Im really surprised with these wheel combos
Where is the logic in that choice of wheels?
There is no point to run that big of an exhaust wheel with that small of a compressor wheel on these 109 motors.
Thats one of the easiest way to break the turbos if they get pushed.
That 70 turbine wheel will do 1100+hp even in a 3 bolt ex housing
The 64mm compressor will overspeed and so will a 66
The 68mm compressor has its tongue out when pushed on a 70mm turbine and can be overspeed as well.
There is a spool difference between the well matched 6466 and the 70 turbine wheel on just about every 109 I have seen.
The 6870 does very well on a stage motor and some 109s because a good build, but in reality that kind of build would benefit greatly with a bigger turbine wheel and compressor like a 7270 or a 7675 or greater.
Guys really need room on the compressor side when the motor and turbine size allow for it.
But hey everybody loves ratings and most may not push things to even find out, so maybe worse case is guys oversize the turbos, slow down the spool but feel good about having lower backpressure but have a million dollar 10 sec combo.
somehow
