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Cm870 upgrades - Rig Wrench - 01-02-2017
I'm in the process of overhaulin a CM870 in a 379 Pete 565hp. Anyone ave any recommendations for upgrades while I'm in there? I know it needs a new cac, any recommendations on a better than factory replacement? Not lookin for the most durable, but the best flowing/most efficient. Any other recommendations are welcome. Hope to get another 850k mi out of it.
Thanks
RE: Cm870 upgrades - Rawze - 01-02-2017
(01-02-2017 )Rig Wrench Wrote: I'm in the process of overhaulin a CM870 in a 379 Pete 565hp. Anyone ave any recommendations for upgrades while I'm in there? I know it needs a new cac, any recommendations on a better than factory replacement? Not lookin for the most durable, but the best flowing/most efficient. Any other recommendations are welcome. Hope to get another 850k mi out of it.
Thanks
* Counter-bore and raise liner height to 0.014" or 0.015".
* Have the head hand torqued to 300-ft lbs, and let it sit overnight so that the gasket will crush properly. Torque it a second time the next day, then do the 90-degree final torque on the bolts after that. Most shops will not bother to let it sit overnight, then re-torque because they are in too much of a hurry.
For the CM870 ..
* Make sure you look up your engine serial number and find the exact timing code. CM870's have timing codes based on engine individual ser# and it does not always match the engine cover sticker. they also have ECM programs to match this, so use the original program for it and have it custom tuned instead of replacing it with a different hp one. - Very common mistake people do on them.
* A better intake manifold for the CM870 has slight improvements. Exhaust manifolds for them on the other hand, are a waste of time/money and you will see no measurable gains from them. Not even from the high performance ones.
RE: Cm870 upgrades - Rig Wrench - 01-02-2017
(01-02-2017 )Rawze Wrote:(01-02-2017 )Rig Wrench Wrote: I'm in the process of overhaulin a CM870 in a 379 Pete 565hp. Anyone ave any recommendations for upgrades while I'm in there? I know it needs a new cac, any recommendations on a better than factory replacement? Not lookin for the most durable, but the best flowing/most efficient. Any other recommendations are welcome. Hope to get another 850k mi out of it.
Thanks
* Counter-bore and raise liner height to 0.014" or 0.015".
* Have the head hand torqued to 300-ft lbs, and let it sit overnight so that the gasket will crush properly. Torque it a second time the next day, then do the 90-degree final torque on the bolts. most shops will not bother to let it sit overnight, then re-torque because they are in too much of a hurry.
* Make sure you look up your engine serial number and find the exact timing code. CM870's have timing codes based on engine individual ser# and it does not always match the engine cover sticker. they also have ECM programs to match this, so use the original program for it and have it custom tuned instead of replacing it with a different hp one. - Very common mistake people do on them.
* A better intake manifold for the CM870 has slight improvements. Exhaust manifolds for them on the other hand, are a waste of time/money and you will see no measurable gains from them. Not even from the high performance ones.
Yea. I let even the cat I do set overtime and re tourque. The engine has been rock solid, events cams and rockers look great. Just want it to Be as good as possible.
Thanks
RE: Cm870 upgrades - Hammerhead - 01-03-2017
(01-02-2017 )Rawze Wrote: * Have the head hand torqued to 300-ft lbs, and let it sit overnight so that the gasket will crush properly. Torque it a second time the next day, then do the 90-degree final torque on the bolts. most shops will not bother to let it sit overnight, then re-torque because they are in too much of a hurry.Ok, just wanna make sure I understand this correctly.
-Hand torque the head bolts to 300 ft/lbs
-Next day (24hrs?) re-torque to 300 ft/lbs
-Then rotate the head bolts 90*
Do you wait a specific amount of time between re-torque & 90, or just do the 90 after completing the re-torque?
Rawze Wrote:Exhaust manifolds for them on the other hand, are a waste of time/money and you will see no measurable gains from them.Would there be any gains by ceramic coating an exhaust manifold?
The ceramic coating should, in theory, reflect the heat away from the metal of the manifold reducing heat soak and directing the heat to the exhaust wheel, making more efficient use of the heat energy.
Has anyone tried it?
Is there, or would there actually be, any measurable gain?
I ask because I have an extra manifold and I've thought about sending it to be coated and wonder if it's worth it.
RE: Cm870 upgrades - RPM1 - 01-03-2017
I know guys that do the ceramic coating 1 to make the exaust last longer cat equipment is not cheep even the exaust also coating the exaust manafold they don't rust and u get that rust stain bleadi g down in things , I have Hurd is also not as warm around engine , I wouldn't think. Not By much though ,
Performance wise , I dough u would notis, just my 2 cents
RE: Cm870 upgrades - Rawze - 01-03-2017
(01-03-2017 )Hammerhead Wrote: ...
