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

Post by Tommy Cookers » Fri Mar 23, 2018 9:42 pm

fwiw my guess would be that thousands of DKW motorcycles got there first
DKW cars also

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

Post by johnny comelately » Fri Mar 23, 2018 10:03 pm

Pinger wrote:
Fri Mar 23, 2018 7:30 pm
The world's first looper?

https://oldmachinepress.com/articles/page/23/

Scroll about 1/4 way down.
What a fantastic story, something for everyone.
Halo effect (maybe) from being trapped underwater upside down in mud.
Thin section wings for invigorating laminar flow discussions :wink:

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

Post by johnny comelately » Fri Mar 23, 2018 10:05 pm

J.A.W. wrote:
Fri Mar 23, 2018 9:30 am
@ Pinger, recent 2T developments in (highly constrained rules-wise) Kart racing have included (AFAIK)
exhaust port-nozzle-pipe research into both liquid cooling ( to reduce temp of the returning fuel-air charge),
& 'sonic' nozzle design shapes - to obviate 'shock-choke' - gas-flow issues at high rpm..
High speed inlet hysterisis is a fairly mysterious area, but of huge significance
, do you have any information?

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

Post by J.A.W. » Fri Mar 23, 2018 10:20 pm

Check this thread-site, Johnny, look for recent posts from member 'Wobbly' & others.. or try a 'search'.

https://www.kiwibiker.co.nz/forums/show ... gine-tuner
Dr Zachary Smith sez..
"Yes.. spare us your ridiculous remarks, you insensitive idiot!"

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

Post by johnny comelately » Fri Mar 23, 2018 10:36 pm

Pinger wrote:
Fri Mar 23, 2018 5:06 pm
J.A.W. wrote:
Fri Mar 23, 2018 9:30 am
@ Pinger, recent 2T developments in (highly constrained rules-wise) Kart racing have included (AFAIK)
exhaust port-nozzle-pipe research into both liquid cooling ( to reduce temp of the returning fuel-air charge),
& 'sonic' nozzle design shapes - to obviate 'shock-choke' - gas-flow issues at high rpm..
Cooling the 'stored' charge is pretty cunning. Highlights an inherent problem with branch manifolds which is that the piston at or around TDC gets a positive pulse (which it has no use for) which can only add heat to its skirt. The pulse will be of lower pressure than with a full fat expansion chamber and will impact only the skirt - not the rings. A minor problem given the lower state of tune, but any unnecessary heat flow to a piston is unwelcome.

Re 'adjustability' of tuned pipes to rpm. Power valves do a good job there as well as their primary task of masking the port. The change in timing neatly re-synchs the pipes to the rpm. High maintenance though by what I can ascertain, requiring regular cleaning of carbon if they are not to stick.
VE (or ME) and effective gas exchange during transition and over the rev range is one of the keys (highly sensitive to throttling), the other being combustion (where they have an inherent advantage over the 4T).
All these methods above have been fantastic at improving the charged two stroke

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

Post by johnny comelately » Fri Mar 23, 2018 10:45 pm

J.A.W. wrote:
Fri Mar 23, 2018 10:20 pm
Check this thread-site, Johnny, look for recent posts from member 'Wobbly' & others.. or try a 'search'.

https://www.kiwibiker.co.nz/forums/show ... gine-tuner
Thanks for that. If only they would have used methanol :)

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

Post by J.A.W. » Fri Mar 23, 2018 11:05 pm

Kart racing engine parameters are ~ rules constrained as F1 currently is..
..but methanol based fuel - is still used in several other competition classes..
Dr Zachary Smith sez..
"Yes.. spare us your ridiculous remarks, you insensitive idiot!"

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

Post by Mudflap » Fri Mar 23, 2018 11:13 pm

johnny comelately wrote:
Fri Mar 23, 2018 10:36 pm
Pinger wrote:
Fri Mar 23, 2018 5:06 pm
J.A.W. wrote:
Fri Mar 23, 2018 9:30 am
@ Pinger, recent 2T developments in (highly constrained rules-wise) Kart racing have included (AFAIK)
exhaust port-nozzle-pipe research into both liquid cooling ( to reduce temp of the returning fuel-air charge),
& 'sonic' nozzle design shapes - to obviate 'shock-choke' - gas-flow issues at high rpm..
Cooling the 'stored' charge is pretty cunning. Highlights an inherent problem with branch manifolds which is that the piston at or around TDC gets a positive pulse (which it has no use for) which can only add heat to its skirt. The pulse will be of lower pressure than with a full fat expansion chamber and will impact only the skirt - not the rings. A minor problem given the lower state of tune, but any unnecessary heat flow to a piston is unwelcome.

