De-snorkal a NA car?

ciper · Post by **ciper** » Sat Jun 14, 2008 9:04 pm

I always wondered why Subaru would have put so much effort into designing such a complicated intake part that was before the filter and MAF.

I also get a kick out of the idea that even the newer Subarus are essentially the same cars as ours. The "Legacy" lives on heh

BXSS · Post by **BXSS** » Sat Jun 14, 2008 11:08 pm

To reduce noise.

I guess BC Legacys are not as smart as OBDII Imprezas.
The wifes cars runs fine (for 1+ years now since snorkectomy) & started chirping the tires on WOT starts (fwd auto) after the snorkectomy.....

The WOT sounds are a bit much for a 17 second car, but it runs well & is no longer a 18 second car.

Soul Shinobi · Post by **Soul Shinobi** » Sat Jun 14, 2008 11:12 pm

I was so surprised the difference it made, I got a bit excited there.

But the whole rev range really is smoother with the snorkus in, the engine is more civil. I do miss the higher top end power though. I think this graph illustrates pretty well how and why power delivery is less smooth; MAF voltage:

Source

I'm considering making one of those hybrid intakes now, but aluminum isn't the greatest material. I think smooth as stock MAF voltage could be had if I could make a hybrid intake out of a similar plastic as the stock one, just removing the accordion piece, more or less. The reason I think a soft plastic (like stock) would be much better than aluminum is because aluminum doesn't absorb vibrations, most likely causing the more excited MAF voltages seen above.

Post by **Legacy777** » Tue Jun 17, 2008 5:14 pm

What was the alpha reading doing? Or did you check it?

I'm still not convinced the issue posted on NASIOC is the same issue experienced here on the first gen legacies.

I honestly think that most if not all of the issues stem from the MAF sensor not accurately reading the air entering the engine. The snorkel and how the airbox are designed are done to help improve the accuracy of the MAF, by means of flow restriction.

If the car was retuned with a stand alone using an open intake or removing the snorkel, I think you wouldn't have the problem....

Soul Shinobi · Post by **Soul Shinobi** » Tue Jun 17, 2008 6:51 pm

So you're saying the issue with my car is due to truly erratic air flow confusing the MAF while the one on NASIOC has to do with resonant interference with the MAF?

I didn't check the alpha. I'll check the Fuel Trim (alpha) today.

Post by **Legacy777** » Tue Jun 17, 2008 6:56 pm

More or less....yes that's what I'm saying.

The reasons I'm saying that are because our ECU's don't stay in closed loop much, so the direct measurement they did can't be done with our ECU's.

It's very possible the two issues are related, I guess I'm just not convinced they are.

evolutionmovement · Post by **evolutionmovement** » Tue Jun 17, 2008 6:58 pm

I never had any issues, though I kept the stock airbox hole and just replaced the snorkel with an intake hose (same diameter as hole/former snorkel) that opens to a NACA duct in the front bumper. Only time I ever had hesitation issues was when the intake was clogged from punching through snowbanks. Which makes me wonder - does the WOT hesitation you guys are experiencing only happen from a stop? Could the engine be pulling too much air from the semi-closed space of the fender too quickly?

My Mazda3 with it's bullshit electronic throttle bogs when you stomp it from idle. I have to pump the throttle to get it to move quickly off the line and beat the bog. It's one of the reasons I want to go back to old Subarus.

Soul Shinobi · Post by **Soul Shinobi** » Fri Jun 20, 2008 5:44 am

I really don't know what to make of my ECU readings at this point. I'm suspicious my O2 sensor's on its last legs, which might be making this difficult.

SILINC3R · Post by **SILINC3R** » Tue Feb 17, 2009 6:14 am

ok so im trying to catch up here. was your readings Soul Shinobi that having the stock intake was better than than doing anything to it. i have done 3 different levels of intake design on my 89 Leg. first got rid of the box and dropped a cone filter in.
Then i put the cone filter in the fender with various hoses an tubes. so good increase, was able to pull 100 in 4th. wasnt able to do it previous desing. and tonight i put in all aluminum tubing. havent finished yet have to put the little hoses into the piping somehow i need these correct? im just hoping i didnt do this for nothing. if i did i may just run down to the pull a part and grab a stock air box and every thing. here are my pics for reference

http://picasaweb.google.com/silinc3r/IntakeDesign#

Tony

Soul Shinobi · Post by **Soul Shinobi** » Tue Feb 17, 2009 1:18 pm

You certainly will get power gains, as you have noticed. However there is a trade off. Those aftermarket oiled filter can get your MAF dirty and they don't filter as well. Also, without the snorkus the car may bog severely if you give it a lot of gas below 1,500 RPM.

Those little hoses are very important. They're for your PCV (Positive Crankcase Ventilation) system, which brings fresh air into the inside of the engine to remove acidic gasses and moisture.

Referring back to tests of williaty from NASIOC again (link), leaving the intake entirely stock except replacing the corrugated piece between the MAF and throttle body with a straight pipe has proven to give roughly 80% to 90% of the gains with none of the drawbacks.

SILINC3R · Post by **SILINC3R** » Wed Feb 18, 2009 1:22 am

well here is my go at it

http://picasaweb.google.com/silinc3r/IntakeDesign#

Soul Shinobi · Post by **Soul Shinobi** » Wed Feb 18, 2009 1:40 am

Where did you get the parts?

