Street Reeper

According to this web sight I used to think that the resonator between the throttle body and MAF was just for noise reduction. But then a thread came up about how a member felt that the thin black box was making him faster when he switched back to it from the midpipe. Others replied with their results from track times,

(speaking of the midpipe) "both 1/8 and 1/4mile, and it made me slower. I ran .1-.2 sec faster with stock box" (resonator box)


Another member stated -

“Avg. times with stock resonator were .12 faster than the mid-pipe in the 1/8 mile.

Avg. times with stock resonator were .18 better in the 1/4 mile.”


Another member posted links about resonance tuning and the intake

http://www.users.bigpond.com/pgscott...resonator.html

http://www.users.bigpond.com/pgscott...rsAcoustic.htm

I am resurrecting this to find dyno’s that say the midpipe with a Stillen/JWT filter is superior then the original design, also track experience is welcomed. I just want to get all I can out of my car and hope this thread will help. More specifically I would like to know where each intake is making power, I had no complaints about my DIY midpipe but have sense taken it off do to the previous thread, I am trying to figure out if anyone could give me a reason to put it back on.

Nealoc187

iTrader: (23)

You're not going to find dyno proof of something that is probably on the order of 3hp either way. Dynos can vary by 5% easily, and 5% on our cars is more than 3 hp. I've dyno'd back to back and gotten a 4hp difference.

Also those time claims are bs. .12 seconds, .18 seconds, whatever. Don't buy in to what these people say. They gained almost 2 tenths of a second from a mod that does nothing (or unmodding, whatever you want to call it). .18 seconds would require the addition of probably 10hp in a car the weight of ours. I'm going to say this one more time so that everyone can see it "YOU CAN'T COMPARE TRACK TIMES FROM DIFFERENT DAYS, DIFFERENT TRACKS, DIFFERENT CARS, ETC." I have about 175 timeslips sitting in a folder in my desk. I could start pulling timeslips and make any sort of looney and ludicrous claims I wanted and I guarantee I could back them up with empirical evidence. Example:

My car runs faster on Fridays than any other day of the week.

My car runs slower on wednesdays than any other day of the week.

My car runs faster near a full moon than it does during a waning crescent or new moon.

You get the picture. People are grasping at straws trying to do anything possible to make their car faster and I do the same. But research and being a smart mod buyer and money spender is how to make your car faster.

In short you won't find the conclusive evidence you're looking for.

Street Reeper

OK so since track times should not be much different the midpipe is probably not worth it.

And since the links I posted that researched the need for a resonator state that I resinator is good I should just keep it.

The only reason I brought this thread to life is because a claim was made that the midpipe gave more hp than the Stillen (with dyno's from this sight), I wanted to see the dyno graphs to determine where that hp increase was coming from.

Thanks for the reply.

Whitemax

The only reason I wanted the midpipe was sound. And there arent too many cars that sound that aggressive and sporty with just an intake.

deezo

iTrader: (3)

This is DMBMaxima's Frankencar Midpipe dynos done on a 2k2.....

Before:



After:

Street Reeper

Thanks Deezo.

I have seen these before and noticed that when I do overlays that the aftermarket intake actually loses hp to the stock intake until around 4800 to 4900 rpm.

I wanted to see the Stillen vs midpipe intake to see what gains are made with a midpipe, and what the hp curve is, I figured an open filter gives gains in the higher RPM (the air box is restrictive in that the hole coming from the snorkel is smaller than the hole going to the throttle body) but wondered where the midpipe was seeing gains.

Thanks for the dyno's.

96BLUMAX

iTrader: (3)

Neal is funny. My car runs faster on fridays too.

MaximaMoJo

So which creates more horsepower over the powerband? Which creates "more area under the curve?"

orgasmicNYC

My car runs faster when my ac is on!

Street Reeper

That’s exactly what I want to find out.

