Premium Six for Caddy and Buick

[dwightlooi]

When the so called HF V6 was created, it was the premium six cylinder in GM's line-up. It went into premium models while the 3.5 and 3.9 Pushrod sixes served the Malibu, G6es and other high volume models. With GM going to the DI V6 across the board in the near future, there no longer a Hi-Lo mix.

I believe that it'll be worthwhile to create a new derivative of the DI V6 engine specifically for premium applications as the Standard DI V6 moves into the mainstream. The premium version will focus on delivering greater refinement, performance and runs on 91 Octane. The idea is not to build a sports car engine here, rather it is to give the engineers a free hand to improve the DI V6 without having the compromise of 87 octane compatibility and cost sensitiveness.

3.6 liter Premium Six

Changes

• Aluminum valve covers replace polymer ones for improved acoustics
  
• Aluminum continuously variable intake runner assembly for flatter torque curve
  
• 12.3:1 compression instead of 11.3:1 for improved torque output
  
• Cylinder deactivation on 3-cylinders
  
• Anechoic skirt around engine block for noise reduction
  
• Anechoic acoustic cover over engine for noise reduction
  

Performance

• Power Output: 312 hp @ 6600 rpm
  
• Torque output: 292 lb-ft @ 3600~5600 rpm
  
• Rev limit: 7000 rpm
  
• Fuel: 91 Octane Unleaded
  
• Est. Fuel Economy (RWD CTS w/6L50): 19 (City) / 28 (Hwy)
  
• Price Delta (vs regular 3.6 DI V6): $2000
  

[Drew Dowdell]

It's gotta be able to at least tolerate 87.

[SAmadei]

It's gotta be able to at least tolerate 87.

Agreed... at this power level, requiring 91 octane is not worth the 10~25hp increase.

[dwightlooi]

Agreed... at this power level, requiring 91 octane is not worth the 10~25hp increase.

Actually, hp is not a factor. The 87 octane DI V6 is alrready making 312hp in the Camaro. Increasing the octane rating allows you to increase the compression ratio. This in turn means you can make more torque. With the hp target being relatively unchanged, you can move the torque peak lower and flatten the curve. This improves the perceived power delivery in daily driving. The higher compression also improves specific fuel consumption.

[SAmadei]

Actually, hp is not a factor. The 87 octane DI V6 is alrready making 312hp in the Camaro. Increasing the octane rating allows you to increase the compression ratio. This in turn means you can make more torque. With the hp target being relatively unchanged, you can move the torque peak lower and flatten the curve. This improves the perceived power delivery in daily driving. The higher compression also improves specific fuel consumption.

Ah. Yeah, area under that graph is sweet... still not sure its worth the cost of 91 octane.

[ZL-1]

a question: if this V6 got pushed to 320hp (I'm using that figure with the Northstar V8's power in mind), how would torque and torque curve compare with that V8?

[regfootball]

first off, for GM to call a DOHC engine 'premium' is laughable since most of the rest of the competition had been making them and putting them in garden variety cars for quite awhile. For GM to say its premium was them putting their own band aid spin on why they kept shoving boat anchor 6's on the car buyers when they were clearly showing not a love of love for GM's motors anymore.

2nd, why the expense for a rare engine that only uses premium? Some dip$h! will put 87 in it and you are back at square one.

If you are gonna blow money on ANOTHER new engine for GM, do a DOHC v8 OR a couple diesels.

[Drew Dowdell]

Dwight, I've been schooled by experts in engine technology, like my friend who posted just previous to me, that torque doesn't matter, So why should I want an engine that makes more torque if it means I have to run 91 through it instead of 87?

first off, for GM to call a DOHC engine 'premium' is laughable since most of the rest of the competition had been making them and putting them in garden variety cars for quite awhile. For GM to say its premium was them putting their own band aid spin on why they kept shoving boat anchor 6's on the car buyers when they were clearly showing not a love of love for GM's motors anymore.

2nd, why the expense for a rare engine that only uses premium? Some dip$h! will put 87 in it and you are back at square one.

If you are gonna blow money on ANOTHER new engine for GM, do a DOHC v8 OR a couple diesels.

Reg, it's a rework of the existing 3.6 with additional technology and more aggressive power tuning. It's not a whole new engine.

