To check out the new 4040+5050 Q8 ledboard that led4power has made and kindly sent to me without charge (including 4 Luxeon V leds :+1: ), I modded my last unmodded Q8 with Luxeon V leds.
The dimensions of the l4p Q8 board are exactly the same of the stock board so it was no surprise that it fitted without problem. Only difference is that with the double footprint there is no space for the two small holes on the side, so the board can not be screwed down by the two M2.5 screws. Instead the board should be fixed like I did here, sandwiched between reflector and shelf (as shown and discussed before in the interest list thread for this board).
It was quite a pain to ream all 4 plastic centerpieces to fit the Luxeon V leds, but I got it done and the leds are centered pretty good.
I made an effort to reduce the already small resistances of the Q8 further, most significantly I bypassed the tail springs and cleaned all electrical contact surfaces. I replaced the stock ledwires with slightly longer ones (still 18 AWG).
The beam that I get is very nice and smooth without obvious tint shifts, I think even a bit nicer than the stock beam, but I have no stock Q8 left to directly compare them. (If you are really nitpicking, on a white wall the corona is slightly yellow and around the corona is a faint blueish ring. This however is very remote from anything you will notice in actual use)
The highest output with the stock XP-L leds that I measured was 6200 (djozz-) lumen. But that was not with fully bypassed springs but with phosfor bronze springs, I estimate 6500 lumen with bypassed springs. This Luxeon V modded Q8 does 7500 lumen (30 seconds, 30Q batteries). At start-up it is 8000 lumen and it takes minutes to get under 7000 lumen.
7500 lumen, great beam profile, nice tint: this mod is a succes, and the l4p Q8 board works as planned.