IW STi Forum banner

1 - 20 of 55 Posts

·
Registered
Joined
·
3 Posts
Discussion Starter #1
The Subaru WRX-STI has gone through a number of changes from the earlier models leading to the latest generation. One of those notable changes to the 2008+ (GRB) STI is the new twin-vein turbo that boosts the maximum 226.9 ft-lbs torque at the wheels just around 3300 RPMs. This is a commendable improvement upon the max 211.7 Ft-Lbs at 4400RPMs produced by the 2007 STI. Since the numbers from the dyno are increased, so are the expectations from those who enjoy tuning their Subarus.

As is common for most factory turbocharged cars, there is a torque lull just after the maximum spike where one might be let down that the initial punch of the STI doesn’t seem to hold throughout the entire RPM range. Often times, when someone just looks at the advertised torque & horsepower gains of performance products, one might over look the other improvements that would be shown in overall performance. If enhancements are made to improve the airflow into the engine, not only will maximum torque rise, but even greater improvements will be noted in the torque curve where the factory setup starts to fall behind. It’s this crucial middle-to-top end of the power band where AEM has capitalized their expertise in modifications with a highly-tuned cold air intake.


The AEM cold air intake for the GRB STI offers a means for the Subaru to maintain the impressive power produced at low RPM range through the entire power band. According to AEM’s dynographs, the cold air intake system provides a maximum gain of 36 horsepower and 35 ft-lbs torque at the wheels of the GRB STI, vastly dwarfing the return of any other intake system for the GRB.

Such results are definitely felt on the road. With the intake installed, up to about 3000 RPM performs just about the same but climbing past that is where a commendable amount of power is freed up. In 4th gear, the acceleration from 3500 to 6000 RPM is over a full second faster with AEM’s intake installed. This responsiveness enables the Subaru to pack quite the punch at freeway speeds. While competing platforms typically walk away from the factory STI at high speeds, the intake enables the GRB to overtake cars that used to see the freeway as its forte.

Aside from the boost in performance, the AEM intake provides an audible difference that intimidates any that recognize the sound of a turbo spooling. The massive 9-inch micron filter is tucked into a compartment in the front-right fender with ducts supplying abundant airflow and allowing the sounds of the intake to be un-muffled. This causes the spool of the intake to scream like a Harrier at anyone along the side of the accelerating Subaru. The sound of the factory recirculation valve is also more vocalized and could even been mistaken for an aftermarket blow-off valve.

A noticeable trait of the intake system’s hardware is the crinkle-red powdercoated piping of the intake. Not only does this match the color of the STI’s intake manifolds but it also repels heat from soaking through the pipe into the intake air charge. Additionally, a heat shield is supplied to separate the air filter’s location from the rest of the engine bay. Beneath the heat shield is the massive Dryflow filter that uses no oils while filtering at an unparalleled 99.52% efficiency, providing the cleanest intake possible at the highest volume possible.

In the past, cold air intakes for turbocharged cars have been under criticism. There were complaints that the increased amount of airflow being measured by the mass airflow (MAF) sensor caused check engine lights. To address this problem, AEM has engineered a housing for the MAF sensor inside the intake piping that retains the same diameter as the factory intake, as well as an airflow straightener that ensures the airflow channels past the MAF sensor accurately. Since the MAF sensor does not see abnormality in the air intake mass, the engine management has no reason to illuminate the check engine light.

If no check engine lights are triggered with a vast increase in performance from a bolt-on upgrade does not sound appealing enough yet, another aspect to consider is that it’s 50-state C.A.R.B. legal. If the local fuzz decides to take a look under the hood after hearing a screaming turbo spool, he’ll be surprised to see there’s no reason for a modified-car ticket. With so many benefits from one enhancement, the AEM intake for the GRB is something that is greatly recommended for anyone with goals ranging from a better-than-stock streetcar to a fully built racecar.
 

·
Registered
Joined
·
59 Posts
According to AEM’s dynographs, the cold air intake system provides a maximum gain of 36 horsepower and 35 ft-lbs torque at the wheels of the GRB STI, vastly dwarfing the return of any other intake system for the GRB.
Reeeeeaaallllly? 36 HP to the wheels? Call me skeptical.
 

·
Registered
Joined
·
580 Posts
This is a review? It sounds like you're quoting sales brochures.

36 hp? :bs: All it is doing is leaning out the tune.

