Oddjob

>"Actually, they are not warranteed at all. They rebuild the engine, more or less, after every run."

That was a joke, I was referring to the jet engines hopefully lasting longer than 900 revs.

botoo

OH, ok, I should have read it more carefully.

special tool

AND... can you imagine that they STILL don't produce the horsepower-per-cubic-inch as the '89 (that's right, 1989) BMW turbo Formula one engines did!!!!

-And get this - the formula one engines ran for several laps in this "qualifying trim", not this mamby-pamby Nancy boy 1/4 mile sht.


Yes, its true

gjvander

A CF6 jet engine (there can 4 of those on a 747) produces about 60,000 lbs of thrust. You can roughly extract that amount in shaft horsepower if you choose to. So the comparison to a jet engine is way off.

Top Fuel car are impressive though.

Regards,

Geo

Cupcar

Interesting technology differences pointed out above between the:

The NHRA's V8, pushrod, 2 valve, roots blown, non-intercooled, uncooled engine burning nitromethane

and

BMW's F1 straight 4, overhead cam, 4 valve, turbocharged, intercooled, cooled engine burning the so called "rocket fuel" the gas companies were making for F1 at the time.

special tool

Cupcar - don't forget that the dragster is almost 20 years newer technology and the F1 cars could run a few laps around SPA - making more power per CC.

alvin ulan

i beleive that hp is aprox. twice thrust i.e 60,000 lbs of thrust is 120,000 hp. i don't know what % of thrust a 747 needs to maintain cruise at 40,000ft. the higher a plane flies, the more efficient it becomes, so good luck figuering anything out. my guess is that a 747 engine is a more impressive powerplant than a dragmotor.

gjvander

The thrust is about equal to hp you can extract. An example is the CF6-80C2, which produces close to 60,000 lbs of thrust. The same engine is used on the LM6000 gas turbine generator. The 6000 stands for 60000 shaft hp. There is also a LM2500 etc etc.

I know the LP shaft torque and rpm numbers on the GE90 base & GE90-115B, and the ratio of shaft horsepower to thurst is close 1:1 on a modern high bypass ratio jet engine.

Cruise thrust will drop from 100,000 to 15,000. Luckily drags drops too...

Regards,

Geo

tonytaylor

The landspeed record holder Thrust SSC used 2 Rolls Royce 205 Spey Phantom jet engines rated at 25000lbs of thrust each and was rated at the equivilant of 110 000bhp.

gjvander

They might calculate the hp requirement by using drag and speed, instead of shaft torque and rpm. ie it would take x amount of hp to get to the speed using a piston engine.

The total hp inside a modern jet engine can include both the low pressure and high pressure system. If you want to calculate it that way, the power is approximately twice the thrust. But you can't use the high pressure system power because it is being used to drive the high pressure compressor. You can easily have 600 psi in the combustor before ignition, but unlike an internal combustion engine the presure does not increase with combustion. The fact that the gas expands is used in turbomachinery.

Regards,

Geo