FIAT 124 Crosspipe Comparison

My buddy’s stuffed turbo 124 had an issue with the exhaust rubbing due to the EC crosspipe not being compatible with the GWR system. We swapped in the GWR crosspipe, but not everything goes as planned…

If you remember from our last adventure with Gabriel, he received his Spider back from the turbo installer with the Eurocompulsion crosspipe. This was installed because he kept getting P0137 errors, and it was hypothesized that the O2 sensor bung on the Good Win Racing crosspipe was the culprit. More on that later…

Problem is, he has the GWR exhaust system on his car, and the EC crosspipe was causing it to rub. You could hear the rubbing when the car was running. EC clearly states their crosspipe is only compatible with the factory exhaust system.

When we got under the car, we could see the EC crosspipe was pushing the GWR midpipe against the body of the car. It’s very obvious the two systems are not compatible, and I don’t think the car should’ve been left that way despite the P0137 errors seemingly being corrected by it.

Removing the crosspipe was a piece of cake. Secondary O2 sensor was removed. Two nuts on the downpipe studs were carefully removed as those studs are delicate. Two bolts on the cross to midpipe connection, and then one bolt on a bracket.

Once we had the crosspipe out, it was interesting to see the various crosspipes next to each other. Obviously the GWR one is the fattest, but the geometry is more fascinating. The EC one is the same length as the factory one, but has more graceful bends. The factory crosspipe is covered in some heat cladding and is very crudely bent. The GWR pipe has tighter bends, and is shorter in length.

Installing parts are never as straightforward as taking them off. The GWR crosspipe was designed to re-use the factory cross to midpipe studs with springs, but the EC was using through bolts of a different thread pitch. We dug Gabriel’s factory crosspipe studs out of a box, but unfortunately the nuts were seized on them. Quick run to the hardware store, and we had M10x1.25 bolts that would work for bolting the cross and midpipes together.

Holding the downpipe gasket in position while putting the crosspipe on the downpipe studs was a trick in itself. We had all the fasteners in position but with everything still loose to make sure the alignment was good. It was immediately apparent the GWR exhaust now had adequate clearance.

I tightened up the downpipe to crosspipe connection, but noticed the gasket between the two was still loose. After a bit of fooling with it, I noticed the nuts were contacting the welds on the GWR crosspipe. This was causing the nuts to bind and get tight on the studs, without actually tightening up the connection.

I think this was the issue that was causing P0137 errors when the GWR crosspipe was previously installed. The reason why the EC crosspipe “cleared” those errors is because it was firmly seated to the downpipe. It doesn’t have the problem of the nuts contacting the welds partly because it’s a smaller diameter, but also because its welds are more flush.

So after realizing that, the GWR crosspipe had to come back off so we could come up with a solution. Just one little problem, the nuts had bound themselves to the studs. Despite being very gentle, I snapped off one of the studs. For the moment I just snugged everything else back up, and will have to tackle these issues in the future. Spoiler alert, it’s already fixed. Stay tuned for that write-up!

Check out the video below to see how all this went down.