THX723

iTrader: (3)

VQ37VHR, the new designation for Nissan's naturally aspirated 3.7L VQ.

This time they are back on the variable valve lift bandwagon with VVEL (Variable Valve Event and Lift). Some may recall the now defunct VVL system, a virtual VTEC copy, that enabled the SR16VE to generate ~108hp/L (or an astounding 128hp/L for the N1 version), but have since gone the wayside. The new system works nearly identical to BMW's Valvetronic setup, only faster and more efficient according to Nissan. I'm very glad to finally see such an incorporation in Nissan's arsenal. It will only be a matter of time before VVEL is also implemented on the exhaust side (currently only adopted on the intake valves).

While I love the relatively fat low-mid power of the VQ, the top end has always left A LOT more to be desired. On the track, past VQs are simply uninspiring. I expect the VHR to be a lot better in that respect.

vasqo

^nice info! Thanks!

MIAPLAYA

iTrader: (3)

Wow no kidding. That's going to be interesting. I smell Skyline in the future of that motor..

Trav4011

iTrader: (2)

Well, I got some scoop on the valvetrain design.. apparently, the engine still has 4 camshafts.. but, they're not designed with lift/duration in mind.. in other words.. the camshaft is designed just as another "link in the chain" so to speak.. Between the cam lobe and the lifter bucket.. there's a jackshaft, and 2 wiper pads.. the jackshaft has a progressive profile cut onto it for each cylinder.. On one end, the profile starts at 1mm lift and something like 50-60 degrees of duration.. On the big end, the shaft has something like 11mm lift and 290-300 degrees of duration.. the shaft turns approximately 270 degrees back and forth.. So, if you set the jack shaft to the small end, at 0 degrees, you get 1mm lift and 50-60 degrees of duration.. this would be the engine at idle.. if you want to increase engine speed/power, you turn the jackshaft (operates like a worm gear) using an electric motor on the front timing cover.. as the shaft spins towards 270 degrees, the valve lift and duration increases.. eventually getting to the full 11mm lift and around 290-300 degrees of duration. The cam is still there to tell the valve to open.. but, the jackshaft is what tells it how much to open and for how long.. This eliminates the need for a throttle plate, because at 1mm lift and very little duration.. the engine barely runs.. which is interpreted as "idle".. Atomization on cold start is dramatically improved as well.. because the velocity of the fuel/air entering the cylinder goes way up as it passes through the 1mm opening between the valve/valve seat. By increasing the velocity and "squishing" the fuel.. you get much better atomization, and less unburned fuel on cold start. There is still a throttle plate in the system, but, it's only used for emissions and a failsafe, in case something fails in the VVEL system.


There's a small pic showing the basic design..


There's a pic showing the difference in fuel atomization between the VQ35DE and VQ37HR with VVEL

Travis

Trav4011

iTrader: (2)

So, now, the big question is.. do you grind new jackshafts.. or new camshafts to get more lift/duration?

michaeljr6

iTrader: (14)

nothing can beat the K20

Trav4011

iTrader: (2)

K-what? lol..

michaeljr6

iTrader: (14)

the engine in the RSX......



fyi god made it

NickRaine78

iTrader: (4)

Its a combo meal @ KFC

Resolute

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One of my ME designs in college was to use an electric solenoid to control the valve. This offered infinately variable lift and duration, and eliminated the camshaft and throttle plate. In theory, an electrical current run through the wire would open or close the valve, the amount of the current determined how strong the field was and could open the valve a little or a lot. It was a sweet design that worked for very low rpm and soft spring seats. The concept of having a system that did not rely on a mechanical means to open the valve was the real goal, since it eliminated a huge source of friction, parasitic loss, and offerred awesome potential for emissions and power. It seems Nissan has worked to a similiar means using hydraulic measures rather than electrical. I'm very curious to see this engine come out, and in what applications.
Will
EDIT: nope, I just read it again and I see that they are using an electric motor to turn the jack shaft. My first thought would have been hydraulic, but I guess the motor allows more flexibility in tuning. Either way, the variability sounds great, and the lack of large lobes on the cam should cut friction quite a bit, not to mention reduce the rotating mass. With an electric motor driving the jackshaft, this means we won't have to swap cams at all most likely, just reprogram the motor turn the jackshafts earlier in the rpm band for more lift and duration. If we really needed to make more lift than the jackshaft provides, I guess we'll have to see which is easier to replace- the cam or the jackshaft.

