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Doug Dutra Cast iron headers
https://slantsix.org/forum/viewtopic.php?t=32537		 Page 2 of 3
Author:  wvenable [ Thu Dec 04, 2008 10:17 am ]
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Thanks Doc, that helps!
Author:  daniel_depetro [ Thu Dec 04, 2008 12:28 pm ]
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Absolutely does!
Author:  Adrenalin [ Fri Dec 05, 2008 3:40 am ]
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these are really scientific explanations, thank you for such a detailed and true info. Doc, did you ever tested your manifolds on the dyno? How much extra power do they make?
Author:  armyofchuckness [ Fri Dec 05, 2008 7:09 am ]
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Thanks, Doc! Those are some great exhaust tips. (Pun unintended) I'll keep this in mind when I go to replace my manifold.
Author:  Doc [ Fri Dec 05, 2008 9:33 am ]
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I have never done any dyno runs but I have done some dragstrip work where I ran a car with a stock set-up and then changed to a D.Duals system... I picked-up a little over 12% improvement with that car and test.
DD
Author:  mopardemon71 [ Fri Dec 05, 2008 10:20 am ]
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the question I have for Doc is when are you going to make long tube dutra's? Something a few inchs longer and with that taper you spoke of? that would be sick. Works for front and rear location for exact same flow characteristics. Wow really sick!
Author:  63dartdude [ Fri Dec 05, 2008 12:34 pm ]
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I wish I would have seen that photo before I took my car in for a wye pipe. The guy made a wye pipe for me okay. But the two lengths are far from being the same. He dumped the pipe under the right manifold right into they wye. I am lucky if there is 6 inches there, compared to the much longer pipe coming from the front manifold. How much is that going to make a difference? But realistically speaking. I was lucky to get this wye pipe built. It took him about 4 hours to complete it.
Author:  Doc [ Fri Dec 05, 2008 3:32 pm ]
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As first noted, most of the gain from doing a "3 & 3" split is from increased pulse separation time.
Getting the primary pipes the "right" and the same length is more important with power band tuning and scavenging... where you want to carefully time when and where a high pressure pulse wave enters the collector area.

As for making a new exhaust manifold casting for the SL6, I did a design a while back that does have longer runners and it is a "tri-Y" configuration. Here is the cool part... it keeps intake manifold heating and has a large outlet flange that comes out sideways, just right for mounting a turbo. :shock: :D 8)
It is a big, heavy manifold that has a lot of metal content in the center. I am concerned about casting problems (shrink and twist) as well as cracking problems when used in Turbos applications.
DD
Author:  wvenable [ Sat Dec 06, 2008 12:08 pm ]
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Doc, could the stock hyper pak exhaust be used as a model to make a longer cast iron header? Thanks, Wayne.
Author:  Aggressive Ted [ Sat Dec 06, 2008 12:27 pm ]
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Good idea........Doc do you have a set of these to use for patterns????
Author:  Reed [ Sat Dec 06, 2008 12:43 pm ]
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Quote:
Doc, could the stock hyper pak exhaust be used as a model to make a longer cast iron header? Thanks, Wayne.
I doubt it. The exhaust manifold has to make a turn down almost immediately to avoid running into the intake manifold.
Author:  SlantSixDan [ Sat Dec 06, 2008 2:42 pm ]
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There already exists a really nice "long sweep" front-3 exhaust manifold. Plans are underway to reproduce it. It won't be soon, but it probably will happen.

The rear-3 item presents fit challenges; remember the Hyper-Pak item barely clears the '60-'61 direct-drive starter (and only if that starter is modified), and will not clear any gear-reduction starter — neither the Chrysler- nor the Nippondenso-made unit.
Author:  Wesola78 [ Sat Dec 06, 2008 2:55 pm ]
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If nothing else, you don't have to worry about your exhaust manifold cracking if you have Dutra Duals.:)
Author:  Reed [ Sat Dec 06, 2008 3:00 pm ]
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Quote:
There already exists a really nice "long sweep" front-3 exhaust manifold. Plans are underway to reproduce it. It won't be soon, but it probably will happen.
Image Does anyone know if this front exhaust manifold will clear accessories like A/C pump/brackets and P/S pump?
Author:  Rick Covalt [ Sat Dec 06, 2008 3:06 pm ]
Post subject:  Pics please
Do we have pictures of this manifold Dan? Or is it top secret, I'll have to kill you kind of stuff.
Thanks, Rick
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