cold air intake

legacy92ej22t · Post by **legacy92ej22t** » Thu Dec 12, 2002 1:47 am

does anyone know if all these cold air intakes,like dragon ect..,will actually bolt right on to the legacy turbo?every time i do a search for the turbo legacy it comes up with multiple intakes thata are supposed to work but never here of anyone using them.

Post by **Legacy777** » Thu Dec 12, 2002 3:30 pm

You'll soon learn....if you haven't already....."simply bolt on" and "legacy" don't go well in the same sentance. I don't believe there is an intake out there that works well with the turbo legacy. I custom did one on my legacy n/a, however have since taken it off in favor of the stock air box for the time being.

mile hi · Post by **mile hi** » Fri Dec 13, 2002 4:36 am

I custom built one for my Turbo Legacy motor in my'95 Impreza coupe but I haven't seen any bolt on cold air intakes for the turbo models and as Josh said bolt-on can be a rather vague term meaning it might work. A friend of mine runs a Motorcycle shop and in his suppliers catalogs they say "fits most bk's". He has determined that this means "fits most Buick's"
AL(CO)

LegacyT · Post by **LegacyT** » Fri Dec 13, 2002 11:34 am

I think cold air's are more for under hood looks and sound than performance. with the stock airbox, you get plenty of hp and torque. put on a cold air and your low end torque will diminish. A friend of mine dynoed his WRX with and without a cold air, turned out he had 2 more hp and 7 ft/lbs more torque on the stock airbox with the stock air filter than with a cold air and a K&N mushroom filter. Even Sti modified Subaru's come with stock airboxs, not cold air. Besides stock your already pulling cold air from the fender.

Just my 2 cents,
Mark

IggDawg · Post by **IggDawg** » Sat Jan 04, 2003 11:37 pm

If our EJ22t ECUs are at all the same as WRX ECUs, there's a problem. The reason WRXs run better with stock airboxes and silencers is that they have a correction factor built in that is applied after all the MAF and O2 sensor data. the correction factor takes the stock airbox, silencer, and all the plumbing into effect. As a result, removing all this screws with the fuel mixture esp. in closed loop mode. the only reson I still have my silencer off is so I can hear my turbo and recirc valve

.

Shik · Post by **Shik** » Tue Jan 21, 2003 12:50 pm

The Maf sensor on the Legacy Turbo works differently then the WRX's. The WRX MAF is very small and only takes a sample of all the air coming in, which, as was mentioned, must take into account piping diamter,length, etc to get a good reading of the air that is actually in there.

The Legacy turbo MAF monitors all the air that passes through it, if memory serves me correct. So what happens before it is meaningless and will not affect the ECU in any way, unlike the WRX.

FWIW, I noticed little to no gain with an intake on my turbo vs stock airbox with a K&N. Although, maybe a bigger turbo/more boost would have a different effect.

vrg3 · Post by **vrg3** » Tue Jan 21, 2003 2:21 pm

I'm not sure exactly how the WRX's MAF sensor measures air through only a portion of the flow, but...

The Legacy Turbo MAF is a hot-wire type sensor, so it doesn't actually put a heating element in front of all the air; there's only a tiny pair of wires near the center of the sensor. I believe that if you were to make the airflow non-homogeneous through the MAF sensor housing, you'd end up with a bad reading, since it only measures the flow at one portion of the cross section. I'll try to get a picture of this, if I don't forget like I usually do.

IggDawg · Post by **IggDawg** » Tue Jan 21, 2003 4:22 pm

Shik wrote:The Maf sensor on the Legacy Turbo works differently then the WRX's. The WRX MAF is very small and only takes a sample of all the air coming in, which, as was mentioned, must take into account piping diamter,length, etc to get a good reading of the air that is actually in there.

The Legacy turbo MAF monitors all the air that passes through it, if memory serves me correct. So what happens before it is meaningless and will not affect the ECU in any way, unlike the WRX.

FWIW, I noticed little to no gain with an intake on my turbo vs stock airbox with a K&N. Although, maybe a bigger turbo/more boost would have a different effect.

Wow. I totally didn't know that. thanks for the info. I'd give you IggPoints, but they're no good here

. how robust are ours with respect to WRX MAFs? are they as prone to getting blown?

IggDawg · Post by **IggDawg** » Tue Jan 21, 2003 4:25 pm

vrg3 wrote:I'm not sure exactly how the WRX's MAF sensor measures air through only a portion of the flow, but...

The Legacy Turbo MAF is a hot-wire type sensor, so it doesn't actually put a heating element in front of all the air; there's only a tiny pair of wires near the center of the sensor. I believe that if you were to make the airflow non-homogeneous through the MAF sensor housing, you'd end up with a bad reading, since it only measures the flow at one portion of the cross section. I'll try to get a picture of this, if I don't forget like I usually do.

That's counterintuitive tho

. look how the MAF is hooked up to the airbox. The velocit of the air is going to make the flow very heterogeneous. The air pulls a very sharp corner just before the MAF. That being said tho, it seems that it wouldn't matter what happens before the airbox since that sharp curve has such an impact on flow anyways. unless you actually change where the air comes into the airbox, it seems like the flow density cross section would be proportional.

vrg3 · Post by **vrg3** » Tue Jan 21, 2003 4:25 pm

Our MAFs are hot wire, which are generally more sturdy than the hot film ones. The early Impreza RSes had problems with their original hot film sensors, and the new replacements are hot wire.

vrg3 · Post by **vrg3** » Tue Jan 21, 2003 4:27 pm

IggDawg wrote:That's counterintuitive tho :confused: . look how the MAF is hooked up to the airbox. The velocit of the air is going to make the flow very heterogeneous. The air pulls a very sharp corner just before the MAF.

Hmm, you are right. Maybe the ECU is designed to take that particular type of heterogeneity into account then?

IggDawg · Post by **IggDawg** » Tue Jan 21, 2003 4:36 pm

I remember reading an article on "the library" at the legacycentral site where some aussies introduced a new intake point into the airbox. between this and fabbing a custom piece of nice wide piping for that pre-turbo resonator chamber, they got .6 seconds on their 0-60. They mounted a pipe on the front side fo the airbox. it seems to me that this would help smooth out the flow thorugh the MAF. or it could just be the extra airflow. that bend before the MAF always messed with my head... why they didn't just make it straight is beyond me. that suggests a purpose, but I can't figure what it would be for the life of me.

Post by **Legacy777** » Wed Jan 22, 2003 3:05 am

There are several things subaru did originally.....and I'm not sure if they continued to do so with the legacy that helped the heterogeneous mix problem.

I'll show you exhibit A

Pic of my stock air box:

The metal piece there is a nozzle, its more common name is a velocity stack. What it does is help smooth and speed up the air as it goes from a larger 'infinite' volume to a smaller 'fixed' volume.

I think one of the reasons subaru decided to make the box like this and have a smaller volume directly in front of the intake/MAF was to create back pressure there to help create a more equal pressure gradiant acrosse the opening.

Example.....take a straw, nozzle, or tube about the size of your finger or whatever.....blow through it.......air comes out fairly easily...depending on the size of the tube. Now move your finger in front of the tube.....not blocking it, but just enough to create some back pressure. The air will be coming out around your finger with more equal pressure at all the openings to atmosphere.

I had written Al about an intake idea I had......I think it is a good idea.....just not sure there is enough room to do it, and to fab all the parts.

I'll search through my emails and post.......

In all honesty....intake design will touch a lot of bases, fluids is probably one of the more fundamental ones......

legacycentral bbs

A forum for 89-94 BC-BF(BJ) Legacy Owners and Fans

cold air intake

cold air intake