Gas Turbine Project Diary
How to build a real jet engine in your garage
Last updated 26 September, 2001

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26 September 2001 - Amsoil passes the test
I've now been using the Amsoil 0W30 synthetic oil for some time now so thought it was about time I reported on just how it has performed.

It flows far more freely when cold than the Mobil Trisynthetic 0W40 that I was using before (particularly important when spooling up in colder weather) and I've had no problems running the engine for prolonged periods at high power settings.

No wear has been detected either on the turbocharger journals or thrust bearing despite long, hard runs at over 120,000 RPMs with exhaust gas temperatures of more than 650 degrees C.

In short -- I'm sold -- it works as advertised and certainly appears to be superior to the Mobil 1 I was using before.

I can't imagine an oil being subjected to anything like this level of punishment in a car engine so the fact that it has worked so well in this application is truly amazing.

Anyone who knows me, knows that I'm the kind of guy that calls a spade a spade and if this oil wasn't any good I'd say so -- whether Amsoil had provided me with a free sample or not.

25 October 2000 - Construction of a power-take-off assembly underway
For the past week or so I've been working on connecting a second exhaust turbine to the end of my engine so that I can extract some shaft horsepower.

24 October 2000 - My engine got a mention in PC World magazine
The local (New Zealand) edition of PC World magazine ran a feature on yours truly and even included a picture of me and my engine. Unfortunately the article was written before I picked up the Amsoil sponsorship but next time I'll make sure they get some mileage out of it.

9 September 2000 -- Now There's a FAQ!
In order to help those who are interested in building their own engines I have created an FAQ page that covers a fair amount of the basics. If there are any questions you'd like answered which aren't in the FAQ, please feel free to contact me.

1 July 2000 -- Amsoil To The Rescue
Great news... a while back I emailed most of the major oil companies asking them for information on their products and inquiring whether they might be interested in providing some small sponsorship for this project.

The only one which took the time to reply was Amsoil, who not only offered some very valuable information on which of their oils might be best suited for use in my engine but were also happy to assist by giving me some free product to use.

Top mark Amsoil! A company that takes the time to respond to a customer's requests in this way deserves respect.

I am about to try out their 0W30 synthetic motor oil shortly and I'll post a full report on how it compares to the Mobil 1 0W40 I've been using recently.

I have run the engine with Mobil 0W40 and it runs noticeably cooler with the EGT some 50 degrees C lower than when using 5W50.

7 June 2000 -- Disaster Report
Disaster Report
UPDATE 7 June, 2000: Bad news -- when I stripped down the turbo unit a few weeks back to inspect it I found that the thrust bearing had suffered a terminal failure after those ultra-high-speed runs.

Not only had the double-sided thrust-washer been almost totally destroyed but the bronze hydrodynamic bearing surface against which it runs was badly galled and cracked in three places. Clearly the Mobil 1 5W50 oil I've been using to date didn't provide the level of protection I'd hoped it would.

I guess this is not unexpected -- after all, at 160K RPMs, this engine is putting out over 30 lbs of thrust and, thanks to Newton's law, that means a 30 lb loading on that thrust bearing. I estimate the total bearing surface to be less than half an inch -- which means the total pressure exerted on the bearing is in excess of 60 PSI. Given that I was running just 40 PSI of oil pressure it's pretty obvious that the oil was simply forced out from between the bearing surfaces and metal-to-metal contact resulted.

I'm redesigning and building a new thrust bearing for this turbine which will give me nearer to 1.5 sq in of surface and allow me to run at higher thrust/revs. I also intend to switch to Mobil 0W40 tri-synthetic oil to get more protection at high temperatures -- since the oil gets extremely hot as it passes through the turbo-core. The only problem there is that this stuff is priced like gold -- nearly NZ$90 per 4 liters here in New Zealand!

In the meantime I'm up and running again with a new turbo unit and taking great care to keep the oil pressure over 50 PSI and the revs under 130K RPMs.

23 May 2000 -- Got The Afterburner Going!
Now things look even more impressive and the entire neighborhood smells of burning kerosene because I hooked up the afterburner and lit it up.

Check out the afterburner page

16 April 2000 -- Latest Runs
Well today I got my tachometer running and calibrated.

In this image you can see the fiber-optic pickup lead which picks up light reflected from the compressor turbine nut. I painted the nut half black and half white to provide the strongest possible signal. Even so, I had to build an extra stage of amplification into my tachometer circuit in order to get a nice reliable reading under overcast skies.

I installed the pickup by drilling a 3mm hole down the center out of a 5mm hex-socket head machine screw (to take the fiber) and then drilling and tapping the intake tube so that I could screw the machine screw into position.

In order to grip the fiber strongly I used the sleeve of a pop rivet which was a snug fit into the head of the screw. I lightly crimped the pop rivet sleeve around the fiber and this means it all hangs together very nicely -- but it's still very quick and easy to remove if necessary.

Boy... what a surprise -- the engine idles at 60,000 RPMs and this is the lowest sustainable speed. Even at this speed I have to be careful to keep the oil pressure at 30 PSI or below or it starts losing RPMs.

