kinakoes2

Found some time yesterday between jobs... got out the resonator to see what it was like...

I'm normally *not* a fan of mods like this, as they tend to be the type that make a car louder, and usually slower/less drivable. But sometimes, an OEM needs to sacrifice performance to two strict and unforgiving gods -- emissions, and noise -- so taking out a stock component can sometimes -- though rarely -- be the ticket to better drivability.

I'm a strong believer in giving the benefit of the doubt, as long as the mod is inexpensive and reversible. This res-delete is both... so, why not.

Got it out, and it's as easy as everyone says. If you can't figure out how to get this box out, time to put up your keys and consider working for the VA.

So, the first thing about ripping out this plastic wart as many have pointed out, is the sheer real estate removing it gives back to you. That said, the first thing I saw, is the ground right below the opening. This access to the road surface gives the airbox opening direct access to dust and grit from it, not to mention mist when it rains. The stock res setup only takes cool air from the side of the battery in the front corner... the best place for it to get it.

The second thing, is that doing this mod, takes away a ton of airbox volume from the intake... not sure how much resonant supercharging this OEM res box gives it, but it can't be just for noise. I guess I'd have to open up the resonator box to look inside and see. But the volume in the airbox that's left is essentially nil, like putting pod filters on a sportbike's carbs and expecting to go faster (hint: unless you're drag racing with 80-100% throttle all the time... it'll drive like absolute poo).

Lastly... this is a drastic reduction in intake length, so intake resistance. Most likely, this'll require an idle learn again... but my test this AM was with just pulling it and going for a ride...

TL;DR -- I didn't like it.

At least without a brainwash... the setup was way too abrupt. One thing I did like, was that up to maybe 1/2 throttle, it sounds exactly like stock. But that was offset by two negatives: way too abrupt throttle response, esp while rolling at parking lot speeds... and the honk of the thing above 1/2 throttle. What's up in the air is if the delete actually increases performance. I don't give two sh**s about top end performance -- I want midrange in exchange for this noise. Unfortunately, less intake resistance and less airbox volume means midrange usually suffers (torque peaks less AND at higher revs).

Well... I'll try to do the idle learn and see if this improves over the rest of this tank of gas. Res box is in the trunk. Just got 260 miles out of a half-tank this past weekend... so hopefully that doesn't go in the toilet as well.

Poopies

iTrader: (4)

Yeah, it was really weird for me the first time I saw that too. I'm glad mine is gone, but it is slightly chilling to think about water getting on my open element filter.

That's an EXTREMELY short distance between the intake and the TB... have you ever considered getting an aftermarket intake? It would at least give you a little more resistance, what with the added length and all.
I didn't pull my old res apart since I was selling it, but it looked to me like it was just a plastic tube surrounded by that big ol' housing for insulation.

That sounds kind of funny... would you care to post a vid of that?

Is your gauge like mine? When I'm at half, I'll get some nice 200+ numbers on my trip meter, but my light turns on at closer to 350mi. It's really annoying.

ezone

That big air box will hold a good 10 lbs of Kibbles-N-Bits if you have busy rodents in the garage.

kinakoes2

On a Triumph Bonneville (the new ones, not the nut-numbing '60s ones), almost this exact same setup is what feeds the carbs: tiny airbox, filter, venturi. I trimmed ~2" from a 4" intake snorkel on my customer's bike to give her better breathing in the humidity up there in Seattle... and for her it worked great. But then again, a 600-lb, 900cc Bonnie doesn't need much torque compared to a 2600-lb, 1650cc Civic...


If you look at the airbox-side opening on the res, it's a lot more open than the snorkel-side. So it looks like some added baffling and/or steps are molded in there to either reduce noise, aid in resonance, or both. All I know is this car is mighty annoying to drive uphill with now. I could post a vid later, but it's the very ricer-fartcanny sound I'm striving to avoid attracting cops here with.



I can imagine; my Escort used to be like that. But the second half of the tank, while less used than the top half (I refill every half tank) and does register less mileage than the top half... seems closer to it than 50 mi. I guess ~20 mi range diff between the top and bottom halves for me, perhaps due to the filler neck taking a bit more fuel.

