Howdy,

Sounds like something I'd definately make time for too.

As far as the connecting rods, the other engine I'm familiar with that does this is the Chevrolet LS1. There, the technology is called "cracked PM" for cracked powdered metalurgy. Chevrolet makes their rods by press forming metal alloy powder in a mold at high temp. This blank is then heated again and forged as a normal con rod is done. The advantage to this is that the exact quantity of metal is known due to the accuracy of measuring the amount of powder originally put in the mold. They then scribe a stress riser on the big end and crack it (after machining the bearing surfaces).

The advantage to the cracked big end is that the surface roughness helps locate the cap onto the rod accurately.

Due to the accurate limits on finish weight, LS1 rods do not have balance pads on them as other Chevrolet V8 rods have always had. Is the same true of the MB rods? I'd suspect MB engine balance requirements are tighter than Chevy requirements thus still requiring balance pads.

The LS1 also uses cross bolted mains. It in fact has 6 bolts to locate the main bearing caps. Four are bolted from below (much like a M117 engine) and two are bolted at 90 degrees from the side. Two advantages to this are (1) location of the main more rigidly leads to less engine vibration and (2) with an aluminum block, you're going to need more location than the usual American V8 2 bolt main.

Historically, the Chrysler Hemi engines were cross bolted which made them very desireable for drag racing duty. Most Chevy V8's that were 2 bolt motors were converted to 4 bolt by redrilling the webs at an angle. The main caps would then be located more rigidly because the 2nd set of bolts have some triangulation relative to the OEM bolt holes.

One other change with the LS1 that older Chevy V8's didn't have is that the LS1 main webs extend below the level of the crank (as required by the cross bolts). This in itself makes for a much stronger engine.

Sounds like a neat demo. I'm really interested in the 2 spark plug combo. Having the 2nd plug not only allows you to get the combustion over in a shorter period of time, but changing the timing of each spark plug individually with RPM would allow you (as you indicated) to lower the rocking moment. It could also create low RPM turbulence, which adds to output torque and efficiency: very good things.

Sholin

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Lt. Blue 1973 MB 280 SEL (108) with sunroof and console shift.
1996 Chevy Camaro Z-28 LT1.