how much more boost have you gotton with your intake?

tonight comming home i got to 93kpa withc is 13.4 psi

the weather was 0c

 

my friend got 13.6 psi whit an injen intake

 

what intake you got?

 

I was hitting 13-13.5 with my Injen before stage 2. Tonight i just hit 15.6 with the intake and stage 2.

 

injen

 

i didnt think an intake would produce more boost...make sure ur cat's arent clogged causing the additional boost. i could be wrong tho

 

i dunno i never use to get it pasted 80 kpa till the intake...

 

i boost 90kpa before and after the injen intake...no change for me

 

still bosst the same other than it seems to boost a little quicker.

 

Mine starting the extra boost the same day i installed the intake. I doubt that the cat could have gotten clog that fast from the intake or that the cat became clogged the same day just by coincidence.

 

It could still be your Cat. Let me explain...

Air comes into your SC through the intake. If there is a restriction in the intake (that's the suction side of the SC) it will limit boost. Now, you just installed the better flowing intake, so the restiction moves downsteam to the Cat (that's on the discharge side of the SC). This will create more backpressure in the exhaust, hence bigger boost #'s.

Keep in mind that there will always be a bottleneck, unless you can design a perfectly balanced Intake/SC/Engine/Exhaust system. Just not gunna happen. All you did was move the bottleneck to the next restrictive area (the exhaust).

I think you might realize a nice performance improvement by freeing up the exhaust.

 

I agree that the exhaust is what is causing the higher boost to be seen cause of the more air coming into the supercharger via the intake. This in no way means that the cat is clogged. Obviously more air in + same air out = more boost seen. If the cat were clogged i would have been seeing more than a 0.5-1 psi increase (the 13.5 i stated was probably a very high estimate), as Darksun has stated in his thread on overboosting he was seeing at least a 2-2.5 psi increase. The 15.6 i am seeing now with stage 2 and the intake is only 0.6 higher than others with stage 2. I will see what happens to the boost sometime this week when i get my exhaust installed, it should drop some as you have said.

 

yeah if anything the boost should go down as there is more air being disperssed. this doesnot mean a loss of power tho.

 

air intake doesnt equal boost sorry to disappoint

it only allows air to enter the engine easier quicker and more efficient, resulting in more hp not boost

 

I never said "clogged." I mearly pointed out that the Cat (or other exhaust component) could be causing the increased boost #'s after the intake upgrade. Will be interesting to see what you boost #'s do once your exhaust is installed.

 

You make the mistake of thinking the boost gauge is measuring only the effect of the SC. But here, you are wrong. The gauge is only a pressure measurement taken at the discharge-side of the SC and its readings ARE affected by exhaust restrictions. Try sticking a potato, with a 1 1/2" hole through it, in your tailpipe and see what your gauge does (not really reccomended, but hopefully gets my point across).

 

ok with that said ^ your boost would be lowered so are you agreeing or disagreeing. because if you have a free flow of air then the pressure is going to DECREASE not increase. sticking a potatoe in the exhaust tip is just like having a clog cat. so i hope you are agreeing.

 

Oh boy...now I've done it!

Ok, for the short answer: Freeing up a restriction on the intake side could increase your boost gauge reading because of restrictions in your exhaust. Of course, if your exhaust is sufficiently large, you wont see any change. Now, if you get rid of any exhaust restictions, your boost #'s should go down because your SC and engine aren't having to fight as much to get the "air" out.

Now for the full story (this is gunna get ugly):

Let's look at the major players in our "air" flow system. You have:

- Intake (possible restiction)
- Supercharger (neglecting "intercooler") (Pump)
---> Boost gauge goes here
- Engine (pump and restiction)
- Exhaust system (possible restriction)

Keep in mind that the boost gauge is reading pressure relative to atmospheric pressure.

If you put a pressure gauge on the intake and monitored it while pinching off
the intake (like what a restiction would do), you'd see the intake gauge go negative. This is because the SC is trying to suck air through the restiction and creating a vacuum.

The Superchager is a pump (or fan if you like) that's capable of increasing the pressure by a fixed amount (let's say 10 psi for this example). This fixed pressure increase is from the suction side of the SC to the discharge side. OK, so let's say we have a 2 psi restiction in our intake. This would mean that the suction side of the SC is at -2 psi releative to atmospheric. Now our Supercharger increases that by 10 psi, resulting in a boost gauge reading of only 8 psi.

So, any restiction in the intake side of the SC is really just moving the staring point of the SC negative (relative to atmospheric), resulting in a lower boost reading. Hence, freeing up this restiction should increase the boost values. Of couse I don't think our stock intakes are not nearly that restictive, so changes in the boost #'s going to a better intake shouldn't be that dramatic.

 

If you are bringing air into the engine more freely than stock, without taking ti out more efficiently, the supercharger is going to be placing more air into the engine than it normally would hence....more boost. Now given it shouldn't be much and no-one here is claiming much (about 0.5 psi).

The only reason i said clogged was that was a possible explanation to the extra boost, which was where my comment was directed. I completely agree that the cat could be a major source of restriction causing the higher boost level. A few people on here have removed thier cats and seen teh boost drop 1-2 psi.

 

Yah, Yah!