Will VVEL position "stay" with no power?

Def

I'm thinking about starting a new project. It's a mid engine car built from scratch that utilizes a transverse drivetrain. I like Nissan powertrains, and would like to stay NA for this build, so a VQ37VHR seems ideal for this (weight vs. power vs. packaging). It will need some bits to adapt it to a Sentra SE-R Spec V transmission, but I think it's all doable given enough time and $$$.

Now onto questions. It seems the only "cheaper" ECU that can drive 2 DBW throttle bodies, the AEM Infinity 708, cannot do PID control of the VVEL motors on its own. I don't really want to go down the route of getting a stock ECU working without NATS, BCM etc., as paying someone to do that to the harness and then the honestly kinda weak tuning solutions for the stock ECU puts me over the price of a 708. Plus I don't really care about using VVEL to gain efficiency, I want it for crazy big intake cam opening. So I'll use the DBW throttles like "normal" with them being barely cracked for idle, and the VVEL lift being much higher than stock.

With that in mind, my idea to get it up and running is to move each VVEL bank to its "high lift" position and leave the power off the motors to start with. Will things stay where they are when doing this? I was thinking I could put a locking collar on the VVEL shaft if I want a bit more positive retention, so was hoping it'd stay put as is.

Later I'll probably try to control it via an Arduino, using outputs from the Infinity. I can essentially then have it be stepped with maybe ~220 deg duration around idle, going to a ~240-250 deg "mild" cam in the lower midrange, then going full wild somewhere above that.

But for now I just want to know if VVEL will lock with no power to the motors.


Or should I just go with a VQ35HR and some cams off the bat and deal with the lower displacement and compression?

SouthArk370Z

The FSM should have what you need to know.

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Def

???

It says nothing of unplugging the VVEL motors and then running the engine. Pretty sure that'd make a stock ECU Z34 freak out and then some.


And yes, I've looked through the FSM, and understand how the system works. I'm asking if the motor has enough holding torque while NOT POWERED UP to hold the VVEL shaft in the right location.

lj909

I don't think anyone knows that cuz I'm pretty sure it hasn't been done.

For all the headaches your going to have with a computer that doesn't control VVEL, if it was me, I'd ether go with a VQ35HR it's a great engine, or get in touch VitViper about buying one of his MOTec computers. It does everything.

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Jayhovah

Have you considered going with a VQ35 instead of the VQ37VHR? Very similar and without the VVEL to worry about, and a single throttle body to simplify your air plumbing and gain more ECU options (since you mentioned the need to drive two throttle bodies). Since you are staying NA, you could even go with a VQ35DE - which I'd imagine are far more plentiful and affordable compared to a 35HR or 37VHR.

Also, Ecutek on the stock ECU seems pretty powerful for tuning... but as you mentioned there might be additional complexities introduced by trying to keep the OEM ECU. You might talk to Ecutek to see if their software can make it easier to delete a lot of unnecessary things from the loop.

It has always been a dream of mine to take on a scratch built middy project exactly as you are planning to do. Will you be documenting your build anywhere? I am a long time lurker on the locostusa.com forums, and there are a lot of really knowledgeable people there with similar projects.

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Def

If I go with a VQ37VHR I'd eventually get some level of VVEL control. Probably moving it in a few discrete stages to simplify things, but it shouldn't be too hard since it's just a DC motor. I guess a mechanical lock wouldn't be too hard to fab up if it didn't stay in one place...

As for a VQ35DE - there are newer Maxima engines which are basically VQ35DE bottom ends with VQ35HR heads and a single DBW TB. They make decent power, but being a VQ35DE bottom end they don't like to rev very high, so even with replacing the rod bolts with ARPs and the oil pump with a Rev up (which combined costs like $400), it's probably pushing it to expect more than 7200-7400 RPM out of it for track usage.