At idle the compressor is producing 5 PSI of pressure and the exhaust temp is around 650 degrees Celsius.

This is the control panel while the engine is running at 100,000 RPMs. The tachometer dial readings should be multiplied by 3,000 to get the actual RPMS -- hence it's indicating 33 here.

Note that the EGT is just 631 degrees C which is after revs stabilized. The oil pressure (on the left) is about 42 PSI. Compressor boost is around 10 PSI here (top right gauge).

Throttling up to 20 PSI of compressor pressure gives me about 135K RPMs (yes, 135,000 !!) and there's still plenty of throttle left (and it was altogether too loud -- even with hearing protection) to get close enough to get a good shot of the control panel.

This shot shows the engine running with 8 PSI of boost at just over 90,000 RPMs -- note that the temperature is a little higher than in the last shot because I was throttling up at this stage.

Last weekend I did a couple of runs at more than 40 PSI of compressor pressure but that was before I had the tach connected. I guess it must have been spinning in excess of 160K RPMs -- I don't think I'll try it that fast again as I'm surprised it didn't fly to pieces. Besides, my tachometer (which is a 270 degree analog meter that was originally calibrated 0-50 MegaWatts -- so cool!) is presently calibrated to show 150K RPMS at full scale so I can't measure RPMs higher than that.

Now some bad news -- perhaps it was a legacy of those hi-power suicide runs but when I checked the magnetic trap I installed in the oil drain line last night I found a small fragment of steel that looks like a piece of a bearing shell.

Today the engine seemed a little harder to start and the oil pump has to spin faster to generate the same amount of pressure so I'm thinking that it won't be long before the bearing collapses completely.

Do me a favor...
The following two books come highly recommended to anyone considering getting involved in the building of a home-made gas-turbine engine. They both contain a wealth of information presented in an easy-to-read format that can give you a real in-depth understanding of what makes these things work and, just as importantly, what might be wrong if they don't. Of course, if you buy one or both of them by clicking on the picture(s) below and visiting then I will also receive a pittance of a commission which I can put towards the cost of keeping this site running and growing for others who are also interested.

Click for more info Gas Turbine Engines for Model Aircraft
by Kurt Schreckling, Keith Thomas
Click for more info Model Jet Engines
by Thomas Kamps, Keith Thomas

9 April 2000 -- Good news -- my gas turbine runs!
This weekend I finished wiring up the igniter and oil-pump electronics and wheeled it out of the workshop for a trial run.

Surprise, surprise -- after removing the camp-stove regulator on my propane tank which was severely restricting the gas-flow, the damned thing burst into life with only a few prods of the leaf blower.

I've created a 4MB AVI file using MPEG encoding, a 1MB Quicktime movie, and a 800K RealVideo file that you can download and view to see the first test run. Unfortunately the RealVideo server isn't working at the moment but when it is I'll put up some smaller streaming files.

During the video you'll see me turn on the oil pump and set the pressure (you'll hear the noisy motor grinding away) then I apply the leaf-blower

It surprised me just how much fuel was needed to even get an idle out of the engine so it takes several attempts to get the engine up to sustainable revs.

Once it's running I turn up the oil pressure to 40 PSI.

To prove it's not all done with smoke and mirrors, I drop a rag into the exhaust stream -- then have to go chase after it. The hot gasses blew it some 50 feet!

As I've realised in subsequent runs, during this first trial, the engine was running at little more than 1/4 throttle with just 10 PSI of compressor boost. If you listen carefully you'll hear the engine throttle up just a little before I turn it off and it spools down.

That noise you can hear once it stops is the oil pump still going.

In subsequent runs I've had the compressor boost pressure gauge pegged to the stop with over 40PSI -- now that's an experience, you can feel the noise in your body and it's still very loud even with industrial ear-muffs on.

Today I have a headache and my ears are still ringing :-(

Like so many others, I've based this engine on a regular car turbocharger unit (mine came out of Nissan) and simply linked the compressor output to the exhaust turbine input using a combustion chamber.

As you can see from the pictures on this page, it looks much the same as almost all the other DIY gas turbine engines that have been documented on the Web.

Since the the flame tube is one of the most important components in any gas turbine engine, I've included some images and description of my design which seems to work very well indeed.

I'll post some more pages detailing the other components as I get time over the next week or so.

Here are some static images of the engine before it was finished.

The control pannel The intake turbine
Side view Drill-powered oil pump

Rear view

Home | Project Diary | My Tools | Contact Me | Links | My Gas Turbine Project | The Afterburner | Turboshaft Engine
Jet-kart | Pulsejet-powered Kart | Kitsets | Troubleshooting pulsejets | Valveless Pulsejets | Ramjets Explained
100lbs-thrust pulsejet | Turbo-turbine FAQ | Chrysler's Turbine-cars | How Pulsejets Work | Flying Platform
Metal Spinning | My Lockwood engine | Starting a pulsejet | Making Reed-valves Last | Pulsejet-powered speedboat
Pulse Detonation Engines | Thrust Augmentors