MAF adapter

[93TurboLegacy]

does anybody know if they make an adapter plate that fits on the end of the MAF so I can put my cone filter on.

[keirnna]

Yes Autozone should sell one.

[Legacy777]

You probably won't find a subaru specific one at autozone.

Boxer4racing sells one

http://www.boxer4racing.com/motor.htm

[keirnna]

You don't need a subaru specific one there are a bunch of universal adapters there. you just take your MAF and check to see which one will work.

[RJ93SS]

be carefull having your maf so close to your filter, you want your filter to be away from your maf because a filter is going to cause turbulence which your maf really will not like, i believe that it would be best to have your maf after a long strait piece of pipe so that air can be stacked in the system before it hits your maf, you also do not want any reducers just before the maf because they cause alot of turbulence, our system could defintely be improved, also remember that an elbow in the system causes air to tumble which is definitely not something you want close to your maf.

i was at a ford place the other day and they dynoed some svt stangs with different intakes and 1 guy that had a reducer just before his maf lost 20 horse over the stock system because of the turbulence.

if anything i post is incorrect please forgive me Thanks, Ryan

[Richard]

And with a cone filter inside the engine bay, you're sucking in hot engine bay air, not the cool, dense air from outside that you want. So you may be doing alot to gain nothing, I'm afraid.

[asc_up]

Unless you can route the cone filter into the fender.

[keirnna]

And with a cone filter inside the engine bay, you're sucking in hot engine bay air, not the cool, dense air from outside that you want. So you may be doing alot to gain nothing, I'm afraid.

CAI are over rated. I will post some scientific information on this here a little later, but even the WRC cars used an under hood intake for a long time. The density of the air at the MAF is not proportionally representative of the density of the charge air. What is the hottest thing under your hood? The turbo, where is all of your inlet air passing through? The turbo, so all of your air is being super heated, hence the necessity of an intercooler on most turbo cars. The intercooler is what makes your air more dense and cools it. Even then it is impossible for it to be colder than ambient air.

To me this makes sense in the same way that not using SAE correction on FI cars when dynoed. Ambient air tempuratures are not directly scalable to charge air tempuratures. Now in an NA car you would not want an under air intake.

[Legacy777]

You don't need a subaru specific one there are a bunch of universal adapters there. you just take your MAF and check to see which one will work.

You can probably get close with a universal one, but you'll probably need to do some modification to the holes to get everything lined up with the MAF sensor.

[Legacy777]

And with a cone filter inside the engine bay, you're sucking in hot engine bay air, not the cool, dense air from outside that you want. So you may be doing alot to gain nothing, I'm afraid.

CAI are over rated. I will post some scientific information on this here a little later, but even the WRC cars used an under hood intake for a long time. The density of the air at the MAF is not proportionally representative of the density of the charge air. What is the hottest thing under your hood? The turbo, where is all of your inlet air passing through? The turbo, so all of your air is being super heated, hence the necessity of an intercooler on most turbo cars. The intercooler is what makes your air more dense and cools it. Even then it is impossible for it to be colder than ambient air.

To me this makes sense in the same way that not using SAE correction on FI cars when dynoed. Ambient air tempuratures are not directly scalable to charge air tempuratures. Now in an NA car you would not want an under air intake.

I think we're all more or less in agreement CAI's can cause you more headaches then they're worth. However I got lost in your post. You jump around a bit.

Yes, the intake air will heat up when it passes through the turbo. However on the turbo legacy, the system is a closed loop system. The MAF sensor measures the MASS of the air going into the engine. Air density really doesn't matter. You can heat, cool, compress, etc a given mass of air, and it's still going to burn with the appropriate mass of fuel.

Regarding ambient temps, you can do a rough calculation to get air charge temps. The system is a closed loop system, and you can look at it as a constant volume process at specific engine load/rpm/boost level, so you get the equation:
T2 = T1 * (P2/P1) (which came from the ideal gas law)

If you use the following values

P1 = 14.696 psia
P2 = 26.696 psia (12 psi of boost)
T1 = 70 deg F

You get a T2 = 127.1584 deg F

If you raise T1 to 100 deg F (under hood air temps)

You get a T2 = 181.6549 deg F

The point I'm trying to make, which may be the same as what you're trying to say is that even if you have an intercooler, which if large enough can take the charge temps down to a specific outlet temp, it's having to work much harder to cool 181 degree air vs. cooling 127 degree air. So even on a turbo charged vehicle, cool intake air does matter.

[RJ93SS]

josh, i think you got it on the money, thanks for correcting that false info that some of us may have believed!

[BXSS]

T1 on the second example will probably be closer to 120*, but your point was clearly illustrated!

The old HKS EVC manual I have says that once charge temps hit 210* power output will not increase & the chance of detonation increases alot.

[keirnna]

Sorry if my post was a bit confusing. I will let this info sum it up for me:

[keirnna]

Also another funny thing is I have never seen a Subaru here with a CAI.

[skid542]

There are a few true CAI's floating around here with the cone filter tucked up under the fender.

The article posted does show the difference between a true CAI and an engine bay mounted intake - for a naturally aspirated motor. The article mentions increased efficiency of the intercooler due to a greater temp differential, it does not mention that despite the greater efficiency - the air will still leave hotter for the 'pod' vs CAI.

However, Josh's point about the temp rise through the turbo is neglected in the article. This point is very valid.

I would venture a very large wager that you don't see CAI on rally cars because of how often the fenders get crushed and how often they drive through large puddles. You crush the fender with your intake in it and it won't lead to anything good.... Not to mention the performance difference can easily be overcome with another pound of boost.

A true properly executed CAI will out perform the engine mounted filter. The pressure drop, aka drag, associated with the extra piping will be negligable if the CAI is plumbed smoothly.

[555BCTurbo]

I think Josh hit the nail on the head

[Legacy777]

Thanks for posting the article.

While the article isn't necessarily incorrect, I think there's some points that were omitted.

It's talking about the WRX, yet is using a normally aspirated engine in the example.

Temperature increase across the turbo is not linear. A 30 degree change in intake air temp does not give you a 30 degree change in turbo outlet air temps. It gives you almost a 55 degree change in turbo outlet air temps.

The other main thing I would have liked to see in the article is how they calculated that the pod filter flows more then 9.9 more then the CAI or stock intake.

If that's the case, if you add an additional opening to the bottom of the air box or enlarge the stock opening....you should be increasing flow through the stock filter AND still injesting "cold" air.

[keirnna]

Me I will never replace the stock box if I don't have to, but I've yet to see a FMIC that would let me keep it.

[jefferson]

CAI really should be HAI if you ask me. They have been mislabeled.

I love flow, but not at the expense of temperature.

Thanks Josh for the info. You start cooler you end up cooler.

Jeff

[James614]

CAI really should be HAI if you ask me. They have been mislabeled.

Correction: the $500 kits for 1.6L Toyota Echos that have $80 of materials in the box are mis-labeled. CAIs are pure cash cows, the majority of them are ricer trash quickly tossed together to look shiny in your engine bay and rake in profits because kids with '88 Accords are too clueless to know better. The correct labeling would be: "Engine Dressup Kit: Shiney Overpriced Garbage Look-a-Like Kit; fits all Hyundai and Festiva"

K&N doesn't even call their kits (which come with butter-smooth piping custom molded for each application, and properly box off the filter from the engine bay.... and are matte black) cold-air intakes, no-doubt due to the ricer trash that everyone associates them with.