joe_padavano

OK, I'm convinced. Nick, Brian, Mark, their engine builders, NASCAR, et al are correct. I had a "eureka" moment this morning and I think I've figured out why the H-beam rod design is better.

Everyone who looks at the H-beam vs. I-beam comparison focuses on the beam section, and yes, there's no question an I-beam is lighter and stiffer. The problem is that the beam bending is not the driving design requirement. The most important problem is getting the piston loads into the rod bearing and thus the crank journal. The I-beam design does a relatively poor job of distributing these loads into the bearing shell. The web of the I-beam causes load peaking in the bearing, distortion, and squeeze-out of the oil film on the journal. The result won't be pretty. The H-beam, with the two faces flowing into the big end, does a MUCH better job of distributing the load into the bearing. The more uniform loading on the bearing shell keeps the bearing round and keeps the oil film uniform.

I really should have seen this sooner, since this is a design problem we face regularly in the aerospace world (though usually without the 5000 RPM reciprocating load). More smaller webs to spread the load is always the lighter, stiffer solution and that's what the H-beam provides. I stand corrected.

Now, this DOES bring up the question of the very expensive "X-beam" rods. For the life of me I can't see the benefit. The beam section is clearly less stiff than either the I-beam or the H-beam, and the X-beam is no better than the I-beam in spreading the load into the bearing, so what's the benefit, other than they are different?

BlackGold

I'm still waiting for the O-beam.

Texas Jim

why not the "Proven" thing; "H" beam f/ horse power and "I" beam f/ torque. From my understanding, the pros say this is the "fact." I only do the reading... But I'm listening...

cutlassefi

You have to have torque to make hp. H beams seem to handle the higher hp/tq applications, I-beams normally less than 600.
Don't forget piston weights and rpms still have something to do with the longevity of I-beams.

geckonz08

neither H or I and neither olds lol

The crank sitting in the block (also known as a "gondola-style" bedplate). This is a 10 cylinder version. Note the steps by each crank throw that lead down into the crankcase:

engine2.jpg

A piston & piston rod assembly. The piston is at the top. The large square plate at the bottom is where the whole assembly attaches to the crosshead:

engine3.jpg

panos

If im not wrong that is a huge 2stroke motor.

MDchanic

My grandfather used to tell me about working on engines (probably steam) with 4 foot bores, back during the War. I'd love to have seen some pictures from back then, but if he had taken any, they probably would have shot him as a spy .

- Eric

geckonz08

pANOS, YOU ARE the man. I wouldn`t have had a clue that was a 2 stroke engine , but you are so correct.
Larger version of my trials bike .

compedgemarine

so I guess that is a "O" rod?

geckonz08

i WOULD GUESS IT`S A COLUMN ??

panos

I worked a little back in time when i was living in Greece with those huge motors and 90% are 2stroke and the biggest one only turn at about 200-300 rpm

geckonz08

I know this is ,in a way, adding nothing to the original argument on H or I beams but it is mind boggling --please excuse the intrusion

WOW! 108,920 hp - pics of diesel engines for container ships
This is some engine:
Maximum power: 108,920 hp at 102 rpm
Maximum torque: 5,608,312 lb/ft at 102rpm

untitled-5.jpg


The Wartsila-Sulzer RTA96-C turbocharged two-stroke diesel engine is the most powerful and most efficient prime-mover in the world today. The Aioi Works of Japan 's Diesel United, Ltd built the first engines and is where some of these pictures were taken. It is available in 6 through 14 cylinder versions, all are inline engines. These engines were designed primarily for very large container ships. Ship owners like a single engine/single propeller design and the new generation of larger container ships needed a bigger engine to propel them. The cylinder bore is just under 38" and the stroke is just over 98". Each cylinder displaces 111,143 cubic inches (1820 liters) and produces 7780 horsepower. Total displacement comes out to 1,556,002 cubic inches (25,480 liters) for the fourteen cylinder version.
Some facts on the 14 cylinder version:
Total engine weight: 2300 tons (The crankshaft alone weighs 300 tons.)
Length: 89 feet
Height: 44 feet
Maximum power: 108,920 hp at 102 rpm
Maximum torque: 5,608,312 lb/ft at 102rpm

Fuel consumption at maximum power is 0.278 lbs per hp per hour (Brake Specific Fuel Consumption). Fuel consumption at maximum economy is 0.260 lbs/hp/hour. At maximum economy the engine exceeds 50% thermal efficiency. That is, more than 50% of the energy in the fuel in converted to motion.
For comparison, most automotive and small aircraft engines have BSFC figures in the 0.40-0.60 lbs/hp/hr range and 25-30% thermal efficiency range.
Even at its most efficient power setting, the big 14 consumes 1,660 gallons of heavy fuel oil per hour.
A cross section of the RTA96C:

380 Racer

I worked in our municipal power plant for a few years. Got in on one overhaul of the 20 cyl they have. Has an 18" bore. The rods are 5' tall and weigh 750 lbs, then had a cage bolted to them for the crank throw and were O shaped. Rod bolt torque was in the 1200 ft lb range. Each cylinder had it's own head with 4 valves, about 8" in diameter. Was dual fuel (diesel or natural gas). And yes ungodly torque/HP and turned whopping 750 rpms.