[dwightlooi]

Dwight, I've been schooled by experts in engine technology, like my friend who posted just previous to me, that torque doesn't matter, So why should I want an engine that makes more torque if it means I have to run 91 through it instead of 87?

Reg, it's a rework of the existing 3.6 with additional technology and more aggressive power tuning. It's not a whole new engine.

Torque does not matter if, and only if, you can change gearing instantaneously, continually and through an infinite range. That is not reality, at least not with today's transmissions. In any particular gear, the torque multiplication is the same throughout the rev range. Today's best automatics only give you about 6:1 to 7:1 ratio spread to play with. An engine whose torque peak is further removed from the cruising rpm is likely to require more downshifts more often.

Reasons for using 91 octane in exchange for higher compression is as follows:-

• A $0.20 difference in gas price (per gallon) at $3 a gallon is quite well tolerated by owners of luxury vehicles.
  
• The increase in compression yields improvement in MPG numbers
  
• Higher torque at lower rpms allows the vehicle to accelerate more quickly without having to trigger a downshift. This in turn improves the perceived refinement level by allowing a more relaxed operating speed in typical driving.
  

[loki]

what could you do with a lite turbo set-up? with high static compression and lowish boost?

[Drew Dowdell]

Higher torque at lower rpms allows the vehicle to accelerate more quickly without having to trigger a downshift. This in turn improves the perceived refinement level by allowing a more relaxed operating speed in typical driving.

Which is what I was getting at. More torque available at a lower RPM also gives the feeling of being more powerful.

[A Horse With No Name]

Which is what I was getting at. More torque available at a lower RPM also gives the feeling of being more powerful.

...and is also more in tune with what most traditional GM buyers would want in a car.

[smk4565]

How about:

DOHC Straight six turbo

DI, VVT

300 hp @ 5800 rpm

300 lb-ft @ 1200-5000 rpm

20/30 mpg

GM should make that, more torque at lower rpm, better mileage, and an inline is smoother than a V.

[balthazar]

"If the inline engine configuration was so great, everybody would be copying it, instead of no one, so it obviously isn't that great."

"Inline configurations are ancient technology - Pontiac, Olds, Buick & Chevy used to be all inlines back, oh, 60 years ago or so."

[smk4565]

"If the inline engine configuration was so great, everybody would be copying it, instead of no one, so it obviously isn't that great."

"Inline configurations are ancient technology - Pontiac, Olds, Buick & Chevy used to be all inlines back, oh, 60 years ago or so."

Right, when everything was rear wheel drive. Inline six is still more balanced and smoother than a V6, or even a V8. Everyone doesn't use a straight six now because they make mostly front drivers and a straight six won't work in a CamCord.

[SAmadei]

Right, when everything was rear wheel drive. Inline six is still more balanced and smoother than a V6, or even a V8. Everyone doesn't use a straight six now because they make mostly front drivers and a straight six won't work in a CamCord.

I've always been surprised that a small BMW or Supra could hold a straight six longitudally.

Edited October 31, 2010 by SAmadei

[balthazar]

inline 6 or 8 = pre-war 'technology'... ancient, out-dated, toyoyo/lexus builds a bunch of RWD cars- best in world because they sell so much, none have inline engines, bad design, old, V-type much more modern, better packaging, new technology, betterer.

[regfootball]

Which is what I was getting at. More torque available at a lower RPM also gives the feeling of being more powerful.

as long as the engine is not a wheezer at 6500 rpm and still has automotive viagra at higher speeds.....

Right, when everything was rear wheel drive. Inline six is still more balanced and smoother than a V6, or even a V8. Everyone doesn't use a straight six now because they make mostly front drivers and a straight six won't work in a CamCord.

in line six is a large engine, for a lot of engine bays. it only works mostly for the rare rwd chassis....

[regfootball]

Dwight, I've been schooled by experts in engine technology, like my friend who posted just previous to me, that torque doesn't matter, So why should I want an engine that makes more torque if it means I have to run 91 through it instead of 87?

Reg, it's a rework of the existing 3.6 with additional technology and more aggressive power tuning. It's not a whole new engine.

if it requires technology and manufacturing investment, it might as well be a whole new engine. you are talking about switching materials, finishing processes, specifications. generally in manufacturing engines, it sometimes is based on the bore centers and such. you mess with the metalurgy of an engine, and the cam drives / valvetrain, it pretty much is a new engine.

