15/03/2026
Giulia 2.2 JTDm turbo upgrade part 11: project overview and results
In late 2022 we decided to build a true upgrade turbo conversion specifically for the Giulia 2.2 JTDm. The reason, typical hybrid turbos are not delivering the results we are after, which is 350 engine horsepower with a broad powerband and zero smoke output. Especially driveability and torque at low rpm cannot be sacrificed as this takes a lot of the fun away of a street vehicle.
With the previous post #10 roughly one year ago let’s describe the mods that were done in the meantime:
- Several turbo specs were tested
- Modification of the CAC cooling system
- CP4.1 high pressure fuel pump upgrade
Let’s start with the turbo, before we tested the 1756, 2060 and 2262. To investigate how to further optimize the turbo system we added a turbo rpm sensor. Actually the Giulia 2.2 Veloce has one on the stock turbo, but this being a Ghibli turbo doesn’t have it. So we used a Banks Power sensor that we can monitor and log with the Idash. This sensor was placed into a new compressor intake that we had custom CNC milled with anti surge slots for our housing.
First we prepared a 2365 turbo, that was far from a success. The 2365 had so much reduction in boost threshold that it resulted in low boost faults, strange vnt actuator behaviour with extreme turbo rpm spikes of up to 300k rpm, very scary. Once running at the correct boost pressure (we are talking > 3500 rpm) there was hardly any reduction in EMP compared to the 2262.
As this turbo clearly wasn’t working efficiently and potentially dangerous we took it off and prepared a 2265. So same hotside as the 2262, only the compressor increased to a 65mm exducer 6+6 wheel. That was working better than the 2365 in terms of spool, but still much worse than the 2262. Also after a gearshift the boost dropped too much, something that was before never an issue. Somehow these turbos were not working, whatever we tried with the VNT adjustment. We decided to move back to the 2262 combination, but with a different compressor aero (from 9 full blades to 7+7 blades) and another custom made anti surge housing. That brought back the turbo response completely. Now equipped with the turbo rpm sensor we stepped up the manifold pressure to 3650 mbar absolute and with