Slant Six Forum :: Dutra Dual exhaust pipe length

It is hard to say exactly with the Dutra Dual short iron manifolds. My answer for shorty headers (based on experience and testing) is to run those 2" pipes to a spot 4-12" behind the transmission crossmember, and then put them into a Y and then single 2.5" exhaust out the back.

Note that Wkstiner is trying to optimize secondary pipes, not primaries (header/head) pipes.

What is the cam you are using? I assume it's the bigger one you can get from summit? Please post specs.

Lou

Is he still doing anything car or /6 related? It would be cool to see him check in here now and again

I’m using a Hughes Mild Street cam

Author:	Wkstiner [ Thu Mar 12, 2026 8:07 pm ]
Post subject:	Dutra Dual exhaust pipe length
I’m installing Dutra Duals on a modified slant with 10:1 compression, a Hughes Mild Street Cam and dual 32/36 Weber carbs. My question is: using 2” exhaust pipes from the manifolds to a 2.25” outlet Y pipe, how long should the 2” pipes be, for proper scavenging, before the Y collector? Thanks!

Author:	Dart270 [ Fri Mar 13, 2026 7:50 am ]
Post subject:	Re: Dutra Dual exhaust pipe length
It is hard to say exactly with the Dutra Dual short iron manifolds. My answer for shorty headers (based on experience and testing) is to run those 2" pipes to a spot 4-12" behind the transmission crossmember, and then put them into a Y and then single 2.5" exhaust out the back. That should work well for the Dutras too. This will maintain as much low/mid range power and torque and not hurt the top end. I have never done these tests for Dutras, but this is my sense based on other experiences. However, I doubt you will lose much if you put the Y near the bottom of the engine compartment above the torsion bar. Packaging and convenient fabrication may be as much or more important than getting that last 2-4 HP? My 2 cents... Lou

Author:	lgu32 [ Sat Mar 14, 2026 4:32 am ]
Post subject:	Re: Dutra Dual exhaust pipe length
Quote: It is hard to say exactly with the Dutra Dual short iron manifolds. My answer for shorty headers (based on experience and testing) is to run those 2" pipes to a spot 4-12" behind the transmission crossmember, and then put them into a Y and then single 2.5" exhaust out the back. My Dutra duals had about that kind of tubing. It has also 10:1 compression, 236/230 degree Hughes cam and DIY fuel injection. It was very much a low end torque engine with 5000 redline.

Author:	Dart270 [ Sat Mar 14, 2026 5:50 am ]
Post subject:	Re: Dutra Dual exhaust pipe length
Note that Wkstiner is trying to optimize secondary pipes, not primaries (header/head) pipes. What is the cam you are using? I assume it's the bigger one you can get from summit? Please post specs. Lou

Author:	volaredon [ Sat Mar 14, 2026 7:22 am ]
Post subject:	Re: Dutra Dual exhaust pipe length
Speaking of the creator of these manifolds and so many other things "/6". I know that he had a horrible thing happen with one of the California wildfires a few years ago and lost a bunch of his stuff. Is he still doing anything car or /6 related? It would be cool to see him check in here now and again

Slant Six Forum https://slantsix.org/forum/

Dutra Dual exhaust pipe length https://slantsix.org/forum/viewtopic.php?t=68565	Page 1 of 1

Author:	lgu32 [ Sat Mar 14, 2026 8:56 am ]
Post subject:	Re: Dutra Dual exhaust pipe length
Quote: Note that Wkstiner is trying to optimize secondary pipes, not primaries (header/head) pipes. What is the cam you are using? I assume it's the bigger one you can get from summit? Please post specs. Lou All that one N/A 225 can produce fill fit in a single 2,5" tube with no rush in it. D-duals are not the hottest exhaust a slantsix can get. Just a nice pair probably doing extra 10 hp if all other parts are good. Gill welding seem to like produce tubes which are Y-connected in the engine compartment. I got mine from local muffler shop. In the 1st setup they were true duals but I didnt like the sound at all. So the were Y-connected at the rear of transmission until I removed them before turbo installation.

Author:	Rick Covalt [ Sat Mar 14, 2026 12:00 pm ]
Post subject:	Re: Dutra Dual exhaust pipe length
Quote: Is he still doing anything car or /6 related? It would be cool to see him check in here now and again Yep I miss having Doug on here too!

Author:	Wkstiner [ Mon Mar 16, 2026 7:47 am ]
Post subject:	Re: Dutra Dual exhaust pipe length
Quote: Note that Wkstiner is trying to optimize secondary pipes, not primaries (header/head) pipes. What is the cam you are using? I assume it's the bigger one you can get from summit? Please post specs. Lou I’m using a Hughes Mild Street cam

Author:	mcnoople [ Mon Mar 16, 2026 1:21 pm ]
Post subject:	Re: Dutra Dual exhaust pipe length
Quote: I’m using a Hughes Mild Street cam It gives me a warm feeling everytime I see 65 signet mentioned. I will have had mine for 27 years tomorrow and will never get rid of it. Bought it st pattys day in 1999, 2dr ht with 60k ish miles when I got it for $200. take care of it and make sure to enjoy driving it.

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