I get normally ~220 mi on 7 gals of fuel, mixed 3 x 92oct and 4 x 87oct. I drove the usually-weekly 50 mi work run this weekend over July 4th, another 4 times -- all but once in the height of rush hour traffic. But I think the car really likes the long moderate-speed runs in one gear vs. several runs from cold in the city with varying throttle openings and loads -- to the tune of 38 mpg vs. 31.


Oh hell yes -- I lived in WA, remember? Lots of bud's streetbikes with airboxes and air filters piled full of dog food... luckily the only think I've had to worry about here is small roaches in the interior eating the goldfish cracker crumbs and other rugrat mess under the seats from the last 'owner'. Combat Source Kill Max goop atop the carpet in the passenger well... 2 days later, boom -- all dead.


As this week is as busy as the past weekend... I'll try to get that video in and take apart the res to see what's in it. I will give this setup a chance with a tank of fuel and an idle learn soon.

kinakoes2

^Oh -- and to answer Poopie's question about an aftermarket intake... am leaning towards two in particular -- the FIPK2 and Typhoon (in the future to be joined by a HHC5019 header and Magnaflow catback after my suspension's fresh). The closest other one I see positives about is the AEM SRI... but the ratings (at least in the Perf forum) are all over the place, and I don't know if the rating is for how loud it is, or if it actually increases performance (both are often mutually exclusive). As before, I've had my fill of obnoxious and slow... would much rather have obnoxious behind me, where it belongs.

kinakoes2

Update 20140710:

So I've gone about 40 miles with an idle relearn and some mixed driving... and the abruptness has gone down some, but not all is positive. Read on...


So far, the pros of this airbox-only setup are as follows:

-- much shorter intake length... thus, much less intake resistance. This means practically, that off-idle response is MUCH better. None of this slipping the throttle dance just in order to take off anymore.

-- much less intake resistance, also means less vacuum when on trailing throttle. This is good because closing the throttle doesn't load the gears (in a manual), thus your shifts become much silkier. I haven't had a crunchy downshift (or upshift) since removing the res...

-- all this means is that the engine can take in more air with less energy lost (pumping loss), meaning your accessories work better. Power steering effort's gone down, and the car feels much less kneecapped by the A/C compressor. Both mean the engine is producing more output than before.


The cons so far, though... are as follows:

-- when opening the throttle from closed, or closing from WOT, with this short airbox setup, produces variations in the airflow that causes abrupt, jerky response. This is unavoidable with a PCM programmed from OEM to expect the airflow and resistance of the stock setup.

-- there is more output at idle... but not everywhere. Esp right before the VTEC crossover from 3V/cyl to 4V/cyl (SOHC VTEC) at ~2800 rpm... if you decide to mash the throttle in 4th at that rpm, expect lots of noise without a whole bunch of forward motion -- there's a big fat hole right at that point (it does climb out of it okay, but it's not as obvious res-in due to the rest of the powerband rising without it.

-- opening the throttle more than 1/2 at less than 3000 rpm will sound like a Transformer farting after one too many drums of frosty draft diesel. Not the stealth setup, this res delete.

::

Gonna give the setup a full tank, and see if it improves further. I'll also do a test with the res in... but missing the long snorkel to the front corner, and see what differences that makes.

Poopies

iTrader: (4)

You sir, are a pioneer.

kinakoes2

If by 'pioneer' you mean 'stretches-pennies-into-wire Civic hack with some tinkering experience clubracing powersports', then .

Besides... I hate when someone suggests removing a stock part improves their ride over swapping with a performance part, but can't tell me how or why. This way, at least you all get to witness my successes (and failures) with that, as I'm documenting it all here. You learn as I learn, and the forum gets to archive my process.

lowlife9

the AEM kit uses a synthetic filter element so it filters better doesn't require oil and has a lifetime warranty not to mention way way easier to clean. also the filter itself has a built in velocity stack. most people including myself just buy a cheap ebay intake and slap on a quality filter like AEM.

sdaidoji

iTrader: (1)

hunh.

never thought much about, but part of the jerkiness that i notice might be my CAI...

kinakoes2

Any increase in intake flow numbers will result in this, as the rest of the intake length (airbox, TB, and intake runners) was designed to use the stock res and snorkel. Since the D17 was, even in slightly more fruity EX trim, *never* designed to be a performance engine in a detuned trim like the B-series engines were, the stock setup won't be just a bunch of obstacles piled atop a strong motor wanting to be freed... but designed from the start to be quite mild... so will not reward any old intake swap. We all know which has been proven to be true.

