April 2023

Pre Covid I ordered an exhaust system from Autobionics that should fit the LS3/GTR setup. This system looks amazing - much better in my opinion that the standard factory system for the LS3. Chasing up Autobionics would get the response that the fabricator was unavailable. This continued for some time Autobionics did introduce me to one of their customers that had there exhaust system for sale but we were not able to agree on a mutually acceptable price. Well Covid seemed to make this system elusive. On my last contact with Autobionics they advised me that they had sold the rights to all of their Ultima products to Ultima Sports. Autobionics had not taken any deposit for the system so I was not out of pocket.

I contacted the factory regarding ordering this particular type of exhaust system for my GTR they needed to verify they had all of the jigs etc. and late September 2021 I placed 50% deposit with a 12 - 14 weeks lead time. The expected lead time turned out to be a tad optimistic. The factory did keep me updated and did offer to refund my deposit and allow me to cancel if required. Eventually I got the email from the factory that the system had been test fitted and was ready to be shipped. I took delivery of the system in February 2023, three and a half years from my initial request to Autobionics. I guess its a good job this is not a quick build :-)

Part of the exhaust system included heat shields for the headers, I had assumed that I would have to fabricate something similar so this was a nice bonus.

With the remaining sections of the system it starts to look very impressive, I am so pleased with it and glad I managed my patience to stay the distance.

The tailpipes are massive - I can fit my fist in them.

I order some replacement fuel filler funnels from the factory, as my ones are pretty old now and show some cracking in the rubber. When I attempt to fit the unleaded fuel restrictors in the filler funnels, I find that the are slightly different, one sits at the top and the other at the bottom , hmm that will mess with my OCD. I speak to the factory and they advise that the restrictors are no longer an IVA requirement.

Fitting the washers and nuts to the underside of the fuel filler cap is very challenging. I place two nuts into a socket (the second nut lifts the first so it can reach the protruding screw thread. I then wrap some Bluetack around the socket to secure the washer in place. Now using a handle and an extension shaft and with the aid of a mirror I can attach the washer and nut to one of the screws pretty easily. Rinse and repeat another fifteen times to complete the job.

           


Back to the exhaust system, one thing that became apparent is the roll cage supports interfere with the exhaust. On later RS and possibly the EVO these are mounted differently. I figure that if I change the angle and shorten them, then they will fit further forward of the O2 sensors.

I cut some steel plate and weld together to make a pair of brackets.

I cut and grind the top mounting tubes off and mount them to the top of the roll cage. Then using a long strip of aluminium (a sacrificial yardstick) I can work out the length and angle that I need to reduce the supports to.

Using Fusion360 I can then simulate the join and print out a flat template that I can wrap around the tube and replicate the complex cut line.

Using angle magnets to hold the brackets to the chassis with bolt locating the lower end I can put some tack welds on the join. Now the brace can be fully welded off of the car safe in the knowledge it is at the correct angle.

The final job is to tack weld the brackets to the chassis using the now completed roll cage supports to accurately locate the brackets and then removing these braces and complete the welding.

A coat of roll cage black paint finishes the job.

Rather than just use Sikaflexor black mastic, I design and 3D print a pair of flexible seals to close the holes where the braces go through the rear bulkhead, this present a neat finish.

For the gearbox breather I drill and tap the hex head drain/fill plug, but when the hose connector is screwed in fully the hose is still loose and can move up and down several millimetres. I guess I must have done something wrong although cannot figure out what. It appears that the inner sleave should seat on a face and then when outer is screwed down a seal is formed by inner being pressed into the seat by the outer threaded piece.

To resolve this I buy a connector, cut of the existing connector and re-terminate the hose. Once assembled the connector is effectively a single piece and I can use a copper washer to provide the required sealing.