NastyNissan

Does anybody have some detailed pictures of the inner workings of the MEVI intake manifold? IF you do, or have links some some, that would be excellent. I've got a skunkworks project brewing in the fabrication shop....more details to follow.

Spence

VeeQueue

iTrader: (1)

USVI ??

BBaker025

iTrader: (1)

Ill take some pics when I take mine off next weekend. Just in case anyone is wondering I have already sold it!

tampamax

DAAAAAAAAAAAAAAMMMMMMMMMMMMMMMMMIIIIIIIIIIIITTTTTT TTTTTTT MAN!!!!!!

Story of my life....late for my wedding, and early for my funeral.

I30tMikeD

iTrader: (8)

So you are selling your car or not???

dwapenyi

iTrader: (3)

http://www.vanillaice.com/webmasters/hype/mrc/mevi.htm



DW

NastyNissan

I don't get it...I thought the MEVI altered the length of the runners via a bypass....it looks like all it does is open up each runner into that air-tight plenum? SO..it doesn't actually change the runner characteristics, just the pressure wavelength? More of a selectable Scavenge than an actual variable intake? Please fill me in...I'm extremetly curious...

Spence

dwapenyi

iTrader: (3)

Yup. It's a compromise design. Not a true dual runner setup. Rather, that pouch opens, changing the total volume of the intake runner, making like a psuedo short runner. I don't know enough about the physics/engineering of it, but that's the jist of it. If you compare the dynos of a 4th gen MEVI to a 5th gen VQ30DE which has a true dual runner setup, It's quite close. Peak HP is better on the 5th gen and keeps rising after 5500 rpm, whereas on this MEVI 4th gen the HP stays up on a flat plateau after 5500 rpms, which is way better than the massive drop off of the stock manifold on the 4th gen.

DW

Anachronism

Yet again I typed a long response and my computer crashed

The MEVI uses the chamber to take advantage of dynamic supercharging. When the intake valve closes it cause the incoming air to 'bounce' off it causing a pressure wave that travels back through the intake runner. When it reaches he other end it bounces back and if the pressure wave reaches the intake valve as it is opening it crams extra air into the cylinder. Unfortunately this only works over a narrow RPM range. By using duel intake runners you add a second RPM range where you can take advantage of this effect.
http://auto.howstuffworks.com/question517.htm

The MEVI design is not as effective as a true duel runner design like on the 5th gen though. The MEVI is just starting to show benefits at 5500 RPM vs the 4th gen intake manifold, the 5th gen VIM is already making 20 more horsepower at 5500 rpm compared to without it. In addition the MEVI causes a small power loss in the lower RPM ranges. That the 5th gen VIM does not seem to. For me this low end power loss is not worth a gain that is just starting 1000 RPM away from redline.
5th Gen VI vs no VI dyno
4th gen MEVI vs USIM dyno

If you have some sort of project in mind and resources to make it happen I would recommend looking towards a true dual runner design. There have to be tons of 5th gen intake manifolds in junkyards and even from the dealer they are fairly reasonably priced. There are some major hurdles to be overcome to make this work but if you can do it we will all you. If the 5th gen manifold can be put a 4th gen for a reasonable price I will be one of the first in line to get it.
http://forums.maxima.org/showthread....threadid=41105

bb0ys

Does anyone have dyno plots of an engine before and after MEVI install? I want to see how it deteriorates the low end and improves the top end. Can you list your other mods on the car during each dyno as well. thanks!

I30tMikeD

iTrader: (8)

Look in the links above your post

Anachronism

This is one SteVTEC put together based on available dynos of MEVI and stock Maximas in this thread


I think there are some actual dynos posted, I will search for them after (since you can't ) but I don't have time right now.

Anachronism

I edited and added the links a few minits before he posted so I assume he missed them.

EDIT - I usually make a note of what I changed when I edit so people know if a response is before or close to my time of edit, I was just in a hurry.

bb0ys

I didn't see the 4th gen dyno when i posted last. thanks for putting it up!

