far as NA goes, I suggest the following six engines. Everything else should go.

(1) 2.0 DOHC Dual-VVT DI (base engine for compacts and midsize)

(2) 2.0 DOHC Dual-VVT DI Turbo (High performance compacts, small sports cars)

(3) 3.6 DOHC Dual-VVT DI (premium engine for midsize, base for luxury)

(4) 6.2 OHV (SS class engine for midsize and standard for large sports cars)

(5) 5.0 DOHC Dual-VVT DI (Premium engine for luxury)

(6) 7.0 OHV (Z06, premium engine for large sports cars)

For the global scape, add a 1.6, a 2.0 turbo diesel, a 2.8 DOHC DI VVT, a 2.8 turbo diesel. Thats all, 10 engines for the whole world. My favourite engine in GM's lineup is the LL8 4.2 Inline-6, but unfortunately it won't and shouldn't make the cut.

I also think that GM needs to set a high bar in terms of reliability. Do it because it'll pay off in the decades to come. If you think that there is only a small difference between domestic reliability and Toyota/Honda reliability in the 80s and 90s, you are kidding yourself. A Toyota is basically a chnage the oil and fix nothing for 200,000 miles car in general. I cannot say the same for GMs, Chryslers or Fords. Sure, GM has done A LOT to make up on lost grounds. But when you are fighting a rotten reputation, good enough simply isn't good enough. The bar must be set higher. I think that a car TODAY needs to go at least 200,000 miles with ZERO maintenance other than once every 15,000 mile oil changes. If more than 1% of the cars need a starter, alternator, gasket, waterpump, oil pump, or anything but expendables like batteries and bulbs fixed over 10 years or 100,000 miles then the engineering simply isn't good enough.

[bcs296]

Now that the '08 Malibu ditched the LZ4, there aren't many cars left with it.

G6, Aura, Impala, that's pretty much it. And by the sound of things, the next iteration of these cars will use the 3.6L as well.

So the family is dead, basically?

DAMN RIGHT! It's about ******* time too!

The LSX engines have been the only respectable pushrod engines from GM for way too long.

And who cares what they are called, they are going bye bye.

[Intrepidation]

I would like some IBC cream soda...but I never see that in stores...just root beer and the other 2 flavors...

[76ChevyTrucker]

I always call 'em pushrod or OHC engines. Becuase asside from a flathead, they're all OHV engines like balth said. I'm kinda glad that the engine has died. With the exception of the LS engines (or any SBC engine for that matter), the OHC and DOHC engines are doing better (although I still don't like the timing belt driven ones (give me a chain and no interference and I'll be happy), and that's really what the world is going to. I don't see any reason for GM to stop producing the LS-series pushrod V8s, they're too good at what they do.

[dwightlooi]

I always call 'em pushrod or OHC engines. Becuase asside from a flathead, they're all OHV engines like balth said. I'm kinda glad that the engine has died. With the exception of the LS engines (or any SBC engine for that matter), the OHC and DOHC engines are doing better (although I still don't like the timing belt driven ones (give me a chain and no interference and I'll be happy), and that's really what the world is going to. I don't see any reason for GM to stop producing the LS-series pushrod V8s, they're too good at what they do.

Interference is not an issue. In fact it is often necessary given today's compression ratios of ~10.3:1 for regular gas engines and ~10.8:1 for premium gas ones. And this is going to get higher with the popularization of direct injection. It'll get to ~11:1 with Regular, 12.5~13:1 with Premium, even turbos will run about 10.5:1 (eg, VW's 2.0 FSI Turbo in the Rabbit, Jetta and Passat -- 10.5:1 compression, ~14.5 psi boost).

If you use a timing chain, the chain is not going to ever break thus there is never an issue with bent valves. Chains are become more popular because manufacturers want to get rid of the 60~90,000 mile timing belt replacement intervals -- a significant number of customers are not going to replace it and when it breaks they are going to say the manufacturer's engine is unreliable. The problem with timing chains is that they are noisier than belts. The new slim roller "silent" chains are quieter, but still noisier than belt drives. If not for the noise issue all the accessories would have been chain driven too.

[Sixty8panther]

The only pushrods I care about have 16 or more valves... and for ther record I agree with

Balthazar, maybe it's too late to retrain the media but those of us in the "KNOW" could be

more accurate about our description. IBC makes a lot of sense, even if it is also rootbeer.

