Cat diesel power!!!!

Any good ECM settings for a MBN to 6NZ swap? Stock everything else.

 

As for lowering compression for big horsepower, I agree, but too low can be detrimental, there are plenty of guys making big power with 16:1 C15s. Ideally 14.6:1 will make the power with a lot less stress on the engine and therfore allow room for even more power. Marine engines can get away with lower compression and big turbos because they need very little torque, a truck engine with too low compression and a big turbo would suffer when trying to pull at lower engine speeds.

Oh, and technically a turbo reduces and engines efficiency ( this will get some interesting comments ), a turbo is a form of supercharging and all supercharging takes some power to run ( you dont get anything for free ), in the case of a turbo the exhaust gas pressure powers the turbine to produce boost, this exhaust gas pressure in the manifold and cylinders caused by the the restriction of the turbine creates some load on the engine therfore reducing efficence.

WOW!!!! Where to start??? 14.6 :1 will make H.P, true, 21:1 will make more H.P, ie 2 stroke Detroit, More compression ratio more stress not only on the bottom end but the deck also. 30 lbs. boost makes H.P but 50 lbs. makes more H.P. ANY form of super charging takes power away from the job to be done, turn the crankshaft, but the ratio on added power to used power is the great equalizer there. The lower the compression pressure in a compression ignited engine (diesel) the more difficult it will be to start at lower temperatures but the more "additional charging" pressure it will take. The bottom line is a structural & a sealing problem, reason for main bearing girdles & "O" ringed heads in fuel engines. Like the man said "H.P.costs $$$$$ how fast do you want to go?????"

 

You're on the money, we only lower compression so the engine will survive when we wind up the whick. I have never seen anyone shove 50lb boost into a 21:1 engine but I bet it would be something to see, just wouldn't want to stand too close. Essentially the lower the compression is the more boost you can jam in and the more power you can make without blowing the motor apart but there are other factors, like you said lower compression will be a ##### to start when cold, it will also be less fuel efficient, timing has a big effect on what compression ratio is suitable for an application, and a low compression engine with a big turbo will suffer from a lack of low end torque.

 

Compression over 16:1 makes so much more sideload to pistons that friction losses are higher than efficiency increase from higher compression. Then we add boost to that, turbocharger is spinned by exhaust waste energy so it IS kind of free power, without turbocharger that energy is just dumped away. If built right (no nox limits), turbocharged diesels have close to 50% thermal efficiency, naturally aspirated maybe 35%. But that is at 100% load, at light loads turbocharged is less efficient because of exhaust restriction.
So about 16:1 is optimal compression if engine can take it. When injecting big amounts of fuel you need bigger combustion chamber for all that fuel and air, then you just have to accept lower compression ratio, you can't get big combustion chamber and high compression at the same time. This is not my theory, it's all in the books written by more intelligent people than me. When building high HP engines it's good to read some theory so that you know what you are doing, otherwise it's easy to think that more and bigger is always better(more compression, bigger exhaust manifold).

 

Seems we have the inevitable "trade off" here <G> Speed or power, flat land or hill climber, hi-flow or hi-pressure, beauty & money, NO, NO, NO, oops, sory about that last one. Got carried away, Gonna quit tryn' <WINK>

 

That is an excellent point you make however I am looking at this from a different angle to you. Yes, a turbo diesel is more thermally efficient but thermal efficiency refers to how much of the energy produced from buring the diesel is used to do work, but that work is not always pushing the crankshaft down to produce power. I try my best to use a general example to illustrate my point.
Consider a clean burning properly tuned 15 litre naturally aspirated diesel making I guess 150hp and 35% thermally efficient. now we add a turbo charger but do nothing else, the engine is now 50% thermally efficeint like you said (using 50% of the energy produced to do work) however that extra 15% is being used to drive the turbocharger and produce boost but the output at the crankshaft will be maintained at 150hp (or less as the back pressure created by the turbo will loose a little power). That is how I see it as making the engine no more efficent, ie. for a given amount of fuel and all other things remaining equal, the power output and therfore efficiency will not increase with the addition of a turbocharger alone.
Where all this gets interesting is when you consider what is possible with the addition of a turbo to an engine. with the addition of a turbo charger pumping 35psi we can now add aditional fuel to our 15 litre N/A diesel, it is now producing 500hp. to get 500hp with a N/A diesel we would need a 35 litre engine. The 15 litre engine would be far more efficient than the 35 litre engine to produce 500hp for several reasons, weight, cylinder bore heat loss, rotational inertia, etc. This is were the notion that turbo diesels are more efficient than N/A diesels comes from.

 

Thermal-efficiency means how many % of fuels energy is used to turn the crankshaft, but we are on the same tracks.

 

can we just figure a way to get more power easy so i can get at least 600hp without getting the boss in a spin [the less he knows the better he wont be able to handle the truth]

 

I think you already know this, the quickest, easiest, simplest way to do this without your boss knowing is Bully-Dog. You just download the info. The next best is PP but your boss will see the box in your cab. Then there is one more quick & simple way if you can have a few days downtime on your truck, send your ECM to PDI. All this can be done without anyone noticing with the end result being HP.

 

6nz81432 ar#226-6764 its at 435hp now wat is needed to uprate to 550hp? a 550hp ecm is on it but it dont perform, by the way 550hp w900l am gonna use your slogan of 1time abt 'load em like rail cars drive em like race cars' on the back of the yellow 9400i ok thanks and it is a cat so it will stay honoured