When I was first making my intake I only thought about improving flow. However, the links that I posted in my original post opened my eyes to the complicated world of resonance tuning. I also always wondered why companies like Stillen/JWT didn’t use midpipes in the design of their intakes. I know they do a lot of dyno tests before being satisfied with an aftermarket product, I figured they would have thought to replace the resonator with a midpipe. I am interested in looking at the dyno’s that compare an open filter with a midpipe and an open filter with a resonator to see what the resonator actually does for our Maxima's and why Stillen/JWT left it there. I also want to see if one intake has an advantage over another in differing RPM ranges.

sryth

Most people claim that the stock airbox resonates at a certain frequency, and that frequency is tuned to the engine. Your aftermarket intakes are not tuned. Whether this hurts you, or simply shifts a "sweet-spot" up/down the speed range, I don't know. For more in-depth stuff, read on (long).

Now, I'm in the process of learning about all of this, but here are my thoughts at this point (corrections welcome):

The intake tract will have a certain resonant frequency, as will everything between the throttle-body and the valves. When air travels through the intake, the piping will amplify the resonant wave present in the incoming air. When it enters the intake runners, the intake runners amplify by it's resonant wave. When the valves close, the wave travels back up the runners, and some bounces back down from the butterfly valve.

If the runners are the perfect length (an integral of the wavelength), the wave phase will stay the same when it bounces, and in fact be at a perfect peak/valley when it comes in contact with the valve again. Modifying the frequency of this wave can result in the wave returning to the valve when it's open. To do this, you need to generate a wave that is harmonic to the resonant frequency of the runners. Any wave that has the same periodicity will work, actually.

Basically, these wavefronts cause high/low pressure areas in the piping. It is possible that these areas (if in the right spots) can "force" more air into the cylinder.

It is thought that Nissan designed our stock intake piping to produce a certain resonant waveform. It's possible that they produce the same waveform as (or a harmonic of) the resonant wave of the intake manifold. It's obvious that an aftermarket intake will have a different resonance than the stock piping, thus could hurt performance.

My personal opinion is: It's all bull****. The state of the butterfly valve in the throttle-body changes the resonance of the entire system. WOT will produce a different wave than half-throttle.

I've been toying with the idea of creating a variable intake system that would modify the piping to create the "ideal" resonant waveform. It'd basically produce a customized modulated wave that has the same periodicity to the wave in the intake manifold, tuned to create optimal pressure areas/times.

The only problem with this is that it would need feedback from the throttle position (a butterfly valve flaps it's wings in Peking...well, you get the point ). I'd make it electronically programmable so I could compensate for varying throttle levels.

Even with a continuously variably tuned intake system, I doubt you'll see much gain in the way of power. I'll have to do some research on that. I sincerely doubt that I'll undertake this project, unless I find that I can increase power by some substantial amount. It's been my findings that professionals tune their intakes when they've done absolutely everything else to make power.

Hmm...I just had a thought: What if the TornadoAir modifies the resonant frequency? Is it possible that this product isn't crap?

Street Reeper

I think dyno's could answer the questions of where the aftermarket intake gives gains. On one of the more popular websights in the FAQ's section it asks - "Will i lose low end with this intake, I hear you do with POP style intakes?"

The answer given - "With a traditional POP style intake you would but this setup is a hybrid setup and it engineered so that you will not have a loss in low end like with a standard POP and not lose high end like with a CAI. It just performs well all around all without having to drill a huge hole in your car or position the fitler just inches away from a HOT HOT radiator like the "I" brand CAI does, and leave the filter close to the ground ready to suck up water from that next rain storm."

