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Righto..
those who follow badger5 on facebook will already have seen this but for those who dont, here's some info from first stage testing of the new Garrett G25-660 turbo. Much "hyped" online unit.. GT28 size, GT35 abilities.. (claims from garrett)
So... Test engine is my poor little ibiza racecar.(as usual). Its engine spec in outline is 82.5mm bore, std stroke, 9.3:1 compression, ported smallport (largeport), dimpled cnc head, catcams,supertech etc etc.
Previously running GTX3076Gen2/0.63 and HTA3076/0.63
2bar ~500bhp region
The G25-660/0.72 unit is garrett vband but fitted directly onto my current tial flanged manifold & downpipe, which was a pleasant surprise. Made installation a breeze. Clocked to fit my setup, all the lines fitted. Nice feature of this G25 series is the chra is vband clamped to the hotside so no more bolts to backout of the hotsides! yay! and easy to rotate.. Double yay!
The size of the unit is indeed compact.. GT28 size.. small turbine but different slightly larger turbine than a 28, but way smaller than GT30xx turbine
comparison plots are of different boosts and against the HTA3076 I removed to do this test. boost onset torque onset etc are what I am looking for.
some plots... more to write when I get a mo to add to this.
G25-660 at different boost levels
HTA3076 compared to G25-660
Some "wobbly boost" experienced from the G25.... Hmmm. Not good.
Thoughts are currently that there is a potential wastegate issue here... possibly just sticking (inconsistent onset of boost), but also I believe back pressure related in the oscillation seen when higher boost at higher revs seen...
the ecu is DTA S80 unit, running STC drive by wire... and boost control is fixed duty cycle driven, not closed loop, so the ringing of the boost is not a PID thing.. there is no PID control active. Its a physical thing. Back Pressure is my concern. Bad thing that.
Wastegate is being replaced, it is as old as noah, and has served me well but we did have to weld its valve head back on a couple months ago where it detached itself. Early old large 44mm tial gate. Trying out a new 44mm GFB wastegate this time.. cos I have'nt tried one, and fancy seeing how it is. I will plumb the new gate in dual port tho, as was only ever single port up to now.
So we will resume testing when parts are in and its modified to work again, this time with back pressure measurements measuring at turbo hotsides.
more later...........
those who follow badger5 on facebook will already have seen this but for those who dont, here's some info from first stage testing of the new Garrett G25-660 turbo. Much "hyped" online unit.. GT28 size, GT35 abilities.. (claims from garrett)
So... Test engine is my poor little ibiza racecar.(as usual). Its engine spec in outline is 82.5mm bore, std stroke, 9.3:1 compression, ported smallport (largeport), dimpled cnc head, catcams,supertech etc etc.
Previously running GTX3076Gen2/0.63 and HTA3076/0.63
2bar ~500bhp region
The G25-660/0.72 unit is garrett vband but fitted directly onto my current tial flanged manifold & downpipe, which was a pleasant surprise. Made installation a breeze. Clocked to fit my setup, all the lines fitted. Nice feature of this G25 series is the chra is vband clamped to the hotside so no more bolts to backout of the hotsides! yay! and easy to rotate.. Double yay!
The size of the unit is indeed compact.. GT28 size.. small turbine but different slightly larger turbine than a 28, but way smaller than GT30xx turbine
comparison plots are of different boosts and against the HTA3076 I removed to do this test. boost onset torque onset etc are what I am looking for.
some plots... more to write when I get a mo to add to this.
G25-660 at different boost levels
HTA3076 compared to G25-660
Some "wobbly boost" experienced from the G25.... Hmmm. Not good.
Thoughts are currently that there is a potential wastegate issue here... possibly just sticking (inconsistent onset of boost), but also I believe back pressure related in the oscillation seen when higher boost at higher revs seen...
the ecu is DTA S80 unit, running STC drive by wire... and boost control is fixed duty cycle driven, not closed loop, so the ringing of the boost is not a PID thing.. there is no PID control active. Its a physical thing. Back Pressure is my concern. Bad thing that.
Wastegate is being replaced, it is as old as noah, and has served me well but we did have to weld its valve head back on a couple months ago where it detached itself. Early old large 44mm tial gate. Trying out a new 44mm GFB wastegate this time.. cos I have'nt tried one, and fancy seeing how it is. I will plumb the new gate in dual port tho, as was only ever single port up to now.
So we will resume testing when parts are in and its modified to work again, this time with back pressure measurements measuring at turbo hotsides.
more later...........