Honda's new A-Vtec system

[siegen]

Nothing official from Honda yet, but the guys over at www.vtec.net posted an article concerning a patent Honda placed which definitely appears to be the new A-Vtec system they announced recently. There are some sketches too. The system seems to be very simple, at least compared to BMW's fully variable lift system. And there's a good chance it will make its debut in the 2008 Accord.

Full Article

Edited February 9, 2007 by siegen

[regfootball]

as long as it helps with real american pleasing torque and mpg, more power to them

[Drew Dowdell]

This is a case of Honda catching up to GM in engine technology. The HF3.6 has this technology now. Of course, by the time Honda gets it to market, the 3.6 will also have DI.

[siegen]

as long as it helps with real american pleasing torque and mpg, more power to them

The main advantage of this new system will be increased low/mid rpm torque. The increased efficiently throughout the entire RPM range will also increase fuel efficiency.

[siegen]

This is a case of Honda catching up to GM in engine technology. The HF3.6 has this technology now. Of course, by the time Honda gets it to market, the 3.6 will also have DI.

Can you link me more info on the HF3.6?

[Drew Dowdell]

Can you link me more info on the HF3.6?

The 3.6L global V-6 develops 255 hp (190 kw) at 6200 rpm and 255 lb.-ft. of torque (346 Nm) at 3200 rpm and is mated to the 5L40-E automatic transmission. The adoption of fully variable valve timing for both intake and exhaust valves provides outstanding flexibility, fuel economy and emissions reduction. link

VVT systems use electronically controlled hydraulic camshaft phasers to alter the relationship of the intake and exhaust camshafts as much as 50 degrees relative to the crankshaft. The ability to adjust the timing of intake and exhaust valve opening and closing events improves the full load performance in the entire operating range. link

[siegen]

The 3.6L global V-6 develops 255 hp (190 kw) at 6200 rpm and 255 lb.-ft. of torque (346 Nm) at 3200 rpm and is mated to the 5L40-E automatic transmission. The adoption of fully variable valve timing for both intake and exhaust valves provides outstanding flexibility, fuel economy and emissions reduction. link

VVT systems use electronically controlled hydraulic camshaft phasers to alter the relationship of the intake and exhaust camshafts as much as 50 degrees relative to the crankshaft. The ability to adjust the timing of intake and exhaust valve opening and closing events improves the full load performance in the entire operating range. link

A-Vtec incorporates continuously variable valve lift and duration, in addition to continuously variable valve timing (VVT) which has been in Honda i-Vtec engines since 2000 (and others since before that). The only other manufacturer to have a system like this is BMW.

Not only is the closing/opening event timing controlled, but the distant of the opening and duration are controlled now as well. Since 1989, Honda's vtec system has been able to control valve lift and duration, but only in two steps. This was still a huge improvement, as an engine could operate efficiently at low and high rpms, as if it had a camshaft dedicated to each rpm range. Now, the lift and duration are continuous.

Edited February 9, 2007 by siegen

[siegen]

The 3.6L global V-6 develops 255 hp at 6200 rpm and 255 lb.-ft. of torque at 3200 rpm and is mated to the 5L40-E automatic transmission.

Cadillac CTS 3.6L

255hp @ 6200 rpm and 255tq @ 3200 rpm

Acura TL 3.2L

258hp @ 6200 rpm and 233tq @ 5000 rpm

Acura TL-S 3.5L

286hp @ 6200 rpm and 256tq @ 5000 rpm

Acura MDX 3.7L

300hp @ 6000 rpm and 275tq @ 5000 rpm

The Honda engines are SOHC originally designed in 1996 (J-series engine), while the GM engine is DOHC designed in 2004.

Who's playing catch up?

Of course if we compare any of these engines to Toyota's new GR 3.5L engines, they would pale in comparison. But the GR engines are also new, designed in 2003, and DOHC.

It's still unknown, but Honda may be coming out with a new V6 engine for 2008 (the j-series is getting long for this world). With the addition of A-Vtec, it seems like the perfect chance.

