VQ37HR VVEL discussion..
03-22-2007, 12:19 PM
#1
VQ37HR VVEL discussion..
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 "chain in the link" 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.
Travis
Travis
03-22-2007, 03:41 PM
#8
Unfortunately, no.. but I do have one in English now.. 
I'm hoping that this technology gets adapted to FWD VQ's.. and eventually trickle down to 4 cylinder Nissan engines as well..
I'm hoping that this technology gets adapted to FWD VQ's.. and eventually trickle down to 4 cylinder Nissan engines as well..
03-24-2007, 08:26 AM
#11
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Originally Posted by SR20DEN
They're still being conservative with it. This is the kind of technology that gets you 100+ hp/l. I hope they get more aggressive with it in the near future.
I cant wait to see these 3.7L's in action....
~Alex
03-24-2007, 08:42 AM
#12
Originally Posted by TurboS13Hatch
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, this second picture shows the valve set differeces between high loads and low loads on VQ37HR with VVEL. Both valve sets in the picture are about the VVEL itself. The left side valve set is about the modified lift at wide open throttle (high load), and the valve on the right is the lift at part throttle (low load). This is about using the valves to further atomize the fuel particle size.
On high loads, valve lift is lower to squeeze out smaller fuel particles, 2-mm lift gives 9-micrometer average fuel size.
On low loads, 8-mm lift gives 157-micrometer (relatively larger) average fuel size.
The two works at set values that are continuously optimized according to loads and conditions. VVEL gives every opportunity to optimize duration and (minimal) lift dynamics to give better fuel atomization at all times. This picture only explains the atomization part on lower rpm bands. The higher bands are different because fuel atomization is actually compromised when air flow increases by higher lift and longer duration.
-Peter-
04-01-2007, 06:35 AM
#13
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http://www.nissansportmag.com/newsno...echnology.html
quoted from my350z.com, thought it was good info.
More pictures.
http://www.worldcarfans.com/news.cfm...lve-technology
quoted from my350z.com, thought it was good info.
Nissan's new VVEL system is a completely different beast from their legacy VVL system. The two are not even in the same zipcode. BMW's Valvtronic is the only other system in the market that operates with the same concept in mind.
It's probably good I quickly summarize the different types of existing variable valve systems.
Type 1
- Nissan VTC/CVTC/EVTC
- BMW VANOS
- Toyota VVT-i
- Porsche Variocam
These systems work like adjustable cam sprockets, which allow advancement or retardation of camshaft timing/phasing and subsquently the valve timing/phasing. The re's the ability to alter settings in real-time and via infinite steps over a set range. Valve lift cannot be altered with these systems.
Type 2
- Honda VTEC
- Toyota VVTL-i
- Nissan VVL
- Mitsubishi MIVEC
These systems have the ability to switch between two (three in the case of MIVEC) cam profiles that are optimzed for different conditions. It is therefore possible to alter between discrete sets of valve lift and timing/phasing that are built into each of the available cams profiles. Discrete means the settings are not infinitely variable.
Type 3
- Honda i-VTEC
- Porsche Variocam Plus
This system is litterally the combination of Type 1 and Type 2 systems. Valve timing/phasing is infinitely variable, while valve lift remains one of the two fixed settings (a confine of Type 2 system).
Type 4
- Nissan VVEL
- BMW Valvetronic
These systems have continuous variable control over valve lift (from a mere crack to full stroke open), making standard butterfly throttlebody a virtual obsolescence. When coupled with their respective Type 1 systems they also gain continuous variable valve timing/phasing capability. These are the next generation control systems with FULL ABSOLUTE control over valve activities. Aftermarket camshafts will be all but unecessary because virtually any cam profile can be replicated via simple alteration of two ECU tables.
It's probably good I quickly summarize the different types of existing variable valve systems.
