Trying to decide on exhaust for my 340. I put it in my Dart which was originally at 273 and has a 2 to 1 pipe. I was thinking about just cutting off the 2 to 1 and extending the pipes back with mufflers. Then I started reading about X pipes and Y pipes and how those assist with exhaust. If I don’t put one of those on what’s the worst that could happen? I assume they’re not absolutely necessary as I’ve seen others run straight pipes back with mufflers.
X pipe, Y pipe, NO pipe
- Thread starter Tad
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Phreakish
Well-Known Member
X or H pipe will help quiet things compared to straight (even with mufflers).
If your exhaust is full length and not very free-flowing, then an X or H can help improve flow.
H is easier to plumb in, an X takes more time/clamps/space and will be farther back than most H pipes and so may not reap as much benefit (power-wise).
If your exhaust is full length and not very free-flowing, then an X or H can help improve flow.
H is easier to plumb in, an X takes more time/clamps/space and will be farther back than most H pipes and so may not reap as much benefit (power-wise).
TTI has everything you’d want - headpipes, X pipes, etc that connect to stock manifolds if that’s what you’re running.
What you have now is a Y pipe.
Technically the placement of the X or H should be tuned (placement from the end of the exhaust manifold give or take) To achieve the desired scavenging effect.
In a street car the benifit of either is probably negligible.
An H pipe could be added after the dual exhaust is installed, an X pipe would need to be created when you are bendind your tubes.
Just my two cents.
Technically the placement of the X or H should be tuned (placement from the end of the exhaust manifold give or take) To achieve the desired scavenging effect.
In a street car the benifit of either is probably negligible.
An H pipe could be added after the dual exhaust is installed, an X pipe would need to be created when you are bendind your tubes.
Just my two cents.
The X will give you about 8-10 hp on a 340 over no crossover. It makes that HP in the mid to high torque range. It will also smooth out the tone of the exhaust. It pretty much eliminates the popping noises common with a v8 at certain rpms.
There are also different types of X designs. the Siamese style works best. Home made X's made by welding two pipes to a 3rd pipe don't do anything for performance and can actually hurt both performance and sound.
Clamshell X's are rally H pipes.
The H pipe will make low end torque and a few hp but most motors are built with a huge amount of low end torque already. So the H is mostly recommended to keep the traditional musclecar sound.
That being said, you can see that none of them are really necessary. I'd place a higher emphasis on using mandrel bent pipes with whatever system you choose as the mandrel pipes make a much bigger difference for performance. You can pick up 25-50hp depending on your motor.
if you or anyone else is interested in a special forum member price, shoot me a PM.
Hope this helps.
There are also different types of X designs. the Siamese style works best. Home made X's made by welding two pipes to a 3rd pipe don't do anything for performance and can actually hurt both performance and sound.
Clamshell X's are rally H pipes.
The H pipe will make low end torque and a few hp but most motors are built with a huge amount of low end torque already. So the H is mostly recommended to keep the traditional musclecar sound.
That being said, you can see that none of them are really necessary. I'd place a higher emphasis on using mandrel bent pipes with whatever system you choose as the mandrel pipes make a much bigger difference for performance. You can pick up 25-50hp depending on your motor.
if you or anyone else is interested in a special forum member price, shoot me a PM.
Hope this helps.
Professor Fate
Push the button, Max...
you didn't say, but going by your avatar you have an early A ('66 or earlier) and you say you are using the stock 273 manifolds? Anything you do for an exhaust system will be a negligible improvement for a 340 trying to breathe through those exhaust manifolds, sorry. First order of business is to eliminate that bottleneck. Lots of threads on here about manifold/header options for early As, the biggest hangup is whether you have power steering or not. If you don't, your most cost-effective solution is a pair of Magnum manifolds off a Ram or Dakota (possibly others) that generally fit manual steering with minimal tweeking.
Then you need to mod your transmission crossmember for dual exhaust. Lots of threads on here about that, too.
Then it's a matter of getting some head pipes bent up locally and add the exhaust system of your choice.
Many other options too, but those 273 manifolds really should go...
Then you need to mod your transmission crossmember for dual exhaust. Lots of threads on here about that, too.
Then it's a matter of getting some head pipes bent up locally and add the exhaust system of your choice.
Many other options too, but those 273 manifolds really should go...
Last edited:
ir3333
Well-Known Member
oh boy...here we go.
save your money and just run duals. unless you want a quieter exhaust
save your money and just run duals. unless you want a quieter exhaust
I had my muffler guy do exactly what you suggested — just cut off and weld shut at the Y and run a second pipe straight back. This was on a 273 4bbl so the pipe was good sized to start with. Used 1968 340 OEM replacement mufflers. Not too noisy, just right. Any kind of crossover is significant extra hassle and hangs lower.
Thank you. Yes I need to get some manifolds. I found a pair of magnums for a great price. I’ve read a lot of the threads on here about those manifolds. I wasn’t sure if both driver and passenger side work. I thought I remembered reading only one side works and you have to find a 340 for the other side. It’s going in a 65 Dart. Manual steering.
and a badly sized and placed X pipe can make reversion worse.
don't ask me how I know this.
The most important thing in terms of flow will be muffler. That can be much more a restriction than the tubing. Spend the time and money on that first.
don't ask me how I know this.
The most important thing in terms of flow will be muffler. That can be much more a restriction than the tubing. Spend the time and money on that first.
Professor Fate
Push the button, Max...
You don't HAVE to use a 340 DS manifold- they have similar fitment issues in early As, and cost a TON more. Interference is usually at the steering coupler- a little grinding on the manifold there, maybe a bit on the coupler itself, and a little jiggling/shimming at the motor mounts usually gets them in. Pass side is a drop-in.
famous bob
mopar misfit
Speaking of h pipes , will an h pipe have any bad effect on an 02 sensor for aftermarket fuel injection . ??
I have been thinking about installing one as close to the headers as possible ,''limited by the 727'' of course.
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