Re 'adjustability' of tuned pipes to rpm. Power valves do a good job there as well as their primary task of masking the port. The change in timing neatly re-synchs the pipes to the rpm. High maintenance though by what I can ascertain, requiring regular cleaning of carbon if they are not to stick.
VE (or ME) and effective gas exchange during transition and over the rev range is one of the keys (highly sensitive to throttling), the other being combustion (where they have an inherent advantage over the 4T).
All these methods above have been fantastic at improving the charged two stroke
What's the inherent combustion advantage over 4T ?
How much TQ does it make though?

J.A.W.
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Location: Altair IV.

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

Post by J.A.W. » Fri Mar 23, 2018 11:20 pm

Apart from firing - twice as often?
Most 2Ts have no poppet valves to compromise the combustion chamber shape/cause heat control issues.
Dr Zachary Smith sez..
"Yes.. spare us your ridiculous remarks, you insensitive idiot!"

johnny comelately
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Location: Australia

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

Post by johnny comelately » Fri Mar 23, 2018 11:41 pm

J.A.W. wrote:
Fri Mar 23, 2018 11:20 pm
Apart from firing - twice as often?
Most 2Ts have no poppet valves to compromise the combustion chamber shape/cause heat control issues.
Yes precisely, and you can spend your time on boundary layer management amongst other things

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

Post by johnny comelately » Fri Mar 23, 2018 11:46 pm

johnny comelately wrote:
Fri Mar 23, 2018 6:32 am
J.A.W. wrote:
Fri Mar 23, 2018 2:48 am
No reason some technical sophistication cannot be added to the exhaust to gain a wider power-spread
for road machines..

A internal cone, able to be moved fore & aft - within the fat part of the pipe - in tune with rpm change,
(controlled as exhaust 'power valves' & the like have been - for the past few decades)..

http://www.rpdinc.com/10435-thickbox/plastic-funnel.jpg
we did have that where the distance between the two cones was varied via a rack and pinion system according to rpm, eventually banned
Further, it was a mach 4 and flogged the factory bikes (late 70's). Rev activated stepper motor. And the bloke that got it banned (sore loser) is mentioned elsewhere in the forum.

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

Post by Mudflap » Sat Mar 24, 2018 12:00 am

J.A.W. wrote:
Fri Mar 23, 2018 11:20 pm
Apart from firing - twice as often?
Most 2Ts have no poppet valves to compromise the combustion chamber shape/cause heat control issues.
I read that as 2T combustion being somehow superior to 4T on a 'per powerstroke' basis.
I would argue that the lack of poppet valves in a 2T does not make up for the poor charge motion.
How much TQ does it make though?

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

Post by Mudflap » Sat Mar 24, 2018 12:00 am

johnny comelately wrote:
Fri Mar 23, 2018 11:41 pm
J.A.W. wrote:
Fri Mar 23, 2018 11:20 pm
Apart from firing - twice as often?
Most 2Ts have no poppet valves to compromise the combustion chamber shape/cause heat control issues.
Yes precisely, and you can spend your time on boundary layer management amongst other things
You what ?
How much TQ does it make though?

J.A.W.
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Location: Altair IV.

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

Post by J.A.W. » Sat Mar 24, 2018 2:37 am

Mudflap wrote:
Sat Mar 24, 2018 12:00 am
J.A.W. wrote:
Fri Mar 23, 2018 11:20 pm

Most 2Ts have no poppet valves to compromise the combustion chamber shape/cause heat control issues.

I would argue that the lack of poppet valves in a 2T does not make up for the poor charge motion.
"You what?"

Do by all means, present your reasoning..
Dr Zachary Smith sez..
"Yes.. spare us your ridiculous remarks, you insensitive idiot!"

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

Post by manolis » Sat Mar 24, 2018 11:11 am

Hello all.

Are the best engines in the world the giant two stroke marine engines?

With the cheapest fuel (the residual of the distillation) they achieve more than 50% BTE (BSFC less than 160gr/kWh).

Typical compression ratio: only 12:1.

And they have a big exhaust poppet valve on the cylinder head.

Image


Adding an intake-transfer poppet valve on the piston crown, the lubrication problem of the 2-strokes has been solved (portless cylinder liner, 4-stroke lubrication):

Image

Thanks
Manolis Pattakos