DmcL

well after having bought an ebay CAI a while back and not fitting it i got tired of looking at it and rather than pull my bumper off to install the full thing i cut down the end of the section that the MAF mounts in to allow me to squeeze in an old HKS mushroom filter i had laying around and run it as a short ram intake for the time being/for testing and ease of reverting back to the airbox if needs be.

im a newbie to subaru mapping but im a seasoned vet mapping old BMW's and have plenty of mapped turbo conversions under my belt as well as modded n/a setups all the way down to standard.

so.. i broke out my innovate LM-1 and put it on the car for about 3 days a couple weeks ago and drove around as normal, to/from work, etc, etc. and kept an eye on the AFR's at operating temp idle readings were around 14.5 AFR give or take 0.2 or so. at full throttle AFR's were between 12.5-ish and 10.5-ish, little leaner prior to boost coming on.

so i swapped the airbox and standard rubber intake pipe for the alloy intake pipe and my old HKS shroom. put the wideband back on the car and took it for a drive. idle AFR's are the same as before and full throttle AFR's are also near identical though it does seem to be running ever so slightly leaner though so far the most i have noticed is maybe like 0.2 AFR max so for comparisons sake AFR's remain the same before/after as on my 06 WRX atleast it ran very rich standard so even assuming a 0.2 AFR leaner mixture thats still in the mid to low 11's or still in the mid 10's higher up the RPM's. transitioning from no boost to spooling to full boost gradually richens the mixture as before and there are no lean spikes suggesting fuel not increasing quick enough to keep up with the turbo spool or anything like that. noticed no jerkyness, hesitation or any signs of knock and im running a mix of tesco 95 octane and go 97 octane if you want to split hairs.

the intake pipework is the same diameter as the original intake hose, shares a similar S shape and has the MAF placed in more or less the same position and in a straight section of the intake pipe. i will continue to keep an eye on my AFR's over the next half a week or so but i dont expect to see anything that would give me any cause for concern tbh.

i will report back in a few days to confirm whether AFR's remain as they are or if any changes develop but my initial observation is that its perfectly safe running an intake prividing the MAF is in the same location and the pipe diameter is the same as the original intake hose.

Blue by You

iTrader: (23)

If you are going to alter the air flow characteristics of your engine it makes sense to take measurements of the AFR readings, amongst other things.
I don't see any myth busting though. It's no 'myth' that altering the air flow through an engine will require corrections to fueling and ignition settings. The changes you have obviously not altered the air flow significantly enough to require other changes to be made to cope with that.
You say you used an 'old' filter. Is that old as in dirty (unlikely I know), or old as in purchased a long time ago? If all you have done is effectively replace your original filter with a clean one, that is what anyone does when servicing their car, and they don't need a remap for that.
Just because the changes you made haven't caused a problem with your particular set up, doesn't mean the next guy to try it will get away with it.

DmcL

im not saying people shouldnt map for an intake, just saying it appears that an intake with the same diameter as the original rubber intake pipe with the MAF in basically the same location seems to function perfectly normal and not cause any changes in AFR worth mentioning. whether the tune is ideal for the new intake is another matter entirely (it wouldnt be, but to what extent you wouldnt know until tuning it).

the myth im looking to disprove is that any intake requires a tune as so many people like to regurgitate to newbies or people looking to fit an intake.

by old filter i mean one i had laying around that was previously in my old bmw 325i for space reasons (the shroom filter is very compact). it was bought new before that FWIW. its visually darker on the outside than inside as it has done some milage but its not overly dirty.

id say even a dirty filter in an intake will alter airflow characteristics from a standard airbox.. not sure about your reference to effectively changing only an air filter as the intake pipe is internaly smooth and would be a marginally larger ID as its alloy so wall is thinner than the OEM rubber hose and it haslt got the flex ribs at either end.

also FWIW i have/had an HKS panel filter in the airbox prior to fitting the short ram so filter material is essentially the same on the intake as it was in the airbox.

what im saying is that it looks like you can safely install an intake providing the OD of the intake matches the OEM intake hose and doesnt put the MAF sensor on a bend or in a different location from where it was originally. i know tune wise its not going to be running as best it could but for is it safe to fit then so far id say yes unless i see different AFR's over the next few days.

besides, we all know an intake really isnt necessary as the airbox can handly a good amount of power so the majority who havent got a highly modded setup (which would be mapped anyway) would be buying an intake for the sound or if not too technically minded or green behind the ears may think it will add some power. plus if i was really wanting to go whole hog id also be checking MAF output before/after as well as AFR which i could do but tbh with an intake of the same diameter for the sake of arguement then i know the airflow characteristics wont change that much.

depending if im near a dyno at some point in the near-ish future and ave a little cash to spare i may try and get a couple back to back runs with this short ram vs the airbox for fun and giggles.

