A few notes of interest sure the UFI pump is a lot nicer to tune not that you have to do much but they are nicer straight up. For auto i dont know but probably just as nice.
EFR6258 is a 7x7 wheel probably a bit more suited to diesel it wont surge so the SXe cover is not required. hmm well you will be restricted to about 18 - 20 psi but the volume flow is exactly the same as the 6x6 efr6758 at those pr levels. It may spool a bit faster but not the volume criteria you are looking for or as much as you might think its a 7x7 wheel so requires a little more drive to reach that 122K shaft speed compared to the 67 6x6 wheel at 115K for the same volume so there may be a slight torque rise more than the 6758 due to a slightly better density. The other issue which is also very difficult to explain but contributes to why a little turbo falls flat after say 2500 rpm compared to a bit bigger wheel. For example the 6258 has to increase an extra 20K rpm to maintain the increased volume flow and pr which our TD and 6258 cannot do. Compared to only 5 or 6K extra shaft rpm on the 67 6x6 wheel to maintain the same volume at a 2.3 pr. In simple terms the 67 will hold volume a lot better then the 62 on a TD42 hence why we have a power dyno map typical efr6758, looking like the one you posted. The 6258 isn't going to come close to that rising power curve always building to compensate for the drooping torque curve we always have with the TD. Remembering both these turbo's are designed with petrol in mind. Just my judgement here not proven by any means.
EDIT:- Dont be to concerned about a EFR and a overspeed condition. The 18 ceramic ball metal caged bearing system is a precision 1 system, the tolerances and stability strength of this bearing is beyond silly for its designed purpose. The probability of bearing failure is very small. All other ball ceramic bearings i know off are precision 2 with very much looser tolerances with less stability to control the riggers of very high balanced component speeds.
The UFI units have always been a nice turbo with always continuing development. They are not better or worse than a EFR just different in what they do and how they do it. The EFR is a slightly bigger turbo than the 18g with very different tech hence it does power/torque differently.
Looking at your dyno graph your spool speed is quite slow for a efr on a auto, i would have expected better on a locked up 3rd gear pull. The AFR hump peak at 1800 is not doing you any favours the big dip is not good either. like most good designed turbos now days i like to see a fairly constant fuel delivery especially for the EFR something like a constant 16 through the spool makes these turbo make volume.
Its hard to make comment on a graph set out like that it makes the curves look flat i use 1100 to 3800 rpm maps auto scaled for full screen usage without point correction or so much smoothing of the lines. Its just what i do to actually see what is going on. This is Not a criticism of the tuner by any means as its a output printed graph for you to see your results not for me to try and deduce what is going on in that tune or fuel mapping. Also there is a bit of stuffing about with the internal ratio in the dyno software to get wheel speed to read correct rpm for a auto due to TC slippage on acceleration even when locked so that could be why the graph suggests a bit late on spool rpm, and again its not a criticism on the tuner. He doesn't need real world accuracy really the dyno is a tool to measure change not for comparing results to other tunes or other dyno's or for fools like me trying to second guess his tune parameters like ramp rate, run time etc etc not printed on the bottom of the sheet. For accuracy you can set the start rpm to be correct by using the hold rpm feature of the dynotech then adjust the software to the cars tacho reading then have the dyno hold the start rpm for a bit longer like 3 seconds so the TC can stabilise. I am suggesting he has the dyno start rpm set at 1100 rpm but TC slippage has 1300 start so a 200 rpm miss making the sheet look like it does. The end point is only 150 or so rpm out due to locking up as torque comes off.. I am surmising here of course trying to explain the late looking spool. Its unusual for a tuner to rev a moderate performance TD out that far suggested on the graph i doubt very much he revved your engine to 3950 rpm hence why i suggest the rpm set up is all a bit late. The evidence is my experience and knowing the EFR's attributes, The end HP would be dipping a lot more if the engine was actually revving to 3950 rpm, to me the characteristics look like 3750 rpm real.
Just a side note when i have done any testing on a pump having that sort of dip in the spool criteria. i have always noted a dip in fuel timing at that point which is not very good for turbine drive thats for sure. The pin and spring might need a bit of rework but its more than likely a product of how the pump is setup. It took me many year of stuffing about and understanding to set a pump up so it didn't do that. UFI 12mm pumps don't do that now day's anymore.
