Infiniti World Takeover continues with steer-by-wire

[GoCougs]

N55 uses Valvetronic, so yeah, its complexity is a superset of the VQ's.

And turbo lol...

[hotrodalex]

Since when does nobody care about MPG? I can see the argument for weight, but MPG is a large driver for new car purchases with $4-5/gallon gas.

AWD on a sports sedan is just wrong, btw.

[SVT666]

You've obviously never driven one.   I didn't want the AWD but when I drove it I was pretty blown away.

[850CSi]

Since when does nobody care about MPG? I can see the argument for weight, but MPG is a large driver for new car purchases with $4-5/gallon gas.

AWD on a sports sedan is just wrong, btw.

Weight is a primary concern for me. It's a large part of what I find wrong with so many new cars. And like you said, MPG is important as well.

As for AWD... to each his own, but I don't think I'd trade RWD for AWD EVAR, having owned one AWD car and one RWD car.

[MX793]

N55 uses Valvetronic, so yeah, its complexity is a superset of the VQ's.

Nissan's VVEL system in the VQ37HR is very, very similarly to Valvetronic.

[GoCougs]

Nissan's VVEL system in the VQ37HR is very, very similarly to Valvetronic.

Not overly similar; Valvetronic has additional tech (both mechanical and electronic) to use the intake valve as the throttle.

[MX793]

Not overly similar; Valvetronic has additional tech (both mechanical and electronic) to use the intake valve as the throttle.

VVEL uses a DC motor driving an eccentric shaft to shift the fulcrum point of the valve rocker arms, just like Valvetronic, to continuously vary the lift of the valves.  The biggest difference is that Nissan's system is desmodromic, so it can support higher revs than Valvetronic can.

As to the throttle control via the valves, Nissan's system could in theory do the same.  The range of valve lift variability is limited only by the profile of the eccentric shaft, meaning that with the correct profile you could shift the rocker fulcrum enough that the valves stop opening.  In practice it greatly reduces the role of the throttle valve, though does not outright eliminate it.  IIRC, Valvetronic BMWs still have a throttle as well, despite the fact that Valvetronic makes it redundant.

[Eye of the Tiger]

VVEL uses a DC motor driving an eccentric shaft to shift the fulcrum point of the valve rocker arms, just like Valvetronic, to continuously vary the lift of the valves.  The biggest difference is that Nissan's system is desmodromic, so it can support higher revs than Valvetronic can.

As to the throttle control via the valves, Nissan's system could in theory do the same.  The range of valve lift variability is limited only by the profile of the eccentric shaft, meaning that with the correct profile you could shift the rocker fulcrum enough that the valves stop opening.  In practice it greatly reduces the role of the throttle valve, though does not outright eliminate it.  IIRC, Valvetronic BMWs still have a throttle as well, despite the fact that Valvetronic makes it redundant.

I love desmodromic. I had no idea Nissan was into that.

[MX793]

I love desmodromic. I had no idea Nissan was into that.

The valves are not desmodromic, the cam follower (or its analog in the VVEL system) is.

[GoCougs]

VVEL uses a DC motor driving an eccentric shaft to shift the fulcrum point of the valve rocker arms, just like Valvetronic, to continuously vary the lift of the valves.  The biggest difference is that Nissan's system is desmodromic, so it can support higher revs than Valvetronic can.

As to the throttle control via the valves, Nissan's system could in theory do the same.  The range of valve lift variability is limited only by the profile of the eccentric shaft, meaning that with the correct profile you could shift the rocker fulcrum enough that the valves stop opening.  In practice it greatly reduces the role of the throttle valve, though does not outright eliminate it.  IIRC, Valvetronic BMWs still have a throttle as well, despite the fact that Valvetronic makes it redundant.

Valvetronic uses two separate cams and two rocker arms per intake valve. VVEL uses a fulcrum adjusting single cam and two rocker arms per intake valve. The systems aren't overly similar. Also, VVEL is not desmodromic - still uses valve springs to return the valve to its seat.

[MX793]

Valvetronic uses two separate cams and two rocker arms per intake valve. VVEL uses a fulcrum adjusting single cam and two rocker arms per intake valve. The systems aren't overly similar. Also, VVEL is not desmodromic - still uses valve springs to return the valve to its seat.

As I already stated, the cam follower is desmodromic, not the valve.

The principle of varying the valve rocker fulcrum via an electrically driven eccentric shaft is the same between the two.  The rest of the mechanism is obviously different.  From a complexity standpoint, they are pretty comparable.

Valvetronic has the regular camshaft, the eccentric/cam shaft that is actuated by an electric motor to shift the rocker fulcrum, the variable rocker and the actual valve rocker.



VVEL has the camshaft, Link A (desmodromic to the cam), the electric motor actuated eccentric shaft, the variable rocker (resides on the eccentric shaft), Link B, and the Rocker B which actually acts on the valve. 




Nissan does double up the intake valves so there's only one set of links/rockers per cylinder whereas BMW has a variable rocker on every valve, but Nissan's system has some extra pieces so in the end, their complexity is very similar.

[Laconian]

My point was that Sporty said VVEL was scarier than a turbo, and BMW uses both.

