GM HFV6 Thread

[Nick R]

So let's have a thread about these engines. That would be either the 3.0L or the 3.6L GM High Feature V6 (HFV6). If you own one, post your experiences, thoughts on it, etc.

I fairly well covered mine in our equinox review, but I'll briefly touch on it again. It's a very smooth engine, barely any vibration is transmitted to the steering wheel or engine compartment. It makes a good noise too, a nice growl. IT has plenty of torque down low for getting around town, but above 4,000RPM is where the power really comes on. It's probably one of my favorite engines. It's capable of halfway decent MPG when driven right too.

 

[dishdude]

I have the 3.0 in my Terrain, and although adequate I think the 3.6 would make a very good CUV/SUV excellent. You're right, it is smooth and I do get decent fuel economy but the lack of low end torque is disappointing. I feel the 3.6 would give very similar fuel economy with much better driveability.

 

[Colt45ws]

My Grandpa's CTS has the 3.0L. It runs nice, sounds good. Like above, Ive found the low end to be disappointing, need to wrap it out to get some powder out of it. Fuel economy is great though. Does need good oil. Last test had 3 or 4% fuel? Thats the DI for you though. The earlier ones with PI dont have that problem, I would assume.

 

[Win]

I have two 3.6's: a wrong wheel drive in the Torrent GXP, and a rear wheel drive in the G8. Neither are direct injected. The one in the G8 is the Alloytec High Output built by Holden (many G8's had U.S. sourced engines - mine is Australian), and the Torrent has a Japanese built engine, presumably by Suzuki. So these are truly global engines.

I've only owned three V6's in my life - A GM 4.3 pushrod V6, and the two HF V6's.

Generally, I'm not a fan of V6's, I would rather have a straight 6, but I have no complaints about the HF V6's. They are thoroughly modern engines, light years ahead of their predecessors, with a broad powerband of adequate torque and power for the large (by today's standards) cars they are installed in. I'm actually a little surprised at how strong they feel, given the puny 217 CI displacement.

Unfortunately, CAFE will make even these puny engines look large in the very near future.

edit: one thing I've noticed is that the cam phasing is very seamless on the 3.6. The AJ-v8 in our Xj8, which has similar full cam phasing on both the intake and exhaust cams and a variable inlet manifold (as does the HFV6), really has a big burst of power as it phases the cams, there is nothing subtle about it. But it's only about 30 HP stronger than the HFV6. The 3.6 HFV6 has a very smooth and progressive power delivery, it just continues to build up to about 7200 rpm or so, where it is programmed to shift.

 

[hardcore302]

I have one (correct me if I'm wrong: Saturn Vue XR). It moves the heavy SUV effortlessly. The thing hauls. Sounds awesome. But the gas mileage is horrible. Might just be the application, though.

 

[jetmech1]

I got an idea for a friendly discussion on this subject, if I may..

10-15 years ago, especially after the advent of OBD-2, I would have bet dollars to donuts that the internal combustion engine was probably at it's developmental limit. But they came up with variable cam timing and so on. Now you can get muscle car HP on half as many cubes and still get good mileage.

Sooooo, have we now wrung just about everything out of the ICE as can be had? Or, is there still more to get? I'm really curious on what everyone thinks about this.....Thanks

 

[Oil Changer]

Originally Posted By: jetmech1
I got an idea for a friendly discussion on this subject, if I may..

10-15 years ago, especially after the advent of OBD-2, I would have bet dollars to donuts that the internal combustion engine was probably at it's developmental limit. But they came up with variable cam timing and so on. Now you can get muscle car HP on half as many cubes and still get good mileage.

Sooooo, have we now wrung just about everything out of the ICE as can be had? Or, is there still more to get? I'm really curious on what everyone thinks about this.....Thanks


I heard talk of electronically controlled valves (ie. no camshafts at all).

The ICE is here to stay. The oil execs will see to that.

 

[A_Harman]

I work at a Tier One supplier of engine components, and work with engine developers and manufacturers from all around the world. I assure you that the ICE has many avenues of development being explored.

