Ran 15 high for xc and now doing vo2 and 400 repeat workouts in practice, and 30s and 100s at top speed. Lifting regularly and can run 3x mile repeats sub5 with 5 min recovery and 8x400 at 70/8x200 at 30 with equal recovery
Why cant i go under 2:10 for 800? need more racing? How to alter training so I dont hit the wall at 450m in?
Hard to say without seeing your schedule, but it sounds like you are going too heavy with the VO2 max stuff, and not focusing enough on lactate tolerance and 800 pacing. No need for more mile repeats or 400s at 70, back off on the workload a bit with rest/easy days and hit sessions such as 4x400 at 61-62 w/4 min rec., 12x 200 at 30-31 with 60 sec, etc.. And yes, race more, shooting for splits of say 30/31/32/31. Don't get sucked into the scrum on the first lap, just run assertively but evenly with minimum effort, then focus on the second back straight where you should start taking scalps of those who hit the first lap too hard.
Also get in some 400s and 4x4 carries. Even a 200 can be an asset to your speed profile. Congrats on the 5K (XC or track?), but the 800 is a different animal, like trying to bust a bronco instead of riding the Pony Express.