I find this hard to believe since we already know that the midpipe designed intake loses low and mid range power when compared to stock. I just want to see the dyno's comparing the Pop vs hybrid which where claimed to be on this sight, "Provides a 3hp and 7tq advantage over STILLEN INTAKE, as proven from dyno's at www.maxima.org"

I loved the sound that the midpipe gave, I just want to know what is happening in the way of performance.

bigdo26

iTrader: (3)

Anyone ever read this article? While its based on snowmobiles, the idea is the same as cars. Pretty interesting, here it is:
Ram Air, Hot Air
Marketers just can't resist it. Ram air! The words themselves summon up images of rushing wild beasts, or of secret military aircraft operating on futuristic principles.
Unfortunately, on snowmobiles, ram-air is as functional as tail fins were on cars of the ’60s.
What is it? Ram air just means using a forward-facing air intake to gain some extra intake pressure. We have all, as children, felt the pressure of moving air on our hands when we held them out the window of the family car. When moving air is brought smoothly to rest, the energy of its motion is converted into pressure. Motorcycles went through a "ram-air" period in the early 1990s, during which street bikes were equipped with the forward-facing "rocket-launcher" engine air intakes seen on many road-racing machines.
While it's appealing to imagine the forward velocity of a snowmobile being converted into free supercharge, the actual air pressure gain is extremely small at snowmobile speeds. For example, at 150 mph, the pressure gain when air is efficiently brought to rest is 2.75 percent. Because this is a dynamic effect, it is proportional to the square of the air velocity. At a more realizable snowmobile speed of 75 mph, the effect (again with 100 percent efficient conversion of velocity into pressure) will be only one-quarter as great — that is, just under seven-tenths of one percent.
In fact, velocity energy is not converted into pressure at 100 percent efficiency. A figure of 75 percent efficiency is usual, which reduces our notional ram-air gain at 75 mph to one-half of one percent.
Therefore, at normal snowmobile speeds, ram air is a myth. However, something much more interesting lies behind it, ignored by the advertiser's busy pen. That something is airbox resonance.
In order to implement ram air, the carburetors or throttle-bodies of our engine must seal to an airbox whose volume is large enough that the intake cycle of one cylinder cannot pull its internal pressure down significantly. Box volume is typically 10-20 times the engine's displacement. Then the forward-facing air intake is connected to the box. When this assembly is tested on the dyno — even without an external fan to simulate the high-speed rush of air past the intake — it is discovered that the engine's torque curve is greatly altered, with new peaks and hollows.
Why? The answer is airbox resonance. If you hold the mouth of an empty bottle near your open mouth as you loudly hum scales, you find that at certain “hum frequencies” the bottle reinforces your humming, which becomes louder. What is happening is that the springy compressibility of the air in the bottle is bouncing the slug of air in the bottle's neck back and forth at a particular frequency — higher if the bottle is small, lower if it is larger. Your humming is driving a rapid plus-and-minus variation of the air pressure inside the bottle.
The same thing happens inside a resonant airbox. The volume of air in the box is the “spring” in this kind of oscillator. The mass of air in the box's intake pipe is what oscillates. The “humming” that drives the oscillation is the rapid succession of suction pulses at the carb or throttle-body intakes. If the volume of the airbox and the dimensions of the intake pipe(s) are correctly chosen, the airbox can be made to resonate very strongly, in step with the engine's suction pulses. The result, when this is done correctly, is that the engine takes air from the box only during the high-pressure part of its cycle, while the box refills from atmosphere through its intake between engine suction pulses. This produces a useful gain in torque.
Using this idea, motorcycle engines have been able to realize torque increases, in particular speed ranges, of 10-15 percent. In race engines, it is usual to tune the airbox to resonate at peak-power rpm to increase top speed. For production engines, it is often more useful to tune the box resonance to fill in what would otherwise be a flat-spot in the torque curve, resulting in smoother power and improved acceleration.
Early resonant airbox systems used long intake pipes that terminated in forward-facing intakes. More recent designs do not connect the ram-air pipe to the box at all, but terminate it near the airbox entry. The actual entry pipe is a short piece of tubing with bellmouths on both ends. This is done because (a) the potential gain from actual ram air is too small to worry about, and (b) it's easier to tune the airbox with a short tube.
Where vehicle speeds are very high, gains from ram air are significant. This was discovered by Rolls-Royce in the late 1920s as the company developed its R Schneider Trophy air racing engine. At speeds above 300 mph, it was noticed that the R’s fuel mixture leaned out enough to cause backfiring. When the mixture was corrected for ram-air pressure gain, the engineers realized they had a "free" source of power. At 350 mph the gain from ram air is almost 15 percent. Similar mixture correction is necessary when ram air is used on drag-race and Bonneville cars and bikes.
Intuition suggests that a forward-facing intake made in the form of a funnel, large end foremost, should somehow multiply the pressure of the air, resulting in a much larger pressure gain at the small end. Sadly, intuition is wrong. In order to convert velocity energy into pressure, the air has to be slowed down, and this requires a duct that widens rather than narrows. Next time you fly on a commercial airliner, note that its engine intakes widen as the airflow approaches the compressor face. Such widening passages are called diffusers, and they are universally used in the conversion of velocity into pressure.
Language often plays tricks on us — especially when language is used by product advertisers. "Ram air" sounds much more appealing than "resonant airbox." Nevertheless, it is airbox resonance that actually generates a significant power gain. At snowmobile speeds, ram air is just words.

