Exhaust
I chose the 4.9L PFI V-8 as a power option mainly because of the feel a V-8 gives you as well as the performance. As Tyre has demonstrated, if I was after just raw power I could have used a 3800 SC & gained more horsepower. I like that the X-11 has a classic muscle car look to it, and now a fitting V-8 to match. With this I decided to go with true duals. Yes, completely TRUE DUALS. If I restored & modified a classic camero I wouldn't put a Y pipe to a center pipe & split off dual mufflers, so I didn't do it to my X-11. No offense to anyone with that exhaust set up, in most cases it probably adds more performance. I like true duals & now my ride's got some !!! Hee hee
Front Manifold: Heat shielding was used to protect the starter & electrical lines on the front side of the engine block.
Rear Manifold: The clearance here is tight but very workable. Thanks to the custom cutting on the exhaust manifold this connection was very easily made. (See engine prep for manifold details) The pipe will be taken back down & heat wrapped as to limit the heat exposure to the CV shaft.
View of how the exhaust flows under the engine cradle. Heat shielding was used on the tranny pan to limit heat exposure. Not visible, there is 1/2" clearance between the pipe & pan.
Full exhaust view from the front end. The Catalytic converters were staggered for better fit.
Rear end exhaust junctions made the most clearance around the gas tank, while still clearing the rear suspension parts.
Full exhaust view from the back of the car.
The Catalytic converters are Catco, and the mufflers are Summit Turbo mufflers. Both are high flow items, so performance is not hindered. In fact, performance was probably gained being the 4.9L I used is completely stock - no performance mods. With ony 27K on the motor, it doesn't need any yet ...... So going to a higher flowing exhaust & a better filter lets the motor breathe better than when it was in the Caddy. I choose the Turbo mufflers because I had one on my X when it had the 2.8 in it. The muffler is quite enough, but still gives a nice grumble...
O2 Sensor issues:
This is the result of the engine running incredibly rich !!! The result of an oversight in the planning on my swap. The Caddy Deville (Donor car) uses a the wrap around exhaust with one 02 sensor after the two manifolds meet. I installed dual exhaust & only one 02 sensor in the rear manifold. Basically the computer is looking for all the exhaust on the one sensor. Since its only getting half of what it's looking for, it was dumping in twice the fuel to compensate !! Scene above, this is the carbon deposit after 100 miles !!!
Solution:
Install a second 02 sensor, setting both in the pipes & convert the PROM to a Caddy El Dorado setup. This set up uses two 02 sensors in separate down pipes, which best matches my exhaust set up.
Front 02 sensor.
Rear 02 sensor.
Let's see if that helps the 11 MPG average !!!!
I had to add new lines to the computer harness & move the 2 existing lines to a different connector in order to let the PROM read both 02 sensors properly. As you can see Tyre's custom umbilical cord is quite complex and was difficult to get open because he insulates the wire very very well. I had to slice threw the wrap without cutting any of the dozens of lines. After getting to the wires I needed & not harming any others, I just might be cardiovascular surgeon material !! Ok, maybe not.....