Headers Thread

[OoskylineoO]

extractors with 1.5'' primary, 1.75'' secondary and 2'' outlet.

Is this beneficial for a series2 rb25de?, would that provide alot more response over stock extractors?

[Hesh]

the stock extractors are cast. all the primaries, ie th tubes from the outlet on the head are different lengths. in terms of torque its advantageous to get all the primary's as long as possible, and equal in length. th reasoning being that it evens out the pressure wave "pulse" when the exhaust gas is vented from the combustion chamber.

however the larger diameter the tube..the lower the pressure..and you want a decent pressure wave to help "suck" the exhaust gas out of the combustion chamber at the end of the stroke, as the drop in relative pressure between the header and the combustion chamber produces this "scavenging" effect.

so as you can se from this its a balancing act. too big a tube drops the pressure and then you get a very flat engine with no power. to small and it wont flow the gases as quickly as it could.

the exact "best" set up for an rb25 de or rb20 would need to be computer modeled and then built from scratch, and even then beecause of space constraints ultimately the tubes will perhaps have to be less than the theoretical idealas they have tofit the car. essentially the d12's allow the car to perform closer to its mechanical and theoretical maximum potential, though probably not at it.

if that makes sense.

Edited April 17, 2008 by Hesh

[OoskylineoO]

thanks for the write up Hesh, appreciate it, was helpful

the extractors i stated above are the ones I have (they are smaller diametre d12), I just got them but havn't fit them on yet. Seeing how most people ordered 2.5'' outlets, compared to my 2'' is there much difference??

[inthisglass]

you tell us

[OoskylineoO]

haha after IF I put them on xD, btw, LOVE YOUR ROCKER COVERS >< guess I might do that too

Edited April 17, 2008 by OoskylineoO

[inthisglass]

well if you already have them may as well put them on

cheers, that picture really doesn't do the paint justice

should see them in day light

[Hesh]

no probs mate. sorry i cant be specific about the figures and benefits of one ovr th other. thing is here in the uk most skylines as turboed so not much info exists at the present regarding tuning options for the de's as not many people have done it to find out! ....so if ya fit your 2inchers and collect all the info you'll be one of the first .....

[OoskylineoO]

I'm just curious, is it possible to have JUST HALF of the headers HP Coated? since the only problem (that I am aware of) is keeping the heat out of the engine bay. i.e, JUST coating the primary pipes and a bit of the secondarys and just some cheap heat wrap around the rest of the headers?. Enough so you could see the bling and coated enough away from the intake pipe, you guys get what I'm trying to say? lol.

I know you would end up with ugly ass half cross breed HPCoated extractors/ heat wrapped lol but you'll only see the top of the extractors anyways.

Would this be possible and cheaper?? or HPC workshops don't do these kind of coatings? or is there some other factor involved?

Edited April 18, 2008 by OoskylineoO

[Hesh]

im reaching a bit here but id wager that it would create a hotspot at the join of the treated and untreated portions. which may lad to complications. id just simply heat wrap and paint the whole thing as that's essentially doing the same as the ceramic coating.

it isnt just about keeping heat out of the engine bay, although that's a factor. if the exhaust gasses cool to quickly (i.e. via convection of heat from unwrapped/non treated pipes) they slow down...thus leading to a drop in power similar to too large and exhaust bore. keeping the exhaust gasses hot until out of exhaust means a better breathing engine.

[OoskylineoO]

yea thats what i thought as well.

what size piping diametre you guys have?

primary, secondary, outlet

[Hesh]

mines still standard mate. its taken me ages to track down any headers for th rb20/25de's. like i say evrything still turbos here. out of a whole forum of like 3000 plus theres five interested in this group buy...cos no on bothers withthe NA's......but i aim to change that.

Edited April 18, 2008 by Hesh

[_bobo_]

Hey just a question about my setup mentioned earlier....

its been about a month since i got extractors ans exhaust done but recently i noticed its quite quiet..not as much drone or rumble....any idea why????....anything to do with fuel ...or possibly cause it has been driven in close too a week

...or could it be im now going deaf compared to how loud it was at the start lol

[Eug]

as the carbon deposits and lines the exhaust you will find that it tends to smooth out the insides and quietens down.

[OoskylineoO]

hey guys with the fitment of the extractors, would the A/C hose? i think it is, be in the way of the extractors?, because it seems to be close to them, and the D12s come out more then the stock extractors.

[OoskylineoO]

nvm i fitted mine today and bent them a bit to get extractors in there lol.

btw, r you meant to feel the gains str8 after you put the extractors on?, i feel very little or bugger all lol