GT6041 turboshaft boat engine project

[enginewhisperer]

Decided to start a thread on this since I'm stuck in the USA for work at the moment and can't do any jet building


I recently acquired a ski boat, complete with a trailer and all the drive train and steering hardware minus the engine.

Plan A was to install a sensible engine, but while on the way to pick up a heat exchanger for the cooling system I thought maybe I should resurrect my turbine engine project.

I'd built a couple of engines using fairly small car turbos, and had mostly built a larger one using a Rolls Royce Dart combustor can and a large diesel turbo.

Numbers suggest it should have been possible to make about 60hp with it (thanks Racket!) and I have two of those turbos - although one has some comp wheel damage.

As soon as I got home I did a quick ebay search for "giant turbo" or similar, and turned up what appeared to be a CAT branded GT6041 (again thanks to Racket for the identification help!)
I asked the seller for some measurements, and it definitely appeared to be a 6041 variant - so I bought it, for $200.

Here it is next to a GT2871R:



You know it's serious when it has a cast iron comp cover!





So, combined with the Dart combustor after some minor mods - it should be a pretty decent gas generator!

The hardest part will be the freepower setup, especially the gearbox - so I'm on the lookout for suitable gears.
I'll need somewhere between 6:1 and 10:1 ratio.

I want to pull apart an automatic transmission and see if I could use the planetary gearsets to make a simple 2 stage reduction.
It will need some serious forced lubrication to handle the rpm, but it should be possible. At least boats don't tend to have too much shock loading.

[enginewhisperer]

This is the boat. It's suitably pointy:




And the Dart combustor liner:




And the new spark plug mount I machined up, including a super long electrode spark plug.
In the past I used a modified "normal" spark plug, but it didn't really protrude far enough into the chamber for reliable ignition.




I'm still deciding whether to use LPG as fuel - which is obviously very easy for delivery, and forgiving for combustion and ignition.
If I use a car LPG tank it's also the cheapest fuel per litre to buy - which may become important if I actually want to use this thing!

[Johansson]

Cool project!

Skip the LPG and run on diesel instead, I´ve had more trouble with propane combustors than diesel ones over the years and refuelling is troublesome since you cannot top off the tank. Plus the added fire hazard in case a hose leaks.

Cheers!
/Anders

[enginewhisperer]

thanks

I'll probably at least test with LPG since I have a working setup from the previous engine using the same combustor - but I will try to get another Dart fuel injector and set up a high pressure pump for diesel.
Otherwise a large centrally mounted evaporator is probably possible with minimal mods to the combustor

[racket]

Hi Andrew

Looking good :-)

Cheers
John

[enginewhisperer]

Not much progress here yet!

I've been flat out rebuilding my car, and have been overseas a bit for work, but still processing this in the background

Yesterday I found a very solid cast iron, belt driven blower fan assembly at the scrap metal shop so I grabbed it.
Essentially it's a big scroll housing with a ~100mm inlet and ~130mm outlet, with a nice fat shaft and bearing setup which is all easily dismantled and modified.
The blower fan is around 200mm diameter, and should work as a low efficiency, low rpm turbine - but I can also easily replace it with something custom made.

In other news, my mill is up and running (it was rescued from scrap, missing a few parts), so I should be able to make some more jet progress soon!