Mazda 6 Forums banner

1 - 9 of 9 Posts

·
Registered
Joined
·
163 Posts
Discussion Starter #1
Mazda lost its way during the mid-1990s. Now it's back!

Visually, Mazda6 get off to a good start - sleek and modern in design.

Went over to a launch last month in Singapore.Open the doors and is immediately struck by the build quality. The doors close with a nice thud.

Spacious cabin, good dynamics, general reinement and desirable.

Minus : Mazda's 2.0-Litre I-4 engine noise on full throttle.

Hoping for the 2.3l version to come and only next year.
 

·
Premium Member
Joined
·
5,097 Posts
Replying to Topic 'SIX Appeal. Striking new direction'

Agree.

The noise you describe is there on purpose. It's supposed to add a sporty touch. In higher speeds, that noise disappears...

I find it appealing to hear the sound of the engine, at least a bit. The noise isn't so loud it's disturbing. At least not under the hour or two I was out driving. On the other hand, I tested the 2.3l version...
 

·
Registered
Joined
·
163 Posts
Discussion Starter #3
Replying to Topic 'SIX Appeal. Striking new direction'

How's the 2.3L version? It's reportedly a more sophisticated and smoother powerplant compare to the 2.0L version.
 

·
Premium Member
Joined
·
5,097 Posts
Replying to Topic 'SIX Appeal. Striking new direction'

QUOTE
Originally posted by jon


            How's the 2.3L version? It's reportedly a more sophisticated and smoother powerplant compare to the 2.0L version.[/b]
It's great. Willing, strong, explosive...the lot. And it sounds like a sports car engine also, but not too loud.

Can't tell what's the difference between that and the 1.8 or 2.0 besides volume and power (and some technical differences in the engine).
 

·
Registered
Joined
·
1,216 Posts
Replying to Topic 'SIX Appeal. Striking new direction'

I think those technical differences (balance shafts and cam profile) give the 2.3 that added character. Because the 2.3 is the premium engine for many markets, I think they went to a lot of trouble to make it the sportiest possible. Besides that they will be using it in the MPS 6 as well.
 

·
Premium Member
Joined
·
5,097 Posts
Replying to Topic 'SIX Appeal. Striking new direction'

QUOTE
Originally posted by kenoka


            I think those technical differences (balance shafts and cam profile) give the 2.3 that added character.  Because the 2.3 is the premium engine for many markets, I think they went to a lot of trouble to make it the sportiest possible.  Besides that they will be using it in the MPS 6 as well.[/b]
True. But most people think that the 1.8 and 2.0 lacks balance shafts. Wrong. But the 2.3l engine got 12 weights on their shafts while the other models got only six.

The cam profile, however, is more refined. But in recent tests I've read in swedish magazines, it turns out that even the 1.8 engine almost matches the 2.3 in acceleration and attitude. This at higher rpm:s though...what you can't have with the engine, the gearbox can fix...
 

·
Registered
Joined
·
1,216 Posts
Replying to Topic 'SIX Appeal. Striking new direction'

From the CarsEverything article:

I love this article. I think this is like the tenth time I've quoted it. Have you guys all read the whole thing? It's about 30 pages long and a rather tough read, but well worth it for the wealth of technical detail. Anyway back to the balance shaft issue:
QUOTE
Mazda's use of S-VT and balance shaft in the 2.3-liter version of the company's new family of 4-cylinder engines provides the Mazda 6 an extra level of refinement and another level of NVH reduction.[/b]
Steve, if you'll note, they imply the balance shaft and S-VT only belong to the 2.3. We know that the S-VT is definitely only offered on the 2.3, therefore I conclude that the balance shaft is also only offered on the 2.3. I think you're confusing the balance shaft with the crank shaft:
QUOTE
Weight savings were obtained using a nodular cast iron crankshaft that requires only four counterweights for the 1.8-liter and 2.0-liter. The 2.3-liter engine has eight counterweights because of its larger displacement.[/b]
The balance shaft is located under the crankshaft, and spins in the opposite direction.
Actually, as an exercise I'm going to list all the features unique to the 2.3:
1. S-VT (variable valve timing)
2. Balance Shaft
3. Variable induction nylon intake manifold with equal length runners
4. swirl control valves (tumble flaps) in the intake manifold
5. Cold air intake and resonator
6. Organ pipes to feed back sporty sound to driver under high load conditions
7. Stainless steel exhaust manifold
8. Catalytic converter located under the floor
9. Stainless steel exhaust system, tuned for sporty sound
10. New engine management control module

These are all the things listed under the 2.3 liter section. Wow! It's quite a list. Much of this list looks like things you would normally do to a car in the aftermarket to open up its breathing and such. I wonder how much "tuning" potential this car will have with the usual bolt ons given that so much has been done already.

