I've been reading all the threads about the Variable intake for a while. And have ordered mine from New Zealand and should be sent out today. Last night I was thinking of something that should work, we just need a way to measure the air flow. But as many people have seen the difference of course in the Collector is the added chamber that stores air until the butterfly opens and lets the extra air out. Well, I had talked about in threads about rigging the vacuum to open the butterfly everytime you hit WOT the problem is that when the butterfly opens...it will only give you that power increase for about 800-1500 RPMs most likely (will dyno once we get it hooked up to see the power range curve and set for the best performance). This is what I thinking. What if you take the lid or the top off of the butterfly and let's say link it to an air filter with a hood scoop to it. Basically making a ram air out of it. So, when the butterfly opens up to give more air let's say set at WOT it will always have more air going into the manifold. Therefore giving you more power and torque through out all RPM's at WOT. The only problem is that with that could you possible run to lean??? Therefore you would need a MAF for that new mod also. What do you guys think about that idea. When we get the part and put in on we are actually going to spend time dynoing the car. Do you think doing a run with that plate of would cause a problem for one run??? Because I think we are going to do it just to see the difference in the power curve. Any input would be great. Also maybe just connecting an Air filter to it and have like a second air filter in you engine bay just for that. Like rig something that bolts onto the top of the butterfly.

Give me your input please!!!

 

I don't think that much air from the intake would make it run lean...because of supercharged cars...but then again supercharged cars have to go through the MAF so maybe the ECU compincates for the increase in air. Just wondering about that.

 

You can't do that. You'd be bypassing the mass air flow (MAF) sensor and the engine would run terrible if at all. All air going into the engine needs to be routed through the MAF sensor.

Not only that, but if you could route the air through the MAF to the plenum above the butterflies, you'd alter the plenum volume Nissan intended with this intake manifold. The tuned rpm wherein the resonance boost occured would likely be so high that you'd never see any benefit on your engine (would tune to an rpm above redline). It would make the

Also, throttle position (WOT, mid-throttle, etc) has NOTHING to do with whether or not the intake manifold butterflies should open. The butterflies should always open at the same rpm regardless of throttle position, as the theory behind it is to add airflow at a certain rpm. Has nothing to do with WOT. If you opened the butterflies at 3000 rpm because you went WOT, you'd lose power over keeping them shut. They should open at ~5000 rpm all the time.

 

1) I'm not totally bypassing the MAF...I understand how it works...but I don't understand why the engine would run like crap. I mean my CAI would still be going through the MAF and flowing through the manifold like normal. The only modification I would be making is taking the lid of the variable part of the manifold and hooking up to an air filter so when the butterfly opens up it allow more air in. Therefore sucking more air in.

2) The way I was looking at hooking the vacuum up to work. Was rigging a thing like a rpm swith that opens the vacuum up but actually have it be a circuit. and having the circuit be completed when the throttle goes to WOT position. Therefore it would open up the butterfly.

The only problem I see with the more air being let in when the engine demands it is that it might cause the engine to run lean because the air is not going through the MAF. But, for it not to run at all wouldn't make sense because your not robbing the engine of air you dumping more in. So, maybe getting another MAF and wiring it to the other MAF on my CAI therefore it gauges the air going into the engine through the butterfly.

So, one thing I'm wondering is I'm going to run a dyno test when I get the piece is it going to hurt it to run one test with the top off. For instance I have let's say an RPM switch and set it to like 1500 RPMS to open it up. Do you think I might kill my engine? And if it doesn't show any gains then this is probalby something I don't want to do.

 

From what I know, you set it to anything below 4500 or so RPM's, and you'll lose alot of torque and power. There's a reason Nissan sets them to 5000 RPM's.

I'll be getting mine also soon, and getting "Before" and "After" Dynos, and setting the RPm switch to several different settings ranging from 4000RPM's up.

Good luck.

IanS

 

I hear you about setting it earlier you might lose power. I just don't understand how more Air when it is on demand would lower torque and power. But, I will be dynoing it out to find out what is going on. You see my theory is if you can set it up by taking the lid off so that the resorvoir has an open shot to more air. So therefore if you take the lid off the resovoir you have immediate access to more air throughout all RPMs instead of it just being on reserve for that extra air to be used around 4800RPM's. So, therefore you get power thoughout all RPMs and not just at the top in. Just my theory.

 

You guys arent understanding how the variable intake works. The chamber does not store extra air for later use. When the butterflies open, the effective volume of the intake system increases. This changes the resonance of the system. It is this resonance tuning that is they key to the variable intake. The butterflies, stay open only in the RPM range where the resonance of the larger volume is effective.