Edited February 9, 2007 by siegen

[Drew Dowdell]

Cadillac CTS 3.6L

255hp @ 6200 rpm and 255tq @ 3200 rpm

Acura TL 3.2L

258hp @ 6200 rpm and 233tq @ 5000 rpm

Acura TL-S 3.5L

286hp @ 6200 rpm and 256tq @ 5000 rpm

Acura MDX 3.7L

300hp @ 6000 rpm and 275tq @ 5000 rpm

The Honda engines are SOHC originally designed in 1996 (J-series engine), while the GM engine is DOHC designed in 2004.

Who's playing catch up?

Of course if we compare any of these engines to Toyota's new GR 3.5L engines, they would pale in comparison. But the GR engines are also new, designed in 2003, and DOHC.

It's still unknown, but Honda may be coming out with a new V6 engine for 2008 (the j-series is getting long for this world). With the addition of A-Vtec, it seems like the perfect chance.

I don't see any "catch up" with the stats you posted at all. The hondas are tuned to providing more HP at the expense of torque while the Cadillac is tuned to produce more torque at the expense of horsepower. I'm sure if Cadillac dialed the torque to reach it's peak at 5000rpm instead of 3200rpm it would have a much higher horsepower number than it does now. It's not about catch up, it's about two different styles.

Personally, I wouldn't want an engine where torque reaches full boil all the way up at 5,000rpm. You may want that. That doesn't make either engine "better". Of course, once DI is available in the Cadillac and A-Vtec in the Honda, all bets are off.

[Sixty8panther]

I know I'm old fashioned but I'll keep my pushrods and the

occassional DOHC, simple IS better. Just Ask Mr. Muprhey.

Don't get me wrong I've owned several DOHC cars, the

Northstar was by FAR the best of them, as beat to f**k as

my Cadillac was at just 101,000 miles. I gues the Infiniti's

4100 is alright but even HP/Liter wise it's not even close to

the Cadillac. Still it gets the job done. The quality of my

life would not be somehow increased expinentially just

because the MPG goes up a couple percentage points or

perhaps because my hydrocarbons or C0 is reduced by

about the equivelant of a Taco Bell fart.

I think that about 75% of today's "progress" is just needless

complication and B.S. that only results in more repairs and

headaches while emptying out our wallets.

[Sixty8panther]

As you can see from the drawings, the implementation of A-VTEC is classic Honda technological innovation. It is simple and compact, with a minimum of moving parts and easy adjustability. The key to the system lies in an innovative circumferential, cam-centric rotationally adjustable drum mechanism.

It certainly SOUNDS very simple. Eight words and a hypen is about as basic as it gets for a part description.

To put it more simply, the intake camshaft (and the intake camshaft only in the proposed implementation) is surrounded by a drum that rotates around the same axis as the camshaft. The position of this drum is determined by a computer controlled gear.

Fantastic! We all know computers never fail.

[siegen]

I don't see any "catch up" with the stats you posted at all. The hondas are tuned to providing more HP at the expense of torque while the Cadillac is tuned to produce more torque at the expense of horsepower. I'm sure if Cadillac dialed the torque to reach it's peak at 5000rpm instead of 3200rpm it would have a much higher horsepower number than it does now. It's not about catch up, it's about two different styles.

Personally, I wouldn't want an engine where torque reaches full boil all the way up at 5,000rpm. You may want that. That doesn't make either engine "better". Of course, once DI is available in the Cadillac and A-Vtec in the Honda, all bets are off.

Consider this, even though the peak TQ of an engine occurs at a given RPM, it doesn't mean that the engine isn't making one less ft-lb of TQ at every other rpm. That's where peak numbers really don't show the whole story and you have to look at a complete graph. Of course no engine is perfect like that, but some are closer than others, and variable valve lift and duration is a very important part in leveling out the complete torque curve.

