2 stroke thread (with occasional F1 relevance!)

All that has to do with the power train, gearbox, clutch, fuels and lubricants, etc. Generally the mechanical side of Formula One.
johnny comelately
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Re: 2 stroke thread (with occasional F1 relevance!)

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J.A.W. wrote:
Wed Apr 27, 2022 8:49 am
2023 iteration of Rotax/BRP/Ski-Doo 850 snowmobile, 180hp with (altitude compensation) turbo.

https://sledmagazine.com/ski-doo-pushes ... c-turbo-r/
This is a good expose of that little gem too:

vorticism
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Re: 2 stroke thread (with occasional F1 relevance!)

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J.A.W. wrote:
Wed Apr 27, 2022 8:49 am
2023 iteration of Rotax/BRP/Ski-Doo 850 snowmobile, 180hp with (altitude compensation) turbo.

https://sledmagazine.com/ski-doo-pushes ... c-turbo-r/
The expansion chamber ahead of the turbine reminds me of Merc's exhaust headers.

Image
Defend the right to 140 character limited speech.

johnny comelately
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Re: 2 stroke thread (with occasional F1 relevance!)

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This may interest you then. As an example of some current 4 stroke MX ideas.
Image

gruntguru
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Re: 2 stroke thread (with occasional F1 relevance!)

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Stepped header primaries are becoming very common but the use on a turbo application is curious.
je suis charlie

vorticism
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Re: 2 stroke thread (with occasional F1 relevance!)

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Helps evacuate the cylinder just as in a two stroke. Helps reduce power required for exhaust stroke. Also advantageous during wastegate open regime.
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J.A.W.
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Re: 2 stroke thread (with occasional F1 relevance!)

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gruntguru wrote:
Thu Apr 28, 2022 11:08 pm
Stepped header primaries are becoming very common but the use on a turbo application is curious.
The Rotax/BRP/Ski-Doo 850 turbo has a 'Y' junction 2-into-1 header, & the attached expansion
chamber/diffuser cone pipe - has to be gas-pressure sealed - yet not fracture prone.
"Well, we knocked the bastard off!"

Ed Hilary on being 1st to top Mt Everest,
(& 1st to do a surface traverse across Antarctica,
in good Kiwi style - riding a Massey Ferguson farm
tractor - with a few extemporised mod's to hack the task).

gruntguru
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Re: 2 stroke thread (with occasional F1 relevance!)

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Ahh interesting, thanks J.A.W. Does that layout (with or without turbo) function the same as one chamber per cylinder in terms of expansion chamber "supercharging".
je suis charlie

J.A.W.
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Re: 2 stroke thread (with occasional F1 relevance!)

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gruntguru wrote:
Thu Apr 28, 2022 11:31 pm
Ahh interesting, thanks J.A.W. Does that layout (with or without turbo) function the same as one chamber per cylinder in terms of expansion chamber "supercharging".
With a 180 degree crankshaft 2-stroke, firing intervals allow for this expedient, but packaging/costs
trump max output/efficiency gains ultimately shown by running individual systems per cylinder.

A larger number of cylinders will allow closer combustion events & synergistic flows accordingly as
gas flow can be timed as continuous, or over-lapping (3 cyl 2-strokes = 6 cyl 4-strokes, pulse-wise).
"Well, we knocked the bastard off!"

Ed Hilary on being 1st to top Mt Everest,
(& 1st to do a surface traverse across Antarctica,
in good Kiwi style - riding a Massey Ferguson farm
tractor - with a few extemporised mod's to hack the task).

gruntguru
gruntguru
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Joined: Sat Feb 21, 2009 6:43 am

Re: 2 stroke thread (with occasional F1 relevance!)

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. . and of course wave supercharging becomes less important when you have a hair-dryer hanging off the side.
je suis charlie

johnny comelately
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Joined: Thu Apr 09, 2015 11:55 pm
Location: Australia

Re: 2 stroke thread (with occasional F1 relevance!)

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I always understood the step is to prevent the pressure wave going back into the engine.
We have used reverse cones with some success to achieve same .

gruntguru
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Re: 2 stroke thread (with occasional F1 relevance!)

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The two stroke "pipe" is designed for the pressure pulse to go back into the engine (the pulse contains fresh charge not exhaust gas).
je suis charlie

johnny comelately
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Joined: Thu Apr 09, 2015 11:55 pm
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Re: 2 stroke thread (with occasional F1 relevance!)

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gruntguru wrote:
Fri Apr 29, 2022 5:33 am
The two stroke "pipe" is designed for the pressure pulse to go back into the engine (the pulse contains fresh charge not exhaust gas).
I meant the step on the 4 stroke pipes, a la F1 (at least the older NA ones), NASCAR etc

J.A.W.
J.A.W.
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Re: 2 stroke thread (with occasional F1 relevance!)

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gruntguru wrote:
Fri Apr 29, 2022 4:46 am
. . and of course wave supercharging becomes less important when you have a hair-dryer hanging off the side.
That's a bit of a 'curly one' gg, if its natural vs perm, (& don't get us started on H-peroxide additives)..
"Well, we knocked the bastard off!"

Ed Hilary on being 1st to top Mt Everest,
(& 1st to do a surface traverse across Antarctica,
in good Kiwi style - riding a Massey Ferguson farm
tractor - with a few extemporised mod's to hack the task).

vorticism
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Joined: Tue Mar 01, 2022 7:20 pm

Re: 2 stroke thread (with occasional F1 relevance!)

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gruntguru wrote:
Fri Apr 29, 2022 4:46 am
. . and of course wave supercharging becomes less important when you have a hair-dryer hanging off the side.
This would depend on the differential pressure between cylinder and turbine inlet. I assume never as extreme as venting to atmosphere directly, perhaps unless during WGO. Regardless, wave tuning should still be possible, pipe enlargement will lead to a pressure and velocity drop locally. Same for the 'supercharging' wave, maybe there is a small gain to minimizing crossflow beyond what is needed. Less compressor work.
Defend the right to 140 character limited speech.

Pinger
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Re: 2 stroke thread (with occasional F1 relevance!)

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From this:

Image

To this:

Image

No mention of why the turbo was relocated to the end of the pipe.