If you recall, BART came with an aftermarket 'performance' exhaust from CSC. These are quite popular among the x1/9 community if you are seeking to gain a bit of extra power, however, they are normally used as part of a performance package that may include a highlift cam, ported head and upgraded carburettors. These modifications are aimed at improving the flow rate of the engine.
BART has none of these performance parts fitted so the only purpose for the CSC system on BART is to make it look good and sound 'meaty' from the outside, thats it!
The real issue is the noise; when you are in the car it's intolerable unless you wear ear defenders. Because you sit so close to the engine and exhaust it is truly defending at any speed above ~40mph and under acceleration. Pedestrians here you coming a mile off and stop to take a look!
I also suspect it affects the low down performance of the car despite my upgrade of the main jets to richen the mixture. The higher flow rate of the exhaust causes the mixture to weaken and I compensated partially for this with the new jets...but...that noise...something had to be done!
OEM vs CSC
OEM vs CSC
I obtained part of the OEM system from EuroSport UK as they are freely available but as the CSC system also had a custom exhaust manifold/header I needed to find an original cast iron manifold for a 1300 engine to mate to the silencer unit These are not easy to find. I tried a few outlets like x19spares but they where in the process of moving warehouse and where unable to respond to my inquiry so I looked to eBay and found the correct item in Italy! Incredibly, the manifold arrived just 5 days later and looked to be perfect.
With all needed parts to hand including new gaskets, studs and nuts I set to work. Stripping everything down was simple enough and reassembly was going swimmingly well when I discovered an issue where the top exhaust mount (hockey shaped bracket) would not line up with the mount on the silencer...blast. Oh, and I found a few bits of rust breaking out underneath the underseal which I treated and then applied Dinitrol to. This is something I will need to revisit next year when the weather improves.
CSC Manifold on the car
OEM Manifold
Ah! Thats not going to fit!
Some rust patches
A series of emails to Eurosport and a enquiries elsewhere led me to the conclusion that the mount had been modified for the CSC system. Sure enough, removing the mount and inspecting it showed it had been cut 'n' shut to line up with the CSC silencer. Why they didn't simply move the bracket on the CSC silencer is anybody's guess.
A call to x19spares calling for help saw a used bracket arrive the following day, thanks guys I really appreciated the fast turnaround and help. I cleaned up the new mount, painted it and fitted it the following day. A bit of levering and the mounting holes lined up, phew!
With the carburettor refitted and plumbed in I fired BART up...what a difference to the noise output! I bled the cooling system as the inlet manifold is water cooled and it has to be removed along with the exhaust manifold and went for a drive. What bliss, a gentle purr from behind with a bit of transmission whine I could now hear what was going on around me, result. Performance seemed better in the midrange and low down, the response was more linear and smooth, there was a touch less punch though when the second carburettor choke opened up...I will revert the main jets back to standard at some point.
When I got back I checked the engine over and found a pool of petrol on the carb mounting plate which was alarming, I traced the leak back to the petrol inlet filet housing and tightened the large brass nut up. I hope that cures it.
Because of the changes to the exhaust I thought it a good idea to recheck the idle mixture for piece of mind and at the same time just check the timing. This was out by a few degrees I probably didn't set it correctly last time so I reset it to 5/6 deg BTDC. After the engine had cooled down I went over all the bolts and nuts to make sure they where tight. Result, thats another job ticked off the list!