Cm870 upgrades

[Rawze]

(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?
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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?
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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.