I would like to know if anyone has ever had a stage 2 protune car and then a stage 2 with CAI protuned again. You always see people quoting an OTS stage 2 map versus a CAI with a protune and claiming the gains were the result of the intake.
 

·
Registered
Joined
·
4,332 Posts
:rofl:
 

·
Registered
Joined
·
3 Posts
Discussion Starter #9
I don't work for AEM, I actually work for a tuner magazine and I reviewed the part because AEM hadn't received a buyer's review on it.

Now as far as 36whp, that's according to AEM's dyno images already up on their site, if you think they're lying, ask them about it. All I said was it makes sense because the 2008 STI baseline has a huge power lull at the RPM that the intake provides a power spike. When the baseline curve and the mod-install curve are heading in two different directions, a big difference appears.

THE 36 HP IS NOT THE GAIN OVER MAXIMUM HP. You'll be lucky probably to see 12-15 whp difference between maximum HP numbers.
 

·
Registered
Joined
·
3 Posts
Discussion Starter #10
Does the car need to be "tuned" to run the intake?

I'm at Stage 1 now...all stock except for Cobb AP.
Honestly, the AP does a good job of negating the stock tuning's lack of power after max torque, so you'll see a gain of power, just not as profound as one would see one a completely stock STI.
 

·
Registered
Joined
·
12,474 Posts
I don't work for AEM, I actually work for a tuner magazine and I reviewed the part because AEM hadn't received a buyer's review on it.

Now as far as 36whp, that's according to AEM's dyno images already up on their site, if you think they're lying, ask them about it. All I said was it makes sense because the 2008 STI baseline has a huge power lull at the RPM that the intake provides a power spike. When the baseline curve and the mod-install curve are heading in two different directions, a big difference appears.

THE 36 HP IS NOT THE GAIN OVER MAXIMUM HP. You'll be lucky probably to see 12-15 whp difference between maximum HP numbers.
how did you review it? you just took the info from AEM and copied it.

i have this intake myself, so, i'm a bit surprised by the lack of actual factual info, instead of the sales pitch you can get from the AEM website.

did you install this intake on an sti and do a before/after dyno yourself?


J.
 

·
Registered
Joined
·
630 Posts
I've seen some wacky sh!+ since the economy started tanking. Apparently it's going to get even better. Sit back, enjoy the entertainment.
 

·
Registered
Joined
·
497 Posts
I've seen some wacky sh!+ since the economy started tanking. Apparently it's going to get even better. Sit back, enjoy the entertainment.
Gold, Guns, Bullets, Canned Food, and water. It's all you should be buying.

Me, I don't have a family so I'm going AEM CAI, Cobb AP, and Pink Springs.

I'll wait for Obama's next stimulus for the exhaust and downpipe.

Once Obama starts paying for my health insurance, I'll go to stage 2 and FMIC.
 

·
Registered
Joined
·
582 Posts
Generally speaking, you would ned a tune after installing a CAI to be on the safe side, since the stock tune runs lean and a CAI would make it even leaner.
I wonder why it is that everyone says the stock tune is lean. It is very rich where the CAI would be detrimental. On the high end where absolute compression is high.
The low end where it is lean due to emissions has a low absolute compression and does not really cause engine damage even if it stays lean until a bit after boost starts to build.
A tune would do more damage in general because it leans out the top end while adding boost and timing.
The AEM intake is "ok" on stock tune and the gains advertised are from their prototype unit, not from the production model. The prototype increased boost by almost 2psi and leaned the fuel curve over a point when the peak gain was reported. The production unit sees less gains.
 

·
Registered
Joined
·
4,503 Posts
/\ really?!
 

·
Registered
Joined
·
249 Posts
I wonder why it is that everyone says the stock tune is lean. It is very rich where the CAI would be detrimental. On the high end where absolute compression is high.
The low end where it is lean due to emissions has a low absolute compression and does not really cause engine damage even if it stays lean until a bit after boost starts to build.
A tune would do more damage in general because it leans out the top end while adding boost and timing.
The AEM intake is "ok" on stock tune and the gains advertised are from their prototype unit, not from the production model. The prototype increased boost by almost 2psi and leaned the fuel curve over a point when the peak gain was reported. The production unit sees less gains.
A tune would only do more damage in general, if the tuner did not know what they were doing. You are tuning your car to run better with the new parts.

A tune is recommended with any modification to the intake (even taking the intake silencer out) especially on the GR STi, because of the long term fuel trim logic.
 
1 - 20 of 55 Posts
Top