SPT intake or stock airbox, proof is in the numbers

[ras_sto_99]

I've read over and over that the stock air box is the best intake you can get, I've had a spt intake for a few years and loved it but at times wished I'd kept the stocker, I can now breath easier. I just stumbled onto this, thanks to the folks at Flatirons Tuning, and thought I'd share it.

http://flatironsrally.typepad.com/flatirons_tuning_project_/2006/10/part_5_intakes_.html

[williaty]

Sadly, that test was very badly done. It should in no way be considered proof of anything other than that Flatirons has no clue how to test something. The fact that they were letting IAM change alone completely invalidates their test. Not to mention they made no reference to AFR at any point.

It's just a bad test.

[ras_sto_99]

Good point, I didn't think of that. I'm not to great with the ins and outs of dyno tuning or how the ecu does the IAM changes, but I do think that if Subaru puts a part out that it is probably going to work in your favor, I've had no problems and I can see how some of the other intakes out there can mess with the MAF readings. Wouldn't the IAM change no matter what? To me that just seems like what the car would do anyway.

[573]

As good as the stock air box is, the ricer in me still wants a SPT intake for the sound. I've been going back and forth on this in my head for a while.

[MConte05]

A well tuned car should have the IAM at it's max at all times. The WRX they tested should have had an IAM of 16 no matter what. An IAM of 12 means that it was knocking severely prior.

[ras_sto_99]

I learn something new from you guys everyday, it helps so much.

[williaty]

I've had no problems and I can see how some of the other intakes out there can mess with the MAF readings.
Actually the SPT is well known to be one of the worst out there in terms of screwing up the MAF scaling. Bad MAF scaling results in uncontrolled changes in AFR. If it happened that the SPT intake was skewing that car lean, you'd pick up power but turn the engine into a grenade. That's part of what I mean about that being a half-assed test.

Wouldn't the IAM change no matter what? To me that just seems like what the car would do anyway.
No, as MConte says, a properly tuned car with have an IAM of 16 (or 1.0000 on a newer car) at all times under all conditions, so long as it's being given the correct fuel.

A well tuned car should have the IAM at it's max at all times. The WRX they tested should have had an IAM of 16 no matter what. An IAM of 12 means that it was knocking severely prior.
What's even more scary is that they were doing multiple dyno pulls with an IAM of 0. It's shocking they didn't blow the damned motor.

[ras_sto_99]

wow, I had no idea, would a good tune fix the problem regardless of the intake since they can see what the car's doing on the dyno?

[williaty]

A good tune can run the intake safely. However, our contention is that, for engines making less than 300WHP, the properly tuned stock airbox and a properly tuned SRI/CAI are going to make the same power.

Actually, I've cleaned up some of Flatiron's messes before. I would NEVER take a car there or let someone I know take a car there.

[ras_sto_99]

I'm glad it can be fixed, I've been meaning to get a tune for a while anyway.

[bue car]

i plan to use my spt again when I tune..just cuz it carb legal :)

[wolfman79]

Actually, I've cleaned up some of Flatiron's messes before. I would NEVER take a car there or let someone I know take a car there.

Care to elaborate, since I am going up to see Jon tomorrow.

[williaty]

Care to elaborate, since I am going up to see Jon tomorrow.
Well, best example is a new STi owner that moved into the neighborhood here. She'd never worked on the car herself before, Flatirons had done all the work. There were just a number of dodgy things done to the car that made it a real PITA to help her do service and whatnot. Things that had obviously broken (as things do, nothing special) and then the repair job hadn't been preformed properly. Other places where a mod had been done, but hadn't been done quite right.

If she wants to post with details, she can, but I'm not going to because the last time we talked about it, she was considering actions to get some of her money back and I don't want to get involved in that in any way.

Note that this is also me talking about things that have happened here at the house in my garage. It in no way reflects the opinion of my employer.

[04caliwrx]

I ran the spt with my 18g, now that i have a gt30 i had to have something costume done, but i did like it on my 18g

[ras_sto_99]

now just a day off work and a nice drive to atlanta and I'll be good to go haha

[Moby45]

any intakes worth buying?

[lorenkb]

I've ranted elsewhere about this, so I might as well rant here too...

I wouldn't care if some magical SRI came out that granted +15 WHP over a stock intake (which, lets face it, is not EVER going to happen). I would still prefer a stock intake, simply due to the fact of how well it deals with water and dirt.

Go take your car and play in a huge puddle/lake/mudpit. You will experience, as quite a few here have already, that unboxed/unshielded SRIs are a recipe for soaked MAFs and limp mode.


any intakes worth buying?

The one you bought with your car (AKA stock).

Unless of course you're pushing more than ~300WHP... in which case the question becomes "which tuner should I spend money with after I buy just about any SRI?" Also, see rant above about unshielded/unboxed SRIs :mrgreen:

[ras_sto_99]

will sealing up the holes in the fender from the stock intake get rid of most of the water/mud/dirt problems? Or are there any easy ways to shield it?

[williaty]

The problem for an SRI comes from the hood scoop and the shut line between the hood and fender.

[A1337STI]

first off, your factory intake is "cold air" and the SPT intake is technically a "hot air" intake. your factory intake is also ram air (to a small degree) as a high pressure zone builds up around your radiator and the intake allows some air to try and flow Above the radiator and into the air intake.

cold air intake just means you are sucking in non engine compartment Air (air that will be hotter due to being around the hot motor)

A friend of with a ESP Tuned WRX on the stock turbo is making about 310 TQ and 295 HP on the stock turbo. His tuner has said he has never seen anyone on the Stock turbo being limited by the stock breather box. in fact even people with the stock turbo on the STI won't need to swap out intakes to avoid being HP limited. *to the best of my knowledge*

If you have an upgraded turbo that can pull in some searious CFM you'll need to upgrade, short of that you don't need to at all.


now moving past just "what does the data show me" there are lots of reasons to go full on cold air / short ram air intakes.

Looks
sounds
compatibility with off the shelf maps
great deal on said part
future long term plans

:)

[ras_sto_99]

I'm glad I now have a better understanding. Lucky for me I'm getting a tune this friday to go with my shiny new vf43 ;-)

[lorenkb]

will sealing up the holes in the fender from the stock intake get rid of most of the water/mud/dirt problems? Or are there any easy ways to shield it?

It may help a little, but it doesn't help enough. All of the holes on my apron panels on that side are taped over. SPT intake still sucks water.

[ras_sto_99]

hmmm, I guess I'll just have to live with the fact that it might happen and try to stay out of the deep stuff.

[wolfman79]

hmmm, I guess I'll just have to live with the fact that it might happen and try to stay out of the deep stuff.

With the SPT intake on my FXT the only time it had issues with water was in 12+ inches of water at speed. Won't be doing that again regardless of my intake.

[SilverSleeper04]

i have the cobb sri and cobb cold air box along with a sock on the filter. so i still have the elbow piece and that ram air scoop thing up front installed. it's plenty protected if you ask me

[ras_sto_99]

Well thanks to all of you for your input and wisdom, that matched with the tuning skill and wisdom of Scott over at Forged Performance, he was able to pull 301 whp and 288wtq. Not too bad if you ask me.

[Nateclimb]

good info!