When people think of Honda engines, they always think they're gutless or torque-less. They get that impression, because Honda usually uses less displacement for a given vehicle size. The reality is, if you compare a Honda engine to another that is the same displacement, and compare the dyno charts, the Honda's generally have similar mid-ranges, but without sacrificing high rpm torque. And the overall torque curve is flatter, resulting in more linear acceleration and performance.

[siegen]

I know I'm old fashioned but I'll keep my pushrods and the

occassional DOHC, simple IS better. Just Ask Mr. Muprhey.

Don't get me wrong I've owned several DOHC cars, the

Northstar was by FAR the best of them, as beat to f**k as

my Cadillac was at just 101,000 miles. I gues the Infiniti's

4100 is alright but even HP/Liter wise it's not even close to

the Cadillac. Still it gets the job done. The quality of my

life would not be somehow increased expinentially just

because the MPG goes up a couple percentage points or

perhaps because my hydrocarbons or C0 is reduced by

about the equivelant of a Taco Bell fart.

I think that about 75% of today's "progress" is just needless

complication and B.S. that only results in more repairs and

headaches while emptying out our wallets.

Who cares about just one person? Look at the big picture. If the MPG goes up even 5%, consider that it will be going up 5% on hundreds of thousands of vehicles every year. Honda won't be the first to introduce a continuously variable valve lift/duration mechanism (BMW is), but they will be the first to bring it to the mainstream economy vehicles.

So if 350,000 Accords per year and 310,000 Civics per year get 5% better MPG, that would make a difference, right?

[thegriffon]

Cadillac CTS 3.6L

255hp @ 6200 rpm and 255tq @ 3200 rpm

Acura TL 3.2L

258hp @ 6200 rpm and 233tq @ 5000 rpm

Acura TL-S 3.5L

286hp @ 6200 rpm and 256tq @ 5000 rpm

Acura MDX 3.7L

300hp @ 6000 rpm and 275tq @ 5000 rpm

The Honda engines are SOHC originally designed in 1996 (J-series engine), while the GM engine is DOHC designed in 2004.

Who's playing catch up?

Of course if we compare any of these engines to Toyota's new GR 3.5L engines, they would pale in comparison. But the GR engines are also new, designed in 2003, and DOHC.

It's still unknown, but Honda may be coming out with a new V6 engine for 2008 (the j-series is getting long for this world). With the addition of A-Vtec, it seems like the perfect chance.

Toyota's Dual-VVT GR series debuted some months after GM's 3.6 L. Mercedes of course claimed to be first with their Dual-VVT 3.5 liter, which debuted a year later.

Mitsubishi and Mazda/Ford both use cam profile switching like Honda's VTEC system. Audi uses dual-CVVT on it's V-engines now, and has added CPS on the intake cam of a new engine as well. VTEC is not nor has ever been "continuously variable". It has always been a cam profile switching system, and therefore sequential or step based. It is however not merely two step. Depending on the application there are two- and three-phase VTEC systems (more recent 3-phase systems include cylinder shut-off or an idle mode rather than a 3rd cam profile), and of course it is also possible to apply it to the exhaust valves as well as the intake, although I believe that has only been done on the older DOHC engines Honda has largely abandoned in favor of the SOHC setup. CVVT works best on DOHC engines, but can and has been implemented on SOHC engines such as the Gen IV V8s and the Viper's new V10. The nature of CPS means that it works equally well on SOHC and DOHC engines, but for space reasons is usually only applied to the intake valves of SOHC engines

A few Toyota engines incorporate variable valve lift in addition to straight VVT, as does GM's rwd Northstar V8, and probably the LY7, but not all versions of the Global V6. Delphi has been promoting a 2- or 3-stage CPS as an easier way to do this. BMW has of course used first VANOS CVVT and now Double-VANOS on every gasoline engine for a long time. Most naturally aspirated engines also now incorporate the variable valve lift Valvetronic sustem, which BMW uses for throttle control instead of a throttle butterfly.