Plus, if you open the top of the chamber, air would be entering the engine that hadnt been accounted for by the MAF, thus it would not run.

 

Good article about how variable intakes work...

 

Gotcha, make sense. But for kicks and giggle if I took off during the dyno like my last run an set the butterfly to open up at 1500RPMs do you think I would cause any engine problems?? <--- Sorry probably stupid question just trying to see if I can get more out or the VI

 

Yep...that's what I meant to say

 

If you opened the butterfly at a really low RPM, you would lose lots of power...

That's the point, one setting is optimized ofr low RPM power, while the other is optimized ofr low RPM power. That's why our OEM manifolds are great in the mid range and not good really low or really high. They only have one setting that has to be a compromise.

 

Gotcha...yeah I was reading the article you posted after I had already sent the response. So I see what your talking about. Thanks for the info.

 

You said it perfectly. I wrote a billion words and couldn't even get these basic points across. Ugh. Thanks for clearing this up to these guys.

 

What about "for" top end power? You guys are like newbies, READ THE POST! He said in there twice that he needed some way to meter the incoming air. No, opening it only at WOT is pointless, but using a vacuum or RPM-activated switch would work. Opening up the plenum with a ram-air system is a GREAT idea! Olds 442 W-30's used a vacuum switch to open the top of the air cleaner to the ram air ducts in the hood. It'd be like VTEC, porting the heads would be great for it too. Go for it man! I say go for it!

 

Did you not read the article I posted??

 

He knows. He's just being an **** about the whole thing

See, baddie? No one understands your jokes either

 

Bottom line. The car wouldn't run when that buffly opens up.

 

Don't hate the smarta$$, hate your lack of comeback skills.

I do think he has something though (even though the original basis for the idea was wrong), opening up a ram-air when the intake manifold opens up to increase plenum vacuum at WOT and high RPMs would be nice. After all, if you did find a way to meter the air, it would eliminate the lost velocity created by the friction of restrictive intake tubing.

No "Jeffie", they truly don't... Well, Matt and Geoff (Nismo1989) do.

 

My comeback skills?



Friction has nothing to do with it(relatively)

You are not feelin' my bro. I was being scarcastic about the whole post.

 

I was talking to Mzmtg, sorry.

Okay then, the teensy diameter intake tract.

No I'm NOT feeling your brother...

I know.

 

Try again Extrude Honed intake manifolds were tried but no good gains were had.

 

No, I didn't mean the intake runners, I meant that the ram air system in the hood running directly through a metering system directly into the plenum would eliminate the 2-2.5" diameter plastic tubing called the intake tract. Oh, wait, I have a VG, your intake tract is only like 6" long.

No comment on the brother thing huh?

 

That is what I was thinking...I mean I'm going to run one dyno once I get the piece with it off...like my last run so if it does die or something I don't waste my hour at the dyno. But, I'll give it a try to see what happens, and post the outcome. I was just wondering if I might run to lean that was all. And I know that I will probably be ripped a new one for stating this, like, "It's not going to work." or something like that...but thank for the support. I'll give it a whirl and get back with the results.

 

This kind of experiment *could* blow our motor. Running lean while dynoing? Your a brave soul!

DW

 

You think one run lean would kill a motor??? If so, then I will definitely double think it...but I think on time wouldn't be that bad. But, I'm not a mechanic and don't claim to be so I might be wrong.

 

I hope he didn't ship yours yet. Because if he did, it's the wrong one.

I've been tlaking to him all day. It's the wrong part. He's trying to locate the right one now.

IanS

 

I'm not a mechanic either, my opinions are based on what I've picked up. When you do a dyno, you really run your car hard under full load . . . .and its standing still. There have been stories of motors dying on the dynos, too. Just be careful.

Also, part of the reason I say these things is to get the dialogue going, encourage conversation, and hopefully get someone who knows to show us what's the real deal. After all, it's only talk.

DW

 

Were they used on stock cylinder heads? Because improvements to the intake manifold can only be realized if the cylinder heads can support them. i.e.- Extrude Honing the intake manifold would only improve top end power if the cylinder heads can flow similar amounts of air. Also, bigger cams would help. Personally, I would prefer ported heads with variable intake runners like the 2.5L Ford V6.

*Disclaimer*- I would NOT take the 2.5L Ford V6 over my beloved VG.

 

Try again. Yes on stock heads but the dyno on the varible intake was done on stock heads also.

Think SHO.