yea, he sent me this (thought a while if I wanted someone to insert my mail text on a public forum, but I think this text doesnt really put him or anyone else in a bad light):
Hi, the motor noise is the noise that this particular motor makes. The HEV motors are made in a different way compared with the standard motors we sell. I used 2 different version of the 63mm to check and i got the same results. You can reduce the noise by using a lower timing setting. If that noise is something that annoys you i need to sent you the standard 6355.
I think he replied pretty much to the “resonance” phenomenon and not to the scratching sound - maybe thats also a FOC specific thing and it would sound better in BLDC. I recognize that screaming pattern under load from the sk6374, just that its even more pronounced for this HEV 6355 motor.
we have sent a few mails back and forth and to be honest: it feels like bruno has to respond to a lot of mails - most often you feel that replies are rushed in some way, like he didnt read all details. I think Ill just run that motor until it fails and then go back to my SK6374 168KV … or maybe Ill open it soon due to curiosity - just waiting for my gear puller tool to get that glued pulley of the shaft.
to be fair: it was a very cheap motor for me. I had a 10% discount on my total order because bruno sent me a wrong wheel hub on my last order, so that motor only cost me 58€ - thats HALF of an rspecc and the rspecc is definitely not really better at anything.
I switched out my sk6374 168KV for the HEV and I feel like Im not really lacking torque, I have a slightly higher topspeed due to 15/36 with 190KV vs. 16/36 @ 168KV and the motor is much lighter @ only 508gr (think its the lightest motor around?). it comes stock with superflexible silicone wires (sadly only 14AWG), the closed body is kinda nice and it runs very cool, even under a lot of load (maybe due to the full aluminum mount, that seems to soak up a lot of heat unlike the CFK enertion mount). Ill try the 2nd HEV motor I got probably on my spud - that one has no scraping at least.