Aside from a different bore and stroke, the 2ZZ-GE 1.8 L is distinguished from the 1ZZ-FE 1.8 L by the use of variable valve lift in addition to VVT on the intake cam. Both are being replaced by the new dual-VVT 2ZR-FE.

Edited February 9, 2007 by thegriffon

[bcs296]

Consider this, even though the peak TQ of an engine occurs at a given RPM, it doesn't mean that the engine isn't making one less ft-lb of TQ at every other rpm. That's where peak numbers really don't show the whole story and you have to look at a complete graph. Of course no engine is perfect like that, but some are closer than others, and variable valve lift and duration is a very important part in leveling out the complete torque curve.

When people think of Honda engines, they always think they're gutless or torque-less. They get that impression, because Honda usually uses less displacement for a given vehicle size. The reality is, if you compare a Honda engine to another that is the same displacement, and compare the dyno charts, the Honda's generally have similar mid-ranges, but without sacrificing high rpm torque. And the overall torque curve is flatter, resulting in more linear acceleration and performance.

BINGO!

That is why I hate seeing all these people with their claims, "OMG Honda's are torqueless wonders, you gotta drive the thing at 9999999rpms 24/hrs a day OMG what a piece of garbage."

Get a grip. Let's compare how many complaints there are regarding the power/torque curves of Honda engines to the number of complaints there are about NVH in GM's pushrod V6's. I wonder which number is bigger.

[siegen]

The A-VTEC system is very simply another method of cam phasing, as used by Toyota, BMW, GM, Audi, Mercedes etc.. There are already more than one, and GM and Toyota don't always use the same one, but different systems as provided by different suppliers.

The big difference is that we're talking about LIFT AND DURATION, and not timing. Go Wiki each manufacturer's mechanism to see how they all work. Most of them don't vary lift or duration, only timing. The ones that do vary lift and duration, do it in steps. Honda's Vtec mechanism varies lift and duration in steps, and that is how it has worked since 1989. Only recently (in 2000) did they incorporate a variable timing mechanism in addition to the variable lift/duration mechanism, which is what i-Vtec is. A-Vtec is going to be continuously variable valve lift and duration and continuously variable valve timing.

BMW's Valvetronic system was the first to vary lift and duration continuously, and Honda's A-Vtec will most likely be the second (unless another manufacturer comes to market in the next year before them).

Edited February 9, 2007 by siegen

[Drew Dowdell]

Get a grip. Let's compare how many complaints there are regarding the power/torque curves of Honda engines to the number of complaints there are about NVH in GM's pushrod V6's. I wonder which number is bigger.

GM has sold more pushrod V6es than Honda has sold cars.

[thegriffon]

Who cares about just one person? Look at the big picture. If the MPG goes up even 5%, consider that it will be going up 5% on hundreds of thousands of vehicles every year. Honda won't be the first to introduce a continuously variable valve lift/duration mechanism (BMW is), but they will be the first to bring it to the mainstream economy vehicles.

No, Peugeot was when they introduced the BMW designed Double-Vanos/Valvetronic 1.6 L to the 207, that is, if you don't count the same engine in the Mini (fabricated in Peugeot's Douvrin plant and assembled in either Douvrin or BMW's Hams Hall plant). A 1.4 L version is also due. Both engines (and a DI Turbo without Valvetronic) are further developments of the older BMW-Chrysler 1.4 and 1.6 L manufactured at the Tritec factory in Brazil. Edited February 9, 2007 by thegriffon

[toyoguy]

bout time, the J-series motors are weak south of 3500rpm.

[regfootball]

Consider this, even though the peak TQ of an engine occurs at a given RPM, it doesn't mean that the engine isn't making one less ft-lb of TQ at every other rpm. That's where peak numbers really don't show the whole story and you have to look at a complete graph. Of course no engine is perfect like that, but some are closer than others, and variable valve lift and duration is a very important part in leveling out the complete torque curve.

