Cm870 built with CM 570 internals.

[Brock]

I'm not hung up on anything, I dont care that you went through a turbo and a head..... completely normal with your torque loads. Your preaching to the choir with me man, I live in Grande Praire Ab and have always hauled 100,000 to 160,000lbs...... always, so I know what your talking about.

I was considering going to a 16:1 on my c15 and throwing the 18:1 away but decided to run a ISX871 instead.

What kind of big power are you talking? If your going around 600 or 625 then I would see no need to lower compression as the ISX engines dont really have head pressure issues that I'm aware of and the bigger CPL engines were built for 600 anyways.

As far as the Variable turbo, once again, talk to Hammer and ask him how the Blue Ox exhaust brake he has has been holding up, last I spoke to him he said the thing hits hard, not quite as well as his VG but still real good..... it has been a bit since we spoke though.

Now all of this is just my opinion, its apparent that you have a different one and seem to have already made up your mind. I have zero working knowledge of the internals of the 570 or even what their compression ratios are. If you are wanting real high horsepower then there are s multitude of things you can do, lower your compression ratio, big turbo, new cam etc aussie spec the engine basically.