From an operations perspective.....once you have divergent parts numbers, its a whole new engine too, especially for the people who need to stock parts.

...and is also more in tune with what most traditional GM buyers would want in a car.

.............15-20 years ago.............

these days i doubt it matters. people want what is consistent with the times.

Torque does not matter if, and only if, you can change gearing instantaneously, continually and through an infinite range. That is not reality, at least not with today's transmissions. In any particular gear, the torque multiplication is the same throughout the rev range. Today's best automatics only give you about 6:1 to 7:1 ratio spread to play with. An engine whose torque peak is further removed from the cruising rpm is likely to require more downshifts more often.

Reasons for using 91 octane in exchange for higher compression is as follows:-

• A $0.20 difference in gas price (per gallon) at $3 a gallon is quite well tolerated by owners of luxury vehicles.
  
• The increase in compression yields improvement in MPG numbers
  
• Higher torque at lower rpms allows the vehicle to accelerate more quickly without having to trigger a downshift. This in turn improves the perceived refinement level by allowing a more relaxed operating speed in typical driving.
  

and then one idiot pumps 87 in his tank and all hell breaks loose.

the engine must run fine on 87, if it performs better on 91 than so be it. America has too many idiots to trust them to put 91 in consistently or willingly.

Edited October 31, 2010 by regfootball

[balthazar]

regfootball ~ >>"first off, for GM to call a DOHC engine 'premium' is laughable since most of the rest of the competition had been making them and putting them in garden variety cars for quite awhile. For GM to say its premium was them putting their own band aid spin on..."<<

Where did GM call one 'premium'? Isn't it labeled 'HF' for 'high feature' ?? This is a bad thing somehow?

regfootball ~ >>"if it requires technology and manufacturing investment, it might as well be a whole new engine. you are talking about switching materials, finishing processes, specifications. generally in manufacturing engines, it sometimes is based on the bore centers and such. you mess with the metalurgy of an engine, and the cam drives / valvetrain, it pretty much is a new engine."<<

Why on earth would you need to reinvent metallurgy or machining processes to offer new technology on an engine ??

[Drew Dowdell]

Right, when everything was rear wheel drive. Inline six is still more balanced and smoother than a V6, or even a V8. Everyone doesn't use a straight six now because they make mostly front drivers and a straight six won't work in a CamCord.

The Suzuki Verona had a transverse mounted I6. Look how great that sold.

[Drew Dowdell]

inline 6 or 8 = pre-war 'technology'... ancient, out-dated, toyoyo/lexus builds a bunch of RWD cars- best in world because they sell so much, none have inline engines, bad design, old, V-type much more modern, better packaging, new technology, betterer.

Sorry Balth, Lexus in the 90s partially got where they are today by using the I6 from the Supra in the GS. Once they took the I6 out, the GS lost all of it's cred.

as long as the engine is not a wheezer at 6500 rpm and still has automotive viagra at higher speeds.....

Who cares if it even turns 6,500 rpm if it gets you to 80 at 3,000?

[dwightlooi]

How about:

DOHC Straight six turbo

DI, VVT

300 hp @ 5800 rpm

300 lb-ft @ 1200-5000 rpm

20/30 mpg

GM should make that, more torque at lower rpm, better mileage, and an inline is smoother than a V.

The I6 is naturally balanced and practically vibration free. However, the industry has moved away from it because it is very long and rather heavy. An I6 will require all the current RWD platforms to be altered to accommodate it. It'll also not fit the transverse bays of cars like the Lacrosse.

You can go with high static compression and light pressure turbocharging. But this is significantly more complex and costly than switching out the intake manifold, adding insulation around the block and making half of the lifters collapsible. In addition, turbochargers bring with them a myriad of hoses, intercoolers and bypass tubes. Turbochargers -- especially twin turbo setups typical of V type engines -- are also rather expensive to service 10~15 years down the line. Eg. replacing a pair of turbos on a B5 Audi S4 is a $4500 job. Regardless of how longevity of turbos have improved and how GM markets it, "twin-turbos" will make some buyers hesitate based on reliability and maintenance cost stories related to other so equipped vehicles in the past. With light pressure forced induction, you are investing in all that with practically no return in power output but simply a remodeling of the torque curve.

