Hooking up Dutra Duals

[Darter6]

I just got a 72 Dart Slant with air and automatic and power steering.
Found a set of new Dutra duals at the MATS Vegas show that I couldn't pass up.
Was looking for a set of Clifford shorty's.Already have a Offy intake.
Anyone have any photos of the exhaust pipe connection to the Dutra's ? They came with flangs and gaskets.
I was thinking of doing a Y pipe into 2 1/2'' single exhaust.

 

[halfafish]

I have a 64 Valiant with the same setup. It's an auto but no air or PS. 2" headpipes about 40" long into a wye then a single exhaust is considered the hot ticket.

Give me a few to find my brain and some coffee and I can get some pics.

 

[slantsixdan]

2" pipe off of each of the two exhaust manifolds, into this wye connector, 2-1/4" pipe from there to this muffler. It's in Walker's QuietFlow SS premium OE line, all stainless steel (which is nice for durability), made for the Jeep Cherokee 4.0 so it's easily got the flow capacity for a healthy 225 and it's tuned to keep an inline-6's exhaust from droning, has a 2¼" inlet and outlet (can easily step down to a 2" tailpipe). The inlet has a 2-bolt flange meant to bolt directly to the outlet of the Jeep's catalytic converter, but there's plenty of length to the input pipe that the flange can just be sawed off in 5 seconds at the exhaust shop. It's got the 4¼" × 9¾" housing, muffler shell 20" long, so it'll be a bit of a tight fit in an A-body, but it will fit.

2" tailpipe with resonator. If I'm rich, I like a Flowmaster HP2 stainless unit with 2" in and out. It's 18" long, which is a workable fit behind most A-body quarter panels. If I'm broke, I like a Walker № 17198 4" round can-type unit, 2" in and 2" out, with offset outlet next to a proper hanger bracket.

Speaking of that, whatever muffler you wind up with, make sure to use very soft hangers. The hook-and-O-ring type, for example. Today's popular "rod and rubber box" type transmits a lot of noise to the passenger compartment.

(Tailspout outlet 45° or greater downward.)

 

[halfafish]

Here are the photos. Clearly these headpipes are larger than 2" but you get the idea. The rear pipe is hard to see, but it drops straight down, then runs to the rear, closest to the block. You can barely see it to the left and below the front pipe in the second photo.

 

[Darter6]

Thanks guys. Big help .
I have a local muffler shop to make the pipes and exhaust to the rear bumper.

 

[MidnightSwinger]

Close up

 

[Hyper_pak]

Gill Welding makes a few different types of these.
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[Darter6]

Gill Welding makes a few different types of these.
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Now that's really nice ! I'll look them up.

 

[halfafish]

Now that's really nice ! I'll look them up.

If you're not aware, the pics in #4 and #6 are for a Dutra front, modified rear. The Gill Welding headpipes in #7 are for a pair of Dutras.

 

[Darter6]

Yes I have a pair. $1000 for a head pipe set,kinda out of my range.
It will be awhile before I start the project as other priorities have to be addressed first.
The photos are excellent .

 

[Docmcg]

This is what I’ve done. Gonna put it in my ‘65 A100 P/U.

 

[diymirage]

Gill Welding makes a few different types of these.
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View attachment 1716377624

You'd almost want to run that without an intake manifold

 

[volaredon]

Now how would someone manage that?

 

[RustyRatRod]

Now how would someone manage that?

You wouldn't, dummy. He's just sayin that cause that exhaust is so purdy you wouldn't wanna hide it. lol

 

[RustyRatRod]

Here's what we did with Vixen for head pipes, although she has the Clifford shorty headers.

1964 Valiant "Get Runnin & Drivin"

Thanks, Charlie. That's what I thought. Well, I'd rather have headers than power steering, so there it is. lol I forget is Vixen a 170 or a 225?

www.forabodiesonly.com

 

[Jim Kueneman]

The use case of what you want out of engine is needed as well. Where you connect those pipes together makes a difference. Back when I was working with Doug Dutra on a cam design I talked to him a lot about the Dutras and what he had experimented with. I was running simulation models to zero in on a cam design and I started putting in things he had experimented with so we could get a warm fuzzy the model was in the ball park. The first thing is where do you want the torque peak. The further back you put that "Y" connection the further down in RPM that peak goes. I put mine right behind the crossmember as the model (and driving it agrees) predicted it would be at around 3200 RPM which is where I wanted it as that is in the area of if I was driving along (with the 3.23s) and wanted to pass someone I wanted that extra kick right there. Doug built one that put the "Y" all the way back by the rear axle both the model and his experiment said it should pull hard at 1900 RPM and he verified that it did pull very hard right off the line.

That brings up point 2. Everyone jumps on the bigger the better for pipe diameter which in reality is not always true. If too large the velocity drops to the point where the effect you are trying to achieve (the interaction between the two exhaust pipes at the "Y") is lost. That said I did run a lot of simulations and found you need to get up to 3" or so before that happens with the Duals. That also brings in trying to get two 2" pipes threaded down through the engine compartment and body. It can be tighter than you think. Large exhaust is really more for flow that that really depends on RPM. For an engine that you just want for cruising torque who cares if the exhaust choke it a bit at 5000 RPM and up? I didn't so I used the model to determine the smallest size that did not hurt performance for something that is running like an RV-10 or Oregon Cams 2106 (what I used). I didn't see any difference in the band I cared about until you hit 1.5" so I settled on 1-5/8" down pipes to the "Y". They were very easy to get routed and offered plenty of room around them to work on things in the future. My slant puts puts a smile on everyones face that drives it. I have never proven that it performs like the model but the seat of the pants dyno agrees with where the power should be and where it should start to fall off at high RPM.

My 2 cents

Jim

 

[Darter6]

just want for cruising torque

Yes, this is just going to be a driver not a screamer. Click on the A/C and go.

 

[Jim Kueneman]

Yes, this is just going to be a driver not a screamer. Click on the A/C and go.

Connect the Y as far back as you can