What to tell the exhaust shop.

[cchrishefish]

I found a shop not too far from my house that will install a custom exhaust system on my 225 Slant 6 1964 Dart GT. None of the chain shops bend pipe. This is what my setup will be. Aussiespeed Hurricane intake with Quikfuel 450 CFM Black Diamond Slayer 4 barrel, and Clifford Shorty headers. I have been doing a lot of reading so here are my thoughts. 2 inch Y pipe under the hood to the drivers side. Have them install an oxygen sensor port at the end of the Y pipe in case I upgrade to fuel injection at a future date. From the Y pipe 2.5 inch diameter to a Flowmaster 40 single muffler with a 2.5 inch tailpipe.

If anyone has any better ideas, bring them on!

 

[motorpirate]

Why not go 2.50 the whole way?
The exhaust gas is biggest right out of the header, that is where the bigger pipe is needed.

 

[cchrishefish]

Why not go 2.50 the whole way?
The exhaust gas is biggest right out of the header, that is where the bigger pipe is needed.

Thank you, I appreciate your input before I get this done. I was thinking that an early A body car like mine 64 Dart GT may not have enough clearance in the engine compartment for 2.5 inch pipes. My car is manual everything no power steering, or air conditioning. Has anyone else installed 2.5 inch pipe in the engine bay in a car similar to mine?

 

[motorpirate]

Where there is a will, there's a way.
What size are the collectors?
My thinking is this ( in general, as I have never hopped up a slant, but an engine is an engine, right?)
Whatever size the collectors are, that is what diameter I would make the headpipes at least.
If you want to drop size, do it like the factory after the muffler.
But for maximum flow I would carry the diameter of the headpipes all the way out.
I mean, why put headers on it at all if you are going to choke them down from the very beginning?

 

[vitamindart]

my headers are 2.25 on the outlets. I went 2.25 to a flowmaster scavenger y then to 3"
may add boost later. in hind sight, I wish I went to 2.5" as it should be Plenty! just had the 3" already on my car ( had a small block in it ).

 

[cchrishefish]

Where there is a will, there's a way.
What size are the collectors?
My thinking is this ( in general, as I have never hopped up a slant, but an engine is an engine, right?)
Whatever size the collectors are, that is what diameter I would make the headpipes at least.
If you want to drop size, do it like the factory after the muffler.
But for maximum flow I would carry the diameter of the headpipes all the way out.
I mean, why put headers on it at all if you are going to choke them down from the very beginning?

Here is the header specifications: https://cliffordperformance.net/sto...5-dual-outlet-street-rod-headers-high-starter

 

[Badvert65]

Ask the pipe shop, they may not have all the dies to properly bend 2.5 pipe. 2.25 will be easier to bend and tuck up out of the way. It's only 225 cubic inches, so 2.25 should be plenty. I would take a smooth bend, tucked 2.25 over a crimped up 2.5 that hangs low and rubs.
jus sayin....

 

[motorpirate]

I would do 2.50 right off the headers.
Any competent exhaust shop that does custom bending should be able to handle that.
If you think about it the placement of the collectors was designed so you could get access to them with a large enough pipe to make them worth their while.
That's just me though, if there is a horsepower in there I want to let it out!!

 

[cchrishefish]

I appreciate your suggestion, this makes sense to me. So is everyone in the forum in agreement? I should do 2.5 inches from the header all the way to the tailpipe?

 

[66fs]

Run the 273 4 barrel Charger single exhaust. 2.50 pipe to muffler inlet to 2.25 exit straight through muffler to a 2.25 straight through resonator.

 

[Darter6]

My 64 Dart was a 225,Clifford intake,600 AFB, Clifford headers 2 1/2'' from header flanges into a "Y" pipe,O2 bung,

2 1/2 single pipe to the back bumper.Only photos I have for you.Pipes were homemade on this one.The Y was made at the exhaust shop.

 

[RustyRatRod]

You want the smaller pipe for the wye because you're only evacuating 3 cylinders at a time. The smaller diameter keeps the velocity up and helps scavenge the cylinders really well, especially at the wye itself where the pipes transition into the single 2.5". Think of each trio of cylinders as a separate engine being piped together. That's essentially what you have.

 

[65 Cuda 340]

Two 2-inch pipes will flow more than a single 2.5-inch pipe, and provide enough flow to handle almost 300 horsepower.

 

[cchrishefish]

So my plan to run 2 inch pipes for the wye does make sense when it comes to performance. I think I will go with my original plan. From everything I have read Slants perform best with a single exhaust. So, I think this is how I will hace it done 2 inches for the WYE then increase to 2.5 all the way to the back. I am considering a Flowmaster 40 muffler. What other mufflers should I take into consideration, Thrush, Cherry bomb, Walker? The car is for street use so I do not want to wake up the dead.

