This was taken from Dan Portera, who was the founder of bullseye turbo, but now works closely over at precision. Just another reason why precision is on top of there game.
We have been reviewing one of the Precision 67HPQ T4 units. From testing so far and after taking the turbo apart and getting some measurements we can see why this units does so well.
PTE def did their home work when they came out with the New CEA Billet compressors. What you will notice when you take a look at the compressor design is that the wheel looks very aggressive. It has a small hub and light weight design and what appears to be extended tips.
After looking at the wheel for a bit I started to take some measurements. Right away I noticed an advantage the the smaller hub gave the wheel and things started to become a little more clear on what was going on with the flow numbers I heard. When I got the turbo from PTE Joe told me the turbo flowed 94lbs - 99 lbs a min depends on housings. I was like wow those are big numbers for a 67mm unit. Well here is what I see as a very good feature of the new PTE CEA compressor design.
I measured the compressor wheel from the tip of the compressor wheel inducer to the hub (this is where the compressor nut sits) and I measured 26.2mm. I had a few other wheels sitting on my desk and I reached over to compare numbers and boy was I shocked. The wheel I picked up from my desk was the Borg Warner 67mm and the same measurement on that wheel was 22.7mm I also had a CompR wheel from Bullseye and the same tip to hub measurement on the 72mm wheel was 23.1mm.
What this means is that Precision through the CEA Competition Engineered Areo design is able to take advantage of several things one being taking weight off the wheel which allows them to do some different things with the wheel design. I noticed right away the wheel was much much lighter. Lightning the wheel allows a smaller shaft to be used and a smaller hub design. The smaller hub design allows the CEA design to grow the inducer inward instead of out word. This makes for a much larger leading edge and in this case the 67mm unit has a leading edge that measures what the competitions 70-72mm units measure and also comes very close on flow numbers.
This is huge leap forward in performance turbo design and a very out of the box way of thinking. I was very impressed with the units appearance and design, now lets talk about the performance of the unit when testing on the car.
When I installed the Turbo on the car and went for a drive to see how the car responded to the turbo change I noticed right away the turbo was very responsive so I thought I would do a back pressure log to see how the turbo fit the engine with the .68 a/r. The boost was 11.8 psi and the back pressure was 26psi, the back pressure logs showed the back pressure ratio was over 2 to 1. What was shocking is the car did not feel like it. On most, no all other turbos I have had in that situation you would feel the car loose considerable power when you got to the 2 to 1 back pressure ratio. I have seen cars loose as much as 90whp from the back pressure being that high. I was so amazed at that I had to call and talk to Dan Barlog at PTE and ask if this was normal of the PTE CEA wheel design and Mr. Barlog said yes and that once I install the larger .96 a/r housing he provided me I would notice another power gain when I got the back pressure closer to 1 to 1. I installed the .96 a/r turbine housing and the back pressure is now right at 1 to 1. The back pressure change changed spool up by only 300 rpm but made a huge power gain.
Another great feature of the Precision 67HPQ unit is-
The new ceramic dual ball bearing center section that has cooling fins cast into it and does not have any cooling lines.
Well to rap this up I will say that we were very impressed with the 67mm unit from Precision turbo and would recommend the unit to anyone who is looking for a performance edge on the competition. The 67HPQ has a few different options for the bearing structur. We tested the Ball bearing unit but it does come journal bearing also for those that have cost in mind.
Here are the hub measurements I took from each wheel.
PTE 67mm 16.5mm
BW 67mm 20.3mm
BEP 72mm 22.9mm
Here is some pics of the compressor so you can see what to measure.