Jet turbine powered Go-Kart

[Knobby]

Hi All,
I've introduced myself in the appropriate thread so I thought I'd just follow up in here, hopefully I'm in the right place.

I have a Jet powered go kart which is basically a Garrett 6041 turbo-charger and has been converted into a full after-burning jet engine...the wheels are "not" driven and as such she is thrust driven. At present the engine produces approx 210-220lbs of static thrust ...most normal piston engine go-karts will eat it alive off the line but it will certainly do most karts over for top-end speed.

Am happy to answer any and all questions etc...

Cheers,
Smithy.

 

[planejob]

That's very cool.

I'd be interested in hearing more about how you converted the turbocharger and what electronics you use to control it.

Do you have any videos out there on youtube?

 

[KartFab]

Video. The last video I saw of a 'jet powered kart' was the kart maybe doing 20-30 mph and the claim was that it went much faster.

A video that a lot of people would enjoy would include

1) a brief walk around of the kart with a brief explanation of what it is
2) setting up a mph app or GPS for top speed test
3) kart driving fast
4) after shot of the kart and logged max GPS speed


That would be really cool to see! (Hint hint) theoretical stuff is nice to talk about, and you made the theoretical happen, now Let's see You turn a theoretical max speed (or at least a really fast soeed) into a documented reality!

 

[Knobby]

G'day Planejob,
The turbo is essentially stock, I've just constructed a combustion chamber, (the big can on the top) and associated fuel system for it. It's entirely mechanical with very little in the way of electronics controlling it.
The engine fuel system consists of a simple fuel injection pump from a car and a home made fuel control which is basically a by-pass needle valve attached to the throttle pedal via a cable. Maximum boost pressure at the moment is restricted to ~35psi (~50psia), which equates to ~70,000rpm. The turbo is in it's most efficient range from ~74,000-78,000rpm, anything higher than ~80,000rpm and the air is just being beaten to death due to the impeller tip speed approaching the speed of sound...not much use going any higher to be honest, very little in the way of gains to be had.

The after-burner is also pretty simple, the pipe itself is a divergent/convergent 8" dia 304 stainless, a 3/8" dia stainless spray ring and flame holder inside fed by two bosch 044 fuel pumps, a hot-streak system lights the A/B fuel which is fed by another fuel pump.....yes, this machine has four fuel pumps, hence the rather large car battery at the front. The A/B system also has a supplementary igniter in the tailpipe, essentially just a glorified spark plug.
To start the engine I use a 3 1/2hp 2 stroke blower to spin the turbine up to ~4-5,000rpm...I then use a spark ignition system to light the engine off using propane, once the EGT is up to ~350C, I then open the fuel shut-off and she then runs on Jet-A1 fuel, the propane can then be disconnected. Idle rpm is ~22-23,000rpm @ 3.5psi P2 pressure...! P2 pressure is just a fancy name for the combustion chamber pressure.

Cheers,
Smithy.

 

[Knobby]

Video. The last video I saw of a 'jet powered kart' was the kart maybe doing 20-30 mph and the claim was that it went much faster.

A video that a lot of people would enjoy would include

1) a brief walk around of the kart with a brief explanation of what it is
2) setting up a mph app or GPS for top speed test
3) kart driving fast
4) after shot of the kart and logged max GPS speed


That would be really cool to see! (Hint hint) theoretical stuff is nice to talk about, and you made the theoretical happen, now Let's see You turn a theoretical max speed (or at least a really fast soeed) into a documented reality!

Hey KartFab,
I'm not claiming speeds amounting to anything silly, just suffice to say this machine is capable of well over the 20-30mph you mention Most turbine go-karts are made from small T-03/T04 type car or small truck turbos, the turbo in my kart is rather large and is similar to the ones fitted to those big yellow mining trucks.