I think this thread is hilarious now.

[Morris Minor]

If they could do away with mechanical steering linkages, they wouldn't need steering wheels.

[MX793]

If they could do away with mechanical steering linkages, they wouldn't need steering wheels.

Ah, the Prometheus project.  I remember seeing that car on a television segment on a show on the Discover Channel (it might have been on "Beyond 2000" or "Beyond Tomorrow") many years ago.

[hotrodalex]

You've obviously never driven one.   I didn't want the AWD but when I drove it I was pretty blown away.

What's so great about it? Adds more weight and doesn't it also raise the ride height a little bit? (not sure on that bit)

I know BMW's AWD system isn't the enthusiast option. Infiniti's seems better, but I still don't see how it's better than RWD unless you're constantly driving in bad weather.

I would tolerate AWD in an Audi just because they're FWD otherwise.

Weight is a primary concern for me. It's a large part of what I find wrong with so many new cars. And like you said, MPG is important as well.

Weight is one of the top priorities for me as well, but I don't think the average customer cares about or notices extra weight, so that's why I said it might not matter as much.

[Laconian]

A majority of BMWs sold in the PNW bear the dreaded "x".

Same with Infiniti G sedans, too.

People suck.

[SVT666]

What's so great about it? Adds more weight and doesn't it also raise the ride height a little bit? (not sure on that bit)

Ride height is not increased.  It's a really good system.  Barely noticeable at all since the it's only in AWD if there is slippage detected, otherwise it operates as RWD.  Unfortunately, in Canada we can only buy the "x" anyway.  We don't get RWD G37's unless you get the M6 (virtually impossible to find) or you go to the US to buy the car (cheaper to buy in Canada surprisingly).  It's certainly not better than straight RWD, but it's probably the nicest AWD system I've ever driven.

[Raza]

A majority of BMWs sold in the PNW bear the dreaded "x".

Same with Infiniti G sedans, too.

People suck.

In the Northeast, Lexus dealers don't even stock RWD versions of cars that have AWD variants.  You have to go pretty far south to get a RWD version of an IS or GS.

[GoCougs]

Meh, AWD pwns all for performance-oriented street-driven DD, if it's done well (Infiniti ATTESA). The G37x outperforms the G37 in all objective handling measures including track times and suffice it to say that both handling and acceleration performance (and safety) advantages are ginormous in the wet is an understatement.

[Eye of the Tiger]

The valves are not desmodromic, the cam follower (or its analog in the VVEL system) is.

Boring!

[Laconian]

I am pretty sure my 4000lb car would have type 2 diabeetus if it also had AWD.

[GoCougs]

Boring!

IOW, not desmo.

[MX793]

IOW, not desmo.

I never said the valves were desmodromic, I said the VVL mechanism was desmodromic.  The assorted rocker linkages that make of the VVL system are positively actuated in both directions by the camshaft.  That is "desmodromic".

[TurboDan]

I have no idea which car I'd buy in that segment right now. I don't like turbos, but I just hate the way the G looks and how heavy it is. Not really a big fan of the VQ in general when I've driven it.

I'd probably get a used E90. Surprise!

Same here, for the same reasons. Although I'd test drive an ATS to see if I'd want to roll the dice.

[Laconian]

335 sedan curb weight: 3591
G37 sedan curb weight: 3628

The G37 is only 1.01% heavier than the 335.  You guys are pulling these arguments from places of emotion and not reason. A preference for BMW is fine but don't wantonly distort the facts.

[GoCougs]

I never said the valves were desmodromic, I said the VVL mechanism was desmodromic.  The assorted rocker linkages that make of the VVL system are positively actuated in both directions by the camshaft.  That is "desmodromic".

Doesn't count really; it can't be anything else. Desmodromic is only of note if it is an alternative (i.e., desmo valves vs. spring valves).

[GoCougs]

335 sedan curb weight: 3591
G37 sedan curb weight: 3628

The G37 is only 1.01% heavier than the 335.  You guys are pulling these arguments from places of emotion and not reason. A preference for BMW is fine but don't wantonly distort the facts.

335i sedan is 178.2" so at 3591 lbs = 20.2 lb/in.
G37 sedan is 187.9" so at 3628 lbs = 19.3 lb/in.

Thus, the 335i is denser by 4.4% (= heavier).

[850CSi]

335 sedan curb weight: 3591
G37 sedan curb weight: 3628

The G37 is only 1.01% heavier than the 335.  You guys are pulling these arguments from places of emotion and not reason. A preference for BMW is fine but don't wantonly distort the facts.

I'm speaking from my own perspective I guess - I've already said I wouldn't drive a new 3er due to the lack of NA engine options and the more vague steering. My car weighs <3300 lbs. That's an enormous difference.

[Lebowski]

335 sedan curb weight: 3591
G37 sedan curb weight: 3628

The G37 is only 1.01% heavier than the 335.  You guys are pulling these arguments from places of emotion and not reason. A preference for BMW is fine but don't wantonly distort the facts.

The fact remains the G's primary selling point is price. Nothing wrong with that, just not the stuff of world domination.

[SVT666]

It's more fun than the 3 series too.