Butty

iTrader: (2)

I suggest you also log the MAF air flow along with AFR with both set ups. That may surprise you.
When was the LM-1 oxygen sensor last calibrated/ how old is it?

Alan Jeffery

The stock airbox is good up to the sort of flow levels that give 350 bhp (ish). After 350 bhp most would be looking at a front mount intercooler in which case the stock box would have to go anyway.
For the small gains and possible losses I see no point in fitting some old Ebay crap.
If one can't be bothered to set a car up properly, one shouldn't mess with it in the first place.

DmcL

oh i know MAF output will be a bit different and that there isnt much point of an intake over the airbox for typical sub 400hp-ish setups. i just fancied seeing how much water the old "you must tune for an intake or your engine will implode" story holds. i am/will be setting the car up properly, this is just a little experiment to keep me amused for a bit. also the wideband was recalibrated before use though thats not strictly necessary according to innovate but i like to play safe. the sensor hasnt seen loads of use so readings would be accurate as i dont run it on a car all the time. its only used when checking, logging in conjuncton with the LMA-2 and some other bits or tuning. also FWIW readings are being taken from the tailpipe with the innovate attachment for using it in the tailpipe so AFR's mentioned above will be reading leaner than they actually are by about 0.5AFR or so given the car has cats in the exhaust so it still runs as stonkingly rich as it did originally.

i have experience messing with airflow related maps in the old BMW's as have tuned for a larger OEM flap type airflow meter from scratch as well as building/wiring/tuning from scratch for a MAF conversion or two on the old cars as well so im fully aware of how something small can require a good bit of work to properly tune for but that wasnt the reason for this thread, it was literally only to see if the no tune = imploding engine story people regurgitate holds water, which for a standard sized intake at least, does not. lets not forget that i am an established tuner, allbeit not for subaru but i may tune my own and potentially branch into it at a later date so i do know a thing or two in general and about how ECU's work in general as well as manufacturers utilising different setups such as torque based, speed density, alpha n, etc, etc, etc. as such i will admit i dont know everything about everything as no one does and any good tuner will admit the more they learn the less they find they know, or atleast tuners who arent stapled to one specific brand/software/hardware type. my site is ethosmotorsports.com if you want a look though its somewhat content limited as recently set up a new site, etc.

also there is nothing wrong with ebay parts as such.. the problem is with badly designed or low quality parts that often flood ebay. as long as you know what your looking for/at then theres nothing wrong with ebay stuff. an example would be the intake i bought for like 50 quid. its basically a direct copy of another brand name CAI, i forget which off hand but i looked into it and it is a like for like copy just without the big brand price tag.

my 3 inch catback also came from ebay. its toyosport branded but its the same generic 3 inch catback you can buy from china. bends are all mandrel bends and fitment is pretty damn good for a 150 quid catback though i did have to introduce 2 strategically placed dents to avoid potential rubbing on the edge of a bracket and in another place under the car but for 150 quid vs the price of a branded 3 inch catback id happily smack it with a hammer twice.

Alan Jeffery

It might have been better if you didn't infer that replacing the stock intake system with a completely unknown one without bothering to check the tuning is ok as it most certainly isn't. Every MAF based system is prone to this.
Myth Busted? No. By all means post your own findings of course! tuning your own car is just fine.

alcazar

iTrader: (2)

"Yeah, go ahead dudes...it worked on my RS Turbo, why would a Scoob engine be any different?.........."

