with work being slow for the last couple days, i decided to sign myself up for some "continuing education" with chrysler's training. Cam in block Phase 2. Covers the 3.3/3.8, 5.7/6.1, and 8.4 engines. needless to say, majority of the time was invested in the updates for the new hemi's, codenamed Eagle.
firstly, a lot has changed, we all knew about the variable cam timing, and i quoted the master tech earlier on that topic. Quote: all next generation 5.7L engines receive Variable camshaft timing, or VCT. if you are familiar with the system on the Viper 8.4L engine, the one on the 5.7L engine will look familiar. The PCM controls VCT based on a number of inputs. Included in these is an oil temperature sensor to help the PCM determine when to actuate the solenoid on the oil control valve. That is attached to the block behind the timing cover. The PCM operated the valve by means of pulse width modulated signals which can range from zero to 100%. when the pcm is changing cam phasing, pressurized oil flows from a passage in the block into the oil control valve. from there it is directed into one of the two passages in the camshaft number one bearing journal. the oil then flows to one side of the vanes in the camshaft phaser. oil on the other side of the vanes is exhausted via the other camshaft passage. at zero percent duty cycle, the valve directs oil to the advance dise of the vanes, which results in a fully advanced cam phaser. at 100% duty cycle, oil is directed to the retard side. this results in a timing of about 36 degrees BTDC. at 50% oil is directed to both sides, and maintains the current cam phaser position. Its a very interesting design but apparently only designed to negate the use of the EGR valve. there is performance potential though.
The block has been revised to house the Oil control valve, a duty cycled solenoid placed in the block, facing the back side of the cam sprocket. three new oil passages were added to facilitate the cam phasing, and a much larger #1 cam journal is used as it also is used as an oil passage to the hydraulic cam phaser. the oil pump is new, a higher output than previous models, and is NOT compatible with the previous versions. chrysler said so, and i even tried on an 03 hemi. it will not work. the timing chain is different as well, colored links appear to be gone, replaced with lazer etched rectangles on the links. of course, number of links appears to have changed as well due to sprocket size differences too.
the timing chain tensioner is now a spring loaded piston, not the leaf spring powered tensioner as used before, the tensioner is no longer part of the thrust plate either.
for the most part, the crankshaft appears to be the same as previous versions, connecting rods look similar as well though some early models (like the one i "tested" on) had full floating wrist pins. sources said it was planned, but scrapped early, apparently early production versions made it, but are expeced to all be in the durango hybrid engines.
Pistons: for the most part, nothing ground breaking. shorter piston skirts, less dome, and now 1mm compression rings.
now for the useful stuff. Cylinder heads. big changes here, new closed chamber heads have smaller chambers (duh) than previous engines , 66.3cc in fact vs 84.9cc. even smaller than the 6.1's with 73.0cc. bolting these on to a previous hemi without modification would result in nearly a 12:1 compression ratio. valves are slightly larger. intake is 2.05" vs 2.00". exhaust is the same. both valves have a longer stem though. new bee hive valve springs, identical on both intake and exhaust are now in use, and seem to mimic what we have been doing in using the 6.1 exhaust springs across all valves. pushrods have changed as well, they are now approximately 4mm longer, putting them very close in length to the 6.1's pushrods.
ports appear to have a 6.1 sized window on the intake side, as well as a 6.1 style D shape on the exhaust. a quick comparisson with a 6.1 exhaust manifold looks like it was nearly a perfect match.
tappets: i wouldnt normally cover this, but i actually made notes in class because of this. they have been revised for higher lift with proper MDS actuation. the stock cams have higher lift, requiring more capacity to collapse in MDS. the new lifters do this constantly in factory form. further more, they are backwards compatible. they will drop right in to an older 5.7 (or any previous hemi built with MDS)
intake manifold: this is a gray area, as there are approximately 4 or 5 different manifolds available for use on the eagle. the trucks use an active intake version where as the cars do not. the active intake allows the ram to have 390 horsepower and 404 ft*lbs of torque by giving it short and long runners in the intake. a very cool design, but nothing groundbreaking, v6's have it as well.
these are the active intake, from the ram, durango (non hybrid) and aspen (non hybrid).
Exhaust manifolds. again, different depending on models, but seem to have a slight advantage over previous engines. looks like they spread a bit more, as well as clearer ports and possibly larger midpipes than the older hemi's.