Here's the relevant portion of the article in its entirety (sorry for the length):

QUOTE
High Technology 2.3-liter Engine
Among the key objectives for the new 2.3-liter engine was achieving more torque, horsepower and smoothness, while delivering improved fuel economy, lower emissions and minimal maintenance requirements. The new engine hits all of these marks, thanks to the use of lightweight aluminum, innovative engineering, such as the use of S-VT, balance shaft and a keen attention to detail.

Mazda's S-VT allows the point at which the engine's valves open and close and the duration they stay open to change with operating conditions, such as engine speed and air volume. Varying these parameters allows the engine to operate more efficiently at all engine speeds while maintaining drivability, improving power, fuel economy and emissions. Traditionally, camshafts open and close intake and exhaust valves at fixed points in the engine cycle, regardless of engine speed or air volume.

Located under the crankshaft, the balance shaft minimizes vibration by rotating at twice the speed of the crankshaft and offsetting the secondary inertia force of the rotating system. The balance shaft is fitted in its own housing and attached to the cylinder block for optimum positioning. It is driven by a gear to reduce drive losses.  

Meanwhile, variable valve timing delivers more torque and more power than a conventional engine.

To achieve the aggressive targets on improving torque, horsepower and smoothness, Mazda engineers focused on several other areas, as well. First was developing a new intake manifold. Using an array of powerful computer aided engineering (CAE) tools to compare various designs and options, engineers developed a sophisticated new friction-welded nylon intake manifold with equal length runners that incorporate new devices called swirl control valves. Mazda engineers fitted these specially designed control valves into each of the intake runners, close to the cylinder head flange.  

These valves or "tumble flaps" in the variable induction system are controlled by a solenoid actuator and are closed during light-load operations, such as idling at traffic lights, shifting actions and deceleration, to maximize combustion efficiency, fuel economy and emissions performance.  

The valves are fully open during higher load conditions, roughly 5,000 rpm, to maximize volumetric efficiency and power output.  

The intake manifold is constructed of part-recycled material. Its design improved engine sound quality by emphasizing the even-order engine harmonics - a key to the equal length design.

This innovative intake manifold design is further enhanced by the careful design of the air cleaner system. Mazda's air cleaner does more than simply clean the air. The system features a performance-tuned, bell-mounted, cold-air pickup duct at the very front of the vehicle, a large noise, vibration and harshness-tuned resonator in the wheel-arch and "organ pipes" designed to selectively feed back sporty sound to the driver under high throttle conditions.

To enhance fuel economy and reduce NOx emissions even further, Mazda engineers developed a water-cooled, electronically operated exhaust-gas recirculation (EGR) system. The EGR valve, actuated by a stepping motor, precisely redirects exhaust gas to the intake side of the engine, where it is inducted into the intake manifold through a short duct. The EGR passage is cast into the cylinder head.  

To reduce engine back-pressure and to ensure quick catalyst warm-up efficiency with the 2.3-liter, Mazda uses a fabricated stainless steel exhaust manifold design of welded tubes. Unlike a conventional cast iron constructed exhaust manifold, the stainless steel exhaust manifold delivers low-heat retention in normal operation. A typical 4-cylinder exhaust manifold funnels into a single pipe and then into the catalyst.

In the Mazda design, a heat-insulating layer surrounds the portion where the four runners meet and a divider plate is located longitudinally in the exhaust pipe. This arrangement combines the heat retention benefits of a single pipe structure with the engine performance benefits of a dual-pipe structure. This concept of heat management allowed Mazda to simplify the rest of the exhaust system and eliminate the need for a close-coupled catalyst.

Eliminating the close-coupled catalyst and locating it under the floor, reduces engine back pressure, helping improve real-world performance and high speed fuel economy.  

High quality stainless steel materials also were used for the extended service life of the muffler system, which has been tuned for a sporty sound quality under high-load driving conditions.

The engine and exhaust systems of all Mazda 6 variants - critical for keeping emissions low - are continuously monitored by a so-called onboard diagnostic system. The system uses a control lamp in the instrument cluster to warn the driver ("Check Engine") of a fault affecting a component relevant to pollutant emissions.

The 2.3-liter in the Mazda 6 also marks the appearance of a new engine management computer module. At its heart is a microprocessor, incorporating logic by Mazda. The system works through a CAN-bus to the chassis controls for intelligent vehicle dynamics features such as anti-lock braking and traction control. With the speed and capacity of this advanced computer chip, Mazda engineers were given the ability to fine tune the engine's performance with more extensive and sophisticated algorithms developed with the use of state-of-the-art, real-time simulation tools.  