DmcL

you can install intakes on most MAF equipped cars without retuning the ECU. yes its a different kettle of fish on n/a cars generally speaking but providing the intake pipe is the same diameter as the original part then it should be safe enough. this is most likely why cobb, k&n, etc, etc. state you dont need a tune to run their intake as it matches the oem diameter and places the MAF sensor in the same location.

if the tuning was horrendously off id see signs of it in the AFR readings. perhaps a small lean dip before the ECU picks it up and corrects, etc.

i know where your coming from though. any intake change will mess with the MAF readings, how much so depends on many factors but that wasnt the point of my thread. i wanted to prove or disprove if you can run a standard diameter intake without tuning and so far it looks like its perfecly safe to do so. is it ideal, probably not but safe enough then it seems yes it is. so for the likes of same diameter short ram intakes or the cobb/k&n same diameter intakes stating safe for stock tune then id be inclined to believe what they say. just dont get me started on the bogus HP claims lol

i will try and get on a dyno sometime to run a back to back just for the sake of it to see exactly what, if any difference there is. i previously ran 256bhp/262lbft with 3 inch catback and HKS panel so if im near that dyno again ill see if i can get a better rate than paying for 2 runs and do one on the intake and one with the airbox reinstalled.

btw, slightly off topic but i see you work with ecutek/simtek. is there any way to get a tune but not have the ECU locked so i could go back in at a later date and tweak some stuff myself via romraider or ecuflash? i dont know enough to comfortable tune the engine from standard myself but if i got a tune for say a TD05 and STi pinks or similar and then added some small bits and peices id be ok with making smaller adjustments for things like that. the car is my DD hence not wanting to dive into tuning an unfamiliar setup head first.

i figure a pro tune for lack of a better word word might yeild better results than a verified good opensource tune to which id have to essentially build the engine to match the spec of the tune.

DmcL

act your age, not your shoe size

Aaron1978

iTrader: (12)

He buys his shoes in France and is a size 50

dabiscuit

So no point in an induction kit till how much bhp? 400?

DmcL

there is likely no golden number to say when you need an intake but it seems fromwhat i have read up from various people/tuners/etc that the standard box is good for 350-400 or there abouts.

i dont know if there would be any benefits to running a well designed intake over an airbox below that threshold but its something i wouldnt mind finding out as i have built my own intake setups on most of my previous cars and a good cold air or ram air intake has always bested the standard airbox in my experience so id like to think that might be the same with a scoob also but my previous setups were all on n/a cars so the scoob being turbo may prove different. theoretically speaking cooler air is denser and results in a bigger bang assuming your fuelling correctly for it so you would think it shouldnt matter what HP your at or whether turbo or not.

there is a big ifference between having some benefit and actually being necessary though..

dabiscuit

I have noticed from looking at multiple engine upgrade packages that induction kits aren't part of the package till the 400bhp mark.

I might get one anyway as it looks and sounds cool

DmcL

i havent looked into any kits/packages but 400 sounds about right from what i hear from others. i think if properly tuned you may see some slight improvements regardless of HP purely for an intake being a more straightforward system for air to get from the filter to the turbo but it would probably be so little you wouldnt really even notice.

just got back in from a good hours worth of driving with my intake and wideband in the car. still no deviation from readings i was seeing yesterday. this time i wasnt as hesitant to put the foot down and did multiple 2nd to 4th or 3rd to beginning of 5th pulls as well as a few quick 1, 2, 3's and planting it from low revs in 4th/5th. leanest im seeing while deliberately trying to catch the car/ECU off guard so to speak is about 13.6 at about 0.4 bar of boost if i gradually increase throttle to slowly spool the turbo. i was able to hold it at the 13.6 AFR region at 0.4ish bar and noticed no adverse effects. also bearing in mind im measuring from the tailpipe of my catback with all standard cats still in place so that 13.6 reading would be more like 13 AFR or so if measured ahead of the cats. if i pin the throttle from there it instantly drops to a nice rich mixture and boost increases to peak as normal.

so anyway, so far so good and nothing out of the ordinary going on.

not sure if its a placebo effect of the spool noise or an actual improvement but i could swear it pulls a little harder in the lower gears before its on full boost, seems to me like it feels a little sharper on a 1, 2 ,3 sprint. definately want to see if i can get it on the dyno for a comparison to see if its just my imagination or not. i may dust off my gtech pro RR and do a couple pulls on the intake and one the airbox with that as atleast that would let me know if im imagining it or not.

providing readings dont change in the coming days im going to look about making a carbon fibre shield/box for it. have done something similar out of perspex previously for a past car of mine so shouldnt be too hard and should reduce intake temps and look nice and clean. may even set about building boxed/shielded short ram intakes to sell on as the layout for the newage WRX is a peice of cake compared to other cars i have built/sold a run of intakes for.