sryth

Nice stuff, Bigdo26. I guess it is a worthwhile pursuit after all. I think I'll get started on this. My design should be very simple to make, it's just that testing it will be tricky. Anyone have a spare intake manifold I can borrow to do some testing?

My design will allow the resonant frequency of the pipe to be changed variably. Actually, I have 2 designs...one is a discrete state system, the other is a continuously variable system. The continuously variable system isn't as good (from a manufacturing standpoint) as the the discrete state one. If it's gonna take a while for my tranny to come back (in the shop for bearings), then I'll pull the manifold off, and do some testing.

TXMAX

That article ONLY touches on air pressure and fails to recognize the fact that air density is also a factor in producing more power. In the 60's, "Ram Air" was not touted as a means to add pressurized air into your engine, least not any advertisements that im aware of, but was a way of getting colder air to an engine.

Ram air designs of the 60's were very simple and didnt even consist of "resonator boxes".

I agree that Ram Air in relation to todays intake systems may be just a marketing ploy, but that is not to say that all "ram air" systems are just a marketing ploy.

Street Reeper

I am beggining to think this of some other intakes

maxger

I know this intake is not for a maxima but it applies the same Idea of a resonator. I don't know it might be a hole lot pf BS.http://www.aempower.com/default.asp
Look up the AEM V2.

sryth

That's pretty similar to what I want to do, however their design is static. It may produce a more complex modulated frequency with the same periodicity as the resonant frequency of the intake runners, but the resonant frequency of that pipe doesn't change.

I want mine to change constantly to be in phase with the valves. Actually, I guess I'd have to make it double the frequency of the valves, as they open 3 at a time.

davidme

why not do 3 dynos?
1. stock
2. intake
3. intake with resonator.

???????

Anachronism

dwapenyi

iTrader: (3)

Better yet do several dynos with each config;

1. 4 dynos stock.
2. 4 dynos with a JWT or Stillen. They both use the stock resonator between the throttle body and intake manifold.
3. 4 dynos with a mid-pipe added to the JWT or Stillen.

Take the averages of 1,2, and 3 to have a more consistent comparison.

Of course, where do you find a dyno guy who will be flexible? When I dynoed my car in Queens, they were having a slow day. My $100 entitled me to 6 dynos, but they were willing to lett me run for however long. I wish I could have taken advantage of that with a test like this.

DW

sryth

I know...let's all chip in, and buy a Dynojet!

Dave B

A few weeks ago I swapped in my resonator between the TB and MAF just as an experiment. To my delight low rpm driveability improved and topend acceleration felt better. Much of the sound of the intake disappeared though which is something I use to really liked. All I know is I've read all the articles about resonators and I'm of the belief (now) that maybe today's engineers develop stock intakes, while ugly, that do perform. Hell, even BMW uses an intake setup much like our 4th gen setup. If I ran a 14.4@99.5mph with a cut stock airbox (hacked), K&N filter panel, and mid-pipe, I'm seriously wondering if I'll be even quicker with the resonator in place. I plan on going to the track soon to give it a shot. I have a ton of slips with my midpipe/hacked setup in various weather conditions so there won't be much of a lack of data for comparisons sake when running with the resonator (same track).