 

[Cuda65Steve]

Thank you, I appreciate your input before I get this done. I was thinking that an early A body car like mine 64 Dart GT may not have enough clearance in the engine compartment for 2.5 inch pipes. My car is manual everything no power steering, or air conditioning. Has anyone else installed 2.5 inch pipe in the engine bay in a car similar to mine?

I have 2.5" from stock manifold through a Flowmaster all the way back. Awesome sound even with 1bbl

 

[/sixchall]

Ok......here’s what I did, a few of my own modifications. Starting with a Super Six set up, I worked my way to the back. Hooker headers 3 into 1, off the collectors 2.25” aluminized pipe all the way back w/ an H pipe welded in. Then to the back with dual 26” Cherry Bomb glasspaks around the gas tank to couple of chrome tips on each side under the valance.

 

[RustyRatRod]

So my plan to run 2 inch pipes for the wye does make sense when it comes to performance. I think I will go with my original plan. From everything I have read Slants perform best with a single exhaust. So, I think this is how I will hace it done 2 inches for the WYE then increase to 2.5 all the way to the back. I am considering a Flowmaster 40 muffler. What other mufflers should I take into consideration, Thrush, Cherry bomb, Walker? The car is for street use so I do not want to wake up the dead.

I think that's a fair assessment. Inline engines.....and small cube V8s in general do tend to like a well thought out single exhaust as far as torque goes. At least that's what real world testing shows and not some online chart B.S.

 

[RustyRatRod]

So my plan to run 2 inch pipes for the wye does make sense when it comes to performance. I think I will go with my original plan. From everything I have read Slants perform best with a single exhaust. So, I think this is how I will hace it done 2 inches for the WYE then increase to 2.5 all the way to the back. I am considering a Flowmaster 40 muffler. What other mufflers should I take into consideration, Thrush, Cherry bomb, Walker? The car is for street use so I do not want to wake up the dead.

As for the muffler, take a look at the Dynomax Ultra from Walker. They are said to flow better than an open pipe. Their info is easy to find online. I have the largest one in 2.5" for mine, although I have not gotten to the exhaust on it yet.

 

[65 Cuda 340]

I think that's a fair assessment. Inline engines.....and small cube V8s in general do tend to like a well thought out single exhaust as far as torque goes. At least that's what real world testing shows and not some online chart B.S.

My point above was that two inch pipes coming off the headers would not be a flow restriction into the single 2.5 inch main pipe.

 

[RustyRatRod]

My point above was that two inch pipes coming off the headers would not be a flow restriction into the single 2.5 inch main pipe.

I agree! I wasn't trying to argue with what you were saying. In fact, in certain circumstances, a dual system might be of better benefit. I think like everything else, it's combo dependent.

 

[65 Cuda 340]

As for the muffler, take a look at the Dynomax Ultra from Walker. They are said to flow better than an open pipe. Their info is easy to find online. I have the largest one in 2.5" for mine, although I have not gotten to the exhaust on it yet.

I agree. And testing has shown that Flowmasters don't flow that well. Dynomax Super Turbos flow better than most Flowmasters, and are quieter than the Ultra Flows if that's important. Another chart:

 

[RustyRatRod]

I agree. And testing has shown that Flowmasters don't flow that well. Dynomax Super Turbos flow better than most Flowmasters, and are quieter than the Ultra Flows if that's important. Another chart:

View attachment 1715519698

That's one of the charts I was referring to when I was talking about the Ultra Flow numbers. Kinda hard to wrap your head around, but I'm sure it's accurate. You know how technology and all that goes nowadays.

 

[65 Cuda 340]

One other thing to consider is that a single exhaust system is a good bit lighter than duals (and also less expensive). Of course if you need the extra flow, then you need it, but if you don't, a big single can be a perfectly sensible choice - even for some small V8's, but certainly for a slant six.

 

[volaredon]

the flowmaster 40/44 series has to be the worst sounding muffler ever made. very cliche' and it seems like everyone with a 302 powered, Fox body Mustang or 80s/90s Camaro, would run them. that don't necessarily make them "cool".

 

[RustyRatRod]

the flowmaster 40/44 series has to be the worst sounding muffler ever made. very cliche' and it seems like everyone with a 302 powered, Fox body Mustang or 80s/90s Camaro, would run them. that don't necessarily make them "cool".

The Fox Rustangs are the only thing I really like Flowmasters on. But it has to be a mostly stock Rustang and the right Flowmaster. Other than that I think they suck.