Jason removes the old Precision Turbo. If your target is around the 450 whp range, this is a fine turbo. To make 500 whp, the powerband gets narrow as the power drops and the intake air temperature starts to shoot up. To make 450 whp only takes about 17 psi but 500 takes a hurting 26 psi. The compressor is getting way outside the range where it is most efficient and falling into choke flow. This is where the efficiency falls below 50%. At this point, the turbo is blowing hot air and the turbine must recover a lot of power from the exhaust stream making more back pressure. This is not good for your engine in the long term, especially on the track.
You can see how the inducer of the new compressor is a lot bigger in diameter. The new turbo is 58mm vs the old 55mm. Also, the inlet is now a full 3″ and we will no longer need the black step-up adaptor for our 3″ inlet tube. The compressor wheel is the same major diameter so the rotating inertia will stay virtually the same. Hopefully, we will not have much more turbo lag for this reason.
The exhaust side of the turbo is the same. The ratio of compressor inducer to turbine exducer is the same as many successful turbos on the market so it is not an unbalanced or mismatched combination.
We had noticed that some of the heat shielding on the hoses for our IAG AOS was discoloring after a track day. The hoses still were good but we have found that exhaust heat on turbo cars can be extreme on the track so we decided to add more and thicker heat shielding. We wrapped our AOS hoses with DEI Form-A-Shield which is dimpled aluminum bonded to a basalt thermal barrier material. It can withstand 1400 degrees and we felt that it had better insulation than just a wrap. We fastened the shield in place with some stainless safety wire.
We also put some Form-A- Shield on the downpipe in the area of the AOS hoses to further reduce the heat being radiated on them. Now we think we are perfectly safe from hose damage and potential oil fires.
6 comments
Been waiting fir this one. Cannot wait to see the results.
Dreams I tell you. Dreams. I wish I can just be a spectator at the tuning session. Seriously. DM me on IG lol
Re stock location: BCP x500r please explain to me why this $2k journal bearing turbo is just hype and not real… don’t let me be fooled
Not ball bearing center section. Smaller exhaust housing. It’s probably decent.
It looks like there’s quite a difference between the 55mm and 58mm compressor wheel beyond the size. 7 primary vanes vs 6. The leading edge is swept vs straight. Is the 58mm a newer generation wheel vs the 55mm or is it just the size warrants different vane geometry to improve flow?
Thank you for more Subaru content.