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Cm870 built with CM 570 internals. - Printable Version

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Cm870 built with CM 570 internals. - SC Josh - 03-08-2020

Thanks for taking a moment to read my post and thanks to rawze for allowing me to join. I have a cm870 with a build date of August 05. It has been a great engine, it was mandate’d around 5 years ago. It currently has 890,000 miles and just shy of 41,000 hours. It is on it’s second turbo and second head. I have done a lot to the truck, but it’s never been rebuilt. Oil consumption has increased some, though not horrible. (1 gallons for even 7 or 8,000 miles).

This brings me to my question. I would love a new X15, but I really don’t want a $3,000 a month truck payment. I do heavy haul and that’s about the going price for a new truck. I run 4.30 rears and keep the hp fairly low when the tune was done. (5 or 515 hp). I drive slow, but have never achieved any fuel economy (4.25 on ifta reportings). I am leaning real heavy towards building this motor, but I want to build one that will eat a cats lunch.

Ok on to the question. Are the cm570’s pistons lower compression and will they work in this truck? If I get the cpl for a sig 600 can I use that to order parts? Also where can I find the dual oil cooler housing? Cummins says they no longer offer it, could just be because my Cummins dealer is stupidly I don’t know. They told me the only oil thermostat out there was a 235, and I found a 215.

Also, I am real worried I will lose an ecm while on the road, does anybody keep a spare ecm in case of this?

Again thanks!


RE: Cm870 built with CM 570 internals. - tree98 - 03-08-2020

Why in the world would you want to put 570 parts in an 870? Why not just build the 870 properly? Also your running a bad delete, I know your going to disagree with this but two turbos and two heads is a telltale sign your running an engine destroying tune.eventually you will see the light if you do the right things suggested on this forum. First and foremost have your program looked at by Rawze, Unilevers, or mommaburt.
And why would you care about "eating a cat's lunch" get yourself reliable equipment that you can make a living with and let the cat's and all the rest blow past you like the ignorant a holes getting 3 MPG. Why do you want a dual oil cooler housing? Is your oil temp to high? That would be another symptom of a bad delete.


RE: Cm870 built with CM 570 internals. - SC Josh - 03-08-2020

Thanks sir, but I believe you don’t know what you’re talking about. First the tune was done by unilevers. Second the first turbo wore the VG parts out and was not allowing it to fully open and the head was valve guides leaking oil into #5 cylinder. I want the dual oil cooler because yes in the summer pulling sandstone mountain or saluda grade at 150,000 the oil can get hot. Thanks for your reply, but save the BS for someone else.


RE: Cm870 built with CM 570 internals. - tree98 - 03-08-2020

Good you have a Uni tune. What happened to the second head and second turbo? Nothing in my post was BS. Every new guy that comes on here gets asked the same questions and given the same advice because we've all seen it a thousand times, 99.9% of them have a bad tune. You're going through turbos and heads for a reason right??


RE: Cm870 built with CM 570 internals. - Brock - 03-08-2020

Message Hammerhead on here, he does true heavy haul with his big CPL CM871 and was having issues burning through turbos so he switched out. He can probably give you some insight into how things have been so far since and what was needed.

I personally dont see a need to change out internals but that's just me. I had my mid CPL CM871 at 625 in my Prostar and I would absolutely destroy Cat on the big hills hauling 140,000lbs all day every day and I would do it while getting way better fuel mileage!

Unilevers would also be a great guy to talk to, he knows those engines really well but more importantly, he completely understands what these engines need while hauling over 100k as every single truck out here does.

Good luck.


RE: Cm870 built with CM 570 internals. - SC Josh - 03-08-2020

Yeah I know hammerhead. I was mainly thinking the 570’s ran lower compression than the 870. To build big power it’s safer to lower the compression ratio. Then you can add fuel and air without building crazy head pressures. The 870 is air actuated where as the 871 is electronic. I have thought about dumping the VG but I love the jakes so I think I will keep it.


RE: Cm870 built with CM 570 internals. - SC Josh - 03-08-2020

Let me say this. Replacing one turbo and 1 head on a truck with 900,000 miles and 41,000 hours is not in heard of. I don’t want y’all getting hung up on that. There is nothing wrong with the truck other than getting long in the tooth. I want to build big power partly because of the work I do and partly because I can afford to.


RE: Cm870 built with CM 570 internals. - Brock - 03-08-2020

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.


RE: Cm870 built with CM 570 internals. - SC Josh - 03-08-2020

(03-08-2020 )Brock Wrote:  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.
You may be right. I may not need to do anything different. I would love to build it Aussie spec, but 625 or 650 I could live with. I wasn’t aware that hammer swapped out his VG, it’s been a while since I’ve talked to him. I don’t want to get too crazy as it’s still a working truck and I want it to last, so I’m not thinking 8 or 900 hp. Maybe 700 max.