When people think of Honda engines, they always think they're gutless or torque-less. They get that impression, because Honda usually uses less displacement for a given vehicle size. The reality is, if you compare a Honda engine to another that is the same displacement, and compare the dyno charts, the Honda's generally have similar mid-ranges, but without sacrificing high rpm torque. And the overall torque curve is flatter, resulting in more linear acceleration and performance.

you make no mention of Honda's lack of LOW END torque. At least Toyota and Nissan have torque figured out these days.

What will GM's DI 3.6 produce? 320hp?

Edited February 9, 2007 by regfootball

[thegriffon]

The big difference is that we're talking about LIFT AND DURATION, and not timing. Go Wiki each manufacturer's mechanism to see how they all work. Most of them don't vary lift or duration, only timing. The ones that do vary lift and duration, do it in steps. Honda's Vtec mechanism varies lift and duration in steps, and that is how it has worked since 1989. Only recently (in 2000) did they incorporate a variable timing mechanism in addition to the variable lift/duration mechanism, which is what i-Vtec is. A-Vtec is going to be continuously variable valve lift and duration and continuously variable valve timing.

BMW's Valvetronic system was the first to vary lift and duration continuously, and Honda's A-Vtec will most likely be the second (unless another manufacturer comes to market in the next year before them).

Cam phasing systems vary timing of one or both camshafts. A few engines add a system for variable lift (BMW's Valvetronic engines, the new Northstar, Toyota's 2ZZ-GE Audi's new 2.8 DI V6). Cam profile switching systems as emplyed by Honda, Mazda, Volvo, Mitsubishi et al can vary timing, lift and duration in two or three steps by switching between different profiles. Audi's aforementioned 2.8 DI which debuted last year in the A6 employs both cam phasing on the intake and exhaust cams and cam profile switching on the intake cam—a method promoted by Delphi as simpler than alternative variable valve-lift systems for cam-phasing CVVT engines. This new Honda system adjusts continuously between high lift-late valve opening, and low lift-early valve opening (due to simple geometry as valve lift is increased the valve timing is delayed). Unlike dual-systems altering both timing and lift continuously but seperately, in this sytem timing and lift are altered in parallel, so a throttling function as in BMW's Valvetronic is not possible. As yet there does not seem to be a practical method of continuously altering duration without direct electro-hydraulic valve activation. Neither cam phasing nor this possible A-VTEC system vary duration as can be done with a different cam profile.

[cletus8269]

nice, another sticker the kids in high school can put on their cars... i can see it now '96 honda civics everywhere sporting A-Vtec across the windshields, bumpers, and who knows where else. i know thats not correlating to what is being discussed but i got lost halfway down page one. i just wanted to make a prediction.

Edited February 10, 2007 by cletus8269

[Sixty8panther]

If I was a gambling man I would say don't bet against Cletus8269.

I bet AutoZone and AdvancedAutoParts are already waiting for the

ink to dry on the new "A-Vtech SiR S-Type" stickers in HOT Pink,

Highliter Blue, Metrosexual Purple and Mango Orange. And some

dude with a 1986 Honda CRX is holding his breath.

[GXT]

This new Honda system adjusts continuously between high lift-late valve opening, and low lift-early valve opening (due to simple geometry as valve lift is increased the valve timing is delayed). Unlike dual-systems altering both timing and lift continuously but seperately, in this sytem timing and lift are altered in parallel, so a throttling function as in BMW's Valvetronic is not possible. As yet there does not seem to be a practical method of continuously altering duration without direct electro-hydraulic valve activation. Neither cam phasing nor this possible A-VTEC system vary duration as can be done with a different cam profile.

It is my (limited) understanding is that the though lift, duration and timing are linked, they are linked in a generally advantageous manner.

The system is less complicated than the current iVtec, apparently offers 13% better fuel economy than the current 2.4L (that would mean the new accord should get ~29/38 MPG), and will provider an even wider and higher torque.

It looks pretty nice as well:

http://hondanews.com/CatID2073?view=p&...w=AccordConcept

[carstar]

WHY on earth is VVT not on gm 1.6L and ECOTEC 2.2L where it's needed the most!!!???

