Pulling behind other trucks

[Rawze]

(01-11-2017 )Running rough Wrote:  aperently some guys have dyno tested with different boost levels, and on the dyno max torque was produced between 38 and 40 psi on the 2250, however with these cold frigid temps which can see below minus -30 Celsius up here in the great north strong and free, one has to moniter his boost because due to the nature of @m*m^2 tuning, cooler air will produce more boost, something to due with a certain vgt position at a certain rpm and trottle position vs mass flow calculation that stock Cals use, that's why some guys have to separate custom Cals with different turbo mapping, one for winter and one for summer, that's why a boost and pyro is so important when a guy does and tuning, my turbo is calabrated for warmer weather, so I keep boost in check with my right foot, however I would take rawzes advice and keep the boost lower to be on the safe side especially in cold weather, it is easy to get a viberation in cold weather when over boosting, (the cold air is so dense so it takes less boost to make the same torque) I believe the viberation is a symptom known as crank flex, defintlely not good for the engine as it can snap the crank, because it only is noticeable in cooler weather, I will say this, I have seen my Acert c15 do the same thing when it had a big boy tune with the variable valve timing disabled and making over 50 psi boost,

You can't compare a cat to a cummins engine in regard to boost. They have much different designs, compression ratios, etc. both internally and externally. That is one common problem I see a lot of people do whenever I recommend a bit lower boost on the red engines.

YES, I always recommend to stay on the safe (lower) side of boost levels,.. and even you have pointed out just now in your dyno result that you are pushing it a bit far by comparing boost levels to torque output. For engine longevity, and reduction of liner issues, etc. you should always be slightly under where it peaks, not right at it, and certainly not above it. - This ensures the prevention of detonation, the reduction of piston/liner vibration, and ensures crank angles are not too low, resulting in crank flex like you have mentioned. -- Also, there are a lot of other factors that will alter where boost levels should peak vs torque, like timing, and about 10,000 other factors that determine final crank angle at high torque levels. -- Running higher than recommended levels of boost for more power is not the answer when considering longevity. Adjusting the entire engine with all its settings together is what is needed to do it safely.

For others reading this -- A lot of people do not consider that there is such thing as "too effecient", where that last bit of torque, or last bit of extra fuel mileage/efficiency, yes can be achieved, but at the cost of shortening the life of everything, and loosing the engine pre-maturely,. What good is another 0.4 mpg if you have to spend 28,000 inframing the motor prematurely to get it.

I am always the guy who fights tooth and nail against more power, or too much of a good thing, because most truck owners that I have met at the end of the day do NOT want to go anywhere near something that would cause them to have to pull their engine apart sooner rather than later. -- I see the trends of these newer engines leading up to show that the days of million mile engines are ending. It seems pretty clear to me, though the engine makers claim otherwise, that is the direction they are all taking. - Combine that with higher costs of parts these days, I would think that squeezing more longevity out of one would have the best long term profit over any power or other types of gains.