MG ZT V8

[pipme]

The old 'ker-thunk, chuff,chuff, chuff,ker-thunk' of a marine motor on TVO, being just a little cold, missing the odd couple of firing strokes, utilising the flywheel as a crutch ......

Doesn't the tuned V8 tend to an almost big twin, on straight thrus, mo-bike or is it 'ripping calico' ?

No sound like the old F1 having it's neck well wrung at a circuit like the 'Ring ..

 

[AdamW]

Come to think of it, I got a nice nosh off a mademoiselle in the grandstand, so maybe you're right.

Well the French are famed for their cooking I suppose...

Not sure what racing rotaries rev to, but I believe the RX-7 in standard guise redlined around the 8000+ mark (pre variable valve timing piston engines ). Perhaps it revs higher because there aren't valves in such an engine.

The Honda S2000 worries me, redline at 9000rpm. That's just not right! I would love to hear one of those being properly wound up.

Did a quick calculation: according to the internet the S2000 has a stroke of 84mm. Now, at 9000rpm a piston is completing 150 full up-and-down strokes every second. So it is travelling at:

150 * 84 * 2 (cos it is up AND down) = 25,200mm/sec = 25.2 m/sec = 56mph.

But what about the accelerations? Well, I believe the piston would be moving basically in simple harmonic motion (I'm sure that isn't entirely true, but its near enough). Bear in mind it is nearly 1am and I am knackered so I will probably get this totally wrong (this will be embarassing if I get it wrong, SHM is the physicists equivalent of the two-times table )

Maximum acceleration at the ends of the stroke:

a = -(angular frequency)^2 * displacement.

So, our angular frequency is 2*pi*150 radians per second, = 942 rad/sec

a= 942^2 * 0.0042 = 3731 m/s^2

a = 380g... not as impressive as I thought it would be, certainly not at turbine impellor-tip accelerations. What does a piston weigh? Quite a force on the gudgeon pin!

 

[pipme]

Valve-less ?

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 it's most efficient power setting, the big 14 consumes 1,660 gallons of heavy fuel oil per hour.

This, is a Crank sir !

Now they are real studs !!

 

[keyplayer]

Wow, that's a big one! Can't find his torque wrench though, can he?

 

[AdamW]

I can hear the Longbridge engine-builders now: "Oi, Dave, careful you don't fall through that inlet valve, sport!"

You could use a piston ring as a hula-hoop!

Jezza's Extreme Machines had a super-efficient container ship, I believe Japanese built, most efficient in the world at the time. The figure that sticks in my head was something insane like 1kg of diesel (not fuel oil) to move 1 tonne of cargo 1000km. Obviously was a single-prop design, I have a feeling it was a 3-cylinder engine.