[aaaantoine]

Does LZ4 include both the 3500 and 3900 or is it just the 3500?

Also, don't forget there are still 3800s floating around in the Buick division...

[I hope GMRULES again]

Does LZ4 include both the 3500 and 3900 or is it just the 3500?

Also, don't forget there are still 3800s floating around in the Buick division...

LZ4 = 3500 and LZ9=3900. 3800 will be around 1 more year and then its toast too.

[loki]

LZ4 = 3500 and LZ9=3900. 3800 will be around 1 more year and then its toast too.

don't forget the LZ8 3.9L w/ afm lol

[dwightlooi]

Let's put it this way...

The LZ family of 3.5 and 3.9 V6s is VERY GOOD as far as pushrod sixes go -- especially the 224hp 3.5 with CVVT for its single in-block cam. Defnitely an entirely league above the 3.8 clunkers. But there is really no good reason for them to exist anymore. Buyers who care about the engine will get the 3.6 DOHC even if a car equipped with it is $1500 more. Buyers who don't care are better served with the 2.4 Ecotec. Having driven both the 3.5 LZ4 and the 2.4 4-potter, I can honestly say that both are just as smooth in normal driving. And both make an unpleasant clatter when revved hard -- albiet in a different way. The 3.5 makes crude and uninspiring groaning noises, the 2.4 simply vibrates more than a balance shafted four should and you feel it more than you hear it.

For cars like the G6 or Malibu or whatever, it doesn't make sense to have both the 2.4 and the 3.5 in the lineup along with the 3.6 DOHC. And if you have to eliminate one, the 3.5 is the natural one to go... at least the 2.4 is economical to run!

[ToniCipriani]

Actually looking again, I don't think the 3.5L and 3.9L will just die yet. The LZE which is based on the LZ4/9 is the only car engine right now that is compatible with E85. The LZ8 3.9L is the only V6 with AFM.

I wonder if the 3.6L can be adapted to take these?

[dwightlooi]

Actually looking again, I don't think the 3.5L and 3.9L will just die yet. The LZE which is based on the LZ4/9 is the only car engine right now that is compatible with E85. The LZ8 3.9L is the only V6 with AFM.

I wonder if the 3.6L can be adapted to take these?

Using E85 doesn't really depend on the engine type or valve train design. In fact, whether the engine has a Air Flow Meter or not doesn't matter either. What matters is that the fuel system must incorporate certain corrosion prevention measures because alcohol is a lot more corrosive than gasoline. In addition, because the calorific value and stoichiometric ratio for ethanol is different from that of gasoline (~9:1 for ethanol; 14.1~15.2:1 for gasoline depending on additives), it is an engine that runs on E85 or Gasoline or a combination of both must be able to determine what kind of gas it is currently burning. In general this is done using a broad spectrum O2 sensor to detect whether the engine is running rich or lean and quickly adjust the fuel injectors' opening duration to adapt. An E85 capable engine can be mass-air-flow based or speed-density based, and they can use all the existing MAF or SD implementations.

[Sixty8panther]

It would be so cool if a more compact version (height wise) of the

Atlas 6 made it into the base Camaro. Too bad This will probably

not happen. I wish GM developed an Ecotec based I6, 3.0 liters or

even if it was destroked to 2.8 liters but KEEP it an INLINE six.

like a modern day 240Z or an affordable M3.

Inline sixes are soooo much better than V6s.

V-motors are for 12 and more cylinders.

I say we go back to I8s even.

[dwightlooi]

It would be so cool if a more compact version (height wise) of the

Atlas 6 made it into the base Camaro. Too bad This will probably

not happen. I wish GM developed an Ecotec based I6, 3.0 liters or

even if it was destroked to 2.8 liters but KEEP it an INLINE six.

Do you mean the Vortec 4200 DOHC I6?

I have always been a big fan of this motor and I see it as a superior alternative to 5~6 liter class V8s in terms of smoothness and refinement.

The 4200 currently makes 291 hp with VVT on the exhaust cam, port injection and 10.3:1 compressoion running on 87 octane. This is by far the SMOOTHEST engine in GM's stables. It puts to shame even the 4.6 liter Northstar; revs and sounds like a mid-90s BMW M50 2.5 inline six which is to say fabulously turbine like and velvety smooth.