Gasoline Direct Injection
Variable Valve Actuation
Downspeeding & Downsizing
Supercharging & Turbocharging
Heat Recovery
Hybridization and Electrification

These are all terms I hear and work with on a daily basis.
But make no mistake; petroluem is still the best fuel for powering our vehicles. Electric cars aren't nearly as useful as anything powered by fossil fuels.

 

[NateDN10]

Originally Posted By: Oil Changer
I heard talk of electronically controlled valves (ie. no camshafts at all).

The ICE is here to stay. The oil execs will see to that.

The energy density of gasoline as compared to batteries will see to that.

 

[Nick R]

I will say that the 3.0L lacks low end torque compared to some other engines, namely the older GM V6s. However this one also revs much higher (7,000RPM vs 5,500RPM or less). I do agree, I would have liked to have gotten the 3.6L, like the Malibu did. It's not too bad once you get it going, but until then it's not as powerful as say, my cruze even.

 

[rjundi]

Originally Posted By: jetmech1
I got an idea for a friendly discussion on this subject, if I may..

10-15 years ago, especially after the advent of OBD-2, I would have bet dollars to donuts that the internal combustion engine was probably at it's developmental limit. But they came up with variable cam timing and so on. Now you can get muscle car HP on half as many cubes and still get good mileage.



10-15 years ago unfortunately GM,Ford, Chrysler were simply way behind the curve. Honda(1989 VTEC) and Toyota(1991) introduced many things carried over like variable valve timing into the Big 3.

Thankfully it has resulted in some really nice domestic engines in the last 5 or so years for general consumption. Not just performance or luxury models.

 

[OVERKILL]

Originally Posted By: rjundi
Originally Posted By: jetmech1
I got an idea for a friendly discussion on this subject, if I may..

10-15 years ago, especially after the advent of OBD-2, I would have bet dollars to donuts that the internal combustion engine was probably at it's developmental limit. But they came up with variable cam timing and so on. Now you can get muscle car HP on half as many cubes and still get good mileage.



10-15 years ago unfortunately GM,Ford, Chrysler were simply way behind the curve. Honda(1989 VTEC) and Toyota(1991) introduced many things carried over like variable valve timing into the Big 3.

Thankfully it has resulted in some really nice domestic engines in the last 5 or so years for general consumption. Not just performance or luxury models.


Honda was still using carburetors back then, and variable valve timing is a technology that came about during the era of steam engines.

Ford was using SEFI and mass air since the mid to late 80's and had been dabbling in the DOHC/SOHC stuff since the early 60's with their Indy Cammer and of course the 427 SOHC.

Toyota's system is predated by BMW's (and formerly Alpha Romeo's) VANOS system.

The modular and Northstar appeared on the scene circa 1991. Both of these engines had DIS.

Also in 1990, GM released the DOHC LT5. 5.7L, 375HP in the Corvette.

In 1994 Ford had the DOHC, 320HP version of the 4.6L.

And of course Ford didn't follow Honda or Toyota, if they followed anybody, it was BMW (like Toyota), as they adopted a system very similar to VANOS for their variable cam timing.

 

[jetmech1]

That's a bad lookin mammer-jammer there. Would hate to have to work on it though. How long does it take to change the belts?

Is that the oil filter right in front of the right bank? Isn't that kind fo messy? Obviously, I am Corvette challenged........

 

[GMBoy]

Originally Posted By: Colt45ws
My Grandpa's CTS has the 3.0L. It runs nice, sounds good. Like above, Ive found the low end to be disappointing, need to wrap it out to get some powder out of it. Fuel economy is great though. Does need good oil. Last test had 3 or 4% fuel? Thats the DI for you though. The earlier ones with PI dont have that problem, I would assume.



My 2008 CTS with the 3.6 DI engine NEVER has saw more than 0.5% fuel in my Blackstone UOA's. My OCI is 5-7k miles. The highest I did see was on my Dad's similar CTS as mine with 1% and he idles and does lots of short trips. He goes by the OLM which up until the updated software he was doing 10-12k mile changes.