Type 1
- Nissan VTC/CVTC/EVTC
- BMW VANOS
- Toyota VVT-i
- Porsche Variocam
These systems work like adjustable cam sprockets, which allow advancement or retardation of camshaft timing/phasing and subsquently the valve timing/phasing. The re's the ability to alter settings in real-time and via infinite steps over a set range. Valve lift cannot be altered with these systems.
Type 2
- Honda VTEC
- Toyota VVTL-i
- Nissan VVL
- Mitsubishi MIVEC
These systems have the ability to switch between two (three in the case of MIVEC) cam profiles that are optimzed for different conditions. It is therefore possible to alter between discrete sets of valve lift and timing/phasing that are built into each of the available cams profiles. Discrete means the settings are not infinitely variable.
Type 3
- Honda i-VTEC
- Porsche Variocam Plus
This system is litterally the combination of Type 1 and Type 2 systems. Valve timing/phasing is infinitely variable, while valve lift remains one of the two fixed settings (a confine of Type 2 system).
Type 4
- Nissan VVEL
- BMW Valvetronic
These systems have continuous variable control over valve lift (from a mere crack to full stroke open), making standard butterfly throttlebody a virtual obsolescence. When coupled with their respective Type 1 systems they also gain continuous variable valve timing/phasing capability. These are the next generation control systems with FULL ABSOLUTE control over valve activities. Aftermarket camshafts will be all but unecessary because virtually any cam profile can be replicated via simple alteration of two ECU tables.
More pictures.
http://www.worldcarfans.com/news.cfm...lve-technology
04-01-2007, 07:30 AM
#14
I haven't seen anyone point out that the exhaust is back to type 0. There is no VVEL, nor CVTC control on the exhaust cam.
Now we just wait and see what kind of power can be squeezed out of a NA application from Technosquare. We may as well badge these things the software cams, or eCams (like eGas, a name which i hate).
Now we just wait and see what kind of power can be squeezed out of a NA application from Technosquare. We may as well badge these things the software cams, or eCams (like eGas, a name which i hate).
04-01-2007, 08:29 AM
#15
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Originally Posted by SR20DEN
I haven't seen anyone point out that the exhaust is back to type 0. There is no VVEL, nor CVTC control on the exhaust cam.
Now we just wait and see what kind of power can be squeezed out of a NA application from Technosquare. We may as well badge these things the software cams, or eCams (like eGas, a name which i hate).
Now we just wait and see what kind of power can be squeezed out of a NA application from Technosquare. We may as well badge these things the software cams, or eCams (like eGas, a name which i hate).
Originally Posted by LA02MAX
And just to make sure, this is only for the intake valves, correct? What is used to control the exhaust valves? VVEL, VVT, or just the conventional non-variable cams?
I was wondering about that. A little disappointed they decided not to use CVTC but I guess that's just one more thing they can upgrade in the future (hopefully along with Direct Injection)
04-03-2007, 10:57 AM
#16
I'm having trouble seeing how this works. What does the camshaft act on? Where is the camshaft?
This system will probably enable 100HP/L outputs with flat torque curves. This is about as far as the camshaft valvetrain will go. It's great because now we can use cam profiles as wild as we want while maintaining driveability. The only thing is now tuning involves a 3rd dimension... lift (aside from timing and fuel)...
Good stuff. I'm not sure how well this system compares to Honda's A-VTEC system though. That has both built in timing and lift (again only on the intake side).
This system will probably enable 100HP/L outputs with flat torque curves. This is about as far as the camshaft valvetrain will go. It's great because now we can use cam profiles as wild as we want while maintaining driveability. The only thing is now tuning involves a 3rd dimension... lift (aside from timing and fuel)...
Good stuff. I'm not sure how well this system compares to Honda's A-VTEC system though. That has both built in timing and lift (again only on the intake side).
07-23-2007, 04:35 PM
#18
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Originally Posted by skuccio's max
Still confused as to how it all works... what's what, etc...
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