The Vortec 4200 has also given birth to a 2.8 I-4 and 3.5 l-5. These two engines recently got a displacement bump to 2.9 and 3.7 liters respectively.

If equipped with dual cam VVT and direct injection, with or without a displacement bump to 4.5 liters, tis "BIG SIX" should be a 375hp class motor. And a car so powered will have an interesting aspect to it that differentiates it from the rest of the pack. The engine really isn't all that tall. Move the overhead intake manifold to the side and use a more car like oil pan and it should fit under the hood of a Zeta/Sigma platform RWD sedans or coupes. The 4200/3500/2800 engines are 93 x 102 mm (bore x stroke). The displacement bumped 3700/2900 engines are 95.5 x 102 mm. If you really want to reduce the displacement and increase its revability, a 95.5 x 74.8 Inline-6 (same stroke length as the 2.8 High Feature in the base CTS) will yield a 3.2 liter engine. It will also lop about a little over an inch off the block's height. Assuming that you adhering to the same piston speed limits of the 4200 (1285 m/min) you'll also have an engine that revs to 8600 rpm with roughly the same stress level. Even at a very modest 65 lb-ft/liter torque yield (~208 lb-ft for a 3.2 which is really extremely conservative), that translates roughly to 337hp @ 8500 rpm.

[loki]

Do you mean the Vortec 4200 DOHC I6?

I have always been a big fan of this motor and I see it as a superior alternative to 5~6 liter class V8s in terms of smoothness and refinement.

The 4200 currently makes 291 hp with VVT on the exhaust cam, port injection and 10.3:1 compressoion running on 87 octane. This is by far the SMOOTHEST engine in GM's stables. It puts to shame even the 4.6 liter Northstar; revs and sounds like a mid-90s BMW M50 2.5 inline six which is to say fabulously turbine like and velvety smooth.

The Vortec 4200 has also given birth to a 2.8 I-4 and 3.5 l-5. These two engines recently got a displacement bump to 2.9 and 3.7 liters respectively.

If equipped with dual cam VVT and direct injection, with or without a displacement bump to 4.5 liters, tis "BIG SIX" should be a 375hp class motor. And a car so powered will have an interesting aspect to it that differentiates it from the rest of the pack. The engine really isn't all that tall. Move the overhead intake manifold to the side and use a more car like oil pan and it should fit under the hood of a Zeta/Sigma platform RWD sedans or coupes. The 4200/3500/2800 engines are 93 x 102 mm (bore x stroke). The displacement bumped 3700/2900 engines are 95.5 x 102 mm. If you really want to reduce the displacement and increase its revability, a 95.5 x 74.8 Inline-6 (same stroke length as the 2.8 High Feature in the base CTS) will yield a 3.2 liter engine. It will also lop about a little over an inch off the block's height. Assuming that you adhering to the same piston speed limits of the 4200 (1285 m/min) you'll also have an engine that revs to 8600 rpm with roughly the same stress level. Even at a very modest 65 lb-ft/liter torque yield (~208 lb-ft for a 3.2 which is really extremely conservative), that translates roughly to 337hp @ 8500 rpm.

the atlas engines, at least the 4.2 is dual VVT, pretty sure, i looked it up in the past 4 months.

it'd be sweet to see these engines get DI, the 4.2 would get closer to 330Hp, not to mention the compression increase that would be possible.

i wonder what the future of the 4.2 is if the 360's(right?) are killed off in the next 3 years

[cmattson]

Forgive me for resurrecting an old thread -- but I must've missed this one when it was alive -- and I've got some questions for people to opine, speculate, and/or educate:

1) What to make of the Atlas 4.2l? I thought the Trailblazer was dying? If that's true, then this motor doesn't have a home. You could make the case of it replacing the 4.3l Vortec as the base engine in the Silverado -- but the Atlas challenges the 4.8l V8 for hp/torque.. so you'd have the more expensive 4.2l Atlas replacing two cheap-to-build pushrod engines. Would GM really do that?