Here's a few boring videos for you, I had just fitted a new A/B pipe and this was just an engine run and a couple of slow test runs @ ~50% boost, lucky to get up to 80kmh really at a guess, is capable of much, much more:

https://youtu.be/as_hkpOO_hY

https://youtu.be/jBT7IPzDRZ8

https://youtu.be/i1bVaRoXc0E

Cheers,
Smithy.

 

[Knobby]

A video that a lot of people would enjoy would include

1) a brief walk around of the kart with a brief explanation of what it is
2) setting up a mph app or GPS for top speed test
3) kart driving fast
4) after shot of the kart and logged max GPS speed

That's not a bad idea really....I might do a "walkaround", then mount a go-pro on my helmet and just do a run somewhere, just need to find a decent place/area to do it....

Still have plenty of tuning etc to do but that's no excuse.

Cheers,
Smithy.

 

[J_Walker]

How do you keep the front end down? I see a battery, but that's only maybe 50lbs.

also why a turbine powered engine, and not a pulse jet? [I know technical details on the two, Just wondering your thoughts.]

As far as the turbine reaching the sound barrier. there was a fix for that in WW2 props.. Maybe you can take a look how they did it? it became a problem when they would dive. even the Japanese made a fix for it. so it has to be out there on the internet somewhere.

What kind of leaf blower is that..?

 

[Knobby]

How do you keep the front end down? I see a battery, but that's only maybe 50lbs.

also why a turbine powered engine, and not a pulse jet? [I know technical details on the two, Just wondering your thoughts.]

As far as the turbine reaching the sound barrier. there was a fix for that in WW2 props.. Maybe you can take a look how they did it? it became a problem when they would dive. even the Japanese made a fix for it. so it has to be out there on the internet somewhere.

What kind of leaf blower is that..?

The front end doesn't even try to lift...the kart is not wheel driven....plus it will have my fat ar$e in it to hold it down..

The reason for a turbine over a pulse jet is mainly for ease of use, the pulse jets are quite simple but produce very little thrust compared to a similarly sized turbine and they're very thirsty and can be quite difficult to make run well....A nicely running turbine sounds much better than a pulse jet IMHO..!

Regarding the turbine speed issue, there's only so much air the turbine can process, this becomes an issue at supersonic speeds, there's a shock-wave which each blade produces and this leads to poor efficiency, hence the speed requirements....plus the aluminum impeller has material strength issues at high rpm's, it can only take so much before it wants to try and get out.

The "leaf blower" is actually an old back-pack crop sprayer which I have modified to make it into a suitable engine starting device.. Seems to work quite well too.

Cheers,
Smithy.

 

[Badot]

Cool! It's not often that people make these that can do more than just keep themselves running. Just curious about the numbers, have you measured the fuel flow and thrust with and without the afterburner?

 

[J_Walker]

I forget.. I'm tellin you there's a fix for the shock wave issue.... I know because I watched a video on it somewhere! lol

but anyways. cool build, One day I will be able to do such a thing myself!

 

[Knobby]

Cool! It's not often that people make these that can do more than just keep themselves running. Just curious about the numbers, have you measured the fuel flow and thrust with and without the afterburner?

Yes I have...The engine itself is reasonably efficient, at full noise the engine consumes ~2.75lbs of air/sec, (165lb/min), so at ~70,000rpm she'll consume approx 5.1Liters of fuel per minute. Actual static thrust is ~165lbs without A/B depending on ambient conditions.

The After-burner on the other hand is horribly inefficient...uses a ridiculous amount of fuel....but it makes ~30-35% extra thrust and all the right noises so I don't really care.. Static thrust with A/B is ~215lbs @20C and sea level conditions.

Heres some numbers and notes I made some time back...........

70,000 rpm 3.65 PR ( 35 psi P2) at 74% efficiency. With 2.75 lbs/sec - 165 lbs/minute flow.

175 deg C rise in compression stage, 190 C for T2 on a "cold??" winters day at 15 C.

