Turbo upgrade options for the E15ET

Being a Nissan engine, we are lucky to have in my opinion the widest range of turbo-chargers available, that being the popular Garrett brand. And at the same time, being a small capacity engine it allows us to ‘upgrade’ to a turbo that may be considered undersized by other higher capacity Nissan owners.

T2/T02Of course we all know this is the factory turbo item found on our cars. The T02 is the water-cooled version released on the unleaded 86-87 ET. If you have a water-cooled T2 turbo on your car and it’s the low mount ‘leaded’ version, then you most likely have had a turbo replacement.  
T25The T25 is the first upgrade in turbos for the e15et engine. The origin of these turbos is found mostly on CA18DET powered cars such as s13 Silvia’s and 180sx’s. A similar sized turbo can also be found from the VG30DETT engine originating from the Nissan 300zx twin turbo. Its size however is someone in between a T25 and T2, which it has been suggested they run a T25 compressor wheel and a T2 exhaust wheel.  
T25gThe next size up, found on 180sx’s featuring the SR20DET engine. One of the best ‘all round’ turbo upgrades for the E15ET engine. 0.8 A/R Compressor and 0.64 A/R exhaust makes these turbo’s have good mid and top end response.  
T28/GTiR T28The turbo for the more serious. These snails love boost and due to the size they operate in the higher end of the rpm range. Serious top-end response but I don’t recommend running a turbo such as this unless you have adequate fuel supply and programmable engine management. Also tested by some is the GTiR T28, a bigger version of the T28 found on 200sx’s. Bigger exhaust wheels and compressor wheels mean that this turbo will push the usable rpm range that little bit higher, which is not advised on a standard engine.  
RB series T28/T3The RB series engines (Skyline 20,25,26) turbos will not directly fit onto an E15ET engine due to exhaust flange differences. If you really want one of these turbos on your e15 firstly you will need an adapter flange made up or a custom exhaust manifold. However keep in mind most RB turbo’s have ceramic exhaust wheels which don’t like big boost. In the opinion of most these turbos just don’t warrant the added trouble of manifold changes.  

If you are willing to have custom manifolds made up then you have the option of other turbos found on Subaru, Mitsubishi and other engines. One of the most important things to remember is BIGGER IS NOT ALWAYS BETTER! Installing a T04e turbo of the likes will just not work on these engines. Every engine is different and the turbo on one e15et will not mean it’s the best turbo for you engine. You must consider what modifications you currently have and what mods you will do in the future and try to match the turbo for you needs.

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