IMO, the only cars that probably benefit from a true cone intake filter and no resonators are turbocharged cars (from what I've read). BUT, even the WRX guys swear up and down that an intake is not needed until around 300hp and that removing the resonators has been proven to crush certain parts of the power curves.

Us automotive enthusaists love to tinker and change things in order to make more power. IMO, the intake on the Maxima probably flows plenty of air and doesn't need modification.

My concern now is if I should "seal" my hacked airbox and take it back to completely stock using all resonators and no cuts in the airbox.


Dave

sryth

I won't believe it (100%) until I see dynos that were performed back to back. (something I'm willing to do once my car is back)

There are too many variables when comparing timeslips.

sryth

Wow! I just thought of something. A while back I had asked the .org if WOT was the best policy. I could swear my car was faster at times at 3/4 throttle. Maybe this is why. Maybe 3/4 throttle caused a resonance change in the intake tract at certain RPMS.

Or...maybe it's all in my head.

optimus1

if you are running too rich at WOT, 3/4 throttle might fix that ...

Audtatious

Regardless of "tuning variables", ( most ) current aftermarket intakes are dyno proven to increase hp and tq while being track proven in lowering times while increasing topend. Of course, due to design, they may do them somewhat differently. Gotta remember that Nissan designed the factory intake to be functional, quiet, and conservative. This is at the expense of some power. Unfortunately, dyno results and track testing is not a proven indicator of performance increases due to too many variables (temp, humidity, time, heas soak, etc). Of course, back-to-back dyno tests allowing cooldown periods are pretty conclusive...

Any project would have to be developed to give more performance than current intakes on the market. Since R&D is expensive and very time consuming, a project of this magnitude would be a difficult task. If someone wants to have a stab at it, I say go for it!

I do wonder what the resonant frequencies are across the powerband. The articles and info posted reminded me of tuning sub enclosures. Maybe a wiveguide speaker setup, with variable frequencies, computer controlled via the TPS, would increase airflow? Yeah, thats the ticket! Play that baby into the intake!!!

Dave B

Something to consider here is that many aftermarket intakes do gain upper rpm power, but end up causing a jagged power delivery and possibly lower midrange power (Frankencar intake dynos in particular). The intake might gain 5-7fwhp PEAK, but the midrange power lost overall negates the gain. Example, when I installed my MEVI I gained a whopping 15-45fwhp from 5800-6500rpms. To my dismay, I was no quicker in the 1/4 mile. How can this be? The MEVI caused a loss of 10-12 fwhp/fwtq from 3800-5300rpms. The lack of power in the midrange for 1500rpms ended up slowing me down even though I gained big power for the last 700rpms in the rpm range. It all equaled out. Not until I added the JWT ECU was my car significantly quicker.

Remember that you spend most of your time accelerating through the midrange, not the upper rpms. Peak gains are paltry in comparison to average gains. This is why a 650rwhp Supra single turbo making it's power from 5800-7000rpms is no quicker than a 500rwhp twin turbo Supra making it's power from 5000-7000rpms. The 500rwhp is making more average power.


Dave

Audtatious

Good points. Simply upgrading the intake seems to change your powerband. Upgrading the exhaust with the intake seems to help as well as possibly utilizing midpipes. Keeping the car "in band" during hard runs is a must.

I can see where utilizing a true electronically controled "tuned" intake would be useful. Unfortunately, I see that option as quite expensive....

Anachronism

The new G-tech is supposed to be able to make a dyno graph, it can measure RPMs as well as acceleration. Plus it would give real world results with the hood closed and the car moving to see how engine heat affected the pop charger. You could do as many runs as you thought necessary to get a good average and do a pull in one gear to leave out driver influence.