The idea here is to build the V6 GM can build if it is not hamstrung by considerations such as accommodating the 87 octane rating or making the engine cheap enough for deployment in all vehicles right down to the Malibu. 91 Octane ratings are not unusal for luxury marques. In fact, it is typical. Acura, Audi, BMW, Infiniti, Lexus and M-B all drink 91 octane fuel. When you put 87 octane in the engine, it's not going to grenade itself -- no modern engine will, not even a 911 GT3. What'll happen is that you'll lose 10 maybe 20 horses and suffer from reduced fuel economy when the ECU detects the onset of very mild pining inperceptible to the driver and dials back timing and enrich the fuel mix. In extreme cases -- such as pulling a heavy load at low rpms when knocking is at its worst, the over enrichment may get bad enough that prolonged operation may cause spark plug fouling. The ECU will probably flash a warning to the driver in such cases, but not usually. I ran out of fuel once on the freeway and had a gallon of 87 added by AAA into the C55's tank to get to the gas station. The engine ran fine, nothing perceptible in power delivery, no pinging, nothing. I wasn't pushing it of course so I don't know if it made noticeably less power. The M113 5.5 liter SOHC V8 engine has conventional port injection and a pretty high compression ratio (11:1).

[Chazman]

When the so called HF V6 was created, it was the premium six cylinder in GM's line-up. It went into premium models while the 3.5 and 3.9 Pushrod sixes served the Malibu, G6es and other high volume models. With GM going to the DI V6 across the board in the near future, there no longer a Hi-Lo mix.

I believe that it'll be worthwhile to create a new derivative of the DI V6 engine specifically for premium applications as the Standard DI V6 moves into the mainstream. The premium version will focus on delivering greater refinement, performance and runs on 91 Octane. The idea is not to build a sports car engine here, rather it is to give the engineers a free hand to improve the DI V6 without having the compromise of 87 octane compatibility and cost sensitiveness.

3.6 liter Premium Six

Changes

• Aluminum valve covers replace polymer ones for improved acoustics
  
• Aluminum continuously variable intake runner assembly for flatter torque curve
  
• 12.3:1 compression instead of 11.3:1 for improved torque output
  
• Cylinder deactivation on 3-cylinders
  
• Anechoic skirt around engine block for noise reduction
  
• Anechoic acoustic cover over engine for noise reduction
  

Performance

• Power Output: 312 hp @ 6600 rpm
  
• Torque output: 292 lb-ft @ 3600~5600 rpm
  
• Rev limit: 7000 rpm
  
• Fuel: 91 Octane Unleaded
  
• Est. Fuel Economy (RWD CTS w/6L50): 19 (City) / 28 (Hwy)
  
• Price Delta (vs regular 3.6 DI V6): $2000
  

Other than the requirement for 91 octane, I'd like to see GM improve the 3.6 across the board in this way. I find the 3.6 in my CTS to be a coarse, noisy unit, without much eagerness to rev. While it was under warranty, I did complain about it and the dealer found a TSB on the "vibration issue" and updated some software into the ECM. No difference which I could tell.

[regfootball]

Sorry Balth, Lexus in the 90s partially got where they are today by using the I6 from the Supra in the GS. Once they took the I6 out, the GS lost all of it's cred.

Who cares if it even turns 6,500 rpm if it gets you to 80 at 3,000?

because you need to accelerate and pass people, which requires accessing the upper reaches of the rpm band, more often than you think.

by your logic then, a 1 speed tranny is the schizzle.

any engine can be smooth at 3,000 rpm. if its smooth at 6500 rpm as well, you know the engineering is solid, not only the that, the vibration from the motor is less of an impact on the rest of the car. lastly, smoothness at high rpm only serves to underscore the quality of a product.

you can have your iron block dinosaurs like the 3800. There is a reason it was passed by by others LONG ago.

Edited November 2, 2010 by regfootball

[regfootball]

The I6 is naturally balanced and practically vibration free. However, the industry has moved away from it because it is very long and rather heavy. An I6 will require all the current RWD platforms to be altered to accommodate it. It'll also not fit the transverse bays of cars like the Lacrosse.