When you increase the intake pipe diameter to be greater than the TB diameter... there is less air resistance along the whole length, so one intake stroke will have an easier time getting the atmosphere to fill the cyl, than stock:

1/2 x pipe internal radius, same length = 16x the resistance.

same internal radius, twice the length = 2x the resistance.

If you measure the inner radius and length of your aftermarket intake, and compare it against the stock intake's... it's easy to see where a gain can be had.

But pipe diam and length aren't the only forces at play -- each pipe diam and length also has a resonance -- just like a musical organ pipe. Air is elastic; it compresses and expands according to this resonance when drawn down a pipe, and esp when there are a pair of poppet valves opening and shutting at the far end. This pressure wave can also be felt as overfilling in the wrong place, causing the mixture to briefly run lean, which is felt as jerkiness.

Get the pressure wave to enter the head at the time it would normally have a big hole in the powerband though, and voila -- you've just solved a powerband hole with inertial supercharging. This is why the more time the tuner puts into testing the CAI or SRI, the more power you'll have at any rpm (most of them don't though since it's less profitable). It's also why I tend to favor the FIPK2's design, since it has a varying, tapering diameter... which can help a broader range of rpm with inertial supercharging, than a fixed diameter pipe. In essence, K&N designed the FIPK2 to be a very long venturi stack... which has been known since the 20s to aid flexibility -- it just has a filter on the end of it. The problem with tapering venturis however, is they act just like trumpets -- they can be loud. K&N obviously knew this and tried to compensate, since it's not an obnoxious intake.

kinakoes2

Ah -- that's good to know. I do realize K&N filters flow more... because they let more crap get through (including filter oil, which can gum up IAC valving and TB plates). Anything they say to the contrary is dog turds, since I've seen the results of a quite formal test on Bob Is The Oil Guy's site -- and I demand better than K&N's marketing schlock.

I hear the Typhoon is better in hot weather (someone said that here IIRC), which could I suppose be fixed in the FIPK with some insulating tape. But what may be happening is the plastic in the FIPK may be softening to the point where it's not be reflecting the pressure waves as well as a hard aluminum tube, which may heat up but won't change hardness at engine bay temps. That can't be fixed with tape...

Based on if your claim about the AEM filter/baseplate is indeed a better experience to use and maintain than the K&N's (which is a pain to wash, dry, and oil unless you get two... and who wants to do that), I may see if one of AEM's filters can fit on a K&N pipe. I want either the FIPK's tapering diameter, or whatever is making the Typhoon perform consistently in the heat... but with a better filter.

Filters are also hugely important to total flow -- if your pipe diameter and length flows a ton but you cap it with a little mushroom foam thing that flows less than the throw cushions on my couch... you may as well stick with OEM. More filter element area = more flow... get as much as you can afford that fits.

kinakoes2

Update 20140712:

So, the stock airbox by itself, seems to get great mileage -- I first took the res off at a bit past the half tank point, and currently am getting 36+. Holy crap that's amazing for this particular EX sedan.

Mind you with A/C on most of the time (except when I used to need some passing power), I was getting 33-34. This past weekend when I had to commute the long, 50-mph, 50-mi Sunday drive four more times... I was getting 38 with the res in and on the heavier first half of the tank.

I've driven the car res-out with the A/C on, just the same or even a bit more often... and am getting 36.2 (just filled up). And the PCM isn't even finished adjusting yet, so it may go up even further after this idle relearn is finally done.

One thing I have noticed, is when you need upper midrange with this setup -- it's not as torquey. Up to about 55 mph, you have noticeably more response and acceleration, but in 5th at that speed, you do need a downshift to get out of another hole in the powerband. This is where a good SRI/CAI will be superior to just the res out.

--

Was wondering while getting gas this AM... what if the res snorkel could mount directly into the airbox? That would solve two problems: dirt and mist having line-of-sight access to the filter element... and getting cooler air from a further location. It's additional length could also maybe fill in the powerband a bit at the cost of a small bit of intake resistance.

