Low Boost, Catback questions

[RETed]

Originally Posted by Boostmaniac

Something was bothering me though about the turbo. I see absolutely no boost until 4k RPMs. This was in dead stock trim with a ghetto cat back install. I haven't verified this yet, but I assume the twin scroll is still completely functioning. At what RPM do you guys start to see boost in your S4 TII's? (I am swapping the turbo out for an S5 turbo and manifold in very good condition to see if this fixes any of my issues.)

I bet that "ghette cat back" was too restrictive.
Boost is also relative to engine load.
1st gear pull is not going to have as much boost as a 5th gear pull.
In general, the turbo starts to make positive pressure in the 2,500RPM range.
The twin scroll acutator kicks in at around 2,800RPM.
It should be making full boost by 4kRPM.
S5 turbo can make positive boost as low as 2,000RPM.

Second, I have an 80mm Corksport DP and MP I just installed (to see if cat clogging was the culprit to my boost woes.) and I was wondering if the RB Rev TII Y pipe and Rev TII dual exhausts would bolt up to my configuration. I love the sound of the RB units and was curious if I could save money by just having them bolt up to my current configuration instead of also having to buy the RB DP and MP also.

I'd be surprised if it does.
The "Rev" spec exhaust is supposed to be proprietary, so it doesn't match with any of the stock "breaks".


-Ted

[Boostmaniac]

Originally Posted by RETed

I bet that "ghette cat back" was too restrictive.
Boost is also relative to engine load.
1st gear pull is not going to have as much boost as a 5th gear pull.
In general, the turbo starts to make positive pressure in the 2,500RPM range.
The twin scroll acutator kicks in at around 2,800RPM.
It should be making full boost by 4kRPM.
S5 turbo can make positive boost as low as 2,000RPM.


I'd be surprised if it does.
The "Rev" spec exhaust is supposed to be proprietary, so it doesn't match with any of the stock "breaks".


-Ted

Yeah, the ghetto catback was some knockoff N1's.

All of my boost woes happened in any gear at full load. I didn't even start seeing positive pressure until 3800 or above (using a mechanical boost gauge). I do have a dyno from a baseline pull I did and it is a little obvious when you are looking at it. Hopefully this S5 turbo takes care of the issue. Positive pressure in the 2k range would make my year!!!

On the exhaust.... damn. Guess I am gonna have to get the whole thing then

[RETed]

Be sure there's no leaks...
Intake leaks can cause loss of boost too.
Does the car make loud PSSSSSSSSHHHHHHHH noises when it's boosting?


-Ted

[Boostmaniac]

Originally Posted by RETed

Be sure there's no leaks...
Intake leaks can cause loss of boost too.
Does the car make loud PSSSSSSSSHHHHHHHH noises when it's boosting?


-Ted

To the best of my knowledge, I have 0 intake leaks. There is no boost leak I can hear while in boost, and I have thoroughly checked for intake leaks since replacing my TID. I should get my new calipers in today and be able to swap out the turbo while I am under there. I just want to have some more low end power than the nothing I have right now. I just picked up an FCD for testing purposes so I guess I'll check it all out if I am lucky enough to get it all in.

Also, I have checked timing and stabbed the CAS appropriately. My timing is literally spot on.