One of the side benefits of this new system is that some of the complexity of the control system required for optimal fuel economy and emissions could be simplified.

To simulate real world environments, Mazda engineers made extensive use of transient powertrain dynamometers that could be operated under extreme hot and cold conditions. These engine test facilities helped engineers simulate real world environments ranging from Artic cold to Saharan heat.  

Mazda's engine development center in Hiroshima, played a leading role in this climate-controlled testing.

Lightweight Aluminum Construction  

Mazda's 1.8-liter, 2.0-liter and 2.3-liter engines are made of a lightweight all-aluminum alloy construction that helps deliver superior performance and fuel economy.

Each 4-cylinder begins life as a precision gravity sand-cast cylinder block of high-grade aluminum alloy with cast-iron cylinder sleeves cast directly into the block. This closed-deck, deep-skirt cylinder block ensures a tight seal between the cylinder block and cylinder head. An aluminum alloy, ribbed ladder-frame structure, which carries the bottom bearing braces, mates to the cylinder block for optimized stiffness. But engineers didn't stop there. As the oil pan has a significant influence on joint rigidity between the cylinder block and transmission and can minimize vibration from the engine and transmission to the body, a ribbed aluminum oil pan was developed to complement stiffness properties and contribute to quiet operation.

Weight savings were obtained using a nodular cast iron crankshaft that requires only four counterweights for the 1.8-liter and 2.0-liter. The 2.3-liter engine has eight counterweights because of its larger displacement. Low friction-coated, lightweight alloy pistons with sinter-forged connecting rods for dimensional accuracy and fraction-split ends are used for a precision fit that enhances reliability and reduces noise and vibration.

Cylinder head construction is of aluminum-silicon alloy - thermally treated for strength and durability after the casting process - with an asymmetrical, four-valves-per-cylinder design. Two inlet valves (32.5-mm for the 1.8-liter; 35 mm for the 2.0-liter and 2.3-liter) are positioned at 19 degrees, and the two exhaust valves (28 mm and 30 mm, respectively) are positioned at 20 degrees. The compression ratio for the family of 4-cylinder engines varies from 9.7 to 10.8 depending on displacement and market.  

The double overhead cams are driven by a hydraulically-tensioned silent chain drive, actuating the valves via mechanical tappets. Unlike previous-generation Mazda engines, the tappets are precision-fit during assembly and require no shimming. The intake and exhaust valves are nitrogen treated for durability.

Displacement variations for Mazda's new family of engines are achieved by increasing bore size (87.5 mm for the 2.0-liter versus 83.0 mm for the 1.8-liter) while keeping the common stroke length of 83.1 mm for the 2.0-liter and 1.8-liter. The stroke for the 2.3-liter with S-VT is 94 mm.

Smooth, Refined Operation

Mazda's use of S-VT and balance shaft in the 2.3-liter version of the company's new family of 4-cylinder engines provides the Mazda 6 an extra level of refinement and another level of NVH reduction.  

The result is smooth, quiet operation even during spirited driving.

All 4-cylinder offerings in the Mazda 6 are mounted via a three-point torque-roll access management engine mount system. This Mazda mounting system supports the engine with two load-bearing mounts along its roll axis, one of which incorporates a hydraulic damping element to reduce powertrain shake on rough roads and reduce transmitted vibrations. A third bushed link - mounted from the transmission case to the subframe - provides rigid resistance to torque. Mazda's philosophy of separating the two primary forces on the engine mounting system leads to a reduction in powertrain vibration and harshness.[/b]
 

·
Premium Member
Joined
·
5,097 Posts
Replying to Topic 'SIX Appeal. Striking new direction'

Kenoka,

I have read that LOOONG text - over and over again. It was in fact one of the first really good descriptions I ever read on the 6.

No, I am not mixing up the crankshaft with the balance shaft. In fact, the information I provided comes from another, usually very reliable source.

The swedish cartest magazine "Teknikens Värld" (Technical world) has in its latest issue a thorough description of the 6.

I quote: "Teknikens Värld has tested the most powerful of the fourbangers. It is a completely new design with large volume: 2.3 liters. To decrease vibration, the engine is equipped with balance shafts working opposite to the crankshaft, a technical solution earlier adopted by among others Misubishi, Porsche and Volvo.

Even the smaller engines of Mazda6 - the 1.8 and 2.0 liter respecively - has balance shafts. But these use four balance weights while the 2.3 liter has eight. Another detail that differs the 2.3 liter engine from the others is the seqential valve timing."

I never had the chance to crank an engine of a 6 open (and experience from Mazda engineering tells me I never will); so I can't know this for sure.

But there you are.

/Steve
 
1 - 9 of 9 Posts
Top