The ultimate lightweight range extenders? rotary!

Post by **AMPrentice** » Mon, 18 May 2009, 17:21

Ummm the rotary will never die it seems.

AVL rotary

Hybrid AC/rotary ICE

Post by **woody** » Mon, 18 May 2009, 17:49

At least you won't need a safety noisemaker speaker with a ported 13B driving your genset.

Post by **AMPrentice** » Tue, 19 May 2009, 02:51

itll make double the noise and power if it was ported.
Surprisingly it doesnt seem to have direct injection
or roller bearings to reduce friction further and
improve economy substantially.
The new mazda rotary will be 22% more efficient so they
clearly have to catch up in that department.

Post by **Electrocycle** » Tue, 19 May 2009, 04:53

rotaries are great for power vs size, and ok for power vs weight, but there are fundamental reasons why they can't be particularly efficient!

something about a very large combustion chamber surface area with a horrible shape

Post by **Tritium_James** » Tue, 19 May 2009, 05:47

I want a gas turbine range extender - the generator will be nice and power dense at 30k rpm!

Post by **Electrocycle** » Tue, 19 May 2009, 14:34

it's really hard to make a fuel efficient small turbine engine... They end up needing heat exchangers to recover a lot of the exhaust heat to get anywhere near piston engine efficiency.

power to weight is very nice though!

Post by **Thalass** » Tue, 19 May 2009, 15:28

And gas turbines chew the fuel like crazy. At work in summer its not uncommon to go through a few hundred kg of kero in an hour with the aircon and power on. In winter with just the power on its still around 100kg per hour.

Post by **Electrocycle** » Tue, 19 May 2009, 16:18

yep, turbine engines don't get much of the fuel's energy out. They run at much lower pressure ratios than piston / rotary engines.

Post by **AMPrentice** » Wed, 20 May 2009, 17:27

for size and weight the rotary is still on its own.

Unless using a motorbike 250cc engine that make around 30hp

Post by **antiscab** » Thu, 21 May 2009, 01:15

yamaha big bang engine (998cc) is around 180hp
present crop of 250cc engines are around 45hp.

Matt

Post by **Thalass** » Thu, 21 May 2009, 01:36

I assume that's petrol? I'd like to see a 250cc diesel motor and what it could do. Mostly because it can run on a multitude of fuels. Namely the kero I can get from work for dirt cheap

Post by **juk** » Thu, 21 May 2009, 02:09

Check out this aussie design bad boy 8 cylinder compact engine.

http://www.ox2engine.com/

Post by **AMPrentice** » Thu, 21 May 2009, 05:50

the main thing is simplicity, economy and compact size.
Simplicity - easy to repair or rebuild
economy - speaks for itself
size - speaks for itself
so there is no use making more than a certain hp
in which it consumes as little as possible