Cobb Stg2 W/k&n Typhoon Sr Air Intake - Subaru WRX Forum
 
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#1 Old 10-12-2008, 12:58 AM
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Cobb Stg2 W/k&n Typhoon Sr Air Intake

Hello all. Please advise.

I have just installed Cobb Stg2 w/K&N Typhoon Short Ram Air Intake.
Some of my findings as compared to when I only had Cobb Stg1 installed are very different from before.

- At first WOT application boost now jumps to 18.4psi then drops a few psi then slowly increases again as RPMs rise in any gear.
- At WOT depending on RPM there is a fluttering sound of air.
- At WOT then gear change depending on RPM it sounds as though I have a vent to atmosphere BOV.

I don't have anyone else to ask as Subies aren't the most common vehicles in my area. I'd just like to know if the above are normal? I've checked all connections for leaks and went the extra mile to have the exhaust installed professionally. Cobb programming is the most up to date. I did install the air intake myself though.

Also, I'm looking into purchasing an unequal length header. Will there be any appreciable gains since Cobb does not have a program that I am aware taking into account headers?

Thanks in advance.
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#2 Old 10-12-2008, 01:39 AM
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The AP's not designed to use with that intake. Take that thing off and put the stock intake back on. It should fix your problems.

And I assume you do have a downpipe on the car?

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#3 Old 10-12-2008, 10:35 AM
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DP with a single CAT. So no way making the intake work on the car? Maybe with a dyno tunned new map?
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#4 Old 10-12-2008, 10:59 AM
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The only two intakes that work pretty well with Cobb's AP maps are: SPT Short Ram and Cobb Short Ram. Your other option is to keep your stock intake and use a high flow K&N panel style air filter and doing the intake silencer delete mod if you want more sound (GP Moto makes a plastic elbow to replace your intake silencer or you can make your own piece). If I were you, I'd try to sell the K&N Typhoon intake on eBay and get a few bucks for it to put toward whatever other setup you decide to go with.

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#5 Old 10-12-2008, 11:32 AM
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Maybe with a dyno tunned new map?
Yes.The sounds do sound normal for an intake.

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#6 Old 10-12-2008, 12:12 PM
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Even with a dyno tune you may experience some loss of performance with the intake. Mod the stock box as MOSC and Man Show said and you will make the same horsepower with out the problems. Sell it and pay for the elbow, KN filter and a nice steak diner for yourself.
I think the reason MOSC asked about your DP is it sounds like you may be getting boost creep. Newer STi's have a different wastegate setup that cures that problem. Since you still have a cat it might not be creep at all, but boost usually tapers toward redline. Something to keep a eye on. A solutions for the creep is wastegate porting.
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#7 Old 10-13-2008, 02:24 AM
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I've compared the intakes mentioned; the SPT and the Cobb. I was planning on purchasing one of those two except the K&N was more readily available. The only differences I found between those intakes and the K&N was that they reuse the crinkle bent plastic tubing while the K&N replaces that portion with a mandrel bent pipe. Could the reason why I'm having the boost concerns be caused by just this? The K&N Typhoon intake is just a short ram just the same as the other two and with a heat shield as well.

I changed my AP map to the (STG2 91 LWG) and it seems to have first of all reduced my peak boost to 17.8psi. Also without actually staring at it while driving at WOT cause I'm the only one in the vehicle; the boost doesn't seem to jump up, go back down again and then climb back up again with the RPM. Is it possible that this has solved the concern? Was it really something to be that concerned about also? What were to happen if I left the boost to spike up to 18.4, catastrophic engine failure?

BTW, anyone have any thoughts regarding my hopes for headers?
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#8 Old 10-13-2008, 09:31 AM
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K&N usually make a quality product so it may not fall in to the same category as some intakes that cause serious problems. Some intakes use a different diameter tubing at the point where the MAF plugs in (causing inaccurate readings) and most aftermarket intakes cause turbulence at certain RPMs across the MAF. This turbulence can not always be duplicated on the dyno so it is impossible to totally tune around. This is why SPT and Cobb have earned a good reputation in the Subaru community. They don't mess the car up, they don't really help performance either but spending money to get a slower car is nonsense.
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#9 Old 10-13-2008, 10:33 AM
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The problem with the K&N intake is exactly that mandrel bent piece of pipe. It creates turbulence across the MAF sensor unlike the factor, Cobb, or SPT intake systems. No, the K&N is not as bad as some. It's not a CAI with horribly funky bends and it does maintain the stock MAF housing diameter. I think what you found out is that using a map that is less agressive, you are supplying enough extra fuel to smooth things out. You could probably switch back to the other map if you put back on the factory intake.

Your stock headers are more than sufficient for a stock turbo. If you go with a larger turbo, you might consider this:
GrimmSpeed

More expensive options include APS's catalog of replacements which replace the factory header with a twin scroll header. You'll also probably be using their turbo, their intercooler, turbo inlet, and their intake. This is serious bucks but it's an awesome setup.

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#10 Old 10-13-2008, 11:12 AM
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So the consensus is that I remove the intake then. Thanks for all the information.
Any thoughts on what I should get instead, that doesn't break the bank?
I was inquiring aswell on headers; it was actually going to be the last upgrade I was going to do until something actually broke. I love this car!
Anyone, have any further input on headers? Maybe I shouldn't bother changing that because of negligible power gains on its own?
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#11 Old 10-13-2008, 11:17 AM
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Quote:
Originally Posted by mlemjs View Post
I've compared the intakes mentioned; the SPT and the Cobb. I was planning on purchasing one of those two except the K&N was more readily available. The only differences I found between those intakes and the K&N was that they reuse the crinkle bent plastic tubing while the K&N replaces that portion with a mandrel bent pipe. Could the reason why I'm having the boost concerns be caused by just this?
No.That would only effect AFR's

Quote:
Originally Posted by mlemjs View Post
I changed my AP map to the (STG2 91 LWG) and it seems to have first of all reduced my peak boost to 17.8psi. Also without actually staring at it while driving at WOT cause I'm the only one in the vehicle; the boost doesn't seem to jump up, go back down again and then climb back up again with the RPM. Is it possible that this has solved the concern? Was it really something to be that concerned about also? What were to happen if I left the boost to spike up to 18.4, catastrophic engine failure?
LEARN TO READ THE MAP NOTES PEOPLE!!!!!!!.The is a reason the AP maps come with map notes.And yes a boost spike can cause problems,more so in the winter when the air is denser.

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