Flexible Compressor Housing
On the large type “C” compressor housing found on the two largest EFR turbos, the outlet is machined so that you can either use a hose connection or a v-band with o-ring connection for an added degree of flexibility. I recommend the v-band connection with solidly mounted engines and the hose connection with rubber engine mounts. Don't believe me? Try a v-band connection with rubber engine mounts and over time you'll find the v-band clamp will spread, the o-ring will fail, and the aluminum flanges will crack. This all of course depends on your intercooler tube design and the amount of movement in your engine.
Integrated Blow Off Valve
An integrated compressor recirculation valve (CRV) is included with every EFR turbo. An optional block off kit accessory is available from BW in case you still want to use your ricer spec valve. The excess charge air is released directly back at the compressor wheel in an attempt to reduce lag further. The diaphragm used in the BW CRV is actually the same part that BW has sold millions of to the OEMs and were designed to last the life of the car. How's that for a reliable track record? The CRV has a fairly low valve lift and isn't very large, but it is more than enough to relieve pressure to avoid compressor surge. There's a general misunderstanding in our little tuning industry of how large a blow off valve really needs to be to get the job done. Large external BOVs (e.g. TiAL 50mm, Turbosmart Raceport, etc.) definitely have their place however. The BW CRV works great on the Sierra Sierra EVO though. Good enough for Sierra Sierra, good enough for you.
All three EFR compressor housing sizes have integrated CRV, BSCV, and turbo speed sensor bungs. Notice that the two larger compressor housings also utilize a ported shroud to enhance the compressor maps.
Forged Milled Compressor Wheels
Another great feature of the Series EFR turbos are the super robust compressor wheels. They are milled from 6000 series aluminum forgings for the ultimate in strength and durability. Sure, some of the smaller turbo shops make billet compressor wheels out of bar stock, but the grain structure and surface hardness of a forged part is superior in every way. What this means to you is less rock chips and jacked up blades.
The EFR compressor wheels span 6 different exducer sizes between 62mm-91mm to cover 200-1000bhp. All EFR compressor wheels are forged and milled.
How good is the machining quality on these wheels? Pretty damn good.