Originally posted by fastcougar:
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As much as I value your input Tom, I don't see how you can say that you can build a 500+hp engine when the rods are not proven to that power rating. However you "feel" is not what has been proven.



Oh, I don't know about that. What would a 500 HP engine put down to the ground?
Assuming about 18% loss, a loss of about 90 HP would yield 410 HP at the wheels?

You also have to understand the rods aren't "proven" to a horsepower rating anyway. The performance companies sell them that way based on artificial assumptions and because HP numbers are what people want to hear.
You should know that a metal part really only has a few mechanical properties that can determine its usefullness. Giving a horsepower rating to a rod is a BOGUS rating , a guideline only, or to just plain sell product. When I mention a power rating I'm talking about the engine package as a whole, not the individual rod.

Dynamic tensile stress, static compressive stress, fatigue and maybe shear that would be stresses I'd be concerned with right off the bat. The properties of the rod are going to be the Yield Strength and Ultimate Tensile Strength, elasticity, K1c fracture toughness; to name a few.
All I'm saying is that it is a load of bunk when you buy rods rated at 1000 horsepower because you don't even know how many rods (cylinders) they are talking about or the loads associated with the engine and how much each rod sees?

Does anyone get what I'm pointing at???


Lets assume you just put in forged pistons to a compression ratio of 9:1 and used stock rods. Then set it up to be a 500 HP engine. The stock rods have been dyno proven to 350 ft-lbs of torque; to 7200 rpm while under 300+ ft-lbs of torque, by me. They've handled upwards of 8000rpm by DemonSVT, 8500rpm under load I think I remember and sustained it no sweat not a mark. Same rod is used in mulitiple engines of differen't power ratings.
The tensile stress is based mainly on rpm and ultimately the accelerations the piston sees. The compressive stress is the load due to the combustion pressure...the power stroke. Therefore 350 ft-lbs at 4000 rpm should be no more harmful to the rods than 350 ft-lbs at 6500 rpm since the rods are proven capable of significantly higher rpms.
Just think, 350ft-lbs at only 6300rpm will yield approximately 420 HP. 420 at the wheels back calculated is over 500 crankshaft horsepower even optimistically using an efficient conversion.YOu want to make power, make your peak torque higher in the power band, end of story.

BTW, when you buy an engine rated at a certain power it is rated at the crank because they have no idea what you coupling the engine to, and what the drivetrain losses.

Hence I can comfortably say that I can build an engine capable of producing 500 HP for $2500.
Then I can be equally comfortable saying that you'd need another 4 grand for the turbo/accessories and tuning. But hey, we're talking drop-in long blocks right?

Former owner of '99 CSVT - Silver #222/2760 356/334 wHP/TQ at 10psi on pump gas! See My Mods '05 Volvo S40 Turbo 5 AWD with 6spd, Passion Red '06 Mazda5 Touring, 5spd,MTX, Black