Deerlope -
I think RaT just solved your problem. When he switched me from my "tractor hat" to my "tree-guy" hat it all became obvious.
I have an 18" capacity Vermeer 1800
chipper with a 115 HP 4-cylinder Perkins turbo diesel engine that can be brought to its knees very easily when it gets into the big stuff. It has the type of auto-feed system that Rat refers to as having been on the Dasko (I think it was probably a Dosko)
chipper that he rented. On my Vermeer, a hydraulic valve will stop the supply of hydr. oil to the feed rollers when the alternator voltage drops below a certain level (caused by the slowing of the engine as it tries to cope with "too big" a load). As the engine speed picks back up, the voltage goes back up, and hydr. flow to the feed rollers is restored. This is (IMHO) a must-have on any
chipper that you can get it on. (As an aside, the newer Vermeers use an optical pickup to monitor engine speed and is even more reliable. Mine works fine though).
I also have two smaller chippers, both Promark model 210's, rated for 6" but obviously happier with smaller than that. One is powered by a 1-cyl 16 HP B&S gas engine, the other by a 2-cyl Kohler 18 HP gas engine. They pack quite a punch for their size, an amazing punch actually. In fact, back in the day, I once cleared a building lot with the 16 HP one and it raised more than one eyebrow with its spunk. They chew up pine and maple branches extremely well, as they are not self-feeding and like the straighter material like that. Twisty stuff like oak and apple is a major pain. But they do kick some butt, you just have to be careful how big/long a piece you feed them so as not to gag them.
That said: I have always wanted to put somethink like a 25 HP gas engine, or 20-ish HP diesel engine on them. With that additional power, they would gain a tremendous amount of chipping power, and give an even better accounting of themselves.
That brings me to my main point. You have 32 diesel HP at your PTO. PLENTY of power I would think to do some fairly serious chipping. The problem, as RaT pointed out, seems to be the lack of an auto-feed. Without the auto-feed, my 18"
chipper would get plugged up 10 times a day, or require constant vigilance by whoever is closest to the safety bar that manually controls the direction that the feed rollers turn. Push on the bar, and the rollers reverse. Even WITH the auto-feed, we often "feather" big pieces into the cutters so as to avoid the lag time that the engine requires to get back up to speed after the auto-feed has kicked in.
Forget the 6800, or the injector tweaks. If you put the auto-feed on that I am glad to see is an option, your chipping experience will be a much more satisfactory one, I am quite sure of it. Also, I know you said the knives are sharp, but they need to be REALLY sharp. Just a little dullness has a geometric effect on the chipping ability of any
chipper. I'd urge you to get at least one more set of knives so the other set can be off getting sharpened and you can still use your
chipper.
Good luck, John D.