[G. David Felt]

WHY on earth is VVT not on gm 1.6L and ECOTEC 2.2L where it's needed the most!!!???

Could it be that GM still has not figured out how to build a profitable small compact? Or maybe it is the fact that the markets that GM sell's these engines into are still strong enough that GM feels it does not need to change yet.

Reality, GM will eventually get there, but the key markets are more into V6 and V8's that GM needs to update than Brazil with the 1.6 or 2.2 engines. Yes I know these engines get sold here also, but their market share I believe is small in comparison to the V6 and V8 market.

Just my thoughts.

[regfootball]

If I was a gambling man I would say don't bet against Cletus8269.

I bet AutoZone and AdvancedAutoParts are already waiting for the

ink to dry on the new "A-Vtech SiR S-Type" stickers in HOT Pink,

Highliter Blue, Metrosexual Purple and Mango Orange. And some

dude with a 1986 Honda CRX is holding his breath.

they all wear AXE too i suppose

[trinacriabob]

Cam phasing systems vary timing of one or both camshafts. A few engines add a system for variable lift (BMW's Valvetronic engines, the new Northstar, Toyota's 2ZZ-GE Audi's new 2.8 DI V6). Cam profile switching systems as emplyed by Honda, Mazda, Volvo, Mitsubishi et al can vary timing, lift and duration in two or three steps by switching between different profiles. Audi's aforementioned 2.8 DI which debuted last year in the A6 employs both cam phasing on the intake and exhaust cams and cam profile switching on the intake cam—a method promoted by Delphi as simpler than alternative variable valve-lift systems for cam-phasing CVVT engines. This new Honda system adjusts continuously between high lift-late valve opening, and low lift-early valve opening (due to simple geometry as valve lift is increased the valve timing is delayed). Unlike dual-systems altering both timing and lift continuously but seperately, in this sytem timing and lift are altered in parallel, so a throttling function as in BMW's Valvetronic is not possible. As yet there does not seem to be a practical method of continuously altering duration without direct electro-hydraulic valve activation. Neither cam phasing nor this possible A-VTEC system vary duration as can be done with a different cam profile.

You always appear to be knowledgeable. On GM systems, how does this work? Isn't it an assembly up in the front of the engine, near the pulleys, that acts as the phaser....I mean, its just a spherical disc or gear with teeth/grooves that makes this happen. Now, is the electronic system that runs this tied into the engine management system such that, if this thing were to start acting goofy, it has a fail-safe, limp-home mode where the engine still functions as it needs to but the valve lift falls back to a "baseline" as in an engine that did not have this?

I understand the concept. I just don't understand what mechanical items make the valve lift duration change?

Is it really that necessary for improved performance and efficiency? Driving Chevy products with pre-VVT engines and post-VVT engines, I can't tell THAT much difference.

[siegen]

Neither cam phasing nor this possible A-VTEC system vary duration as can be done with a different cam profile.

No, that is the idea of this system, to vary duration and lift continuously, and not in steps.

[trinacriabob]

I think that about 75% of today's "progress" is just needless

complication and B.S. that only results in more repairs and

headaches while emptying out our wallets.

I tend to agree, Pantho. Absolutely. The gains are minor incremental strides. The repairs and diagnostics will make things way more expensive. My 1992 Buick is approaching 234,000 miles. It has basic sequential fuel injection and the OBD-I engine management system. In almost 15 years, I have replaced 2 O2 sensors and 1 MAF sensor. I currently have the SES light on and Kragen read a code which isn't even a sensor...plug wires or a faulty coil. Inside, beyond PS and PB, I have no other power accessories but I spent on nicer accessories (console, gauges, alloys) that aren't that complicated in nature.

Why do you think I'm holding off on the new car when mine runs ok and is still so comfortable and quiet? And why do you even think all the cars I am considering are, relative to what's on the market, not that complicated?

I will buy one more new car that is familiar. I think that, by the time beyond that at which I buy again, the technology and types of vehicles out there will be VERY different and more efficient.