I think it was a mistake for Cadillac to offer a stripper CTS with the 3.0L.

 

[mechanicx]

Also GM introduced the Quad 4 4-valve in '87 with 180 HP. Honda desperately needed VTEC to keep up having small engines.

And pushrod technology still works fine in Corvettes. It was fuel economy, fuel cost and emissions standards that pushed the domestics to adopt 4-valves and variable valve timing more than anything else.

 

[mechanicx]

Originally Posted By: jetmech1
That's a bad lookin mammer-jammer there. Would hate to have to work on it though. How long does it take to change the belts?

Is that the oil filter right in front of the right bank? Isn't that kind fo messy? Obviously, I am Corvette challenged........


That engine, the LT5, has timing chains and hydraulic cam followers, so no timing belt replacements and valve adjustments unlike those Japanese jobs

.
The aluminum canister is the A/C accumulator-edit sorry the oil filter is visible but being mounted base end down it is not too messy when removed. Notice it also has a pressurized coolant reservoir.

This is a good site with detailed LT5 engine specs http://www.zr1netregistry.com/ZR1_specs.htm .

 

[T-Keith]

Originally Posted By: OVERK1LL


Honda was still using carburetors back then, and variable valve timing is a technology that came about during the era of steam engines.

Ford was using SEFI and mass air since the mid to late 80's and had been dabbling in the DOHC/SOHC stuff since the early 60's with their Indy Cammer and of course the 427 SOHC.

Toyota's system is predated by BMW's (and formerly Alpha Romeo's) VANOS system.

The modular and Northstar appeared on the scene circa 1991. Both of these engines had DIS.

Also in 1990, GM released the DOHC LT5. 5.7L, 375HP in the Corvette.


In 1994 Ford had the DOHC, 320HP version of the 4.6L.

And of course Ford didn't follow Honda or Toyota, if they followed anybody, it was BMW (like Toyota), as they adopted a system very similar to VANOS for their variable cam timing.


Heck GM was even more ahead of the game than that. The turbo Buick V6 had Distributorless ignition and sequential port fuel injection in 84, all 3.8 got it in 86. They also had low skirt pistons, overdrive transmissions,(honda had a two speed auto in back then) ABS, touch screen digital interfaces, balance shafts and more in the 80s. Unfortunately some people can't get past the OHV part, which is only a small piece of the puzzle.

Believe it or not it's the 90s where GM got behind in the technology.

 

[Spazdog]

the 3.8s all got DIS, but it was that hopeless Magnavox system. They were about $130 and they were short-lived.

By 1984 the Civic had a 3spd automatic and by 1988 a 4spd

The Corvette's LT5 was engineered by Lotus and built by Mercury Marine

The DOHC Mustang Cobra made it's debut in 1996 with 305 hp. The '94-'95 Cobra used a 240hp 302 and the Cobra R used a 300 hp 351. Getting 305hp out of the 4.6 is impressive though considering a similar year Infiniti Q45 makes about 275 out of only 100cc less displacement.

Balance shafts were old news in the Mitsubishi 4G54. (1978 Sapporo/Challenger)

Ford's variable timing came initially courtesy of Mazda and/or Jaguar.

BMW and Audi copied Honda for torque vectoring AWD the basis of which was the torque transfer system in the '97 Prelude SH

 

[Shannow]

Originally Posted By: OVERK1LL
and variable valve timing is a technology that came about during the era of steam engines.


You're seriously joking here aren't you.

 

[Hokiefyd]

It looks like GM is fixing the 3.0L's lack of low-end torque...by replacing it, at least in the Terrain. It appears like it'll be getting the 3.6L next year.

My brother has a 3.0L CTS. It's a 2010 or 2011 model. He says it's "slow", but he compares that to the 1997 SLS he had before, and his 1997 supercharged C5. Watching a YouTube video of even a CTS, the 3.0L does appear to have a lack of muscle on the low-end. Proper gearing and enough ratios in the transmission can usually fix that.

I think the 3.0L CTS is supposed to do 0-60 in 7.5 seconds. Some 4-cylinder family sedans are within spitting distance of that.