Project V8 RX-7: Part 9 – The Exhaust

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MORE than adequate ground clearance!

Primary cats tacked in place the passenger side offered a little more clearance and did not require any modification to the bellhousing.  2 more cats to go!

With our secondaries all tacked together we drilled holes for 4 new O2 sensor bungs.  The E-ROD kit includes 4 weldable O2 sensor bungs, presuming most customers will probably have to make their own custom exhaust.  That was nice!

There you go!  All four catalytic converters included in the E-ROD kit in place and the O2 sensors are within spec to pass the visual inspection portion of the CARB referee inspection!

We skimmed through that part pretty fast; if you want to see the whole thing, check out the time-lapse photography of the whole process below–you can’t even tell it took me 3 days to do it!

With our secondaries built we measured what we’d need to build a Y-pipe and merge to a single tube exiting out the back.  Deciding to go with a single tube rear section rather than doing an X-pipe and duals came down to space constraints, weight considerations and budget—half the material is used, so it should cost and weigh half, right?!  We are going to try to go without a muffler as well.  Our experience with the old LS1 car and its cat-only system without a muffler was pretty pleasant, so we’re confident that the four cats on our E-ROD will absorb enough of the obnoxious sound levels and leave us just enough growl to let everyone know this RX-7 has a big set of nuts now!

We really liked the quality of the Vibrant exhaust parts used to build the ultimate SE-R exhaust so we revisited their website to see what we could find to build our exhaust.  Since our secondaries were roughly 2.5” in diameter we started there and ordered a pair of stainless V-band clamps to fit.  From there we would need some new 2.5” tubing to make the Y-pipe, a merge and then whatever single tube we wanted to run the rest of the way back.  Browsing on we came across “Stainless Steel Oval Tubing”—sick!  Turns out the 4” “nominal” oval tubing was just about 2.5” wide on its short dimension and almost 5” on it’s longer dimension.   You thinking what I’m thinking?

…if you were thinking THIS, then you are as clever as I!

 

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