I hope I willbe able to make myself clear.

I plan to run an MEVI with my turbo. (Don't suggest the 00VI, not an option). I had an MEVI on my NA set up for years and liked it alot.

I want to run it w/o the whole butterfly valve system. This is for 3 main reasons.

First is that I think higher rpm air flow will be helped significantly without the butterfly valves in the way of the upper resonance chamber.

Second, One less thing to worry about working on my car. I got enough aftermarket electronic things to worry about working and don't want to be worried about if my MEVI is activating or not.

Third, no worries about screws falling in my motor.


This brings me to my question about how tq/air flow will be effected by running an constantly open MEVI.

Looking at an old NA dyno of mine where I had the butterfly valves zip tied open for one run and them closed on another show a 15-20 lb loss of torque in the lower/mid rpm range.

On this dyno disregared anything over 5K rpm's. Open MEVI is blue and closed is red
http://img.photobucket.com/albums/v1...miked/dyno.jpg

Now that I am turbo I am wondering how the MEVI will react to boost in the lower rpm range.

This brings me to my question. Will being boosted change the effects on how an open MEVI reacts at lower rpm's? Would the same loss occur before 5K rpm's as did with an NA set up?

I guess I am wondering about compressed air and air velocity. There is a loss on that dyno graph before 5K rpm's because the velocity of the air is not high enough to take advantage of the design of an open MEVI. But what about compressed air.....will having 5, 8, or 10 psi at lower rpm's take advantage of an open MEVI

My thoughts are that the amount of air in a given space is not relevant to how the MEVI works, it is the velocity. The velocity of boosted air and NA air is the same at each given rpm. So...I will see the same 20 lb torpue loss from 3K-5K no matter what boost level I am at.

I am not really sure though and would like to get others thoughts.

 

just hopping in on the thread to see people's answers.

As for the principles behind the 00 VIAS, I guess the butterfly valves on that open a resonance chamber. With the MEVI, aren't there two runner lengths? Which one is open w/o the butterfly valves (or are both runners open)?

 

The MEVI and 00VI work the exact same way. Neither use two sets of runners, both use a resonance chamber. The design between the two is differnent. The MEVI has its resonace chamber on top and the 00VI's is on the bottom...same idea though.

 

Fortunate for you, I have Dynos.

MEVI OPEN 100% of the run - Blue Line
MEVI CLOSED 100% of the run - Red Line

I start boosting at 2800RPM - I know I'm not Turbo, and this doesn't completely answer your question - but maybe you can deduce something from this anyway.



IanS

 

i thought the 00 vi is a true dual intake!!!!!!!

 

no, thank you, come again.

Mike, it seems that the boost pressure will compensate for the MEVI.

 

Not sure what you mean by that...?

But after thinking about it further, the amount of air should not matter, it is the velocity that the MEVI takes advantage of. Ian's Dyno kind proves that for me.

 

Thanks! That gives me what I was looking for. Being boosted at low rpm's is not different that being NA at low rpm's when it comes to the velocity of the air.

On a side note, what is up with the lean condition after 6K rpm's. Obviously that dyno is with a JWT ECU....did you have JWT adjust that AF ratio curve for you? I am sure it has to do with the MEVI and there tune being for a stock manifold

 

I need a Z32 MAF.

I bought the Z32 MAF + new chip and it runs like poo.

See my other thread for that whole mess....

IanS

 

You ask some good questions. I'm not smart enough to give you a technical answer, so you get my opinion.

#1 I think your doing a smart thing by taking out the butterfly valves, rod, and TINY screws

#2 I *think* that your TQ loss will be less than that of a SC'd or NA car. My reasoning behind that is simple... air+fuel+spark= power.... add more air and fuel, you'll get more power. And with the turbo, you'll be adding more air faster than a sc. I know what you said about velocity, but again, more air means more power.

I'm not up on all the math figures/formulas for HP/TQ, CFM, or the thickness of an atom, I dumb stuff down.

So I may be very wrong

 

Having boosted on both a functioning MEVI and an always-open MEVI, I would definately advise using the butterfly valves. I don't see any real reason not to... locktite your screws, and use good electronics to control it. While removing the butterflies could possibly create a bit more power, I would not trade that for the loss under 5k.

My original thoughts were that the manifold was designed for more airflow, so a turbo would provide that at lower rpm and no need for closed butterflies. Wrong, it simulated turbo lag to 5000rpm.

 

I remember you talking about it... I know I advised againist it, but I may change my mind. DId you ever track it or dyno it like that?

I'd actually like to see a dyno comparison. Ian, did the right thing by posting a dyno, thanks Ian

Looking at Ian's graph, it appears to be ~20 WTQ loss.. just as mike stated he got NA.

Mike may be exactly correct in his first post when he said, "So...I will see the same 20 lb torpue loss from 3K-5K no matter what boost level I am at."

And I never had any issues with my screws, I used red locktite, but the thought was still there. If I were to use a mevi, I'd rivet those damn things in there

 

I used Red Loctite and some JB Weld on the bottom and still no problem.

If the MEVI or -k was a true duel runner IM then it might be a good idea to take out the valves. When boosted the short runners will often show more torque since more air is coming in with less resistance. However, since our VIM options are all duel plenum, it doesn't work that way. From every dyno and story I have heard on this subject, the MEVI and -k (same principle) will always need the same switchover point no matter how much air is flowing through it. It would be nice if it showed gains or even less of a loss if you took the valves out when boosted but it doesn't work.

You can try it for yourself. Do a dyno with it functioning and then take all of the valves out and compare the graphs.

 

Remember it is a resonance tuned intake manifold. Taking out the rod will not add more airflow at lower rpm just because you have a turbo. It uses the resonance of the valves/pistons to bring more air in at higher rpm, so this will not change even with boost. Without the rod at lower rpm, the resonance is the wrong frequency to bring air in faster, it will not change with boost. If it were a true dual runner (short/long runner) design, then using the shorter runners all the time with boost would make more power.