back-cut Iconal valves

[Bram]

Did anybody replace the OEM valves with back-cut Iconal valves?
I am looking into a cylinderhead rebuild in the future and from what I read these back-cut valves could increase the flow dramatically. However I also read that this does not always work properly at different valve lift positions and depends per engine type.

Advantages I found using these valves:
- Better Flow
- Less weight in the valve train (10x inlet valve ~3gr, 10x exhaust valve ~2gr = you save 50gr in total)
- Less force on the valve seats, so less wear
- Able to push the RPMs higher, because of more stable base-RPM
- Corrosion-proof against exhaust gasses
- "Quick Heat" valve plate inside design, against cooking of dirt

Will the back-cut valves give only gains in the higher RPMs and will I loose torque and spool-up in the lower RPMs? Or will I see an overal improved performance?



Source: http://www.20v-sauger-tuning.de/

[A80Avant]

do you mean inconel valves?

I thought that ADU and ABY valves were already backcut. I know my ADU ones are.They are not inconel,but definitelly backcut. Also a cyl head i have AAN also came with backcut valves

I was speaking to Peter kowalsch (PKMotorsport) and he thinks that the OEM valves are good enough for lots of hp (600 or so) and he doesnt replace them unless he is making a big project.He does seem to suggest a stiffer set of springs with a set of camshafts though that would work better than ADU shafts and pull from 3500-7600rpm.

When the VEMS arrives i will be able to make those steps one by one,rather than all together,which means maybe less $$$.I may try a ported head,but valves are staying the same. Also im thinking of testing a new turbo/EM with the original cyl.head before going directly to head changes.

[Bram]

Ah, yes, that is the right naming I did not take a good look at the valves in my cars cylinderhead when the head was off, so I can not tell if mij ABY's are already back-cut.
Stiffer springs I was told are only interesting when going higher than 7800 RPM?