SILINC3R · Post by **SILINC3R** » Wed Feb 18, 2009 1:52 am

baught the piping off ebay, just 3'' intercooler tubing. was about 100 dollars with shipping included. came with 2 straights, 2 close to 90s, 2 about 45s , and 2 more pipes i belive. plus the blue things(couplers) and all the ring clamps(not sure what to call them). only used like 2 pipes though. it was worth it. once i got thing going, i would run into problems like fittment and what not. then came the hoses. was stuck there, tried to cut the plastic ones off and use though but that i knew wouldnt hold. so today i spent about 2 hours at Home depot trieng to find some kind of epoxy to seal the hoses which i ended up not even using cause the guy that i finally got a hold of after searching for some one that could tig weld( took me like 2 hours to find someone) told me he could just weld in bongs, bungs. dont know what the correct word is. this made it easier to install hose fittings. just screw them in and i was good to go.

James614 · Post by **James614** » Thu Feb 19, 2009 9:09 pm

You N/A guys have it too damn easy with intake plumbing....

Soul Shinobi · Post by **Soul Shinobi** » Thu Feb 19, 2009 11:45 pm

Yeah.

The newer turbo Subarus aren't bad really.

SILINC3R · Post by **SILINC3R** » Fri Feb 20, 2009 12:21 am

James614 wrote:You N/A guys have it too damn easy with intake plumbing....

you TURBO guys have it so easy with your horsepower.

Soul Shinobi · Post by **Soul Shinobi** » Fri Feb 20, 2009 12:22 am

Here-here. Well put.

supra90turbo · Post by **supra90turbo** » Tue Mar 24, 2009 5:58 pm

The bogging is a pain in the ass, but on the same day, with the same conditions, and the same car, the stock airbox w/snorkel vs. cone filter was a .2 second difference at the dragstrip.

The car was a 95 Legacy Brighton Wagon.

Be that as it may, 17.1 is still slow, but it's a little faster than 17.3, and still really funny.

SPUMONI_RT · Post by **SPUMONI_RT** » Thu Jun 11, 2009 7:10 pm

What if you have the filter down in the fender?
If you have a much longer intake tube you stack the airflow. I have seen some post with 3" exhaust tubing ran down into the fender.
When I was younger I hacked up my intake and shortened it with a homemade ram air. So I was forced to customize again to get a better intake. Also i'm planning some ram air through the turnsignal light. 91 N/A bumper.
But that includes some electrical mods too. So basically does this "stacking" effect work?

amdrunner · Post by **amdrunner** » Fri Jun 19, 2009 2:41 am

In the NASIOC post, he said that he wasn't sure whether it applies to earlier gen Legacy's.

...so has anyone found this issue with 91 Legacy's? I was just considering doing a de-snorkus on mine and now I'm not sure whether it would that great of an idea.

Suigintou · Post by **Suigintou** » Thu Sep 24, 2009 9:41 pm

(EDIT) Nevermind. Did some review of the stock intake and like its been said, pretty well made. Even some of the stock tube is usable I think. Maybe cut it at the bend before the throttle body? and another cut in the bend just after the maf, and install a straight piece of Alu/PVC to join the two sections. Eh, no biggie.

Buffman · Post by **Buffman** » Thu Sep 24, 2009 10:55 pm

Do they offer cheap CAI's for the N/A Subie? I'd like to rid myself of the airbox to TB tube, but don't want spend a fortune.

SILINC3R · Post by **SILINC3R** » Tue Nov 16, 2010 3:39 am

SPUMONI_RT wrote:What if you have the filter down in the fender?
If you have a much longer intake tube you stack the airflow. I have seen some post with 3" exhaust tubing ran down into the fender.
When I was younger I hacked up my intake and shortened it with a homemade ram air. So I was forced to customize again to get a better intake. Also i'm planning some ram air through the turnsignal light. 91 N/A bumper.
But that includes some electrical mods too. So basically does this "stacking" effect work?

Buffman wrote:Do they offer cheap CAI's for the N/A Subie? I'd like to rid myself of the airbox to TB tube, but don't want spend a fortune.

bringing this back from the dead to answear some questions. did yall bother to look at my picture of my CAI which goes into the fender. the piping cost 100 bucks from ebay. still cheaper than buy an after market HKS intake for 200 bucks and is like only a foot long.

evolutionmovement · Post by **evolutionmovement** » Tue Nov 16, 2010 3:58 am

Or yous makes your own:

IIRC, the NACA duct was $25 and the hose that leads to the air box was under $10.

samurai · Post by **samurai** » Wed Nov 17, 2010 10:07 pm

Hi i'm new here and i just bought a 92 auto sedan...i have a Cone intake from my last car (auto zone specter i think) and was debating about putting it on before the MAf and taking the box off...i was reading through the posts and i'm kinda confused....so...is it pretty much a bad idea to do this then? From what i read it seems like if i put it on...it bogs and it's bad but then i read posts where it's been showing gains and no problems....also what about doing something like a Safari rally car with the Air intake up on the side of the A pillar?

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De-snorkal a NA car?

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