14b + downpipe question

[Matts95TSiAWD]

2.5inch or 3.inch? my mechanic says 2.5 for some backpressure, but i was under the impression that no backpressure is best for turbo vehicles...

please help !!

 

[2-0turbo]

2.5inch or 3.inch? my mechanic says 2.5 for some backpressure, but i was under the impression that no backpressure is best for turbo vehicles...

please help !!

You are right--Bigger is better. Your mechanic is thinking NA applications (which I don't feel need backpressure either--a big fallacy). You'll not see much performance difference between the two, to be really honest. Just remember that a 2.5" mandrel bent downpipe will flow more air than a 3" pressbent. Keep that in mind when you click "buy."

 

[Matts95TSiAWD]

i think its all mandrel bent whether 2.5 or 3

but hes saying 2.5 dp attached to a 3 inch back w/no cat and a "stock looking" muffler

 

[Eastwood95]

what he said is correct. On a 14b turbo, you're not gonna see a big difference between a 2.5 and 3" downpipe. Actually, i prefer the the 2.5 downpipe, then 3" after the downpipe all the way back thru a straight thru muffler. Best flow is key to power, but if you want it quiet, get it resonated, and get a different stlye muffler. Definately go with a mandrel bent downpipe though.

 

[DSM90AWD]

Remember that a 3" DP + Internal gate = Boost Creep without proper porting of the W/G inlet. So if you do go with a full 3" system, make sure you take care of that at the same time and you'll be good-2-go

 

[Matts95TSiAWD]

so my best bet would be stick with the 2.5" mandrel DP into a 3inch back to the muffler in order to control boost creep... ? i dont think it will hurt the flow really anyway... can a 14b outflow a 2.5" mandrel dp?

 

[LessIsMore]

A 2.5" in exhaust will cause your internaly gated 14B/16G to creep like a bi***.

Don't think that going with a 2.5" downpipe will eliminate any chances of creep, it won't. Here's a few examples of my car w/ 2.5" turboback and TD05H turbos,

stock 14B, creep to 20psi by 5k rpm
mild port 14b, creep to 20psi by 6k rpm
34mm flapper/ mild port 16g, creep to 20 psi by 6K rpm
34mm flapper/ extreme port 16g, holds 15psi to redline

If you want to avoid boost creep do it the right way, port the shit out of your 14B and 02 housing. If you want to avoid boost creep the cheap and easy way, run a cat or stock downpipe.

With that being said a 2.5" mandrel bent downpipe will handle anything and everything a 14B and even a 16G will throw at it.

My suggestion is to go 2.5" from the turbo to flex section then 3" the rest of the way. 2.5" off the turbo will allow for easy bolt up to the 02 housing and no oil filter clearance problems.

 

[DSM90AWD]

so my best bet would be stick with the 2.5" mandrel DP into a 3inch back to the muffler in order to control boost creep... ?

It's an option, one that I took 10 years ago and have never had boost creep on a 14B, 16G or 50-trim (all internally gated). But, if you properly port the turbo, you can run a 3" without problems too.

i dont think it will hurt the flow really anyway... can a 14b outflow a 2.5" mandrel dp?

It won't hurt flow much, and no, a 14B cannot outflow a 2.5" mandrel DP

 

[Eastwood95]

He brought up a very good point about boost creep that i have to agree with. Boost creep will more than likely be an issue. I would go ahead and prepare for it. Port the stock o2 housing (especially the wastegate area) and get a bigger flapper. Or buy a new(bigger) o2 housing with a bigger flapper already installed. Team Rip Engineering sells the flappers for cheap, assuming you'll want to stay internally gated.

 

[Matts95TSiAWD]

now define what i should be looking for in this boost creep... what will i notice...

 

[noz]

now define what i should be looking for in this boost creep... what will i notice...

you will notice that if you set your mbc to 10-15psi, it will probably hold til 4.5k-5k and then the boost will keep on building as your rpm raises. if you are on stock fuel, you are most likely to hit fuel cut.
this is for my 16g, not sure about the 14b

 

[danielbui]

mine was worse than a creep with stock 14b, 2.5 o2 housing, 2.5 dp bottle nosed to 3inch, then a 3inch catback. i would sit at the light drop the hammer it would keep rising 20+ psi and stick uintil i let off the gas. you can feel power at 15psi then it would fall on its face after that in the 20+ psi range. not worth having until the turbo is properly ported. make it stick @ 15psi and you'll have a good time.

 

[2GeNTSi]

My car stays at 15psi, no spiking or creeping that I notice. I had a 3" downpipe on but I removed it so it's just the stock downpipe with a 3" catback. Even with the downpipe, I didn't notice the boost varying.

 

[Talon96tsiAWD]

i have a ported 14b, 2.5" stainless o2 housing with wastegate dump, 3" turbo-back, no spike or creep, I can set it to whatever and it holds there.

 

[BOOSTIN21]

yeah i too am a little confused here. i have a 14b that was ported inside the turbine housing near the wheel and towards the o2 housing, the turbo is also ported where the exhaust manifold meets the turboi have a fully ported EVO 3 o2 housing, the collector on the EVO 3 manifold is also ported. i only have money to start building an exhaust. i have a buschur 3" DP and testpipe no cat-back though will i see boost creep with this or should i go bigger flapper. i have Profec Spec II controlling boost. so what should i expect here.

 

[Talon96tsiAWD]

you'll be fine. If you have an o2 housing thats ported out nicely, especially the evo3, keeping the wastegate gasses inside is ok. Now if you had a stock o2 housing and ported it out, i would say just spend the 75 bucks and buy an o2 dump like i did.