2 stroke turbo

Post here information about your own engineering projects, including but not limited to building your own car or designing a virtual car through CAD.
Clop
Clop
0
Joined: Sun Oct 04, 2020 8:51 pm

Re: 2 stroke turbo

Post

Really interesting. So you think turbo made a sort of "balance" between intake pressure and turbo pressure it is what you mean?

User avatar
Bandit1216
11
Joined: Fri Oct 05, 2018 3:55 pm

Re: 2 stroke turbo

Post

No. I mean before turbo the presure will be eg 0,2 and back pulse 0,25 but after turbo 0,5 and 0,55 bar. So the diff is the same.

Clop
Clop
0
Joined: Sun Oct 04, 2020 8:51 pm

Re: 2 stroke turbo

Post

OK understand. Anyway in a 4 stroke valves open at different time and the overlap time is not so much like the 2 stroke where the ports are ever open! So really I don't understand that. Under boost, the fuel mixture, is blow thorugh exhaust port there is not a closing valve in petrol 2 stroke. The only back pulse can't contain the boost. What about it?

User avatar
Bandit1216
11
Joined: Fri Oct 05, 2018 3:55 pm

Re: 2 stroke turbo

Post

But there is. The piston is the closing valve.

Clop
Clop
0
Joined: Sun Oct 04, 2020 8:51 pm

Re: 2 stroke turbo

Post

Surely but open and close the ports at the same time. Is like a huge overlap! The question became more difficult if we think that is too rarely find these turbo 2 stroke setup around.

User avatar
Bandit1216
11
Joined: Fri Oct 05, 2018 3:55 pm

Re: 2 stroke turbo

Post

I work for a company that sells plenty 2-stoke turbo’s. 920mm bore, 3468 mm stroke. Only 80 rpm, but plenty off torque :D 6,6 MNm for the 12 cilinder.

Clop
Clop
0
Joined: Sun Oct 04, 2020 8:51 pm

Re: 2 stroke turbo

Post

😂😂😂😂😂 Naval diesel! Different designs!

J.A.W.
J.A.W.
95
Joined: Mon Sep 01, 2014 4:10 am
Location: Altair IV.

Re: 2 stroke turbo

Post

Clop wrote:
Fri Oct 09, 2020 9:13 pm
Surely but open and close the ports at the same time. Is like a huge overlap! The question became more difficult if we think that is too rarely find these turbo 2 stroke setup around.
Clop, you appear to misapprehend the basics of piston-port* 2T gas-flow timing functions.

(Try & conceptualize the idea of a hi-performance resonance-flow 2T piston acting
as the combustion-chamber/timing valve of a pulse-jet - with the reciprocation-to-rotary
power-shaft transmission through to final drive - as analog to a turbo-shaft geared gas turbine).

With a lambda-state air-fuel mixture a 2T will function in the low pressure air found
3km up a mountain, or in a sealed engine test-cell pressurised to +1 bar over sea-level**,
now guess which operating condition - will show more power on the dyno...

*With, or without added inlet/exhaust valve timing control devices.

**Equivalent to what a fair level of turbo-boost will pump.
We are standing on the shoulders of Giants. So wash your feet.

Clop
Clop
0
Joined: Sun Oct 04, 2020 8:51 pm

Re: 2 stroke turbo

Post

Ok now it's clare. In the end to conclude this topic: a turbocharged two stroke gasoline engine (like a classical 2 stroke motorcycle engine 250cc 500cc etc. ) can work and do more hp than the same engine naturally aspirated but turbo should be mounted mandatory after the expansion chamber to maintain his function.

Do you all agree??

Clop
Clop
0
Joined: Sun Oct 04, 2020 8:51 pm

Re: 2 stroke turbo

Post

OT: Bandit1216 I've laughed because you have write 80 rpm and I had imagine this little engine compared to the huge like you say! Not for what you have write in your post don't misunderstand me!!

Pinger
Pinger
8
Joined: Thu Apr 13, 2017 4:28 pm

Re: 2 stroke turbo

Post

Clop wrote:
Fri Oct 09, 2020 7:24 pm
OK understand. Anyway in a 4 stroke valves open at different time and the overlap time is not so much like the 2 stroke where the ports are ever open! So really I don't understand that. Under boost, the fuel mixture, is blow thorugh exhaust port there is not a closing valve in petrol 2 stroke. The only back pulse can't contain the boost. What about it?
The additional backpressure in the entire exhaust system created by the turbo's turbine inhibits direct charge loss.
As per J.A.W.'s explanation of low atmospheric pressure or pressurised dyno chamber the turbo recreates the latter as the engine sees elevated pressure at inlet and exhaust ports - just as if atmospheric pressure were raised.

Scavenging effects from pulse tuning are merely overlaid on that with adjustments for the different thermodynamic properties of the exhaust gas at higher density and probably temperature but only so much as they affect the speed of sound in the pipe. And yes, if exploiting that, the turbo is situated downstream from the expansion chamber.