Turbine powered Dodge Caravan

[Viper007Bond]

This is badass:

(note this isn't a jet engine, it's a turbine -- it turns the rear wheels)

Originally Posted by Autoblog

Chris Krug has what we think might be the most bad-ass late-90's Dodge Caravan in the world. Like us, he apparently thought the 150-hp V6 just wasn't enough and added some supplemental power via a 1,000-hp helicopter jet engine. But he left the original piston powerplant in place to retain its street-legal status.

It's not easy to describe the rapidity at which Krug's green Caravan explodes off the line and down the track. It's seriously disconcerting to watch almost two tons of toddler-hauling mediocrity running an 11.17-second quarter mile with flames shooting out the back hatch. The black and white soccer ball sticker on the liftgate only further cements the surreal feeling that this van is just not right.

The turbine is government surplus and the flames are courtesy of judicious use of fuel sprayed into the helicopter engine's exhaust. Though the pyrotechnics make for a good show, Krug says they provide no boost in acceleration. The whole thing only cost about $17,000 to build. Krug says his Vanzilla tops out at only 113 mph because he still needs to do some work on the rear axle ratio. If it were us, we'd see about getting some wider rubber on those back wheels, too.

After you've watched the video above several times, click through to the jump for even more footage of this unholy amalgam of military might and mom-approved mobility.

[Source: Hacked Gadgets via Gizmodo]

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[Crazyjeeper]

That is the coolest minivan EVAR.

[Aiolos]

Originally Posted by Crazyjeeper

That is the coolest minivan EVAR.

Can you say coolest soccer mom EVAR?!

[Viper007Bond]

Originally Posted by Aiolos

Can you say coolest soccer mom EVAR?!

Soccer dad.

[klutch]

That.....is awesome. It must have a hell of a reducer if its driving the rear wheels directly...from like what, 50,000 rpm down to a couple thousand? Better not leave any loose change or junk food in the cabin, given how that monster is sucking all the air from inside!

[Viper007Bond]

Originally Posted by klutch

That.....is awesome. It must have a hell of a reducer if its driving the rear wheels directly...from like what, 50,000 rpm down to a couple thousand? Better not leave any loose change or junk food in the cabin, given how that monster is sucking all the air from inside!

The owner left a comment Hacked Gadgets:

The jet exhaust is at wide angles for the helicopter application it was in. They wanted the exhaust to go away from the tail boom and have just enough velocity to keep the hot exhaust from being recirculated into the intake. The exhaust provides no thrust, it’s all shaft driven but I do spray fuel into the exhaust to make some smoke and fire. It’s funny how people think a jet engine isn’t working properly if fire isn’t spewing out the back, unless it’s the engine on the passenger jet they’re sitting in. The engine is a Rolls Royce Nimbus 105 with about 1000 shaft horsepower at 2100 rpm. The chain drive steps it up by 1:2.25 and the rear axle has 3.50:1 gears soon to be replaced by 3.25:1 gears. I don’t know about letting anyone drive it but you’re all welcome for a ride. It handles really nice. I’m in Augusta Georgia. I’m looking for a certian jet powered VW for a match race

[klutch]

Originally Posted by Viper007Bond

The owner left a comment Hacked Gadgets:

So...is that 2250 shaft horsepower? Jesus....

I guess the only thing preventing it from absolutely melting the tires is the fact that it takes a while to spool up; he could probably tweak that final ratio a little better; get it so that roll-ons would be devastating: imagine 100-200 miles an hour in about 10 seconds!

[Viper007Bond]

Originally Posted by klutch

So...is that 2250 shaft horsepower? Jesus....

Wow, learn to read.

It's 1000 HP at 2100 RPM.

Originally Posted by klutch

I guess the only thing preventing it from absolutely melting the tires is the fact that it takes a while to spool up; he could probably tweak that final ratio a little better; get it so that roll-ons would be devastating: imagine 100-200 miles an hour in about 10 seconds!

It's only 1000 HP. Some Viper's have 2x that.

[Beni]

But it's a lot more torque then the Vipers have.

[MrChips]

Originally Posted by Beni

But it's a lot more torque then the Vipers have.

Actually, this engine doesn't produce a huge amount of torque, especially from a standstill.

The Roll-Royce Nimbus is a free-turbine turboshaft engine. What this means can be illustrated by a diagram:



This is a simplified diagram of what a free-turbine engine looks like inside. Note that the turbine stage that drives the output shaft is not connected directly to the engine - it can turn at any speed independent of the rest of the engine; it can even be stopped, if necessary. The advantage of this engine layout is that it can be made into an incredibly light, compact and easy to service engine, with a lighter reduction gearbox than a fixed-shaft engine. The most common turboprop/turboshaft engine in the world, the Pratt and Whitney Canada PT6, is of this design. A typical PT6 installation will produce about 850 shaft horsepower, yet weigh only 330 pounds including the reduction gearbox.

The major disadvantage of this engine type lies in it's low speed power output, or lack thereof to be more specific. Turbine engines only produce their maximum torque and horsepower at their maximum RPM, and generally don't produce much power at all below 70% of their maximum RPM. In the case of the minivan, not only are you not getting anywhere near the engine's maximum power from a standstill, but you're probably so low on power that I'd be willing to bet the driver couldn't light up the tires even if he tried. Also, throttle response in this type of engine is very poor - it can take a long time to achieve full power with this type of engine; often in the order of 15 seconds.

Compare that to a fixed-shaft engine, like this diagram:



The fixed-shaft engine avoids some of the problems of the free-turbine engine, but has even larger disadvantages of it's own. The fixed-shaft engine, for starters, is almost constantly run at or near maximum RPM and only when the aircraft is parked will it run at less than maximum RPM. The advantage of this is that the engine is always in it's power band, and you can go from idle power to full power as fast as you can move the power levers. But if the engine is already at maximum RPM, you wonder, how do you get more or less power out of it? Change propeller/rotor pitch (take a bigger or smaller bite out of the air), and change the amount of fuel burned. The effect is the similar to going from part throttle to full throttle in the same gear in a car with a manual transmission. However, this engine has some crippling disadvantages. First, they are generally much heavier than a free-turbine engine, on account of the need for a big, strong reduction gearbox. Second, if the propeller or rotor were to stop for any reason, you could well imagine the damage caused to the engine internals. Third, because it turns at maximum RPM all the time, they're tremendously noisy and have a bad habit of gobbling up stones, dust and other crap found on the ramp that shouldn't otherwise be part of a gas turbine engine's diet.

[-Cpt. J.-]

Good.
Now put it in an Ariel Atom.

[Viper007Bond]

Originally Posted by -Cpt. J.-

Good.
Now put it in an Ariel Atom.

And completely ruin the car? Pass.

[chaos386]

*frantically goes off in search of a helicopter engine*

[Labcoatguy]

I really want to see this lined up against a big block drag prepared car on a strip. The combination of WOT pistons vs. WOT turbine would just make my head asplode.

[thedguy]

Originally Posted by MrChips

Actually, this engine doesn't produce a huge amount of torque, especially from a standstill.

The Roll-Royce Nimbus is a free-turbine turboshaft engine. What this means can be illustrated by a diagram:

Does the usual calculation of figuring out torque from HP not apply to turbines? If it does apply then I'm figuring right around 2500lbs-ft of torque at 2100rpm.

[klutch]

Originally Posted by Viper007Bond

Wow, learn to read.

It's 1000 HP at 2100 RPM.



It's only 1000 HP. Some Viper's have 2x that.

I thought that chain reduction would double output; I thought peak HP was achieved lower in the RPM figure.