What size exhaust pipe? Dakota manifold p/n's?

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737jetdr

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Hey everyone. Looking for advise. Finally getting my 65 valiant wagon back together. 360 magnum and 904 trans. Using stock 273 manifolds and not crazy about them. Would 2.25" exhaust work better than 2.5" with these manifolds? Also does anyone know what part number Dakota manifolds to look for should I choose that route? Thanks in advance .
 
Dorman has new ones in stock 03/94. 360 Dakota
 
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I just got some 5.9 magnum manifolds for my 340 which I have in my 65 dart with a 904. I just measured the diameter of the exhaust pipe coming off them and it’s 1.5 inches ID and 1.875 outer diameter. They came off of a 98 Dakota.
 
This is close but not the same:

im running in a 66 early A a 74 318 with the 273 manifolds from same car.
I went TTI 2-1/2” “X” pipe dual.
it is super tight. I had to cut out sections to clear torsion bars and around transmission. Lots of fab to make it work and clear and even then it’s tight. If doing again.... I would do a custom y pipe and one single large pipe. How that effects performance I’m not sure. These cars are not designed for dual large exhaust even though we make it happen. Lol!

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Magnum manifolds fit with some rework; but if you're running power steering, the factory 273 logs are (basically) the only game in town.
 
Thanks for the input everyone. No power steering in my case so I may check into the magnum manifolds. I was more curious about the pipe size if I use the smaller manifolds concerning back pressure. Wasn't sure if the 2.25" would be better than bumping completely up to 2.5". I guess slowly stepping up to the bigger pipe probably wouldn't be an issue.
 
I know there’s a lot of discussion on this topic on this site. The big pipes aren’t necessarily the better . Think about a garden hose. If you have water coming out of the faucet in a half inch diameter hose and you connect a 2 inch diameter hose to it you’re still going to be limited where the waters coming out of the faucet. You’re only going to get so much volume there. That high pressure coming out of the smaller manifolds is only going to expand and have less pressure coming through the pipes.
 
Then why do the diesel boys have garbage cans for exhaust pipe but the head pipes are 2-1/2"
LOL! Farm boys. Gotta love them.
 
Same reason people put all kinds of chrome accessories and fake chrome on their cars. They think it looks cool. Zero function I bet. to each their own
 
Hey everyone. Looking for advise. Finally getting my 65 valiant wagon back together. 360 magnum and 904 trans. Using stock 273 manifolds and not crazy about them. Would 2.25" exhaust work better than 2.5" with these manifolds? Also does anyone know what part number Dakota manifolds to look for should I choose that route? Thanks in advance .
The dakota has a 2 inch pipe coming off of the manifolds. There are the same exhaust manifolds on 1990-92 that are 2.25 outlets
 
The dakota has a 2 inch pipe coming off of the manifolds. There are the same exhaust manifolds on 1990-92 that are 2.25 outlets
I knew there was a certain year that had a larger outlet. Any idea what the casting numbers are?
 
I knew there was a certain year that had a larger outlet. Any idea what the casting numbers are?
Not off hand, sorry. If I can track it down ill let you know. 1 thing for sure there are none being produced. You could step up fairly easily from 2 to 2.25 then step up again under the car. Do atleast 18 inches of the 2.25 for velocities sake
 
The dakota has a 2 inch pipe coming off of the manifolds. There are the same exhaust manifolds on 1990-92 that are 2.25 outlets
Are they exactly 2 inch when you measure them with a caliper on the outer diameter? I put my calipers on and got about 1.875. Of course the pipe bends right there so the diameter could be skewed
 
Are they exactly 2 inch when you measure them with a caliper on the outer diameter? I put my calipers on and got about 1.875. Of course the pipe bends right there so the diameter could be skewed
Right off of the manifolds they're flanged at 2 exactly. Now, you're correct there are places where the mandrels are stretched near the bends but I've had to buy a few 2.1/8 coupler for the crossover pipe on my trucks & in that area they are 2 exactly. The I'd of the couplers are 2
 
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