noshell
Junior Member
Joined: January 2020
Posts: 83
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Post by noshell on Jan 8, 2022 15:30:13 GMT -5
I think ive found a suitable turbo for a gas producer.... 2.7 mercedes sprinter turbo 39.6mm compressor inducer, 42.7mm turbine exducer Then i can pair this to my 70mm turbine housing (1.0AR) for the freepower unit. Should be a good match?
hopefully 20-30hp could be possible
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Post by racket on Jan 8, 2022 17:05:25 GMT -5
Yep , that sounds OK for gas producer , but your mass floww will limit horsepower to <20hp maybe only 10-15 at most .
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noshell
Junior Member
Joined: January 2020
Posts: 83
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Post by noshell on Jan 8, 2022 17:16:35 GMT -5
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Post by racket on Jan 8, 2022 17:32:57 GMT -5
The problem with smaller turbos is the turb stage efficiency , it can often be <70% , this then means more pressure drop in the turb stage to power the comp leaving less pressure/temp for driving a freepower :-(
Yep , any turbo with a wastegate probably has a restrictive turb stage .
Cheers John
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noshell
Junior Member
Joined: January 2020
Posts: 83
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Post by noshell on Jan 8, 2022 18:16:49 GMT -5
Which of those two turbines would you go for? The 2.7 sprinter one is variable vane aswell. I genuinley cant find anything decent for my 70mm freepower turbine
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Post by smithy1 on Jan 8, 2022 19:04:03 GMT -5
Which of those two turbines would you go for? The 2.7 sprinter one is variable vane aswell. I genuinley cant find anything decent for my 70mm freepower turbine Ideally you want a turbo without a wastegate or variable guide vanes.....can be hard to come by unless you go big. The Garrett GT6041 is a good example...but it's huge compare to the unit you're using. 106mm comp inducer and 141mm exducer...has a straight turbine housing with no wastegate or guide vanes...makes a really good unit for a turbine engine, free turbine can then be made to suit from a 3rd or 4th stage RR-250 engine.....but again, would be way overkill for what you're after. Here it is fitted to my afterburning go-kart. Smithy.
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miuge
Veteran Member
Joined: March 2014
Posts: 199
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Post by miuge on Jan 9, 2022 5:28:34 GMT -5
Hi,
Many Holset HX35, Schwitzer or BorgWarner S200 turbos come with approx. 50mm comp inducer and are matched with bigger turbine, also without internal WG, they are commonly available as used or cheap aftermarket units all over the world. 70mm freepower might not give any impressive performance figures without a gearbox and that's where things become complicated.
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noshell
Junior Member
Joined: January 2020
Posts: 83
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Post by noshell on Jan 9, 2022 5:45:19 GMT -5
Ill look into those turbos, thankyou.
And yes i would intend to use a gearbox. I think a 4:1 or 5:1 ratio into a bike gearbox would be ample. Depends what gears i can get ahold of (probably nicked from work haha). I figure that will be 40 or 50k at the freepower turbine which i think should work as long as the gears and bearings have an oil supply. Im in the middle of moving house at the moment, once i move in i can get my lathe in my workshop and start building.
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