Jet thrust or free power?

[kylehuffman]

I recently built a turbo jet out of a turbocharger from a Mack dump truck.  It's a 4LE-303.  It runs well and is a hoot to run.  Here's a video:


youtu.be/nIFbimQMKy8

I'm currently in the process of fitting it to an adult-sized tricycle.  My plan is to use thrust to propel it; I assume that it won't be that fast, but it should move and make lots of noise.  I need to do some research and figure out how to build a proper nozzle.  After I get this project moving (literally), I want to utilize another turbo that I have.  It's a Cat 232-1811, off of a C15 Acert engine.  It's the low pressure first stage turbo.  Anyway, I'm not sure whether to build a thrust based engine (with afterburner) or use it as a free power turbine to drive a sprocket on the trike.  Is it possible to bolt the turbos together, remove the compressor wheel and snail, and use the shaft to drive a sprocket?  Or would I have to build a custom scroll for the turbine wheel to reside in?

[racket]

Have a look here jetandturbineowners.proboards.com/thread/680/diy-turbines

As long as the freepower stage is large enough to flow the "exhaust" from the gas producer , it would be possible to cobble together a shaft drive engine. you'll end up with a lot more power from a frepower than an afterburner .

You'll be able to use karting sprockets like I did jetandturbineowners.proboards.com/thread/40/2-shaft-turbine-kart-build

Cheers
John

[kylehuffman]

Thanks John.  I was mainly wondering what the basic build guidelines are for a free power turbine.  The current gas producer has an inducer diameter of 62.4mm, and and exducer diameter of 90.9mm.  The proposed free power turbine has an exducer diameter of 101.6mm.  I got to thinking about the possible issues with attaching a sprocket directly to the turbine shaft, and came up with the idea of using jaw couplers to attach the turbine shaft to a self-supported jack shaft that the sprocket would ride on.  This way there's no side loading of the turbine shaft and it will allow a slight amount of misalignment.  I've done this before on a Harbor Freight Predator engine that is used to run a belt pulley.  My only concern would be the RPM rating of the coupler.  I'll have to do some research.

[kylehuffman]

Also, John, the first link that you posted doesn't contain any info. It's just a bunch of posts with the title but no content.

[racket]

You need to click on the icons in each section of the Link .

You might find that your proposed freepower will be a tad small for that sized gas producer , thats not a major problem as long as you don't mind "dumping" some of the gas producers "exhaust" , I did that with my kart build because the gas producer was grossly oversized .

If you use karting sprockets and chains you'll be rpm limited by them to ~20,000 rpm max even with the best quality gear .

Cheers
John

[ebweiss2]

A free power turbine has a separate shaft. You can't connect it to the compressor.