2) The 3.5l/3.9l twins. These motors offered tremendous value, but the automotive public believes in the DOHC design - and GM realizes it. If GM follows suit on the 3.6l / 2.4l replacing these guys, then I believe they are creating a small gap in their engine offerings. While most sedans (and these engines are primarily sedan-motors) offer a 240-250hp V6, GM was unique in offering 'ok' performance (200-220hp) with good gas mileage. I know the engine family that the 3.6l is built upon was designed to offer engines anywhere in the range of 2.8l upto 4.0l. I'm curious to see if GM would have any plans to offer a smaller-displacement DOHC V6 to fit into that 200-220 hp range. Caddy uses the 2.8l in the CTS (210hp). Perhaps a DI-Ecotec could fill that slot as well?

3) The pushrod V8's: Toyota has upped the hp while matching in gas mileage. GM isn't way-behind, but it isn't in the lead anymore. GM's gotta have some plans for these to get freshened up. Anybody heard anything interesting? I'd imaging that they could implement the VVT system that the 3.5/3.9 engines enjoy. Matter of fact, I'd be shocked if they didn't. GM was toying w/3-valve heads for a while as well -- but that was years ago, and I imagine that if it offered significant benefits, we'd have already seen it by now.

[haypops]

If you use a timing chain, the chain is not going to ever break thus there is never an issue with bent valves.

Early 2.2 l. Ecotec engines had premature timing chain problems. Kits are available tooffer better "oiling" to resolve this issue.

[rkmdogs]

I also think that GM needs to set a high bar in terms of reliability. Do it because it'll pay off in the decades to come. If you think that there is only a small difference between domestic reliability and Toyota/Honda reliability in the 80s and 90s, you are kidding yourself. A Toyota is basically a change the oil and fix nothing for 200,000 miles car in general. I cannot say the same for GMs, Chryslers or Fords. Sure, GM has done A LOT to make up on lost grounds. But when you are fighting a rotten reputation, good enough simply isn't good enough. The bar must be set higher. I think that a car TODAY needs to go at least 200,000 miles with ZERO maintenance other than once every 15,000 mile oil changes. If more than 1% of the cars need a starter, alternator, gasket, waterpump, oil pump, or anything but expendables like batteries and bulbs fixed over 10 years or 100,000 miles then the engineering simply isn't good enough.

There is (was) a rumor that had wide circulation, that the '91-'96 "B" body cars were designed around a 300,000 mile life mandate, in order to

successfully produce the 9C1 and taxicab variants. Now I do not know if this was for the whole structure, the powertrain, or what, but I can tell you that my '95 9C1 Caprice recently turned over 195,000 miles, and its early life was a hard one as

an FBI undercover car.

It still runs without a squeak or rattle, but I did have to do some major tune-replacements on the engine.

In this day and era, any vehicle designated for police or taxi use has to have this life mileage value, >300,000 or

the designers are just kidding themselves, and their company!

[dwightlooi]

There is (was) a rumor that had wide circulation, that the '91-'96 "B" body cars were designed around a 300,000 mile life mandate, in order to

successfully produce the 9C1 and taxicab variants. Now I do not know if this was for the whole structure, the powertrain, or what, but I can tell you that my '95 9C1 Caprice recently turned over 195,000 miles, and its early life was a hard one as

an FBI undercover car.

It still runs without a squeak or rattle, but I did have to do some major tune-replacements on the engine.

In this day and era, any vehicle designated for police or taxi use has to have this life mileage value, >300,000 or

the designers are just kidding themselves, and their company!

I think that a higher bar needs to be set as a general rule for GM or for any company trying to buff up a tarnished reliability/durability image. Exceptions is just that exceptions -- good or bad. Toyota had their goofs as well, but never in the majority if their products and hence they did not tarnish their reputation tangibly. The 3.0 liter 7M-GE inline-6 engine (and the turbocharged 7M-GTE) for instance almost ALL had head gasket issues -- partly due to lousy gasket design and partly due to inconsistent deck expansion due to uneven thermal management of the block -- the 7M-GE/GTE is used in the US market 1986~1992 Toyota Supra. Later in the model cycle, Japanese market cars used the 2.5 liter 1JZ-GE/GTE engines which did not have the issue. the 1993~2002 US model used a 3.0 liter version of the JZ powerplant (2JZ-GE/GTE) which also did not have the problem.