Now that i've seen #'s, what are peoples reactions that have put the 4th gen mevi? Do they notice the lower end decline in power? Is it worth the $500+ ?? It's a definate decrease in power, that kinda sucks =(

Dave B

Here's my MEVI graph:

http://www.cardomain.com/member_page...=259675&page=3

As you can see, the MEVI lopes off two torque "mounds" and makes the entire curve flat. When I get my JWT ECU (anyday now), I expect to gain back what I lost and add slightly more power. The MEVI really needs a 7000rpm rev-limiter to take advantage of the power. The 6500-rpm limiter forces you to short shift well out of the ideal power curve. The 00-01 5th gens would be much faster if they had a 7000rpm limiter.


Dave

NastyNissan

Excellent Info! Thanks. I am well aware of the pressure wave pseudo supercharging effect. Now that I have seen the guts of the MEVI, and have a good explaination of how it is supposed to operate, I can honestly say that what I've got brewing could quite possibly blow the top off of current N/A horsepower output in the VE30DE. I'm not going to release any info at the moment (or in the near future) because far too often people jump the gun with promises, only to get ****e on when they don't end up delivering. Lets juts say a significant increase in power from 3850RPM up to redline (not just little bumps on the HP/Tq curve, but a complete curve transposition). Thanks for the info fellas.

Spence

bb0ys

You mean VQ30DE right? Are you planning on mass producing this thing or just making it for yourself? I'm interested.

Dave B

I hope you know what you're doing because developing a variable resonance chamber manifold like the MEVI would be nearly impossible and the same goes for the true dual runner manifold on the 00+ Maxima. Why nearly impossible? Because it's going to take lots of experimentation to get the runners the right length, shape, pitch, and volume. The runners just aren't pipes. They're internal shape changes in diameter at certain points in the tract. You'll need to make multiple castings to figure out the correct volumes and shapes. Turboing a Maxima is far easier than building a manifold.

Good luck though and I hope you prove me wrong.


Dave

NastyNissan

Experimentation would take years...which is why I'm using all of that good stuff I leared in Mechanical Engineering School After doing some math and utilizing equations provided by Helmholtz and others, I've already got ideal runner lengths for an RPM of 3950 to redline. I've just begun doing out the math for ideal runner cross sectional areas to get the most flow with the least amount of PD. The actual cross section of the runner is something an indy car team would be concerned with, but for my purposes anything that is close to round will work. Pressure waves will travel in a conduit no matter what the cross section...the key is to get something that will flow enough air, and is not too small or large to screw up the characteristics of the waves as they travel back and forth. If I get enough power out of this thing and come up with an ideal manufacturing method, I could consider offering it to the public. More to come.

Spence

PS: I mistyped VE or whatever...I meant VQ30DE.

dwapenyi

iTrader: (3)

Wow. I'll be looking out for you. Good luck.

DW

Anachronism

I don't see how someone with a few years of engineering school can come up with a better design than Nissans engineers with millions of dollars of R&D money. Personally I think some sort of kit to use the 5th gen intake manifold would be a much more more practical way to give the 4th gen a significant power boost.

But I wish you the best and I would be more than happy to be proved wrong on this.

NastyNissan

When Nissan engineers do design work, they must factor in reproducability, and majority interest. Most people aren't looking to get the most power out of their 4 door family sedan...those of us who are have to look elsewhere. Anybody who has ever worked in manufacturing will tell you that more often than not, profitability take precendnce over good design. I think the MEVI is a good example...it is a half-*** approach to the problem, and is more focused on packagability than actual use. Don't get me wrong...the design is boardering on brilliant, but it doesn't take advantage of the power available in the VQ. They went got a step closer in the 5th gens by going with a true dual-runner design. If you want to look at a company that has their ducks all lined up...go to the BMW website and find the new 740i. That new 4.4L V8 has it all...period! I'm not saying that Nissan isn't capable of such accomplishments in production vehicles...they just can't justify it in the type of vehicles they generally produce. This is where I come in...

Spence

Dave B

I don't know if I'd say the MEVI is "half-assed" in it's execution. I made 189fwhp/186fwtq with the MEVI, intake, UDP, and Y-pipe with power peaking 6100rpms and still at 183fwhp at 6500rpms. Most 5 speed 00-01s are making 190-195fwhp and 190-195fwtq with a y-pipe and intake. On average you're talking about difference in power around 3-5% when comparing a MEVI vs the 00-01 manifold. Look at where the power starts tapering off and you'll see the 00-01 starts to fall off at nearly the same pace as the MEVI. When you run a JWT ECU with the ECU, it's likely the MEVI/JWT will exceed the power of the 00-01 manifold at all rpms.

