TDIwyse wrote:
So those balance shafts are all down in the oil pan in engines that use them? Do they spin through the crankcase oil or is the oil pan designed to be deep enough so that they don't? I would think if the shafts are moving through the oil that would cause added drag and wasted energy. I would also think from simple physics that any counter rotating mass would have to also lower rotating torque pulses just do the fact that there is extra mass involved in the rotation.
Does anyone have a good link or data on how flywheels and billet covers dampen torque pulses from an engine? Looking at angular momentum equations I can't see how 3 pounds of added mass in a billet front cover can eliminate ~1500 ft-lb of torque pulses from a ~400 ft-lb 4 cylinder engine (
http://www.epi-eng.com/piston_engine_te ... ngines.htm). My expectation is that the extra few pounds of the Suncoast unit will lower the pulses, similar to a flywheel, but they will still be significantly higher than what the Hemi V8's produce (this is conjecture on my part without seeing data) as according to the link above the Hemi would need to be rated at ~770 ft-lbs to get to similar peak torque pulses.
Warp, in a past thread when you were reporting on the spring sizes between the old and new mopar TC you mentioned you were going to report what the suncoast spring sizes were. Do you recall what they were or how they compared to the old mopar unit?
All balance shafts are out of the oil, only small splash engines have anything touch the oil in the pan and then it is only a small finger.
The power pulse intensity does not determine the size of the flywheel, the degrees of rotation between power pulses does. Fewer cylinders the more degrees between pulses. For example a 1 cylinder engine has roughly 120 degrees of power pulse yet the two rotations of the crank amount to 720 degrees. With the 6 cylinder you have 120 degrees of power pulse out of every cylinder and if you divide 120 into 720, you will get 6, therefore, a 6 cylinder engine does not need a flywheel to run. With the four cylinder you have a 60 degree deficit between power pulses and need a flywheel with enough kinetic energy to carry the crank smoothly through. Add more flywheel like with a billet front cover the engine will smooth out. If you get a flywheel too large you will have excess inertia that will slow acceleration. Since there is other rotating mass like the front vibration dampener and crank that helps smooth out the 60 degree gaps between the power pulses, the calculations for fine tuning flywheel mass are quite complex and those who have figured it out keep it to them selves, don't expect Google to find it for you. I believe VM as does Cummins and some others have the info locked away and do not share it with anyone, not even the lower level Engineers in their respective companies.
I know a retired motorcycle racer who now builds cars to race on the Bonneville Salt Flats for fun. When he was younger and racing one cylinder motor cycles, most of the competitors would lighten their flywheels but he would make his heavier. He beat them every time in the race, even though their engines would rev up faster. His determination was by trial and error after understanding the principles I am discussing here.
Since my engine runs smoother with the SunCoast converter than it did with the original, it is due to the increased mass, nothing more. Do I believe that anyone tuned the mass of the SunCoast converter to do this, no it is pure luck.
Why does the engine vibrate more with the stock converter, Chrysler wants to use the same converter on both six cylinder engines (that only need flywheels to have something to hang the ring gear on and bolt the convert to) and the 4 cylinder engines.
Also take into account that the farther from the center line of the crank the rotating mass is the less it takes to do the same job. Just like the figure skater who starts to twirl on the ice and then brings in her arms tight to her body, she is playing with the kinetic energy to speed up her spin (radius of gyration). If my memory serves me right, I believe the relationship between the rotating mass and the distance from the center line is a geometric relationship.
Another factor is that by smoothing out the torsional vibrations caused by the 60 degree deficit of the power pulses, there is less drive line vibration which will result in longer life and less stress on converter dampener springs, transmission guts, drive shaft, u joints, and rear axle.
Now here is why you can't hang your hat on the dampener spring sizes. You can either dampen out the 60 degree power pulse deficit with more rotating mass like SunCoast did and got lucky. Or, you can put in bigger dampener springs like VM told Chrysler to do and finally, Chrysler pulled their collective head out of their @$$ and listened when the came up with the Euro. Now like I said, don't hang your hat, the old SunCoasts like mine had the smaller springs and due to the billet cover, they got lucky and it worked great. The new SunCoasts like changingtime got all have the bigger springs, just because that is what performance builders do weather they need to or not. How lucky did SunCoast get by adding the billet front cover? Well, I have an Experimental TCM that I can lock up 5th as low as 48 MPH and put the full torque to it with no chadder lugging or other objectionable performance!
Now if there is an Engineer with lots of time and money, he/she could determine the radius of gyration of the VM 2.8L engine in the Jeep configuration and by using strain gauges mounted onto small rods that would elongate and shorten attached to both of the motor mounts, could compare the difference between a Euro and SunCoast converter. Then start lightening the SunCoast or adding weight to the Euro or flex plate (smarter move) find the rotating mass of the assembly that produces the least vibration with out robbing performance (measure with a dyno) from excess mass. Then when you are all done, calculate the radius of gyration by placing the torque converter onto a turntable with air bearings, applying the torque load and go for it. Now you will have the perfect flywheel rotating mass for the VM 2.8L engine. Anyone want to bet weather VM knows what it is? Does anyone doubt my belief that in the case of SunCoast and Precision converters, it is pure luck?
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Our VM R-428 engine also has twin balance shafts too 