Whereas a VQ37VHR can do 7.8-8k RPM right out of the box, and has more displacement... It'd be impossible to make the same power on the DE bottom end engine even though it can flow. It just can't do the revs needed.

That said, the FWD engine is more "bolt-in" and go with Nissan components, so less hassle to get it up and going. It just probably won't ever make more than about 310-320 rwhp. Which sounds impressive to you guys, but keep in mind that's going through a FWD transmission, so probably like a minor bolt-on VQ37VHR putting out maybe 290-300 rwhp.

Both engines are about the same cost as well...


As for the build, I'll definitely make a build thread on Midlana – Build a mid-engine Seven using a FWD drivetrain

Here's a pic of the builder's Midlana:



He used a turbo K24 Honda engine, but honestly, I've done the turbo 4 thing and would like to do a VQ. I'd really like to get curb weight below 1650 lbs wet. Not sure that's doable with the VQ, but I'll sure try...


Hmmm, I keep going back and forth on the FWD easy VQ route vs. harder RWD VQ route. I know the RWD VQ route has more power potential, and I definitely will not want to change things after the fact (engine mounts are in different locations for one!), but there are more unknowns and more work getting the RWD VQ to go.

Thanks for the responses guys. I was hoping that maybe I'd get lucky and someone has tested this for the hell of it.

Def

I guess I messed up with putting a pic/link in a reply that still hasn't shown up...

I'm going to actually build a midlana, so if you search midlana you can find the forums where I'll start my build.

I'm still in information gathering mode and planning a few things out. I'll probably buy a 350Z as a track beater while I'm building this thing as well... heh

There is a FWD VQ35DE that actually has HR heads on it ('09+ Maxima). That'd make it a "bolt-together" affair with all Nissan parts to get a 6 speed transaxle on it and support the axle, so definitely easier. But the problem with that approach is the DE bottom end is really pushing it with revs much above 7k. Rod bolts and a Revup oil pump are like $400, and even then it's maybe only good for 7500... maybe.

They'll put down about 300-310 whp with bolt-ons and stock cams, which I'm sure sounds amazing to you guys, but it's going through a FWD transmission, so probably more like a very lightly bolt-on VQ37 putting down ~290ish rwhp.

The FWD VQ is the easy button, but a VQ37 sure sounds nice for future power potential. I think with an exhaust cam and the VVEL tweaked to give a bit more lift and duration it'd push 350-360 whp in a transverse setup. Obviously with other breathing mods as well... But that sounds pretty nice rather than opening up a "weaker" engine and tossing a bunch of parts at it to just barely equal stock performance of an engine that costs the exact same.

If I did go VQ37, I'd eventually get VVEL working with probably just a few stages then use the throttles like normal. That'd be good enough for me, and probably eliminate the throttle lag VQ37s can tend to have.

Jayhovah

Awesome! I have been following Kurt's midlana build from the beginning! Small world. =)

In fact, in my dreams where I get to take on this kind of project, I was going to build a modified midlana (was only going to change some of the non-suspension related frame design for aesthetic purposes).

Good luck! I'll be sure to follow your build on the midlana forums! I have the same user name there, but I only lurk.

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Def

Definitely! I remember reading his Kimini blog back about 8-9 years ago. Then checking up on the Midlana blog a few times here and there. Something clicked when I took my S13 out, and I thought about something new. It's been a great 13 year run, but time for new things.

Given all the scope on the build, I'm maybe leaning a bit more on the FWD VQ. If I can do 320-330 whp, maybe it'll be fast enough for me. I'd ideally like it to run a 10 sec quarter mile on r-comps (not drag slicks). So it'd need to trap probably around 125-130 mph. I don't drag race, just a general want.

I just worry about going to the FWD VQ and either popping engines or wishing I'd gone with the RWD HR variants with their much stronger bottom end.