The true-variable intake of the 00-01 is ultimately a better design, but the power of the MEVI is right on it's heals. Developing an entirely different manifold seems pretty pointless to me. I also find it hard to believe that you can come up with something that will significantly outflow both manifolds. You might be able to do it, but at the cost of driveability. Using straight pipes will cause air pulsating at various rpms causing the power curves to have strange peaks and valleys. This will be felt mostly at part-throttle acceleration. Even the addition of aftermarket intakes cause the VQ to have these wierd power-curve characteristics. I can only imagine how much the worse the power delivery will be with a fabbed manifold.


Dave

NastyNissan

I'm not suggesting that the addition of an improved intake manifold is going to add 50hp to the engine...what I am suggesting is that the MEVI as well as the 5th gen dual stage intake manifold can both be improved upon, and I intend on doing so. Honda is producing 100hp/L...Nissan has 82hp/L with the 350Z, and 62hp/L in the stock VQ30DE. You are claiming 225hp at the crank on your profile Dave, which equates to 75hp/L. This is good, but I would expect at least 90hp/L could be achieveable without losses in drivability. This is a goal of 270hp at the crank. We already have a motor running 10:1 compression....intake and exhaust can both be improved upon (Cattman recently claimed respectable increases with some experimental exhaust headers), along with some headwork, camshafts, and computer upgrades. Anybody who says that improvements beyond the factory designs have their head in the sand. I'll let you guys know how it feels being the fastest N/A in the counrty...

Spence

Keven97SE

You will never be able to approach Honda's or the BMW M-series' 100 HP/L figure on a VQ until you address camshaft timing. There's only so much you can do with intake path tuning. The main problem with the VQ is that peak HP in either VI'd or non-VI'd trim is in the 5500-6500 rpm range. All other 100 HP/L cars reach maximum HP in the 7500-8500 rpm range. To achieve this intake and exhaust timing events last on the order of 260+ degrees. The 3.0 VQs have a measly 220-222 degrees.

What would need to be done to even try and approach a 100 HP/L mark on a 3.0 VQ is hotter cams along the lines of the JWT ones would need to be used in concert with increase compression ratios along the lines of 11-12:1 and a 7500-8000 rpm redline ECU. I think with even that combination a 3.0 VQ would not be able to hit 100 HP/L, because it would be prohibitively expensive for one person to perform all the necessary tuning to yield the additional 25 HP needed to eek out that last little bit.

Intake resonance tuning would just be a wee small part of the overall goal of hitting 100 HP/L. You can only shove so much air into and out of ports that are half-closed.

NastyNissan

Didn't I already say that? Besides...I know 100hp/L is financially unachievable...and I don't feel like running at 8500RPM to gain such horsepower. I think 90hp/L can be attained without too many sacrifices.

Spence

Dave B

I'd think you'd need to run the VQ to atleast 7500 rpms to get 90hp/ltr. FYI, the stock valve springs float after 7000rpms and like Keven said, you'll need some very aggressive cams and possibly some sort of timing control.

Speaking of BMW, aren't the higher end BMWs using a VANOs system which uses a throttle body for EACH intake runner? I thought BMW was also running a variable cam and variable cam timing setup also? They're all about high-tech and they should be.


Dave

NastyNissan

Yeah...BMW is definately on the cutting edge. They aren't running individual throttle bodies, but rather no throttle bodies at all. They are throttling by utilizing an infinately adjustable (within a range) intake valve lift system instead of butterflies. It is ingenious. They are also using a variable intake runner system, and variable cam geometry. That new 4.4L is know as the Variable V8 for good reason. That engine is only getting 73hp/L though...

Spence

Jeff92se

iTrader: (82)

Maybe it would be easier to look at the older V6 Ford SHO dual path intake manifold designs. 12 runners. 6 short and 6 long.

NastyNissan

The SHO manifold is a very cool design...it not only uses the variable runners to alter the wavelengths, but also used resonance between the two manifolds to add an extra kick via a series of "bridging" valves. Nice pic!

Spence