~150 deg C drop through turb stage assuming 78% efficiency.

3% pressure drop across combustor, therefore a 3.54 PR going into turb stage at 900 C - 1173 K for calculations.

We need a 2.046 PR across turb stage to power the comp which should leave around a 1.73 PR or 10.7 psi total in the jetpipe.

I started to make some assumptions at this point to determine the actual PR across the turb stage to account for the velocity out of the turb exducer, I came up with a total PR of ~2.39 across the stage .

The official Garrett turbine stage map gives a Correct Flow of 93 lbs/min thru the 1.47 A/R scroll equipped stage.

Using a 1173K temp and a 3.54 PR along with the 93 lbs/min corrected flow, the actual flow worked out at 163 lbs, pretty close to our 165 lbs/min assumption of flow.

Our non A/B calcs .............1.73 PR @ 1023 K should give us a temp drop of ~117 deg C through a 90% effic jet nozzle at 906 K EGT and a velocity of 1720 ft/sec for a thrust of ~167 lbs.

Density will be ~41 cubic feet/ pound so ~112.75 CFS requiring ~9.44 sq ins of jet nozzle, or ~3.46 inch dia - 88mm, theoretically without any adjustment for boundary layer etc etc, I'd normally add on a couple of mm's, so 90mm would be reasonable .

Now for the A/B

If we apply the "normal?" ............double the CFS because of temperature rise, and divide by 1.4 for velocity increase ( square root 2 = 1.4 ), we get an area of ~13.5 sq ins, or 4.15 " dia, or ~105mm for the A/B nozzle, to allow for any "turbulence" and boundary layer a 110mm ID jet nozzle is required and thrust should be at ~215 lbs static.

Hope this helps.

Cheers,
Smithy.

 

[justinlogue5_0]

Nice build! I to am waiting for real numbers with a gps for back up. I have no doubt it does what you say it does and please don't think I am putting you down. After reading your notes, you obviously know what your doing. I think a lot of us are just tired of the you tubers making huge claims and then when you watch the video they are lucky to reach 20mph after a 2 mile head start,

Question, Did you aim the engine down to give you just a little bit of down force? Or is the thrust coming out really not enough to worry about on that engine (compared to a full size jet car/truck etc...)?

 

[Knobby]

Nice build! I to am waiting for real numbers with a gps for back up. I have no doubt it does what you say it does and please don't think I am putting you down. After reading your notes, you obviously know what your doing. I think a lot of us are just tired of the you tubers making huge claims and then when you watch the video they are lucky to reach 20mph after a 2 mile head start,

Question, Did you aim the engine down to give you just a little bit of down force? Or is the thrust coming out really not enough to worry about on that engine (compared to a full size jet car/truck etc...)?

Totally agree with you Justin....I'm not claiming anything of substance at all, only the fact that the engine runs and the kart does actually move.... the only evidence I have is the few boring videos I have posted....even then it was only doing maybe 45mph (~72kmh) at best.
The kart isn't fully complete yet and will eventually have some nice bodywork to help make it a little more slippery....to be honest it's not very aerodynamic as it is...and has the flight characteristics of a block of council apartments..

I do plan to do some proper test runs in the not too distant future....it's primary purpose at the moment is to do static car shows and demonstrations at schools etc...but I would love to back up the test running with actual numbers...even if just to satisfy myself.

The engine has a small amount of "down thrust", approx 1-1.5 degrees. There's not a huge amount of thrust available, it is only a glorified turbo-charger after all is said and done. It certainly makes all the right noises though..

In reality it can't really be compared to a full sized jet car, they often have thrust to weight ratios approaching 5 & 6:1, my kart is lucky to be 0.4:1, it weighs ~330lb without me in it, I weigh ~200lb...so there's 530lbs to start with, the engine only produces ~215lbs of thrust....so acceleration rates are modest at best.
The numbers do say it will have a fairly decent top speed but it will take quite a bit of distance to do so. A normal piston engine, wheel driven kart will definitely make it look rather pedestrian off the start line...but they will eventually run out of gears or revs..or both.....the jet just keeps on pushing

Cheers,
Smithy

 

[justinlogue5_0]

Can't wait to see the videos!

