| best one to use in a forced induction application. You *could* say that the .86 produces a better VE because it breathes better, however, this is a forced induction application where a large majority of the engine's actual volumetric displacement (specifically, massflow) is dependent on how the compressor performs. This is why I reject the statement that "A higher VE engine will produce lesser maximum boost", because, maximum boost is dependent on turbine performance only. The power output is directly a function of air mass flow through the engine (also on state of tune: A/F and timing, but we assume this to be equal in all cases for sake of discussion) , which is heavily dependent on the compressor's operation; both its performance of pressure, flow, and efficiency, and the compressor's operation is dependent on turbine performance. Alterations in other components within the system (like a dual intake or intercooler upgrade) will affect the observed pressure at the manifold, but this is also opposite of the original statement of "A higher VE engine will produce less boost".. Then again, I would hope that we aren't looking at compressor performance for this discussion by measurement of pressure at the manifold. :) The balancing act has a window of "balance" to it, dependent on what type of application you are building for. Given that we have the good fortune of seeing various configurations of the hot section of the turbocharger on relatively similar setups as well as how they perform, we are all empowered with the knowledge to make good choices for our particular builds. We can see that the .86 is just too big, the .64 is great for top-end performance, and the .63/10-blade turbine is great for bottom end and midrange performance. Back before the GT28RS had come into the spotlight, I was working on developing a turbocharger with almost identical build parameters (during the first few months of my time with Z1). I was aware of the 62-trim T3 compressor wheel and its performance characteristics in that T04B housing (this is the same wheel/housing as in the GT2860RS), but the selection of the hot-side components was a bit of a stab in the dark. The very first prototype of that turbo was built and installed on my twinturbo at that time. Here is how it performed with the following mods: Dual Intake
555cc injectors
DP/TP/crushbent cat-back w/ Naxos muffs
88mm Wiseco pistons
Stock exhaust manifolds
Stock Intercoolers
Stock Cams
Stock valves, very minor portwork (just cleaning up the valvebowls) 
This is the same exact turbocharger on my current Z. At 4000RPM you can see that the HP and TQ are 50HP/TQ lower than my current setup. I could only get a max of about 27psi out of these turbos on this setup, heavily restricted by the stock intercoolers (I dont even want to know what the pressure drop was across them, LOL, probably like 4psi and not doing very well at cooling the charge :). Current dyno:
 Here is a dynochart of a different Z with the same exact turbo: He had upgraded intercoolers and everything else was pretty much the same as my old Z: 
You can see where the intercoolers on that setup were benefiting power almost completely across the board. This was also run at 27psi. His power/torque is only shy of my 300HP/400TQ @ 4000RPM in my current setup by maybe 15-20HP and ~25TQ, but considerably higher than my old setup with stock ICs and the same turbos. The overall massflow (which is affecting the total power/torque over the RPM band) of these setups vary quite a bit (my old Z, Jeff's Z, and my new Z) due to the changes in the components used in the builds, but the peak boost attainable has not really differed. If anything, given that my current setup flows so much better than these other two and I have lower restriction at the intercoolers, my setup has higher VE and produces even more boost (at least, observed at the manifold). I would think a pressure measurement just after the compressor would show that these three cars were actually producing the same boost level at the compressor. So, three very different levels of modifications all with the same turbocharger, three appreciably different performance characteristics, and all operating at similar compressor discharge pressures. VE doesn't have an affect on peak boost attainable: if anything, VE (massflow) is dependent on peak boost that is attainable. It really is more the other way around than the original statement I have protested.. :)
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[ agpowers@bellsouth.net ] Enthusiasts soon understand each other. --W. Irving.
Are you an enthusiast? If you are out to describe the truth, leave elegance to the tailor.
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