There are more differences between the VQ30DE and the VQ30DE-K than the intake design. The VI on the 5th gen appears more effective because the engine was designed to use it to begin with.

The closed loop fuel maps on our 4th gen cars were not designed to use the MEVI.

 

Would an S-AFC or a JWT ECU help correct this?

 

Probably.

 

The MEVI, although it is a dual-frequency resonating design just like the 5th gen's, does not make as much peak torque as the 5th gen manifold because of the WAY it is designed.

The 5th gen manifold uses two distinct runner lengths. The two "manifolds" are isolated from each other, so in either the low or high rpm settings, the air has a clear path from the plenum to the intake ports. On the MEVI, however, the low and high rpm runners are joined. What ends up happening is when the manifold is set to the low rpm (long runner) setting, the compression (shock) wave moves from the main plenum down the long runner when it suddenly encounters the "merge" section where the short high-rpm runners are. At this point, the compression wave loses some of its energy as it negotates the "T". The wave actually splits into an expension wave (not good) that goes up towards the (closed) butterflies while the reduced-energy compression wave continues on towards the intake ports. It is because of this that the MEVI shows less peak torque. In fact, every resonance-induced torque peak is reduced on a MEVI-equipped car when compared to a stock 4th gen engine. Take a look here at Dave B's dyno plot: http://mywebpages.comcast.net/stevte...DaveB_MEVI.jpg Every torque peak (3400, 4500, and I bet also the 2200 rpm peak that's not shown here) is lower with the MEVI.

Theoretically speaking, if one could lower the location of the MEVI's butterflies to be flush with the long runners and change the shaft location so each runner opened up so that they lined up with the long runners, the phenonemon I detailed above would be eliminated. The torque peaks would then be identical to the stock 4th gen manifold while getting the high-rpm gains as well. However, since that ain't gonna happen...the torque losses with the MEVI are very mild, and are more than made up for by the substantial gain at redline compared to the stock 4th gen manifold.

The 5th gen intake manifold is a superior design, but the subsystems designed for it (idle air assembly, EVAP, EGR, etc) are also much different on the 5th gen. Considering the tremendous effort it would take to adapt the 5th gen manifold to the 4th gen, the MEVI is the only real choice we 4th geners have for a variable intake.

 

Since our engines use a MAF sensor, the engine always knows how much air is entering the engine and adapts continuously to compensate. Therefore, the additional airflow of the MEVI doesn't "detune" the motor any more than, say an intake or exhaust would. The engine will retain a pretty decent tuning with these sorts of n/a mods. The only thing you can really say is that the factory program is a bit conservative in that it puts in too much fuel...that can be addressed via a programmed ECU (JWT, etc). However, a MEVI-equipped car wouldn't benefit any more than a non-MEVI n/a motor in terms of a reprogrammed ECU fuel mixture-wise. Now when it comes to an extended redline that a hi-po ECU could offer, a MEVI car would see a LOT more benefit than a non-MEVI car.

 

You may have a point there. But, the differences in output are too small and the effort required to equalize them too large.

It's not that big of a deal...

 

I agree 101%.

 

I disagree .01%

Now that we're getting critical...

 

i have access to fsm's so here is the 5th fsm pictures of the intake manifold to compare to our 4th's

 

bad link.

 

i have not done any measurements or test fits to see if there are any clearance issues. when i made that comment i was refering to some of possibilities alredy stated.

 

I have taken extensive photos of both plenums on my two cars. I will have the pics posted later this evening. I was able to install the 2K1 FSTB on my 97 with minor rubbing. Looking at it from the side, it appears there is no way the hood would close, but it did. I know rubbing with the motor is entirely different than rubbing on a FSTB, but I think it may be possible. I'll keep this post updated.

David

 

It fits

 

 

Good info about the 95-99 cams against the 00's

And dave I knew deap down inside you would love the 5th gen manifold

 

I am going to get 00VI because of this post

 

It does in fact fit.

Please refer to page 3 on my homepage.

 

Ho
Lee
Shat!
Well, I guess that solves this little debate! See! Even his hood closes!

 

I gotta give credit to krismax. He had the ***** to do it first, I followed his lead. We each did it a little differently but they both work.

No clearance issues at all; hood or firewall.

 

That is the sh I it But now that the " I wonders" are out of the way how about a parts list or a "Write UP" I have a spare 4th gen 96 engine at my parents garage and as soon as X-mas has passed my personal gifts will start to come in. So please help out a no Vi guy out! But let Me also say that I'm glad that you got it done! So when will you dyno it and do you have a base line dyno already? Either Way

 

I thought the only cam differences between VQ30DE and VQ30DE-K was a slightly LESS AGGRESSIVE exhaust cam profile?

 

Cam height is different on the DEK exhaust cam. Both the DE/DEK intake cams and the DE exhuast cam are 43.940-44.130mm, however the DEK exhaust cam is 44.465-44.655mm.

Also, the DE intake valve duration is 8-degrees longer, 232 vs. DEK 224, because the valve closes later. Otherwise, the opening and closing points and exhaust cam duration are the same.

So, a 4th gen intake cam and 5th gen exhaust cam could be somewhat better combo for high RPM.

 

friendly bump