THX723

iTrader: (3)

Travis,
Thanks for sharing. I also dug a little deeper after getting home last night and found the details at at Nissan's Global site, except yours in Japanese?
What would one do without Googles these days.

Other interesting Nissan technologies can be found here:
http://www.nissan-global.com/EN/TECH...EST/index.html


VVEL details here:
http://www.nissan-global.com/EN/TECH...VEL/index.html




As mentioned before, VEL works very similar in concept to BMW's Valvetronic system, but obviously not identical. Nissan's implementation has a more direct actuation and alledgedly faster and more efficient than's BMW's. Both systems have complete control over valve lift and thus gone away with conventional butterfly throttle body, other than for emission compliance as well as a fail-safe feature.

What's not clear to me is if the VHR also has VTC working in tadem for valve timing/phasing control, much like BMW's implementation of Valveronic + VANOS. Honda's i-VTEC, also pairs the conventional VTEC system with their VTC equivalence.

Trav4011

iTrader: (2)

Apparently you missed the sarcasm..

THX723

iTrader: (3)

Resolute,
BMW has been in development of the solenoid acutated valvetrain for as long as I remembered. Their goal was to be the first with a production camless engine with a target date of 2003 (last I checked). To say they've missed that mark is an under statement. Mercedes also claimed they have such a system in development for some time, but I have not heard much of it as of late.

The added complexity and reliability issues have plague the implementation of solenoid driven valve trains ... for now. It would be neat to see such a system for production engines one of these days.

Trav4011

iTrader: (2)

This engine is supposed to have CVTC as well..

I know the limit on the "jack shaft" as we are calling it, is 11mm lift.. not 100% on the duration, but I was told that the stock setup will be between 290 and 300 degrees. That's a pretty good bit..

The question is.. who will crack the ECU open first.. One company has a head start already, from what I hear.. Must be nice to know people "inside".

Trav4011

iTrader: (2)

Yup.. I think BMW has been working on the idea for almost 10 years.. apparently, it's tough to build a reliable setup that will stand up to long term/high RPM use.

THX723

iTrader: (3)

Indeed the K20 is a nice piece. But Honda needs to get their ***** together and port the full DOHC i-VTEC system to their larger displacement V6 family!

At the end of the day the K20 is too small for big time use. There's not going to be TL 2.0 anytime soon.

diwun67

iTrader: (13)

No matter what, RSX will ALWAYS be faster.


Glad to see VVEL making a comeback, under a new moniker nonetheless

singh

iTrader: (2)

Sarcasm > You

shushikiary

^^ YES, I was about to say something similar about silenoids... the temperature in the motor is bad for solid magnets and will cause their field strength to reduce with time, causing the motion moved for the current supplied to change drastically. And solid magnets tend to be brittle and I dont think they would enjoy the type of impulse forces the valve train encounters. Not to mention that silenoids tend to use alot of current, and have a very non-linear response curve for motion to current applied (well most do). Taht's why you usually only see silenoids in designs where they are either all the way in or out, not inbetween (all though they do make linear magnetic motors, but they are expensive!) Using a series wound silenoid to get rid of the solid magnet would cause even more current and heat issues, so you cant really do that either.... I'm sure someday they will figure out a way to make it work though.

I think the methodology they have going in this new VVEL system looks like a good design to me (but then again I'm a EE and not an ME), seems like the engineers are doing their jobs.

Resolute

iTrader: (2)

Yeah, I know the technology wasn't original. Although I was very dissapointed when I learned that, because I thought- just for a short while- that I was freaking brilliant for having the idea. But, my kinematics professor said it would work as a senior project in tandem with another project being done by the school, and put in the reccomendation. There is a university in the UK, I forget the name, that has been doing extensive research on the idea and he put me in touch with an instructor over there for some data. We used a series wound set-up but the moment of inertia was too great to overcome at high rpm. The fast operation afforded to injectors just wasn't going to be possible on a larger scale due to the mass involved. Using a ferrous alloy as an implant in a composite body for the valve was the best way to lighten the valve enough to operate at any decent rpm with a realistic power load. Still a great idea, and as metallurgy and generator efficiency continues to improve, we might still see the idea come to production for gasoline engines.
Will