Def

BTW, your build is pretty awesome. Definitely more of a streetcar than my S13.

gomer_110

iirc, the 370z's that ran in the Conti series (Doran and Tim Bell racing) were actually running a VQ35 with a vq37 crank. They were also not running the VVEL heads. Rumors I heard was at least the Doran cars were somewhere close to 400hp.

Just can't see the hassle of dealing with the VVEL system being worth it.

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Jayhovah

I think you are on the right track here... With a scratch-build like a midlana you are going to have a billion tiny things that are going be a lot of work, especially since you won't be able to leverage all of Kurt's work with his K24... I think cutting the corner on motor/trans at the sacrifice of a few dozen horsepower is the right move. Hell, even Kurt's car isn't finished yet, granted it's been 99% for a long time now and he's mostly just been d!cking around with his turbo setup.

You could possibly get through 70% before even really needing to know your engine and trans choice. At the very least a rolling chassis... maybe the right move is to start building now and see later how much time and patience you have for motor work or if you just want to drop in something simple and easy.

Thanks! It's definitely built to be a street car in the "Grand Touring" mold.


Good luck! Come back and ping me when you get your build up and going! I'm definitely interested to follow along.

One thing that might turn your world upside down with this project - over on locostusa there is a guy who built an AWD middy using a Sylva Riot kit. He used the eclipse/talon setup from the 90's by turning the transfer case 180 degrees and mounting the rear diff upside down in the front. Genius!

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phunk

I don't have the answer you're looking for but I don't know if anyone will on that one.

You could always machine a sort of lockout product to keep it in position? Or run HR heads until you are ready to control the VVEL. If you run HR heads with VHR lower intake manifold... when you swap later you shouldnt have to change anything auxiliary.

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Def

This is Kurt's first time with a high powered turbo car (looking at HP/cylinder, which seems to scale with complexity in my experience), so he's experiencing the "little things" that no one can tell you ahead of time. You just have to feel that pain yourself. I still really like turbos, but they are a lot of extra work and make other things exponentially more complicated at times.

I don't think the VQ will really be an issue for fitting in the engine bay. From rough measurements I might need to move 1 tube at the rear of the engine bay, but otherwise it's pretty compact compared to a 4 banger with manifolds sticking out of it. But you definitely need to get your drivetrain on hand before you go very far at all in the chassis build. Should probably have it before you cut even 1 tube, because everything has to fit around it.


AWD on a Locost/Middy just seems weird to me. The whole appeal of the car is the really lightweight nature of it, then adding AWD with a driveshaft and two differentials.... ugh. Too much complexity, too much weight. I'd personally rather use that effort to build up some aero downforce and still have a <1700 lb car.



I've already thought out the steps I'd need to use the RWD VQ blocks, so I don't think it's insurmountable, but it's definitely some extra work. That said, I want the front exhaust to pass over the transmission, and the FWD VQ blocks might make that very difficult with the engine mount placement. They're moved to the transmission side of the engine to allow the front headers to go below the oil pan, which I'd like to skip if at all possible. So using the FWD block might make one part of the build easier, then another harder (header fab).

And I'm sure there's a dozen other "gotchas" that are known unknowns sitting out there waiting to bite me...

Jhill

Like others have said I don't believe anyone is going to 100% have that answer for you but I do believe they would stay. Reason being is usually systems like this (motor drive systems in general) will be using gearing as the mechanical advantage to change position which is why they don't need some huge motor drawing lots of current and building heat. That said it means going the other way (driven gear driving the drive gear) you will have a huge mechanical disadvantage and be very hard to change position.

A seat track is a great example, even if the motor dies and you remove the motor it is still impossible to move the seat and you need to manually drive the drive gear with a drill to get the seat to move and gain access to the frame bolts (ask any Mercedes tech how fun it is when they fail on clk's).

Now the concern I would have is that it is possible from what I've heard to have the valves hit the pistons if the vvel isn't programmed right (tuned right). So with that I'm not sure you can "lock it" at max lift and still be safe (not sure how the vvel valve position interacts with the VTC valve timing events).