New_scooby_04

iTrader: (4)

How many people check their AFRs? What tends to happen is:

1) Joe "I want a gazillion bhp for 50p" Blogs gets suckered in by an intake kit on fleabay
2) Gets kit installed having been assured it'll be fine by someone else who fitted a different kit to a different car or had different mods
3) Joe Rags it
4) Engine says "Byeeeeee"
5) Gets on line to say Impreza engines have chocolate pistons etc.....

The message here is that if you make any changes that could affect your cars intake of air and fuel, you should get the AFRs checked out to make sure it's safe NOT "you can fit x and you'll be ok!"

What I always say to people when reading these posts is to think about who pays if the information you read about lead you to do something that put you seriously out of pocket?
Ns04

Fat Boy

Da biscuit please compare the self proclaimed knowledge of the OP who, with a seriously limited statical base, declares that it's all a myth, with the view of Alan Jeffrey who has mapped and built literally thousands of Subarus and who has an excellent reputation.

I know who I would rather listen to.

Aaron1978

iTrader: (12)

Don't leave us hanging, who?

Blue by You

iTrader: (23)

+1

daveyj

iTrader: (1)

Having had a cheap generic CAI Kit fitted to mine when I bought it and subsequently reverting back to an OEM setup, the difference to the car's performance/fuel consumption was night and day. OEM setup was far better in terms of how smooth the engine was and how well it boosted too. I'd be sticking with OEM and a JR Panel Filter all day long on my relatively standard vehicle. Was certainly not an experiment I needed a wideband for. I think a lot of induction kits are overrated. Sound great but that's not really seen as a positive if the drive suffers imo.

Alan Jeffery

There's nothing wrong with what the OP (Don't know his name!) is actually doing. He's fitted something to his car and he's taking the trouble to check it out. I'm just pointing out that not all of it can be extrapolated onto someone else's car.
Good on him for posting his results!

Alan Jeffery

We tend to pick up at around 350 bhp plus when it comes to air filters. It's a fact that a lot of chaps are fitting front mounts at that time which ties it all in together.
Don't forget the only reason for fitting a "higher flow" air filter is if you find that your OE system is restricting the flow of air. That applies across the tuning world of course. Fitting one just 'cause it sounds good isn't an engineer's solution!

Blue by You

iTrader: (23)

Absolutely agree with that Alan.
However to entitle the thread as 'Myth Busting' is misleading for the uninitiated, and not everybody has access to the right equipment or the knowledge to know what it's for.

dabiscuit

At the risk of throwing a spanner into the works, does the ram aid feed make much difference? When I had some money I had a 2010 WRX STI, I fitted a HKS induction kit and took it to Simon at Jolly Green Monster, with the map it went from 295 to 337. With the kit adding about 24 of those extra 42 horses. Not my words his, well thats what the computer read out was anyway. And I was advised to remove the ram air feed.

Now I have less money and I really don't know what to do to get relatively "cheap" power increases. New filter, no ram feed/with feed, induction kit no feed/with feed.

I have a headache

Alan Jeffery

We'd expect to see those figures (ish) from a remap, filter or no filter.
Without a true back to back, God knows.

Blue by You

iTrader: (23)

Favourite modding quote - "Cheap, fast and reliable. Pick two."

DmcL

i never said everyone can run an intake safely.. as said i an a tuner myself though not of subaru so i know enough to be tinkering with this sort of stuff safely. i never once recommended anyone else do what i am doing. i did, however, state that by my personal experience here a standard diameter short ram intake should be ok but notice i also made no garauntees as it may be fine on my particular setup or one similar but may be the polar opposite when someone adds X part or parts into the mix.

the thread was intended to be an observation and perhaps change peoples blind "you need a map to run an intake" statements something slightly more fitting to the facts. maybe something like you can run some intakes depending on certain variables but if you dont know what your doing best leave it to a pro and get it mapped. i have a pet hate for people behaving like sheep and taking things for gospel without looking much into it, that behavior on large scales such as on here then ends up creating hordes of people that know best and know for a fact when they may have read a horror story and one tuners opinion then decide they are informed enough to advise others which knock on and on and on. people in the old BMW motronic and aftermarket ECU tuning scene kept telling me i couldnt do half the stuff i then went and did for the same reason so i have learned to take everything with a pinch of salt and to check something out myself personally if i want a definate answer.