No go. The airbox grommet is ~70mm ID (~2.75") and round, while the snorkel is close in diameter, but elliptical in cross-section -- it won't seal. Not to mention there isn't a way to hold the snorkel in there since the res box outlet is held into the airbox grommet by its mount bolts, and the one on the snorkel doesn't match up with the res mount's. It's as if 7th gen Honda engineers were trying to make kludges difficult to accomplish, but I know that's just my disappointment talking.

What that does mean, is if you can find a 70mm/2.75" OD pipe of some kind, you could plumb your own snorkel. Just make sure the ID of the pipe isn't too thick -- it could strangle your mod (remember decreasing ID on the pipe by half restricts flow 8x more than doubling its length). Maybe a troll in the j/y could find an intake pipe from another car that could work, for those of you with access to a j/y (something I don't have here)...

So, I'll reserve final judgement until I've gone through the next half tank... but it seems more and more just spending the dosh on a proper SRI/CAI si going to be the ticket...

Poopies

iTrader: (4)

ONE OF US! ONE OF US!

M00n3at3r

I've had my car set up this way for probably over a year. I must agree you get a rattle fart which is annoying when jokingly racing people off the line. Going from stock to delete and then back, I've noticed that it seems to rev faster, but agreeably with less tork so until vtech kicks in its kinda unimpressive. Also unimpressively when you have driven a little while acceleration is decreased. Obviously from all the hot air. To an extent I believe deleting the resonator opens more spaces for air to come in and out though. I did not read the whole thread just the first few posts so if I said something already stated, then take it as a ditto.

kinakoes2

Hahaha -- I'm trying my darnedest to figure out a way to make this setup work even close to what you'd be paying even for an ebay tube and filter... and it doesn't look good. Since I filled up this AM and have gone at least another 50 miles today... I'm gonna call it here. But I'd like to mention some things I've tried and learned that jive with the science...

So... the airbox without the res is basically a big 70mm hole in a box with a volume so small, you can barely put a sliced-bread ham & cheese sandwich in there. So really, when the engine tries to draw in more air, it has to do it all through this hole. It's facing a big space in the compartment from the missing res, and air *will* flow right past it, good and hot from passing through the rad.

This creates, if not a true low-pressure situation (exactly the opposite of what you want), a turbulent, dirty, and hot situation -- all not great for making power.

The res not only gives the airbox some pressure waves at the right time to fill in powerband holes... but also holds high-pressure still air as a reservoir. I'd seen this before in sportbikes that keep the stock airbox, and those that go to K&N pod filters, esp on the carbureted ones. The airbox bikes drove off the corner stronger, sooner, and got better fuel economy even at full race pace, than the pod bikes. If you look at a sportbike airbox, they're *huge* compared to the engine they feed -- this is to retain enough higher-pressure air to feed the motor AND tune resonance to fill in holes.

The res on our cars is big -- but it'd be tire-sized if the D17 was tuned to the same hp/liter as frontline sportbikes. Since it's mild (at best ), a smaller one is used, which was good enough to perform both roles, even if at idle it chokes fuel economy out somewhat (it's no surprise that I've gained 2-3 mpg easy, as pumping losses are eliminated... but also are the things that make the D17 responsive and able to get out of its own way (barely)...

So... for those who want an easy way to gain 2-4 mpg on your EX (not sure about the DX/LX, though it can't be that far off), go ahead and res-delete -- it'll make a daily commuter much easier on the wallet. For anyone who wants performance out of the mill... this isn't the way to do it.

--

I did, however, try something different in order to test my assumption that lack of intake velocity is partly responsible for the losses any EX owner feels with a res delete...

At Lowe's I was looking for something else today, and came across the pipe section. I thought, great -- if a 2.75" OD PVC pipe exists, that'd make a great velocity stack for the airbox opening. A joint would be even better, since they flare at one end. I measured a 3" -> 2" plastic reducer... no mas, it was too small and too big to push into that grommet on the airbox. But a rubber 2" joint was perfect -- 72mm vs. 70mm. Thing was though... it's 10mm smaller ID, than the hard plastic airbox stub that OEM-fits there... so there would be a loss in flow. Eh, for $2 I was curious enough!

