Nismo_Capri

Hi Guys
From doing a bit of a search I see that there is 2 camps when it comes to exhausts
1) Dual with X or H crossover.
2) Single.

Here's the specs of my van....
XD, 302C, Holley 600 vac sec, Pacemaker headers -> 2 into 1, Lumpy cam Unknown specs, std points ign, MSD Blaster 2 coil, Accel plug leads, NGK plugs. Compression tested with bang on 150psi in every cylinder. Engine rebuilt ~ 20,000 k's ago. C4 Auto.

I measured the exhaust and to my disgust it's running a single 2 inch (I'm guessing the std 6 cyl exhaust) and get this.... 1 bank has about a foot long section of 1½ inch. It's just crap!

So it's coming out on payday I can't decide 3 inch single or a dual x (or H) in 2 or 2½ inch. Since it's a van dumping at the diff isn't a problem what would you do?
Any thoughts on what sort of HP I might pick up going from a crap exhaust to a good setup?

Also why is there no XD Post Icon?

brenx

Twin 2 1/4. Twin 2 1/2" is way too much exhaust and it'll drone unless you get more cam and heads happening.

I am sorry, I've never been a fan on a single system. Too many bends can't be good.

Brenden

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XB Fairmont (street car) 11.07@123.02mph.

xdc351

With that combo i'd be looking at a dual 2 1/4" with an X pipe.

That would give you a nice note, plenty of torque and a little headroom in case you decide to do some minor mods later on.

Single systems on v8's are for the elderly and those with poor health... Go the dual!

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Just like a Tsunami.

Nismo_Capri

It's got a lumpy cam, I don't know the specs (yet) but it's healthy and it has that rock and roll idle. That's part of the reason why I think it needs a bigger exhaust to breath...

I don't know if the head has been tickled.... Speaking of the head it has a nothing cast in to it by the tappet covers but on the passengers side of the head facing the radiator down in the casting it has a 4, in the same place a friends '73 falky has a 2. Anyone know if these casting mean anything?

Nismo_Capri

That's my preference, I'm starting to wonder if a twin 2 inch might be the go or is that too small?

If the X is to much of a PIA then the H is a decent compromise right?

"Single systems on v8's are for the elderly and those with poor health... "
Nice line .....I have 2 friends that say they much prefer the sound of a single????
Thanks!

xdc351

I had a single 3" on my XD when i first got it... it was ripped out within 2 weeks! If you've got a decent cam and a bit of head work done then a dual is much better!

X-pipes are a little harder but offer more torque and a quieter note than a H pipe. The quieter note means you can run straight through mufflers and not be too loud compared to a H pipe. Make sure you have one or the other though. Even the toughest V8 sounds like a volkswagen beetle with straight through pipes (i found that the hard way when a bodgy exhaust place didn't install one!).

I'd go the 2 1/4 just for a little bit of headroom for the future. If you decide to get any more work done the 2" will be too small. Plus i'd say the 2 1/4" wouldn't be too big for current setup anyway.

And i'll ammend the line: "Single systems on v8's are for the elderly and those with wimpy cams... "

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Just like a Tsunami.

!Gn|T|0n

I'm going to be attempting my own twin system on my windsor. The discussions here however seem to be of a fairly generic nature so I’ll ask this here. I'm going to go the X pipe option, but I've seen setups where the X section looks less like two joining pipes and more like a chamber. That is the pipes are seated a little bit apart (not like you just cut a hole in each pipe and weld together to make the X but there is like a rectangular section with the pipes entering and exiting each side. Are there any specifically different Xpipe/chamber designs that I should research?

Thanks.

Nismo_Capri

IIRC the chamber is surposed to help with the torque.... that said I think I'm just going to see if the exhaust shop can do an X to keep cost down.

xdc351

I run one of the chamber type ones from sure flo ( http://www.surefloexhaust.com.au ) and i prefer it over the cut and welded jobs. Apparently the cut and welded ones make more power when done right. The formed X I run is great looking and this way I got to inspect it before install, so I know its done right.

Really you just need to ask yourself if your exhaust place is competent enough to make one themselves or if you'd rather buy one preassembled and let them install it.

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Just like a Tsunami.

Nismo_Capri

I'm lucky, the exhaust guy I use is an artist and the guy I do PC support for keeps his dyno at the shop so there's a lot of R 'n D.
I'm hanging out to get the exhaust done as I recon the beast will really start to brethe!
I'm hoping for 10-20 more HP at the wheels.....am I being unreallistic??