You can go with high static compression and light pressure turbocharging. But this is significantly more complex and costly than switching out the intake manifold, adding insulation around the block and making half of the lifters collapsible. In addition, turbochargers bring with them a myriad of hoses, intercoolers and bypass tubes. Turbochargers -- especially twin turbo setups typical of V type engines -- are also rather expensive to service 10~15 years down the line. Eg. replacing a pair of turbos on a B5 Audi S4 is a $4500 job. Regardless of how longevity of turbos have improved and how GM markets it, "twin-turbos" will make some buyers hesitate based on reliability and maintenance cost stories related to other so equipped vehicles in the past. With light pressure forced induction, you are investing in all that with practically no return in power output but simply a remodeling of the torque curve.

The idea here is to build the V6 GM can build if it is not hamstrung by considerations such as accommodating the 87 octane rating or making the engine cheap enough for deployment in all vehicles right down to the Malibu. 91 Octane ratings are not unusal for luxury marques. In fact, it is typical. Acura, Audi, BMW, Infiniti, Lexus and M-B all drink 91 octane fuel. When you put 87 octane in the engine, it's not going to grenade itself -- no modern engine will, not even a 911 GT3. What'll happen is that you'll lose 10 maybe 20 horses and suffer from reduced fuel economy when the ECU detects the onset of very mild pining inperceptible to the driver and dials back timing and enrich the fuel mix. In extreme cases -- such as pulling a heavy load at low rpms when knocking is at its worst, the over enrichment may get bad enough that prolonged operation may cause spark plug fouling. The ECU will probably flash a warning to the driver in such cases, but not usually. I ran out of fuel once on the freeway and had a gallon of 87 added by AAA into the C55's tank to get to the gas station. The engine ran fine, nothing perceptible in power delivery, no pinging, nothing. I wasn't pushing it of course so I don't know if it made noticeably less power. The M113 5.5 liter SOHC V8 engine has conventional port injection and a pretty high compression ratio (11:1).

if a buyers puts 1000 gallons in their car each year and its .20 premium over 87 octane that is 200 bucks extra a year for the fuel x lets say they own the car 10 years, that is 2 grand extra for 91 octane gas.

you could simply modify the displacement or breathing of the car to get more power instead of making it run on 91.

ecoboost runs dandy on 87, makes more power on 91 sure but its not touted that way.

Edited November 2, 2010 by regfootball

[Drew Dowdell]

because you need to accelerate and pass people, which requires accessing the upper reaches of the rpm band, more often than you think.

by your logic then, a 1 speed tranny is the schizzle.

any engine can be smooth at 3,000 rpm. if its smooth at 6500 rpm as well, you know the engineering is solid, not only the that, the vibration from the motor is less of an impact on the rest of the car. lastly, smoothness at high rpm only serves to underscore the quality of a product.

you can have your iron block dinosaurs like the 3800. There is a reason it was passed by by others LONG ago.

Let's see here... no, no, no, no, and no.

NO #1: The need for 6,500 rpm smoothness to pass people? Two words: Racing Diesel. If the torque comes on much stronger at a lower RPM, you engineer the gearbox accordingly.

NO #2: Any engine can be smooth at 3,000rpm? Two words: Quad-Four.

NO #3: Smooth at 6,500 RPM has nothing to do with "solid" engineering. It has everything to do with the size of the reciprocating mass. With a properly configured 6-speed automatic mated to both, I'd pit even the LT-1 against a Nissan VQ any day of the week for solidness.

NO #4: Why is 6,500 rpm the cut off for smoothness requirement? Run a Honda 2.4 up to 8,500 rpm and see how smooth it runs then. Running an engine outside of design parameters will get you unpredictable operation. The 3800 was never intended to be run up that high.

NO #5: The 3800 was done in by it's lack of VVT and it's packaging requirements being a 90 degree engine. The 3900 is a lot smoother than the 3800 was simply because of the cylinder bank angle change. Where GM let both engines down was pairing it with the 4-speed automatic. If either of those engines had a 6-speed auto that was able to keep it in it's designed RPM range, there wouldn't have been so much complaining about it. Don't start an idiotic horsepower per liter argument, it's already been a long day for me.

