Pauls325

iTrader: (1)

im getting ready to build some headers for the GXP this coming winter and am looking for any tips or tricks you guys have whare to get tubing, figuring out primary size, welding tips, and just other things to overlook.

GXP comes with an ls4 makes 303 hp stock at the flywheel with a fairly broad curve on it ill put up my stock dyno i was thinking a 1 3/4 or 1 7/8 primaries but traction is an issue with these cars so losing some torque down low for high end power would not be all bad


thanks guys

orange88ls1s-dime

Primary length- the longer the more low end torque, Stepped kindof splits it up
Merge Collectors are awesome to promote scavenging
T.I.G. welded stainless for longevity and pleases the eye
Purge Each tube when welding to keep "grapes" from forming inside
i usually cap one end with a sponge and add 5 psi "Mison" gas to the other end
if that doesnt help at all just bring the car to my Shop and ill build them for you email me beaudaciousfab@hotmail.com

gtpvette

iTrader: (2)

Paul,
I ordered the flanges from GM (part number 12480130), they are nice and quite thick. I ordered pipe from Schoenfeld Headers http://www.schoenfeldheaders.com. I bought U’s and J’s and a box of miscellaneous bends, 18 gauge. In a perfect world I’d rather have SS headers but as I haven’t built headers before I thought I try the mild steel first. Turns out I mostly used the miscellaneous bends and still have a buch of the U's and J's left over. I cut (abrasive saw) and tacked then took them to a local welding shop for finish TIG welding, then ceramic coated. I finished with an X-pipe and Moroso Spiral flows. In the end I ended up spending about $800 with me doing most of the fab work.

mmmchickenboy

Another tube source:

www.mandrel-bends.com

orange88ls1s-dime

im impressed with those headers but the x pipe you have i hate to say it is useless "poor design" the way that one is built you might have well just put an H pipe in with a 6 inch wide crossover but other than that i like it
I dont like giving out my secrets to everyone but if your interested in knowing why your x pipe is wrong we can email beaudaciousfab@hotmail.com thanks

awd4life

http://www.speedwaymotors.com/

built some for my 240 swap, got the kit for $200 shipped. and they offer both 1 5/8" and 1 3/4" good quality mild steel. i used a TIG welder and made sure to smooth/port the header flange.

gtpvette

iTrader: (2)

I'm certinaly not the end-all be-all of anything. If you've got a better idea,, share it with all of us,,,, that's what the forum is for.

orange88ls1s-dime

OK, nobody on here will be giving me any business anyway so here it goes
an efficient X-pipe is when the centre of the merge is exactly the same size as each of the two tubes coming together ie: if you have dual 3" then the centre of the X must be 3" the longer you make the centre the more low end torque is produced and vise versa for high RPM power. 750% more air is drawn into the engine from the exhaust than from the intake stroke of the piston so just think about that the next time you buy a set of 125$ headers with dents and dings in them so you can reach the spark plugs. i didnt mean any harm to GTPVETTE just wanted to point out something that you could improve on to get the most out of that beautiful car sorry if you took it the wrong way signed Beau

orange88ls1s-dime

here is a custom 3" Xpipe i built for a Olds Cutlass 4-4-2 with a 455 engine
not very symmetrical but hey it fits the car

gtpvette

iTrader: (2)

Beua,,,
No sweat,,, it's all good. After looking at your picture I went and looked at a bunch of different x-pipe designs. There are a some that look like mine,,, but typically the stand alone x-pipe seem to be a bit more like yours. I guess the driver is to get the exhaust gases from both sides to mingle and promote scavanging


http://www.burnsstainless.com/Crosso...rossovers.html

http://www.magnaflow.com/02product/02xypipes.asp

If I redo it in the future I'll look at a redesign...

Thanks

orange88ls1s-dime

In a multi Cylinder engine there will never be two pulses at the same point at the same time so when one pulse gets to the centre of the X it creates a low pressure to the other tube from the other bank and sucks the pulse from that one and vise versa so the faster the engine revs the scavenging gets more efficient EXPONENTIALLY

NemeSS

iTrader: (127)

did u get the exhaust delete when ordered the gtm body?
its supposed to be used with c5 manifolds, iirc. my unc is looking into getting one and i will be one building it.
i like the headers u built, and the x pipe dont really bother me, if thats what u had to make work and fit in there now. its all good

chevellepowered

iTrader: (37)

good source i get stuff there ..