im just stating my observations based on my own personal findings here (and playing a bit of devils advocate). if your a tool and stick a 3 inch intake on your untuned car and blow the engine its your own fault. i am merely supplying information that some folks may or may not find useful. i opted for the thread title as i knew it would draw attention and not be overlooked

@ dabiscuit, a ram air intake will always outperform any other intake so long as its not more restrictive than a shorter intake setup. assuming 3 intakes with the same amount of intake restriction then a short ram intake would perform the worst as it draws the most warm air, a shielded short ram may perform a little better but many shielded kits are gimmicks or dont block out enough heat to make any real difference. a cold air intake will perform better as it draws cool air from an area away from engine bay heat. a ram air intake will perform the best as it draws cold air like a cold air intake but also is sealed before the filter so as the car moves air is essentially forced into the intake by the movement of the car.

i personally tested those 3 intake setups on my old 325i and with a short ram type intake i noticed X AFR at full throttle in basically all gears. with a cold air intake readings were a little leaner which shows me the engine is getting more oxygen into the mixture due to the cooler air. with a ram air intake i noticed similar AFR's as the cold air intake in lower gears but interestingly i also saw AFR's getting leaner with each gear above 2nd gear while the car was moving so the faster the car went the more air was rammed into the intake basically. a ram air intake works in much the same way as the standard TMIC and hood sxcoop.. the scoop seals to the TMIC and forces air through it, faster you go, the more air is forced through in theory..

a good ram air intake will require a sealed air filter or airbox with a sealed air feed from the box to a relatively unobstructed area at the front of the car or perhaps to a naca duct on the bonnet. now we could get into best locations for placement based on aerodynamics but that would require lots of testing, etc, etc. on a hawk eye a good place for a ram air intake feed would be the fog light hole in the bumper. you would have to live without fog lights but it would make an ideal spot for a ram feed to a sealed box or filter.

@blue by you, thats one of the best modding related saying out there and rings true 99.9% of the time, however, it doesnt mean you cant build an intake, for example, that performs as good or better than say a cosworth intake at a fraction of the cost, or potentially buy one if you know what your doing and know what your looking at. this is why i bought a no frills cheap ebay intake because a oem diameter alloy pipe with MAF bung is an alloy pipe with a MAF bung, regardless of if it costs 10 or 100. the only thing im not 100% happy about on the intake is the crappy filter (i expected id change it before ordering anyway) and i notice a little roughness where the MAF bung is welded to the pipe in the small recessed part of the hole that was cut in the pipe prior to welding on the bung. i can easily smooth this off with a dremel/rotary too though.

jazzyjembreaze

iTrader: (11)

Forgive me if I'm wrong but most of your words sound scripted .esp the ( short ram explanation , did you pick it up from a manufacture statement or a thread on NASIOC
The part I don't get is ? Why would you want to stick a short ram onto a stock engine -or any caik , the stock air box works just fine , sure I can see your toying with diff panel filters looking for AFR fluctuations with diff brands . But trying out big filtration without proper adjustments will lead to tragedy , melted spark plugs & holed pistons spring to mind

Good luck on your quest ( I still haven't worked out what your trying to achieve

DmcL

nowt scripted..

not trying to achieve anything, just playing, learning, etc because i can. i agree the airbox works just fine, it would take more than a short ram to improve over the airbox. sure may gain a marginal bit somewhere but on the whole the box would be better unless your at a point where the box becomes a restriction.

if i was after gains from intake tweaking id either be doing a cold air or ram air intake and mapping or replace the snorkus on the airbox with a velocity stack into the front wing as have seen like 4 dyno comparisons of that done on seperate cars ranging from minimal mods to mid 300hp sort of numbers, possibly one nearer 400 and all showed gains across alot of the RPM range after replacing the snorkus with a V stack into the inner wing.

BTW that SAI valve is still going sweetly, i have the dreaded headlight level dash light on at the minute tho so thats another can of worms to be opened soon.