[regfootball]

its simple. drive a lacrosse and an old lesabre and its pretty effing easy to understand which engine is better. part of it is because the high feature v6 is a better design and part of that is because it runs smoother at higher rpms. it doesn't run out of breath and it doesn't sound like a vacuum cleaner.

part of the reason honda engines get accolades is because they are smooth from dead stop to redline, as people access power in all part of the rpm range in normal everyday driving.

[regfootball]

Let's see here... no, no, no, no, and no.

NO #1: The need for 6,500 rpm smoothness to pass people? Two words: Racing Diesel. If the torque comes on much stronger at a lower RPM, you engineer the gearbox accordingly.

NO #2: Any engine can be smooth at 3,000rpm? Two words: Quad-Four.

NO #3: Smooth at 6,500 RPM has nothing to do with "solid" engineering. It has everything to do with the size of the reciprocating mass. With a properly configured 6-speed automatic mated to both, I'd pit even the LT-1 against a Nissan VQ any day of the week for solidness.

NO #4: Why is 6,500 rpm the cut off for smoothness requirement? Run a Honda 2.4 up to 8,500 rpm and see how smooth it runs then. Running an engine outside of design parameters will get you unpredictable operation. The 3800 was never intended to be run up that high.

NO #5: The 3800 was done in by it's lack of VVT and it's packaging requirements being a 90 degree engine. The 3900 is a lot smoother than the 3800 was simply because of the cylinder bank angle change. Where GM let both engines down was pairing it with the 4-speed automatic. If either of those engines had a 6-speed auto that was able to keep it in it's designed RPM range, there wouldn't have been so much complaining about it. Don't start an idiotic horsepower per liter argument, it's already been a long day for me.

some motorcycle engines can run 12,000 or 13,000 rpm, and they are smooth at that speed. why? engineering effort and manufacturing effort and design. point is, the engine needs to be agreeable in all parts of the rpm range, as the driver will use all parts of the rpm range at times.

[Carguy]

With so many less brands within GM these days why not return to unique size engines for those brands? My thought would be like the Ecoboost line at Ford but unique to each brand. Say Chevrolet uses an efficient 1.5L DI Turbo I4 and a 2.5L Di Turbo V6 to replace today's larger normally aspirated engines? While Buick does a 1.8L DI Turbo I4 and a 2.8L DI Turbo V6 and a 3.8L like V8. That would let Cadillac use a more premium 2.0L DI Turbo I4 and a like 3.0L V6 and even a 4.0L DI Turbo V8? They could keep the SB V8 advanced with DI and other tech for trucks and performance cars while using the smaller DI and Turbo engines listed above for standard and luxury car models.

[dwightlooi]

some motorcycle engines can run 12,000 or 13,000 rpm, and they are smooth at that speed. why? engineering effort and manufacturing effort and design. point is, the engine needs to be agreeable in all parts of the rpm range, as the driver will use all parts of the rpm range at times.

Actually, it's most of it has to do with the fact that motorcycle engines that rev to 12,000 rpm also have pretty small cylinders, somewhat tiny pistons and, most importantly, pretty short strokes. Engine vibrations from the reciprocating mass is a function of the mass of the reciprocating mass (piston and rods) and the square of velocity (piston speed). You are building and reversing the kinetic energy of each pistons two times per revolution. Kinetic energy is 0.5MV^2. So, lighter mass helps somewhat. But, having shorter strokes help tremendously.

[Drew Dowdell]

some motorcycle engines can run 12,000 or 13,000 rpm, and they are smooth at that speed. why? engineering effort and manufacturing effort and design. point is, the engine needs to be agreeable in all parts of the rpm range, as the driver will use all parts of the rpm range at times.

A motorcycle is smooth at 12,000 rpm because their pistons are 1/3rd the size and the stroke is 1/3rd as long, and you wouldn't want to drive a car with a motorcycle engine in it because you'd need all 13,000 rpm just to get to 45mph in a reasonable time.

The engine does need to be agreeable in all parts of it's designed rpm range. The problem with the 3800 was GM trying to make it do what it wasn't meant to be doing. A 6-speed auto with appropriately spaced gearing and a tall final drive would have helped the 3800 remain competitive longer.

