Intake pipes theory

[|Maku|]

Hello guys!

I haven't seen such a topic in this forum, so I'm creating a new one. Most of us are upgrading their cars themselves. So I would like to know your theory why intake pipes should be in a specific size or actually there's no difference. Lets take for example my RS2. I'm using T04E/K26 turbo and its gold side outlet is 51mm from outside. I'm using 300x600mm intercooler that has 3" intake and 3" outlet. Also using Wagner reverse intake manny, so from cooler to manny goes 3" pipe, as throttle body is original.

Many of us have read THIS thread where user aby1 got about +40hp when he changed ABY inlet tube from 2.25in to 3in and intercooler oulet from 2.5 to 3in. From that we can conclude that original pipe from cooler to intake manifold was a bottleneck. Right? Any more theoretical explanations?

I have seen tuners that make pipe from turbo to cooler with turbo's outlet size (in my case it should be 51mm). Could you explain why this is good? Also have seen tuners who make right from the turbo changeover, lets say 2.25"->3". In Maximum Boost book its written that makeover must be at least four times longer than difference in those two sizes. Lets say from 2.5"->3" and makeover must be at least 2". Another question is why this makeover is needed when I can take smaller pipe from turbo to cooler? Some say that with makeover air speed reduces a bit and air stays in the cooler a bit longer, some say its a BS.


Looking to hear your thoughts guys!


Marko

[A80Avant]

that is interesting!

OEM throttle body is less than 70mm(around 65-66mm). I know caue i had Aelred transform an AAN TB to 70mm. I was told that making the tubes larger on a larger turbo, basically produces less restriction for the airflow.Now if all the tubes are 2.75inch and there is a restriction somewhere, it takes little effect.But if all tubes have the same diameter,i think it should be able to flow better.

im planning on using the TB on the next setup, along with 2.75mm tubes all the way from turbo to TB+wagner intake manifold

[lind4hl]

A80Avant: is that inner or outer diameter?

[|Maku|]

Yep, stock throttle body is 65mm from the inside but remember that 3" pipe is from inside ca 70-72mm as well (depends on the wall). EFI is offering 70mm TB work as well.

[|Maku|]

I was told that making the tubes larger on a larger turbo, basically produces less restriction for the airflow.Now if all the tubes are 2.75inch and there is a restriction somewhere, it takes little effect.But if all tubes have the same diameter,i think it should be able to flow better.

For example I know a car that had ca 600hp and from turbo to cooler was 60mm but from cooler to manny was 76mm. Also have seen tuners that make right away from the turbo changeover. So why some do that and some not?

[lind4hl]

i have copied an really good answer on this and translated to english, so all words may not be right:

a very qualified such
a 'big' air going 'slow' fill pipes better with less local gauge such as the elbows (dynamic pressure)
Moreover, if a compressed air is contained in a volume and rushes out into a larger volume absorbes heat it gets colder. not much, but still a tiny amount.

a large air works as a plenary for pulses inside the suction and allow it to flow more evenly finer air, great for 'Na engine'

and works Na engine good, then it produces the very rapid effect and what happens?
= very much exhausts coming..
It strikes juh running the turbine speed.
So that it would worsen the response to serious concerns is probably MUCH OF A MUCHNESS in that it churning out lovely Gasmass at the other end a little faster.

I drive like this:

4 "Turbo ----- ----- 3 ----- Inter Cooler ----- 4" ----- Intake

My engine produces full charge (2.08bar) at 2800rpm (2.3 liter and a GT3582 turbo) and produces in the neighborhood around 260hk as sugmaskin.
It also has thrttle responce as an racebike, and possibly not. but almost
Edit: sounds a little sick, but in this movie you guys can hear the throttle responce ignore poff on end
http://www.garaget.org/video/dkgfm4j0a6u7

[A80Avant]

@ lind4hl : inner diameter.

So according to that translation,if you have smaller tubes from turbo to intercooler and larger from intercooler to intake, that helps with air being blown from the turbo to cool better through the intercooler and then go into the intake.

Question: would a smaller tube from turbo to intercooler + intercooler core increase the stress on the turbo to push the air through? If so could that stress cause turbo failure sooner?

[lind4hl]

@ lind4hl : inner diameter.

So according to that translation,if you have smaller tubes from turbo to intercooler and larger from intercooler to intake, that helps with air being blown from the turbo to cool better through the intercooler and then go into the intake.

Question: would a smaller tube from turbo to intercooler + intercooler core increase the stress on the turbo to push the air through? If so could that stress cause turbo failure sooner?

it would reduce turbo lag and more bhp before the turbo comes in ( "NA engine")

i dont think it can cause turbo failure, but too small could be an bottleneck but also earlier boost.

[A80Avant]

so then the wiser way to go would be to match the turbo's exit to the intercooler diameter, then after the intercooler enlarge the tubes at least to the diameter of the TB?

[Billman]

what engine is this? What are the other specs does this engine has? Why "only" 260hk?

[Paul McCleary]

what engine is this? What are the other specs does this engine has? Why "only" 260hk?

The car looks like a Opel Kadett, so I assume it's got a 2.0 16valve turbo (C20LET)http://en.wikipedia.org/wiki/C20LET

Paul.

[lind4hl]

Paul mccleary, its an kadett, and does 0-120 in 2,8Sec 4x4

at LEAST 600bhp is what he claims,

[Paul McCleary]

Paul mccleary, its an kadett, and does 0-120 in 2,8Sec 4x4

at LEAST 600bhp is what he claims,

I've seen a few C20LET's running at the 550bhp mark on engine dyno's so 600bhp is likely to be possible. I'm assuming that's 120 KMH, not MPH??

Back when my wife was 18, I built her an Opel Manta with a C20XE on DCOE 45's. Great little engine once you had cured the usual oil leaks and head problems.

Sorry, for tking the thread off topic by the way.

Paul.

[lind4hl]

yes kph, my bad

[|Maku|]

i dont think it can cause turbo failure, but too small could be an bottleneck but also earlier boost.

What is too small? My Garrett T04 has 51mm from compressor housing outlet. Is it too small to direct to intercooler?