I totally agree. I tested a 2.25" hose w/a 2.25" x 75mm Y-Pipe due to this theory in hopes of improved response and found it dulled my car down a bit and I went back to the 2.5" hose & 2.5" x 75mm Y-Pipe. I tried larger than 2.5" and felt it created too much volume to fill and reduced response time. I like the 2.5" system for a car with upgraded turbos and high boost, it's completely smooth and uniform for the entire intake path with no humps or neck downs like the OEM IC's and Y-Pipe have at each OEM fitting and flows/dynos very well. My car is super responsive with it and runs beautifully. Of course, it is not mandatory, but if you are trying to maximize your highly modified car, I think it's one of the final tweaks to a complete package.

 

You clever little man you, you discovered that everything that is not OEM is a scam and does not actually increase performance

 

I mean what is wrong with you Peyton Manning? At least I have offered some information based on science unlike you and you "I'm 99% sure" crap. I actually do have some limited expertise in flow dynamics, but no Peyton Manning.

I'm not saying no aftermarket parts increase performance. Obviously aftermarket turbos are great as are other items. If your turbo outlet is 2 inches you can't flow more than what that allows out. even then it needs to be a relatively laminar flow. Your smallest diameter in the entire system is your limiting factor.

A 3 inch y pipe is a gimmick and you just don't need it. And while the diameter of even the OEM stuff is fine I expect it could be smoothed out to some degree. While I'm not going to sit down and do any math I expect 2.25 is just fine for any give 2" turbo out.

 

Hey,After all these theories of velocity , volume and size restrictions in the intake plumbing>>I just saw a Intake Plenum from a 997.2 turbo and guess what??
Porsche made the plenum a smaller diameter in the part of the T that connects to each bank of cylinders...Its smaller diameter then our 996 Turbos and smaller then the TB diameter...The Porsche tech says they did the same on the new 997 GT-2...

 

Bad107 and pumptech, how much HP are you all making? I ask because you all make it seem like this stuff is just easily done and nobody knows what they are doing but you all?

 

Powell I asked a simple question that no one seems to have a good answer for. Why don't you answer my question????

 

You make a ton of horsepower on stock y pipe. What were your turbo outlet sizes when you used stock intake? What are they now?

 

I did... I explained why I have the one I have. If you two think it's good to do a 2.5" based tubing then by all means go for it. Would I have gone 4" or some massive number? No because in the end you run into a point where you have to big of a pipe for a little amount of air.

Nobody has a gun to you alls head for this. I'm a firm believer in seeing things done myself and not trusting EVERY word spoken. Just like people thinking the a SET amount of boost will a blow a number regardless of turbo size is beyond me.

Regardless every time you post a "question" you just look for a reason to argue and same with pumptech. If this game is so easy please just get it done and shut everyone up. I can tell you from experience there is a point you hit where it's not so simple anymore.

Just getting tired of it being made like people are idiots and just don't have it figured it like you all.

 

And FYI I made 666rwhp on a stock Y-Pipe, etc... When I went to the Boost Logic kit I added the Y-Pipe because I added TiAL BOV's and fender mounted intakes. I am sure we could have ghetto rigged the car with some kind of janky mount and used the stock Y-Pipe with 2x TiAL 50mm's but we didn't want it to look horrible.

I made 1150rwhp on C23 at 38psi with some boost related issues on a STOCK 997TT T-Pipe and TB. I added a IPD and 82mm TB but we are at a point where we are maxing out the GTX3582's with an .82 a/r. 1200rwhp would have been the cutting point but on C23 vs E85 I'd rather have 1100rwhp on E85 then 1200rwhp on C23 because drivability is better. My plan for the weekend is to drain the rest of the C23 and replace plugs and some couplers and go back to E85.

 

I'm making a full 415 at the flywheel according to Porsche. And I don't ask questions looking to argue but do love to argue if there is discussion to be had. In fact, I have not really posted many technical questions and have really only argued comments of jitsu (who was just chewed up and spit out in the EVOS IC thread for making crap up) who only regergitates facts and to a lesser extent BHT because he takes jitsu's position.

But like bad107 said nobody has an answer that supports the use of anything larger than the turbo out. While I am no physics major, I not only have significant experience in flow dynamics but have taught classes on it in the past as it relates to blood flow. I think I prompted bad107 to ask this question after teasing him about his big pipe. I'm not claiming anything is easy. Most anything is easier said than done!

It's not theory but fact. Il say it again. You cannot flow more than the smallest diameter in the entire system allows. This unfortunately for most is the turbo out at 2" or less. Based on this you don't need anything significantly larger than this throughout the system. Anything large enough to fit the lip of the turbo out is enough. If you want to add a little diameter (2.25) for friction loss seen from the length of the system so be it. But remember air coming out of IC is denser than going in so I expect this negates that need. Again keeping thing smooth, free of size transition, and laminar is key!

But to think that you need 2.5" hoses and a 3" Y pipe is just money down the tube (no pun intended) and at a certain size may even be detrimental to flow and velocity. Nobody has to take this to the bank but it's food for thought before making upgrades and expensive purchases.

 

The smaller piping is likely causing turbulence thus slowing down the flow. It's like the turbo outlet--they are funnel shaped expanding to a larger size to the exhaust system to reduce turbulence. It's clear the larger pipes make a difference on bigger HP set-ups but if people want to put on smaller ones, then that's OK too.

 

so many different opinions!!
the only major restriction i noticed on 996 is the inlet turbo pipes. besides that is good for MAX 580to700hp. stock to A28 TURBO. YES, can you improve certain thaings but at what price. is it cost effective for what you want. remember people are trying to sell stuff not at your best interest and tell you what you want to hear. I do a lot of R&D thay are parts out there that i can't mention on the forum just doesn't work. i also made 1200hp on E98 at 32psi on a AIR COOLED MOTOR ann rand 169mph in a 1/4 236.6 in one mile at 20 psi so i'm not just talking. SO BUYER BEWARE!

 

I agree in that the size of the turbo (ie, the volume of air) is the most relevant. My car made 600whp with 18g's, 93oct pump gas, injectors, exhaust and 100% meth. ALL stock piping, IC's, airbox, air filter and throttle body. The only gain the bigger piping and IC's got me was quicker spool (by about 600rpm), which equated to more power and tq sooner, but NOT more peak power or TQ overall. So yes, the piping helps, but will not help you become a dyno king. And again, this is with 18g's. I'm sure this would change with a bigger turbo with more air delivery potential...

 

Is it safe to say that 93oct + 100% meth is higher oct than ms 109?

 

I think it's been proven to be almost identical. I made a little under 20 more whp on the same dyno, same day, between pump/100%meth and MS109 and 50/50, at the same boost and timing. Now, I think we should all agree that MS109 is a better option, performance wise, as it comes out of a can and is consistant, whereas 93oct differs in cleanliness from station to station...