Hello all FI guys-
Of course with turbo setups it seems everything that is "bigger is better". I did a search and came empty handed... For guys that have 400+ HP turbo setups, what diameter piping are you guys using? If you think about it, everything in your turbo/engine application would have to match in-order to achieve more power. Most turbo compressor outlets tend to have a diameter of 2 1/4 or less. This means you would have to telescope tubing to achieve the 3in diameter. I wouldent trust a coupling to hold a 3inch diameter tube to a smaller diameter compressor outlet. So you get to 3inches in say less than 7inches of tubing length. Then you must have 3inch endtank inputs/outputs. Then three inch tubing to a throttle body that is at least 75mm in diameter if you want all the benefits of 3inch piping. Then, a nice sheet metal intake manifold with runners having an inner diameter of atleast 35mm's.
But bigger diameter piping=less static pressure and more volume to fill. I've heard of people running 2in piping to the intercooler, with 3in output- I dont understand why this would do anything for performance? What are your guys theories on sizing? PICS OF YOUR SETUPS would be awesome to share! Thanks

 

don't worry about the piping too much. A good intercooler and turbo are gonna do way more for you then piping could. Just keep it simple and try to match the piping up w/ the size of the turbo compressor outlet and to the intercooler endtanks.

 

You can't just match to the outlet, or else you will have little dinky piping that is smaller than the intercooler.

You want to use piping about the size of the intercooler piping. If you want to use different sized piping, then go for the larger piping after the intercooler where the air is denser and has less energy.

 

2.25 from the turbo to the intercooler...and 2.5 from the intercooler to the throttle body..thats what I have always been told...

Khoi

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SleepyEG &raquo;</TD></TR><TR><TD CLASS="quote">You can't just match to the outlet, or else you will have little dinky piping that is smaller than the intercooler.
</TD></TR></TABLE> On the E housing's its best to start w/ 2" and flare it to 2 1/4". On the S housings u can come strait out of the compressor w/ 2.5".

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by DIRep972 &raquo;</TD></TR><TR><TD CLASS="quote"> On the E housing's its best to start w/ 2" and flare it to 2 1/4". On the S housings u can come strait out of the compressor w/ 2.5".</TD></TR></TABLE>

Agreed. It is always better to start at the compressor outlet size, and then flare out quickly, but smoothly.

 

True, wouldn't the larger diameter pipe allow the hot air from the compressor to expand and cool some?

 

ok so say u have an i/c with a 2.5" inlet and outlet. and a turbo with an E housing...

would it be good to go...
2" from the outlet, then flare out to 2.5" to the i/c
then 2.5" from i/c to tb?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by DIRep972 &raquo;</TD></TR><TR><TD CLASS="quote"> On the E housing's its best to start w/ 2" and flare it to 2 1/4". On the S housings u can come strait out of the compressor w/ 2.5".</TD></TR></TABLE>

I have a S housing and the outer diamter of the outlet is 2.5" while the inner diamter is 2.25" so I used a silicon reducer and mated it with 2.25" piping all the way to the intercooler which has a 2.5" inlet so I used another reducer. Coming out the intercooler I have 2.5" piping to an AEM CAI which is also 2.5".

I plan on redoing my pipes on the drivers side (turbo to IC) and debating going 2.5" or sticking with 2.25"...Suggestions?

 

THanks for the replys fellas
IncogNitto: How much boost are you running? I know that physics pays a big deal with opropriate diameter and the amount of boost you are running.

 

I'm only running about 10psi from a GT30R, but once I build the motor I'm going to up the boost to an indefinite amount. If it matters, I have my BOV (Tial) on the smaller piping closer to the turbo and it's been responsive. I haven't put it anywhere else so I can't tell you what difference it would make. It's also right in front of the wheel so it blows off pretty loud (with an echo off the floor I guess).

 

I ran a E housing last year with 2" from teh turbo and 2.5 to the Tb and made 531whp, this year I'm running a S hat on a pt67 and run 2.5 everywhere. In your case I would run 2.25 from the turbo and 2.5" to the tb.

 

Thanks hybrid901
Heres the rule of thumb for diameter piping; if you have alot of peak boost 23+ psi, there is less volume for the pressurized air to go with smaller piping (below 2.50) This makes for a slight resistance in the ability for the condensed air to travel around piping bends. This also makes for an almost always constant static pressure within the piping (not always a bad thing ).
With high boosted engines 23+psi, the 2.50 to 3inch piping is ideal. The more volume the air has to move around, the easier and faster the air is to move to the TB at high boost. Their is a downside; the more volume, the more turbo lag, but when your dealing with big turbos to make this sort of power in the first place, this isnt such a notice. Ideally a bit larger piping from the intercooler to the TB would be ideal in any app.

 

3 inch aluminum all around for me... street car..

 

I plan on redoing my pipes on the drivers side (turbo to IC) and debating going 2.5" or sticking with 2.25"...Suggestions?[/QUOTE]

Check this out. i have a small t3t4 with a 2inch outlet. the intercooler is 2.5 and all my piping is 2.5.

I don't have any mid range torque. my top end is insane, you have to consider this,

are you looking for "all or nothing" power, or fun streetable midrange torque where your gears rip.

im not sure on the on outcome but im going to reduce my intercooler piping. the car is gutless before spool. you don't want that.

i think 2.25 inlet, 2.5 outlet

 

end tanks should be the same size as the piping and charge pipe should be close to T/B size. Most likely you will need a silicone adapter piece from turbo to pipe since the turbo oulet pipe is usually smaller

I am running 3" charge pipe side and 2.5" turbo side piping

aluminum i think is the way to go