I would like to get one of these and try it but they are $250 and not in my budget right now ? If anyone wants to lend me one I will be happy to spend a day swapping intakes though.

Audtatious

The problem with utilizing a G-tech for these tests is that it does not let you know where the restriction is. You could fight all day working on the intake and it could be the exhaust, plugs, fuel pump, etc that is the restriction. I forsee a whole slew of equipment being needed to work on these issues and a whole lot of hair pulling since making one change to the powerband can easily affect something else

Who knows, maybe I'm missing something here or am too lazy to even consider the true possibilities...

dwapenyi

iTrader: (3)

Well, neither does a dyno. I think what everyone's looking for is simply to see if there is a benefit to the stock resonator over the straight mid-pipe.

I'm wondering if any info will show up on the dyno/G-Tech because maybe the resonator is more beneficial at partial throttle, and we know that the normal measurements tend to only pay attention to WOT.

DW

chinaonnitrous1

iTrader: (12)

you guys are crazy. all this money spent on the intake could be better used IMO.

dwapenyi

iTrader: (3)

Chinanitrous has got a point. All this fretting over what will at most amount to a 1 or 2 hp difference.

DW

bluemaxx

+1^

sryth

I thought of this, but the problem would be that the resonant frequencies of the pipe would still be amplified. Unless you could put little speakers in the intake runners right upstream of the valves

That's because of the flow restrictions of the manifold, no?

Shouldn't be that expensive at all, and I hope to prove it.

While this would give you a decent approximation, wind resistance and slope come into play.

Yep...that's what I suspect as well.

I doubt the gains would be that low. I've heard estimates of 10-15% in race applications.

On another note...I just referenced a 4th Gen stock dyno...and...uhm...what's that drop at 3.7k?

dwapenyi

iTrader: (3)

Consider that if you replace your stock intake with a JWT or Stillen, both of which still use the resonator between the TB and the intake manifold, you gain like 6 hp. Now, repalce the resonator with a mid-pipe and we don't know what really happens, but if you suggest that the resonator can increase the output by 10% that would be around 16 hp. That would also mean that removing it will lose 16 hp, no? People on this borad have run with and without resonators. The efeect must have been much more subtle than that because I'm sure that everyone would have noticed a 16 hp loss.

By the way, I get the 16 hp from this: 190 HP motor on a 5 speed, on the dyno that comes to around 160 to the wheels. 10% of 160 hp is 16.

As for the dip at 3700, that's normal. The 95-99 US maxima have a fixed intake manifold that uses resonances to increase the flow of air. Resonances naturally have peaks and dips. The dip at 3700 is a major dip. If you compare the fixed intake manifold to the MEVI, the MEVI TQ curve is smooth as silk. The reason the MEVI loses mid range TQ is because it lost a peak resonance in the mid-range the that stock manifold had.

DW

sryth

No, you won't notice that much with a normal intake. I don't mean 10% peak, but across the spectrum (average?) Only a variable intake could make this kind of boost in performance (as far as intakes go)

As above, it will only be a few HP at any given engine speed.

Damn...good info. So, as we can see with the MEVI vs. USIM, USIM performs noticeably better (mid-range) because of resonance. Imagine having perfectly tuned resonance all throughout the spectrum. Couple that with the MEVI, it'll be damn sweet! If what you say is true (MEVI's mid-range breathing is limited by resonance), we could theoretically make the MEVI as good as the USIM in the mid-range portion of the spectrum.

chinaonnitrous1

iTrader: (12)

hehe crazy...but awesome effort and brain skills. It does make sense, but just way far fetched.

Dave B

The only reason to run the MEVI is if you have the JWT ECU. A lot of us learned this the hard way because our 1/4 mile didn't improve with just the MEVI. The JWT ECU will restore all the lost midrange power and then some. To me it was a night and day difference after adding the ECU. Neal can vouch for that too.


Dave