So I got to the car and sure enough... the rubber tube fit exactly into the grommet, and even 'clicked' when I got it set. So there's a 60mm x 3" tube now instead of just the grommet. Fired her up and drove home...

Yup. It relatively tore off the line compared to the res-out setup and accelerated much better in the low end and lower midrange compared to before, meaning velocity was better and the engine liked trading velocity for pressure in the airbox as it opens up slightly after that tube, right below the filter. But the same gremlins of heat-soaked air and not enough airbox volume worked together to make the powerband even more lumpy than res-out -- the short tube strengthened the engine in the wrong places... so no $2 magic airbox trick that eliminates SRIs. But honestly with today's cars, that rarely happens anymore...

An SRI/CAI gives you a huge tube, with a long length -- that length holds lots of air if it's properly designed (notice that the FIPK has a swell right around the final turn into the TB -- this is to reduce the radius the air has to turn, as well as give a bit more volume close to the TB). So you get the benefit of the lack of resistance with a big pipe, along with the tuned resonance benefit of its length. Wrapped with some glassmat and foil tape, even the plastic FIPK should resist heat-soaking. You can bet I'm going to try!

TL;DR -- res-out weakens your D17A2 but gives you gobs of fuel economy in return, esp in the city. So if you aren't looking for performance but just want to get numbers on the commute... res-out is free and works. The only way to get gains in power, response AND mpg, is to get a proper SRI/CAI with a good filter with lots of filter area. Try and get one that actually filters the air, though... I'm looking at you, K&N.

One last thing... I'm going to try res-in, without the long snorkel to the corner. This should be a good compromise until I give the UPS man my sig in exchange for an FIPK2.

kinakoes2

Yeah, with the airbox hole having direct access to all the hot air collecting in that big space... I suppose unless you fabbed hood vents to get it out, it's going to be there, esp when crawling in traffic...

One thing I didn't make crystal clear to those new readers, is that I have *everything else stock*. No catback exhaust, no header, just removed the res on a completely showroom stock vehicle. Perhaps there may be gains if a header and catback were installed, but if that's the case what a couple hundred more for a good SRI/CAI? Sure you're not going to get B- or K-type gains, but I have no doubt the airbox with a 70mm inlet will make more power, perhaps even more drivable, with a complete exhaust solution. On the other hand, I'd guess and SRI/CAI would net even more.

So... just drove on my Sun errand run with the res-in but that end snorkel off. Yes, my mpg just went down again, yes my shift quality's gone down again, and yes the res box does block airflow through the compartment again. But there are still gains -- my off-idle performance is still much better than with the snorkel, and my shifts, while not as good as res-out, are better than the complete system. I get waaaay better acceleration at any rpm now, no doubt due to the res's... well, resonating.

Can't wait for a FIPK2 and that HHC5019 header. Will need to research alternative filters to the gauze one K&N has (which'll ruin my IAC and coat the inside of my TB and runners). Catback will have to wait until after my car is fully paid off... I wonder how hard it would be to disguise the tip as a stock one... the desired result is pure protein performance in an indistinguishably-stock appearance, w/o the carbs of rice. Need a new sway bar out back as well.

kinakoes2

Oh, one more thing when trying out these induction length experiments on your own: be sure to let the car idle-learn after every change, by letting the car idle, all electrical loads off (A/C, ext/int lights, fan, brakes, etc.) for 10 mins. This allows the PCM to relearn how to best set your off-idle behavior, and you'll get best drivability in return.

I'd forgotten to relearn after replacing my res w/o the snorkel Sun, due to a very busy day running around... and found after a day of sitting Mon, it nearly wouldn't start this AM. Seemed like it'd been shut off at a bad time for the PCM, and was that state when cranking (3 full secs before it'd catch, when it usually takes less than <0.5... about gave me a friggin' embolism ). Was also quite wet this AM, so pressure was low and the car hates to adjust to rain anyway... whew.

After a full 10 mins of relearn this afternoon, running noticeably stronger off-idle (on top of how strong it was vs. the res-delete), and passing power was back. Don't forget to do it.