Do you wait a specific amount of time between re-torque & 90, or just do the 90 after completing the re-torque?
...
NO need. You got the steps right. You will often find that the next day, it is not unusual to have to re-tighten the bolts another 60-100 degrees just to get them back to 300 ft lbs.
(01-03-2017 )Hammerhead Wrote: ...
Would there be any gains by ceramic coating an exhaust manifold?
...
In theory yes, but in reality, no. coating is too thin, temps are not quite high enough, and flow not fast enough for the effects to be measurable. At 1,000+ hp maybe, but then again, an ISX at 1,000 HP still only should have roughly 1050 degrees EGT before the turbo. Anything like 500 or even 650 hp, it would not be measurable. That is also same reason why those high flow exh. manifold has no measurable gains either. - I have seen many people try/test this and it is always same result.
Even when looking at a well built after-market manifold, it seems it would have an improvement. They look like flow would be much less restrictive in them, but when measured and compared,.. no gains at any reasonable hp levels someone would put in a highway truck. - It would only serve to stroke ones own ego, nothing more.
Components like that do not result in analogous gains anyways, and that is where people get fooled. Only as you start to approach maximum flow capacity (87% and better), does gains start to become measurable in such devices, where it is more like a wall, ramping quickly towards higher resistance. it only starts to become measurable towards that last 15% or so of capacity. Anything below that point is a waste of effort. This is true for the intake too, but the intake on a CM870 tends to start to do this at around 560 HP or so. That is why the intake piping does have slight gains, but only slight. You will only see them when under heavy load. - even with this intake mod, people who do not drive hard and take care of their engines, trying to conserve fuel etc still never really benefit from such devices. it is the guys who push things hard, and would rather waste fuel instead of re-gearing the truck for its intended use so that they didn't have to torture their engine that see these measurable differences.
I have seen many many people try this and much more, sometimes going to great lengths to improve them. Some of those things done were even very elaborate and expensive. If they worked, I would have mentioned them. i have even seen very expensive billet wheel mods, and turbo mods/replacements, etc.
One of the things I have NOT seen tried in attempts to gain efficiency, is to replace the valve cam with the QSK cam that holds the valves open longer. This, I have seen done for getting the power above 1,000 HP on a couple of them, but not for efficiency gains in any engine with well established data of a "before" and "after" result. - Doing one while Inframing it would not be a good comparison.
That is just what I have seen and what others have tried and did, and their results. I did forget to mention though,...
Grinding out the outlet port on the cold side of the turbo and polishing it does make for slight gains. Polishing the 90 degree elbow that attaches to it does too. This is true for any model Holset I have seen. The rough cast has its place in creating a wall-flow barrier, and improving flow, but the joint is just not quite big enough, and the bend just steep enough at higher flow rates, causing the effect to become unstable. Polishing out the rough surfaces to a high degree (close to mirror finish) proves to have a better effect in every case I have seen it done, including my own truck when I tried it. - Mine gained almost 0.3 mpg. Very difficult to get gains out of a truck that is already breaking 8+ all the time, so it definitely worked.
RE: Cm870 upgrades - Hammerhead - 01-03-2017
Thanks for the detailed exhaust info, I thought I'd read something to the effect of before, but couldn't remember.
Not that I would use a final number, but for discussion sake; re-torqued to 300 ft/lbs plus 90* comes out around what? About 550-575? Or higher?
RE: Cm870 upgrades - Rig Wrench - 01-03-2017
What effect would the qsk cam have on the engine brake? I guess in thoury holdin ehxaust valves open longer should make it stronger, but i dont know. Not quite willing to try without deffinitive results, Lol. Not alot of fun to change back out
RE: Cm870 upgrades - Rawze - 01-03-2017
(01-03-2017 )Rig Wrench Wrote: What effect would the qsk cam have on the engine brake? I guess in thoury holdin ehxaust valves open longer should make it stronger, but i dont know. Not quite willing to try without deffinitive results, Lol. Not alot of fun to change back out
Not enough people have tried it, but the engine break strength is adjustable through custom tuning. Because of this, one could re-adjust the ecm to compensate for it fairly easily I would think.
The other question is will the engine brake even work correctly at all?
For those who read this and think "it can be made stronger?" -- Strengthening above the factory settings it is NOT advisable. Too easy to drop a valve and I have seen many people do it and cause head damage. It is a common mistake that crappy big-box tuners do (and their copy-cats) that helps to destroy engines.