Shortening Pipeing To Plenum

[bigcarl]

im looking at shortening my pipe work to stock plenum and trying to eliminate some twists and turns without buying a greddy $1200 plenum . my aim is to lesson turbo lag and increase throttle response. i intend on doing this by 90 degree right turn coming out of stock plenum and straight down plenum side of my rb25 to intercooler. like people do when they run a high mount turbo and do away with the stock cross over pipe. i want to hear from anybody that has any knowledge on the subject??? at the moment im running low mount gt30 with stock cooler pipes straight over the top but if you follow the pipe coming out from the stock plenum it probably has about 4 bends in it before it reaches the plenum side of the intercooler, sureley i can shorten this pipe by doing what i have said above and reduce the length of pipe work and at least two bends???

Edited February 21, 2006 by bigcarl

[Wazz]

many people have done it.. if you feel like doin it.. go for it only problem i'd see with it is possible bonnet clearance but i doubt that

[R31Nismoid]

yep, you can just do a direct bend out of the plenum and then go straight over and then down the side.

would reduce the amount of piping... as for throttle response in terms of a noticable gain... not sure

[TTT]

isn't this the 120 degree bend that the gibson motor sport car uses?

SK always recommends it too.

I think ROY's piping is like that too. I think..!!

[Sydneykid]

The original;

Later version;

cheers

[Speed Safe]

Here's one I found

Edited February 22, 2006 by Speed Safe

[TTT]

I think that last one is ROY's

[bigcarl]

I think that last one is ROY's

thanks for the replys, thanks sk for pics thats exactly what i want to do! would it be best to use 2.5 inch pipeing as to keep the velocity of air up? howe big is the opening to throttle body 2.5 inch or 3inch? would 3inch to plenum be too laggy? cheers carl.

[R31 POWER]

Here's what we made.

2.5inch for all piping.

[Mr GTS4]

do you find you get more response from going this way?

[Sydneykid]

thanks for the replys, thanks sk for pics thats exactly what i want to do! would it be best to use 2.5 inch pipeing as to keep the velocity of air up? howe big is the opening to throttle body 2.5 inch or 3inch? would 3inch to plenum be too laggy? cheers carl.

We use 63mm pipework from the turbo to the intercoler and 75 mm pipework from the intercooler to the plenum.

do you find you get more response from going this way?

Yes, there is around 5 litres of air (between the turbo and the throttle body) to be saved using this method.

cheers

[Roy]

do you find you get more response from going this way?

LOL...nope , i didnt. But it was worth a try...

Myself i think this falls into the category of its technically the better way of doing it so best do it. But if its is done like the usual kits you wont notice any real difference. The best thing about this setup id the poor guy trying ti tune the ar isnt havign to stuff around with coole rpiping when gettign to your adjustable cam gears..

[bigcarl]

great thanx again for pics and info. i m about to get me low mount hks one piece cast iron manifold fitted and i will probably get this done at the same time. sk was there any performance gains to peak or midrange with these changes when running high boost??? how does it change shape of power curve? mine seems to have a small dip at the top before gong up again .

[Sydneykid]

great thanx again for pics and info. i m about to get me low mount hks one piece cast iron manifold fitted and i will probably get this done at the same time. sk was there any performance gains to peak or midrange with these changes when running high boost??? how does it change shape of power curve? mine seems to have a small dip at the top before gong up again .

It doesn't change the power on the dyno 1 kw, it just lessens the time between throttle depression and engine response. It is most noticeable in the 3,000 rpm to 4,500 rpm range, which is where you do the most driving on the road. I can't say as there is any noticeable difference over 5,000 rpm. Which would be logical as the air speed through the intercooler pipework is much higher and the time taken to flow the 5 litres is less as the rpm rises.

cheers

[maccaz_gts25t]

is it possible to have these ready made any where???? like does any one sell them as an item or are they custom made....

[wolverine]

plazmaman has this for their kits. perhaps they can be bought separately.

[silver gts-t]

i run my piping under the cooler back to the original piping, no complaints..

ill post pics tonight it u want...

was very cheap, just bought 2.5inch piping already bent, cut to lenght and put it together..

most expensive thing was the thermo flex

[caminperth]

Hate to rain on the parade here, but any friction loss you get rid of by using less piping you'll be making up 2 fold in piping bends.

BUT - as it saves volume, perhaps you might see a very small difference, but 5L saved on a 2.5L motor doing 4,000rpm plus isn't going to do much either.

BUT (#2) - the friction loss of air is next to bugger all so it's all a bit futile..

Though the finished article looks farkin cool though with that sweeping bend..

[James Mramor]

Also in the case of loosing the 5L of air by using this bent pipe.... you don't loose very much presure over the entire cooling phase do you... the intercooler that i am getting states that you will only loose about .2PSI over the course of the intercool, from turbo to manifold.

so if you are running 15PSI then when it gets back tot he mainifold you will be seeing 14.8PSI

i just don't understand how loosing this volume would really make that much of a differance?

this is not ment to be rude in any sort of way i am just confused y this would make a differance?

[skidkid]

silver gts-t, I would like 2 see some pics, thanks. Cheers.