Designers of two stroke bike engines try to maximise crankcase compression, to maximise “transfer” into the cylinder. Forced induction by turbocharger or supercharger will help that a lot, but as Yorbles says, you can take the crankcase out of the induction path and blow air or mixture into the cylinder.
Le_Fromage_Grande wrote: ↑Wed Jul 14, 2021 4:49 pm
I'm trying to work out what turbocharging a two stroke would do, pressurise the crankcase is about the best I can come up with.
Been thinking.
The brief peiod that the piston isn't covering both the intake and exhaust ports, you would be shooting the extra boost straight out the exhaust . Too much pressure will fuck things up.
That's why I said a good Spanny will be needed. But they can't work miracles.
They themselves are simple turbochargers in reverse.
They've only done it in last few years on a Skidoo.
inewham wrote: ↑Wed Jul 14, 2021 9:07 pm
You're all overthinking this someone has done it because they can, just because it sounds good. A 50cc engine probably doesn't have enough exhaust pressure to get the turbo spinning properly. It's a just because they can
The exhaust needs to be an expansion chamber to handle the extra pressure.
Yorick wrote: ↑Wed Jul 14, 2021 8:57 pm
Been thinking.
The brief peiod that the piston isn't covering both the intake and exhaust ports, you would be shooting the extra boost straight out the exhaust . Too much pressure will fuck things up.
It doesn’t all go out the exhaust. Port timings and sizes (and everything else) are designed to work with the boosted intake.
Le_Fromage_Grande wrote: ↑Wed Jul 14, 2021 11:14 pm
Let me be more specific, how would turbo charging a FS1E engine work?
Les well than increasing its capacity to 85 cc, but if I really wanted to try forced induction, I’d go for supercharging and I’d remove the disc valve.
Le_Fromage_Grande wrote: ↑Wed Jul 14, 2021 11:14 pm
Let me be more specific, how would turbo charging a FS1E engine work?
Les well than increasing its capacity to 85 cc, but if I really wanted to try forced induction, I’d go for supercharging and I’d remove the disc valve.
Super charged two strokes don't put the mixture through the crankcase, they have a separate charging cylinder that does the same job as sucking the mixture into the crankcase.
Le_Fromage_Grande wrote: ↑Wed Jul 14, 2021 11:14 pm
Let me be more specific, how would turbo charging a FS1E engine work?
Les well than increasing its capacity to 85 cc, but if I really wanted to try forced induction, I’d go for supercharging and I’d remove the disc valve.
Super charged two strokes don't put the mixture through the crankcase, they have a separate charging cylinder that does the same job as sucking the mixture into the crankcase.
You asked about an FS1E.
There have been many and very varied configurations of two stroke engines designed to induct more charge than you get from just crankcase compression.
David wrote: ↑Wed Jul 14, 2021 8:19 pm
Diesel engines are a lot like petrol except for the ignition system and consequent heavier engineering....most diesel engines can be petrolised, doesnt work well the other way round.
David wrote: ↑Wed Jul 14, 2021 8:19 pm
Diesel engines are a lot like petrol except for the ignition system and consequent heavier engineering....most diesel engines can be petrolised, doesnt work well the other way round.
Do you know how a 2 stroke petrol engine works?
Yes.
Right wrist downwards
Ringadingding noise louder
Right wrist upwards
Front wheel down again