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Duals And Headers

H

happyharold4

NAXJA Forum User
Location
So Cal
Do most of the factory V8's come with duals---Can you put duals on the I6---If so, do you need 2 catalytic converters as well as 2 mufflers--Also I guess you'd need headers with 3 cylinnders to each exhaust---Thanks

Happy
 
No, most V8's do NOT come with duals.
yes, you CAN put duals on the 4.0L but there really is no point.
Legally you would need another cat in the system if you ran duals, as far as mufflers there are single mufflers that have dual in/out.
The problem with duals is that there is not much room and really no point. I ncie header/custom mandrel bent y-pipe would suffice.
 
My Pacesetter header has two outlets, each with 3 cylinders, and the downpipe has a Y on it. I've thought of this, but looking at it, it would be very difficult to find room for two pipes, and two mufflers. A lot of custom pipe bending work. You could probably fit two glasspacks under there, in the area where the one muffler is now, the difficult part would be getting both pipes past the xmember, and making a custom tailpipe for the left side. A lot of work for something that would offer no benefit except that it might sound cool.
 
If you want duals on the I6, just use a single inlet, dual outlet muffler and run it from the muffler back. You get the look of duals without two cats, etc. That's the way a lot of factory set-ups including Firebirds and Camaros did it.
 
winterbeater said:
If you want duals on the I6, just use a single inlet, dual outlet muffler and run it from the muffler back. You get the look of duals without two cats, etc. That's the way a lot of factory set-ups including Firebirds and Camaros did it.
Click to expand...

I know a guy that did it that way, I must say it looked, well, IMO like crap and didn't sound any better than my FM50.

on cold days, or when first started you could see exhuast only coming from the shorter passenger side pipe... obviously taking the path of least resistance.

just my opinion, but I am growing tired of the drone of the flowmaster even lately...
 
I usually run straight-thru style mufflers. Such as magnaflow/bullet performance, dynomax ultraflo's etc.
 
I'm not a big fan of the flowmaster drone... I kinda like the sound of a longer glasspack, but they 'burn out' pretty quick so that's out. I've thought about moroso spiral flow. Hmmm...


anyway, as far as exhaust systems go- if it has one cylinder bank, keep it a single exhaust. If you have 2 cylinder banks, run duals. Does your engine have spark plugs? Assuming said gasoline engine is not in a tractor, then NO STACKS. <and no stacks whatsover on a XJ. Even if you have the rare diesel, or swapped in a 4BT.
 
ChevelleSSLS6 said:
I'm not a big fan of the flowmaster drone... I kinda like the sound of a longer glasspack, but they 'burn out' pretty quick so that's out. I've thought about moroso spiral flow. Hmmm...


anyway, as far as exhaust systems go- if it has one cylinder bank, keep it a single exhaust. If you have 2 cylinder banks, run duals. Does your engine have spark plugs? Assuming said gasoline engine is not in a tractor, then NO STACKS. <and no stacks whatsover on a XJ. Even if you have the rare diesel, or swapped in a 4BT.
Click to expand...
IMO, as far as engines go, duals are not always the best way to go even for V8's. If it is highly modified, or old muscle car thats understandable. But a nice set of headers, amandrel bent y-pipe and large enough single work just fine. I honestly dont like seeing a tailpipe so turndowns work for me.
 
One thing to keep in mind, is that if you wheel on public land such as state or national forests, you are required to have a spark aresting exhaust system in place on your vehicle. A straght through type muffler like a glass pack does not qualify. And NO the cat does not count either. You need to run a chambered type muffler such as stock, turbo, or Flowmaster style.

Anyways, my local muffler guy told me that Flowmasters always sound like crap on any 6 cyl, and he recomends the Magnaflow or Dynomax turbo style muffler.
 
I started the thread----I'm a little older and just figured all V8's had duals---As a boy all of our 55-58 straight 6's had duals with glass packs as well as all the 283's, 327's, 348's etc. Can't remember anyone without duals---Probably just a fad.

I have a quad---07 KFX 700 V Force that I just put duals on and it looks and sounds so sweet---it reminds me of those 283's and how they sounded.

Guess I'm regressing to my child hood

Happy
 
happyharold4 said:
I started the thread----I'm a little older and just figured all V8's had duals---As a boy all of our 55-58 straight 6's had duals with glass packs as well as all the 283's, 327's, 348's etc. Can't remember anyone without duals---Probably just a fad.

The Straight sixes in the 50s and 60s had very restrictive exhaust manifolds and by "spliting" them you could get a bit of a HP gain. Mostly though, It was done for the dual look and sound.

Looks and sound do not help performance, the flow and scavenging properties do.
Click to expand...
 
Yeah, you're right---Even my quad gets better HP to the wheels with a 2 in 1 with both header pipes the same length vs. the duals on the dyno.

Just looked at my Motorhome (454 Chevy) and it's got duals???

Happy
 
happyharold4 said:
Yeah, you're right---Even my quad gets better HP to the wheels with a 2 in 1 with both header pipes the same length vs. the duals on the dyno.

Just looked at my Motorhome (454 Chevy) and it's got duals???

Happy
Click to expand...


The stock manifolds on the 454s are junk for performance/mpg concerns. My grandpa has been a RVer since long before I was around, and being the chatterbox and tinkerer he is (he worked at GM and fixed cars at night:repair:) found that replacing the muffler with a straightpipe helps performance, and isn't much louder than stock (inside at cruise/idle). Also sometimes there's an air cleaner hose going near the grille, and it has a 'cap' on it so the air must make a 90* turn to get into the hose in the first place. Remove the 'cap' (so its just the big corrugated hose) for a little extra. Air cleaners might get a few more bugsplats, but its worth it in his book.

I'm not sure what would happen on an RV, but I've heard of pickups gaining 2mpg with headers (small tube type. I'd recommend 'shorties' that connect to stock exhaust pipe rather than the big ol racing style) and a decent exhaust. Of course that 2mpg can go away easily as the decent exhaust sounds better.:yap: The mpg is due to decreased load on the engine in the form of reduced pumping losses- as a 'log' style exhaust is very inefficent at scavenging and flow.

If durability is an issue (do you drive your RV in salty winter roads? Headers rust quickly) I think Sanderson makes LSx- like manifolds, or 'header-manifolds'. I think you old-schoolers call them high flow manifolds.
QP2000.jpg

-Matt
 
edit: you won't have a musclecar with these 'budget mods' as the heads don't flow well and the cam is basically emissions friendly junk, but should help prevent transmission hunting and help mpg if you don't get throttle happy with it too much.

plymatt has a definite point...

as far as duals on inline 6 engines, maybe if we were talking about a 54 Chevy coupe or something, where duals on inline 6 engines were (I'm assuming) era correct mods...
...hopefully it's not like the ricer kids who put dual exhaust on a Honda Civic.
 
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