Turbo gas turbine + Free Turbine + IC engine

[smp]

Hi I'm Shaun and i live in Australia, I've been studying these turbo gas turbine for awhile now and i think they're very fascinating and cool, as someone that builds engines and tunes turbocharged cars i came up with idea with what if i use a a turbine to power a second larger turbocharger so i could constantly have boost in my IC engine.
So I'm planing to use a gt45 turbo to supply the IC engine, what i would like to know if there is anyway to find out how much thrust i need to drive the GT45 and what turbo would you recommend?


Cheers Shaun

[smp]

How do i upload a pic?

My profile pic is the image i wanted to upload.

[racket]

Hi Shaun

Where in Oz are you ??

Which of the GT45 turbo models are you going to use as the freepower stage ??

What turb scroll A/R ??

What "boost" from the GT45 are you wanting ??

It is possible :-)

Cheers
John

[smp]

Hi John,
I live in Townsville North Queensland. Im planing on running 20-25psi boost on methanol

Here are the specs of the gt45 turbo

Specification
Exhaust (Turbo Manifold) Flange: T4 4 Bolt Flange
Exhaust (Downpipe) Flange: V-Band Flange
Compressor Trim: 50   
Compressor Inducer Diameter: 69mm   
Compressor Exducer Diameter: 98mm   
Compressor A/R: 0.66
Turbine Trim: 77   
Turbine Inducer Diameter: 88mm   
Turbine Exducer Diameter: 77.5mm   
Turbine A/R: 1.05
Bearing Type: Wet Float Bearing
Wastegate: External Wastegate

Cheers Shaun

[smp]

I see you live in Australia NSW John.

I also like your 2 shaft turbine kart build.

[racket]

Hi Shaun

You're looking at a fair flow from a 69mm inducered compressor wheel at 20-25 psi , something around 1 lb/second .

1 lb/sec at 2.5 PR ( 22 psi boost) at say 78% efficiency is going to require some serious horsepower .

With an ~110 C degree rise in the compressor , you'll be needing ~68 horsepower from your freepower turbine wheel .

Your turbo appears to be a mixture of bits , the comp is too small for a GT45 , more like a GT 42.

The turbine stage you have will severely limit the flow through it at the normal pressure exiting a DIY gas turbine , you'd be looking at maybe ~7 or 8 psi going into the freepower wheel , at which pressure the stage would only flow ~ 30 lbs/minute - 0.5 lbs/sec , theres no way that mass flow will produce 68 HP , it'd be lucky to produce half that .

To produce 68 HP you'd need to have either a higher pressure going through the freepower stage or a much large freepower stage so that the mass flow can be increased substantially , your current freepower could only be fed by a turbo with an inducer of <50 mm dia

Your high boost requirement is whats causing the problem ..............could you please expand a bit on what sort of outcome you're looking at from the IC engine this will be feeding .

Yep , I'm just down the coast a few thousand kilometers ;-)

To put your horsepower requirements into perspective , my turbine bike which used a Garrett TV84 turbo ( 88 mm inducer on the comp) only produced 115 HP when using a large 187mm dia axial freepower wheel , being fed gases at ~10 psi from the TV84 which was being flogged hard .

Cheers
John

[smp]

What I'm trying to achieve is using this gt45 on a 2.6lt engine and it having boost from idle pretty much trying to make around 800hp at flywheel.

So what your saying is that ill need turbo with a bigger inducer then 50mm for the gas turbine?

Would this GT3037/3082 supply enough to the gt45?

Fit For:
Perfect for all 6 / 8 cyl 3.0L-5.0L
enginesHP:
Capable of Boosting Horse Power up to 500BHP
Cooling Type:Water + OilExhaust Inlet (Turbo Manifold)
Flange:Standard T3 FlangeExhaust Outlet (Downpipe)
Flange:Standard 4-Bolt
Compressor Trim 56
Inducer Diameter 57 mm
Exducer Diameter 76.2 mmA/R0.6
TurbineTrim 84 Inducer Diameter 84 mm
Exducer Diameter 60 mm　A/R0.82
Additional Details:Bearing:Wet Float

This is a genuine garrett gt42

Part Number: 774595
Model Number: GT4202R                              
Approx Horsepower Range for Engine Capacity: 500-1000Hp (4.4L-6.5L)
CHRA(core): 451888-5011
Compressor Housing: 737942-0012
Compressor Housing Air Ratio: 0.72
Compressor Wheel Inducer Size (mm): 67.80
Compressor Wheel Trim: 52
Turbine Wheel Exducer Size (mm): 68
Turbine wheel Trim: 78
Turbine Housing & Air Ratio Size: 1.01 OR 1.15 OR 1.28 OR 1.44
Turbine Housing Inlet port: Dual

Ebay GT42
Model: GT4294
Compressor:
A/R 0.60
Inducer 74.8mm 
Exducer 102.4mm
Inlet 5.0"
Outlet 4.2"
Turbine:
A/R 1.05
Inducer 81.7mm
Exducer 75.4mm
Turbine flange T4 twin scroll
Outlet 6 BOLT
Cooled type: Oil cold
Bearing journal bearing 　
Power 1000+hp 　
Application： Universal turbo

[racket]

Hi Shaun

The problem is the size of your GT45 turbine stage , it would have a Corrected Flow of ~35 lbs/min at a 1.5 PR going into it , if we do the calculations to get Actual Flow it comes out ~30 lbs/min.

Unlike a turbo on an IC engine its impossible for us to "force" gases through an undersized turbine stage , it has to be big enough to voluntarily swallow the flow , otherwise the gas producer will be forced into surge with its unfortunate consequences , this rules out simply increasing the size of the gas producer feeding your Gt45 in an attempt to produce the required horsepower to produce your required boost levels .

One way of producing the horsepower whilst using your GT45 would be to use a very large gas producer and bleed off sufficient compressor discharge air which after heating in a second combustor is delivered to your GT45 , the higher pressure will produce a greater flow and horsepower to power its comp .

Another way is to have a hybrid turbo with a very larger turbine stage mated up to your compressor stage , but you'd be needing probably 75,000 rpm as a minimum to produce your required boost level from your GT45 , a big GT60 turb wheel would do the job

Cheers
John

[mitch]

Is your goal to be making full boost all the time off of idle?

[ripcrow]

Would something like they use in tank engines be viable. It's basically a flame tube Built into the exhaust manifold that Keeps the turbo producing boost so there is no turbo lag

[smp]

Yeah mitch that was the idea.

There is such a thing called anti lag which dumps extra fuel into the engine and opens up a by pass valve from the compressor to the turbo exhaust manifold but i thought it would be cool to have a jet noise consistently.