End of day update: The car is back together and driving. The rocker arm stoppers took longer than expected to install due to the required grinding of the rocker cover. All of this has been carefully explained and illustrated in the new Rocker Arm Stoppers page.

The car initially was only running on three cylinders. I think this was due to idling the car earlier on in the day with the rocker cover not tightened. Some oil blew past the inner gasket and onto the coil packs. When they were reinstalled, a dodgy connection ensued. After a wipe and some idling, the problem went away. I have new spark plugs ready to fit that should eliminate the problem completely.

I ventured out and turned off the electronic boost controller to keep the turbo on the 15 psi external wastegate spring pressure. Having the wide band 02 gauge was amazing! The car is untuned but at least I could see if a dangerous lean out was occurring. I didn’t give it much throttle but under load the air fuel ratio is an ideal 11.5-12:1.

The engine is a touch laggier than before which is to be expected with the larger turbo. On 15 psi it’s a bit slower than the car before the change. The bigger turbo will be able to pump more boost at with more efficiency and therefore cooler inlet temperatures. More timing can then be added hand the power should come. The midrange will improve with more boost, as the electronic boost controller can be tuned to aggressively minimise wastegate creep. The turbo sounds a lot smoother and quieter as it spools. In a way it sounds more precise, which I like.

I’m very relieved to have the car back to a driving state and running okay. Apart from wiring in the Z32 AFM plug in parallel for an instant changeover later on, the car is ready to be tuned. I have to get a quote from Unigroup and save some coin, as registration is due within a month. Hopefully all of the tidying I’ve done pays off in the rego check.