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03:18:43 - 12/29/2024
Dakota Performance
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daver36
Dodge Dakota
JOIN HERE
11/04/2008
23:45:29
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 Subject: full exhaust
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Message:
Anyone with the 4.7L knows the worst par of our exhaust is the manifold to after cat sections. The small tubing and two precats with a full cat afterwards is way to restrictive and HAS to be hurting fuel economy and obviously power. I'm thinking of doing headers and new piping with only one cat up to the muffler (i've already done a 2 1/2" dual catback system) but I've been told that this could make for some problems. Somebody told me that on some dodge's if you free up the exhaust that much it could mess with some O2 sensors and send some trouble codes. I'm wondering if this is true and, if not, what size tubing would they go with. I'll probably stick with y'd together with one cat setup into my single in/dual out muffler. Any advice would be great, thanks guys.
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Kowalski
GenIII
11/05/2008
17:25:05
| RE: full exhaust
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Message:
Some years had the three cat "cali emissions" set up you describe; and also a "federal" one cat version. There was only five HP difference in the ratings between the two. The biggest bottleneck in the system is actually the y-pipe itself - with some versions much more crimped than others. Many run the 4.7 with fairly free exhaust with no problems. It's often better to think in terms of exhaust velocity than "freeness" though. Going too big on pipes can slow down exhaust velocity too much for decent cylinder scavaging, killing low end. 3" seems to be a good size for a single 4.7 set up; 2 1/4" for duals.
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