Owen_N
Well-Known Member
This is about the crankcase-charged variety.
I have found that the record output for a turbocharged 50cc is still around 20 hp.
This seems rather low, as that is about the same output you can get using a tuned pipe and no turbocharger.
What factors would affect slow progress in gaining more power?
1) The available turbochargers are for larger engines, - typically the VZ21 turbocharger, which can be used for 200-800 cc sized four-stroke engines.
2) The pulsing action of a single cylinder exhaust is not efficiently used by the turbine scroll.
3) The compressor housing is not matched to the desired flow rate and pressure. This can lead to stall and surging if draw-off is insufficient.
4) current examples seem to be mounted after the expansion chamber, and tend to lose pressure from the exhaust and suffer from the effects of chamber pulses.
5) aftercoolers are not used. This affects mixture density on the induction side.
6) The sheer heat generated overheats and seizes pistons.- speculative-. two-stroke engines have a precarious thermal balance, and it doesn't take much to upset it.
8) The crankcase cycle limits gas flow through the engine, especially if the tuned pipe is not drawing mixture through as well.- is this true?
Could a non-chamber system work well by emulating a lower speed engine without a pipe, and just increasing mixture density?
These engines normally only make a quarter of the hp of a tuned race engine.
Can design factors for turbine and compressor scrolls be adjusted to improve output?
If the engine runs at 4 bar, will it generate a net 4x amount of power?
How much does running the exhaust at an elevated pressure reduce the output?
This would be assisted by using aftercooling, and alcohol fuel for detonation resistance, and some internal cooling.
Is the 4-stroke cycle inherently better suited to taking advantage of a turbocharger?
Given examples from the race world, it looks like turbocharged engine output is really only limited by the strength of the engine, and a 1600 cc engine when turbocharged can make more power consistently
than a 3.5 litre race engine in Formula One. This is in the region of 1000 hp, or 31 hp for 50cc .
More for a drag-race engine.
I have found that the record output for a turbocharged 50cc is still around 20 hp.
This seems rather low, as that is about the same output you can get using a tuned pipe and no turbocharger.
What factors would affect slow progress in gaining more power?
1) The available turbochargers are for larger engines, - typically the VZ21 turbocharger, which can be used for 200-800 cc sized four-stroke engines.
2) The pulsing action of a single cylinder exhaust is not efficiently used by the turbine scroll.
3) The compressor housing is not matched to the desired flow rate and pressure. This can lead to stall and surging if draw-off is insufficient.
4) current examples seem to be mounted after the expansion chamber, and tend to lose pressure from the exhaust and suffer from the effects of chamber pulses.
5) aftercoolers are not used. This affects mixture density on the induction side.
6) The sheer heat generated overheats and seizes pistons.- speculative-. two-stroke engines have a precarious thermal balance, and it doesn't take much to upset it.
8) The crankcase cycle limits gas flow through the engine, especially if the tuned pipe is not drawing mixture through as well.- is this true?
Could a non-chamber system work well by emulating a lower speed engine without a pipe, and just increasing mixture density?
These engines normally only make a quarter of the hp of a tuned race engine.
Can design factors for turbine and compressor scrolls be adjusted to improve output?
If the engine runs at 4 bar, will it generate a net 4x amount of power?
How much does running the exhaust at an elevated pressure reduce the output?
This would be assisted by using aftercooling, and alcohol fuel for detonation resistance, and some internal cooling.
Is the 4-stroke cycle inherently better suited to taking advantage of a turbocharger?
Given examples from the race world, it looks like turbocharged engine output is really only limited by the strength of the engine, and a 1600 cc engine when turbocharged can make more power consistently
than a 3.5 litre race engine in Formula One. This is in the region of 1000 hp, or 31 hp for 50cc .
More for a drag-race engine.