Outboard Turbine Project

[boatmedic]

Hello,

I have been lurking around this site for quite sometime now and decided it's time to add my two cents and ask lots of questions. I have been planning to build a turbine powered outboard engine for one of my boats . I have aquired a few Cummins VT-50 Turbos and Various Fans from the Allison 250 Turbine, My inspiration comes from the Mercury Racing Allison Powered OutBoard

I would welcome any input that comes my way. My concerns to start are going to be the packaging of the Turbine and Free Power Turbine. MY thoughts are that the Oil Pump (electric) Oil Tank and CNG Tanks will be onboard the boat. I look forward to hearing your thoughts and I will post pictures as soon as I figure out how

Mark

[ernie wrenn]

Now here is OUTSIDE the box!!!! Love the idea.. This is a MUST project with pic's.

ernie

[Johansson]

Ha! A friend and I have been talking about a similar build with a wooden boat, a pair of Schwitzer S500 turbos and a 4th stage C20 wheel. No outboarder but still a fun project, he has gathered the turbos so by the end of spring he should have begun the build.

Welcome by the way! Make yourself at home.

Cheers!
/Anders

[enginewhisperer]

this is something I was planning to do, but never quite got up to the freepower turbine stage

racket and I talked about various options, including using a very large turbine to keep the rpm down and possibly be able to drive the shaft directly.

[boatmedic]

My plan is to work backwards and design the freepower turbine first. Part of this design will incorporate some kind of Bevel gear box to run the mainshaft of the outboard.

[racket]

Hi Mark

What sort of power output are you hoping for ??

Cheers
John

[boatmedic]

Hi John

My end goal is to have a minimum of 150 Hp at the Prop. I do realize I have a lot of math to do first. I did just score a Garrett TV8102 Turbocharger for $10US at a junk yard that was getting ready to close It has an Inducer size of approx 77mm and a exducer size close to 98mm.

I am left with the impression that my freepower turbine design will have the most influence to my net HP rating. Is this true?

[racket]

Hi Mark

150 hp will need a couple of decent sized turbos feeding the freepower wheel , you'll be needing a minimum of 2.5 lbs/sec of mass flow, a couple of VT-50 turbos would do the job .

Freepower wheel will need to be large , the 4th stage Allison C20 turb wheel will be big enough .

Output is dependant on both mass flow and freepower design , freepower design is greatly influenced by the pressures and temperatures being fed to it , its a holistic thing , bits need to match up with one another for the engine to work correctly .

Cheers
John

[boatmedic]

Hey John,

This is clearly the time when I must lower my expectations as I don't have the room for two turbos in this particular project.

I did want to know if the fuel consumption issue has ever been tackled? I have read more than once that these engines use a lot of fuel, Why ?

Mark

[racket]

Hi Mark

The poor fuel consumption is due to the low compression ratio , its just a fact of life whether turbine or piston engine , the use of a heat exchanger between exhaust and compressor discharge air can improve fuel burn rates , but it adds complexity and cost as well as vastly increasing the size of the engine .

If you want good fuel burn rates, use a diesel , if you want bragging rites, use a turbine and pay for the extra fuel .

Power output is closely tied up with air flow rates , turbines flow massive amounts , you just need a big turbo if you want to run a single unit and have 150 hp .

Big turbos are available that will get you your 150 hp .................where are you based ??

Cheers
John

[boatmedic]

Hi John,

There is a practical reason why I am concerned about fuel burn rate. The engine will end up on a boat using CNG (Compressed Natural Gas), there is nothing like running out of fuel in the middle of the bay. As far as the Turbo I have several large turbos available to me including a GT6041 was on a race boat. I am posting a rough drawing of my planned unit. It is out of scale as I drew it on an Ipad while on the train coming home from work. I was thinking some form of heat recovery that could raise the intake temps would help with the fuel burn rate.

I am in New Jersey USA

imageshack.us/content_round.php?page=done&l=img600/2698/heatrecoverymodel.jpg

imageshack.us/photo/my-images/547/mercuryturbineoutboard.jpg/

[ernie wrenn]

Damn the Mercury looks good. Ear muffs and fuel, remember you can put extra fuel cells under the seats..... passengers are not required... Maybe ME!

ernie

[wolfdragon]

CNG is gonna go away very fast on whatever rig you have, especially trying to make a serious amount of power.

If you can get any number of fuel cells onboard pour diesel or kero in there and go nuts

[racket]

Hi Mark

The GT 6041 will flow enough for >150 hp .

Yep, even a 50% effic HX will drastically reduce your burn rate .

Cheers
John

[boatmedic]

Hi John,

Is there a benefit to having a 2 stage power turbine as opposed to a single stage? It would seem that more available HP could be found by adding a second stage to the free power section. Your thoughts?