The HP "rating" of the Eagle rods or our rods is a one size fits all description. Which falls under nearly the same range of difference as a 150 lb woman 4 ft tall and a 100 lb 5 ft tall woman both waring the same pantyhose. HP "limits" are based off difference factors. A 600 HP all motor, 11,000 RPM Honda on a 300 shot of Nitrous will break a 600 HP rated Eagle rod. But the rod will last a good while before it gives. Then comes the lower RPM turbo engines, they stress the engine and rods completely differently.
A high RPM engine sends a lot of vibration through the rod beam and translates it to the block, twisting and stressing the block. With a cast crank these twisting forces get out of control enough to put the rotating parts out of alignment with flex. At this point the rods cap and rod bolts are really important to keeping the rod together. The piston pin and the beam aren't being used as much, most all strength is in the cap end to fail. But a great block like an SRT 4 block or a forged crank or both make high RPM twist issues weak. Honda's just get forged cranks for instance.
Then comes high cylinder pressure lower RPM power makers, like a turbo engine. The T2 rod has a cap and bolt made to hold a 4.13" bore small block V8 piston, but they have only a tiny 3.45" bore piston to hold. In the case of a 2.2 with shorter stroke they can rev all day at 7,000 RPM with 300 HP. Most turbo people drag race and have only short bursts, even on the street you get short bursts. But unlike the RPM engine the Beam and piston pin get a beating. The rod cap isn't doing a lot, the engine isn't revving that high. The beam has to take the force of torque created by the turbo. The guy with the 638 WHP SRT 4 engine is an example. When the engine had back pressure added to it by a better drive train the rods buckled under the torque. But it didn't shatter the rod caps like glass like what happens in a RPM built engine.
Lastly materials and stress breaks. The SRT 4 rod is a cast forged rod with a pressed pin and a cracked rod cap. The T2 rod is a cast forged rod with a HD piston pin that is floating, and all together larger diameter than an SRT 4 pin. Then the rods are heat treated after forging for surface hardness. cast rods like these break from microscopic stress cracks that give way to a large break. The machine cut T2 rod is better suited for RPM use. The SRT 4 rod is snapped at the rod cap after casting, which weakens the rod at the cap. SRT 4s come with a 5,900 RPM rev limiter though. The grain of a cracked cap rod sucks, a SRT 4 rod would like shot peening to smooth the surface cracks from separating the rod caps. Shot peening is a surface hardening, which the T2 basically has stock but hardened with impaction instead of heat. The big one is shot peening though with a cast rod. The cast rod will break on the grain of the casting, then the break will follow through the grain to the other side. Cast rods snap the beam in half, shot peening gets you past this a ways as the microscopic cracks can't start on the surface and work there way in the beam.
Now we have an Eagle rod. The caps are machine cut, not fractures. The metal is a denser grade of forging. In the cast of a T2 rod you get some cap walk from having a bolt and nut, there is some room for movement. The Eagle rod has a bolt on cap, no nut, so the bolt centers and holds the cap from walking. The beam and the rest of the rod can't break along one grain, which is how a cast rod breaks. The reason is that a Eagle rod is a 2 piece forging. The rod can't fail across the grain because the grain doesn't go more than half way through the rod. They sound scary, like you can bad mouth them for it. But the fact is with a turbo or high RPM a beam will snap across the grain of the material. A 2 piece forging breaks up the grain of the whole rod so it can't fracture all the way through. So the eagle rod has more than enough cap for RPM use but the cap isn't a lot stronger than a T2 cap. So in an RPM based engine the Eagle is stronger but not greatly. Most strength comes from the rod not failing along the grain from high RPM twist. Now you talk low RPM boost and torque with an Eagle H beam? 4 bolt mains and a steel crank and a 2.2 could run 1,000 HP with Eagles 8v. If they could get there lol. A SRT 4 has a serious block and girdle, they can get get up to about 900 HP with a rod. Add a forged crank and the SRT 4 block with Eagles can go past 1,000 HP. Then comes tuning, this is with engines tuned right. Any rod will fail with you detonate too hard. An Eagle will take some detonation at high HP levels a lot better than a T2 rod. So make 600 WHP with a T2 rod or SRT 4 rod, but don't screw up, ever. The Eagle will let you hit it a few times at this level.
So as the RPM range, piston weight, rod ratio, block rigidness, main caps and crank material all greatly effect how much power a rod can handle. So when you hear 600 HP Eagle rod there aiming at a not so perfect world with clowns building engines. A SRT 4 with forged crank, super light weight pistons, lower turbo RPM power, ARP main studs, oil repelling engine coating and a great tune? Now your talking about an engine that lives for years at 800 -900 HP with 600 HP rods
600 WHP T2 rod engine? Done right your still on thin ice, but as long as you don't hit an over boost buck or detonate your OK. That is coated, magnafluxed and shot peened though :)
TurboDodge.com 