[regfootball]

Actually, it's most of it has to do with the fact that motorcycle engines that rev to 12,000 rpm also have pretty small cylinders, somewhat tiny pistons and, most importantly, pretty short strokes. Engine vibrations from the reciprocating mass is a function of the mass of the reciprocating mass (piston and rods) and the square of velocity (piston speed). You are building and reversing the kinetic energy of each pistons two times per revolution. Kinetic energy is 0.5MV^2. So, lighter mass helps somewhat. But, having shorter strokes help tremendously.

but that's exactly my point, a larger car engine should have no excuses at all for smoothness at little more than half the rpm of the tiny motor.

[pow]

point is, the engine needs to be agreeable in all parts of the rpm range, as the driver will use all parts of the rpm range at times.

Ding, ding, ding, ding! We've got a winner. This is especially true for a CVT, which puts you in the optimum RPM all the time.

[dwightlooi]

Speaking of smoothness...

High tech doesn't mean smooth and refined. I know a lot of people don't want to hear this, but the 3.5 Pushrod V6 in the last generation Malibu and the G6 was smoother and more refined than the 3.6 liter DOHC DI-VVT engine in the Camaro. Don't believe me? Go drive both. It's significant in enough that you don't even have to do it back to back to register the difference. Now the Lacrosse and the CTS have plenty of insulation to mute the engine, but in the Camaro it has a grainy, coarse, groan that's very annoying from 4500 rpm on up. Rougher than the 2.4 liter four IMHO. Even at 3000~4500 its worse than the Pushrod V6.

Maybe its the higher compression leading to higher combustion noise. Maybe its the plastic valve covers and intake manifold. Maybe its something else, but the engine is irrefutably coarse.

One thing GM ought to consider is a balance shaft. Even though 60 deg V6es generally don't have them because they are reasonably well balanced as is, they CAN benefit from one. A 60 deg six is NOT perfectly balanced like an I6 or a H6, its just better than a 90 deg six in this regard. In fact, if anyone remembers, the Twin Dual Cam 3.4 V6 (LQ1) from the early 90s is a 60 deg V6 with a balance shaft. The engine was built on the pushrod 60 deg block, but had belt driven DOHC heads added. It had a balance shaft where the in-block cam normally was. The motor was not without its failings in terms of reliability and especially serviceability -- the amount of dis-assembly needed to just get to the spark plugs borders on the ridiculous -- but it was one of the smoothest V6es ever.

[regfootball]

Speaking of smoothness...

High tech doesn't mean smooth and refined. I know a lot of people don't want to hear this, but the 3.5 Pushrod V6 in the last generation Malibu and the G6 was smoother and more refined than the 3.6 liter DOHC DI-VVT engine in the Camaro. Don't believe me? Go drive both. It's significant in enough that you don't even have to do it back to back to register the difference. Now the Lacrosse and the CTS have plenty of insulation to mute the engine, but in the Camaro it has a grainy, coarse, groan that's very annoying from 4500 rpm on up. Rougher than the 2.4 liter four IMHO. Even at 3000~4500 its worse than the Pushrod V6.

Maybe its the higher compression leading to higher combustion noise. Maybe its the plastic valve covers and intake manifold. Maybe its something else, but the engine is irrefutably coarse.

One thing GM ought to consider is a balance shaft. Even though 60 deg V6es generally don't have them because they are reasonably well balanced as is, they CAN benefit from one. A 60 deg six is NOT perfectly balanced like an I6 or a H6, its just better than a 90 deg six in this regard. In fact, if anyone remembers, the Twin Dual Cam 3.4 V6 (LQ1) from the early 90s is a 60 deg V6 with a balance shaft. The engine was built on the pushrod 60 deg block, but had belt driven DOHC heads added. It had a balance shaft where the in-block cam normally was. The motor was not without its failings in terms of reliability and especially serviceability -- the amount of dis-assembly needed to just get to the spark plugs borders on the ridiculous -- but it was one of the smoothest V6es ever.

i'll take issue with that to a point. first off, and i know this is a third party observer pointing it out, but most magazine reviews I read on the 3.5v6 whether it was in a saturn vue or a saturn aura etc. in comparison tests they did not speak favorably of the NVH of that powertrain, even in comparison tests against 4 cylinders from other makers.

my own test drives of the aura and other epsilon cars with the high feature vs. the 3.5, the 3.5 is not as refined as the high feature was. so i would disagree the first part of your post.