[G. Craig]

Originally Posted by iceman

Are the internals forged in these engines?

Any guess as to what they will hold on a stock bottom end or where the weak points are that need to be built for near 800 rwhp?

NEW factory 425HP 6.1 HEMI SRT8

This doesn't answer your question directly but is interesting none the less. Below are some specs I found and copied into a Word file. I've had this for a while and don't recall where I got it from but I would contend the bullet points are accurate or I never would have copied the info. In addition I've read in a number of places the pistons are indeed hypereutectic. Probably due to the fact they do not expand and contract like forged aluminum thus providing better emissions regardless of engine temperatures (when cold).
Some good engineering has gone into this engine.

The SRT version produces another 85 horsepower and 30 lb-ft of torque than the 5.7 liter Hemi, and only some of that comes from the extra .4 liters of displacement. The Hemi produces more power per liter than any past Chrysler V8, including the 1966 Street Hemi, though with the technology available today, that's not surprising. Changes to the 5.7 include:
· The basic, deep-skirted engine block structure was redesigned with reinforced bulkheads to handle higher loads.
· To get more air in and out of the cylinders, SRT engineers bored out the diameter of each cylinder by approximately 3.5 millimeters in order to increase the total displacement from 5.7 liters to 6.1 liters.
· Cylinders are honed with torque plates to ensure a truer bore, to reduce friction and increase power.
· Oil squirters, aimed at the underside of each piston, are added to aid piston cooling for engine durability.
· A special oil pump pressure relief valve is added to accommodate the squirter oil flow.
· The oil pan and windage tray are modified to manage oil return to the pan sump at high engine speeds and improve power.
· Larger-diameter, flat-top pistons with high-load capability are specified to handle the SRT 6.1-liter HEMI’s compression ratio, which was increased to 10.3:1 from 9.6:1.
· Connecting rods are redesigned and make use of higher-strength powder metal material.
· New floating piston pins are introduced to handle higher loads.
· The SRT 6.1-liter HEMI’s crankshaft is forged from micro-alloy steel and rotates in tri-metal main bearings for high-load capability. The crankshaft damper is retuned for higher engine speeds.
· The SRT 6.1-liter HEMI features cylinder head ports designed with larger cross-sectional area. This allows 11 percent higher flow in the intake ports, and 13 percent higher flow in the exhaust ports.
· A billet steel, high-strength camshaft features more overlap and lift for better performance.
· Intake valves feature hollow stems and 2 mm larger heads compared to the 5.7L engine, allowing more air flow. The hollow exhaust valve stems are filled with sodium to dissipate heat efficiently.
· Premium valve springs with external dampers enhance the SRT 6.1-liter HEMI’s valvetrain and enable higher engine speed operation to 6,400 rpm. The valvetrain system enhancements allow the peak output engine speed to increase to 6,000 rpm from 5,000 rpm — a 20 percent increase.
· Engine breathing is improved with specially designed intake and exhaust manifolds. The cast aluminum intake manifold is designed with shorter, larger-diameter and tapered runners for high-speed tuning. Internal runners are core-dipped to smooth the runner finish and improve air flow.
· Fuel injector flow capacity is also increased by 14 percent over the 5.7-liter engine.
· Electronic throttle control is shared with the 5.7-liter HEMI, but breathes through a revised high-flow air cleaner box outfitted with a tuned resonator delivering a deep performance sound character (and good for an extra eight horsepower).
· Exhaust headers on the SRT 6.1-liter HEMI are individual tubes encased in a stainless steel shell. Exhaust runners allow increased gas flow while maintaining fast catalyst light-off, while adding 12 horsepower over the 5.7-liter engine’s cast manifolds.
· To control the combustion process, SRT engineers fine-tuned the engine management system using dual knock sensors with premium fuel.

ENGINE: 6.1-LITER, HEMI® V-8Displacement
370 cu. in. (6059 cu. cm)
Bore x Stroke
4.06 x 3.58 (103.0 x 90.9)
Compression Ratio
10.3:1
Power (estimated SAE net)
425 bhp (318 kW) @ 6200 rpm, (69.8 bhp/L)
Torque (estimated SAE Net)
420 lb.-ft. (310 N•m) @ 4800 rpm
Max. Engine Speed
6400 rpm (electronically limited)
Fuel Requirement
91 octane (R+M)/2 recommended (premium)
Oil Capacity
7 qt. (6.6L)