 

[KartFab]

...most normal piston engine go-karts will eat it alive off the line but it will certainly do most karts over for top-end speed.

So it takes off slow, but goes faster? Lets see it go faster than lets say the standard kt100 65-90 mph go kart.

80kmh really at a guess, is capable of much, much more:

Ok lets see it.

....so acceleration rates are modest at best.

The numbers do say it will have a fairly decent top speed but it will take quite a bit of distance to do so.

.....the jet just keeps on pushing

It has poor acceleration - that's fine, not a big deal, you have shown us that.

It can theoretically go faster than its piston powered cousins.
So far you have only stated that it can. You have also stated that it needs more room to go faster, and maybe some other stuff like aerodynamic bodywork.

I would say right now that any body work done to the kart wouldn't drastically affect top speed. So you are really left with finding a road long enough to reach a faster actual top speed.

I'm rooting for you man. I really REALLY wanna see that kart zip along! (you can edit out the boring parts

I just remember looking at jet powered go karts on youtube, and was dissapointed

https://www.youtube.com/watch?v=IND3eAI3YZk

The original post said that the kart was doing 60 mph (which is BS). I just really really am excited that you have a kart, and actually made it move (which who can say that? honestly thats an amazing feat)

You have said that it goes faster, and I wanna see it actually go faster!!!

 

[Knobby]

I forget.. I'm tellin you there's a fix for the shock wave issue.... I know because I watched a video on it somewhere! lol

but anyways. cool build, One day I will be able to do such a thing myself!

Hey J,
I don't think there is much to be gained form "fixing" the shock wave issue....the fact is that the turbine itself just cannot process any more mass air flow, it's restricted by it's size and blade area....forcing more air through it will not improve the thrust, actually it will probably make it run rather poorly. It's designed to process a maximum of ~2.75lbs of air per second...

Anybody who is fairly capable with tools can certainly build something similar....it's only a go-kart after all....and the engine really only has one moving part, the rotor itself. It does have a separate oil pump but that's not really part of the engine.
Unlike the pistons, rods, cranks, cams & clutches of most normal IC kart engines...!

Cheers,
Smithy.

 

[doggerss]

Cool build I did one similar in high school with a t4 turbo. Don't see many people build stuff like this.
I ran my just on propane not jet fuel like you are. Is there a power difference between the 2? Just wondering what I was leaving on the the table.
Benefit of propane was we would stick the propane bottle in a 50 gallon drum with our drinks and some water be cold in no time running that sucker.

 

[Knobby]

Cool build I did one similar in high school with a t4 turbo. Don't see many people build stuff like this.
I ran my just on propane not jet fuel like you are. Is there a power difference between the 2? Just wondering what I was leaving on the the table.
Benefit of propane was we would stick the propane bottle in a 50 gallon drum with our drinks and some water be cold in no time running that sucker.

Hi Doggerss,
Propane is a good fuel when the turbine combustion chamber operation is marginal or you are experimenting with fuel injection combinations etc... as it's already in gaseous form. You're right about the propane tank getting cold too, very useful for keeping the beverages cold..!
Using Jet-A1, kerosene or even diesel is preferred when you have all the numbers right and your engine is running sweetly, mainly because it is a little less volatile...and easier to refill the tank.

Bang for buck kerosene/diesel is a bit better as it has more energy per pound than propane. You'll use considerably more propane to do the same amount of work as the other fuels.

Cheers,
Smithy.

 

[doggerss]

Cool thanks for the info. I don't know how good the chamber was I did redo it a couple times because it was to easy to blow out the flame at first. Yes used a lot of propane but living on a farm with a filling station helped out a lot.