2 stroke software

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JanBros
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2 stroke software

Post by JanBros » Mon Aug 08, 2011 8:41 pm

in this first post I'll gather the links

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http://users.telenet.be/jannemie/FOS%20 ... black.xlsm

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http://users.telenet.be/jannemie/JanBro ... 0Calc.xlsm







ORIGINAL FIRST POST :


Mj's program to calculate cylinder heads, can be downloaded here :

myweb.tiscali.co.uk/teamsparrow/cylinderheadsv2_3.xls

now I've been playing a bit with it, but have some questions :

on the "Hemi head" page :

- what is the "volume layer" ? I can't figure out what it corresponds to on the figure. Is it the volume of the entire squish-layer ?
- if it is so, then the "volume squish" is the volume under the squish only in the squish-layer, without the volume under the dome in the squish layer ?

- "squish area ratio" : as I reed it, it's the % of the squish-surface from the total bore-area ?

- what is the "bowl" in "height of dome in bowl" ? in the formula, there is a reference to "C33" but there is no "C33"-line ? is the dome = the head radius ?

- what should we learn from the graph ? do we have to maximalise the squish-velocity ? or do we want the area under the squish, but above the piston to be as big as possible ? what's the relationship with the piston-velocity ?

- the table below the graph : what are "Vol squish", "Asq" , "Y" and "Z" ?

and a more general question : do hemi heads have an advantage over conical heads ? 'cause conical's are much easier to produce on a lath :wink:
Last edited by JanBros on Sat Feb 03, 2018 3:57 pm, edited 2 times in total.
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Post by mj43 » Tue Aug 09, 2011 9:02 pm

Jan

OK - to be honest I have forgotten :( So here goes

Volume Layer is the volume of the truncated cone that is formed by the squish band - see the calcs sheet.

Volume of the Squish is Volume Layer - the volume of the cylinder (dia D2 x height of Squish [cell c22])

For Squish area ratio see comment in cell B25

Cell 33 is hidden basically if radius is blank it defaults to 999999 basically a flat top piston to unhide select row 32 and 34 right click then unhide.

Squish velocity is related to engine RPM hence piston velocity. I can't remember what is a safe squish velocity. Squish calc is simple so only use as a guide. Comment in cell B82 indicates the source of the method Blair's book.

On Hemi head over Conical I can't comment as I have not done any experimenting.

Hope that helps

MJ

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Post by JanBros » Sat Aug 13, 2011 8:06 pm

I've been playing a bit with it, and added a page myself :wink:

Since I'm trying to make changeable inserts for the KR1 head, and I don't have CNC-machinery, it's hard to make 2 excact hemi-sferical or toroidal heads on a lath.
So decided to make conical heads, which are much easier to make. But then I came up with the idea to make "toroidal-conical" heads :

Image

file can be downloaded here for those who are intrested:

http://users.telenet.be/jannemie/Cyl%20head%20calc.xls
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Post by JanBros » Sun Aug 14, 2011 12:25 am

for those that might have downloaded my file : there were errors in it :oops:

I've replaced it with the right file :wink:

http://users.telenet.be/jannemie/Cyl%20head%20calc.xls
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Post by TwoStroke Institute » Sun Aug 14, 2011 2:57 pm

The easiest way to do the head is with a radiused HSS lathe tool, but the head shape itself is not critical, just aspects of the design.
crochet & croquet

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Re: MJ's cyl-heads calc

Post by JanBros » Wed Jan 17, 2018 10:40 pm

I've created a new calculator :

Image

squish calc is now always correct as per prof Blair, which wasn't always the same in the previous case.

feel free to do whatever you want with it :P . password protected so one can not accidentaly flip it up. pasword = x

link : http://users.telenet.be/jannemie/JanBro ... 0Calc.xlsm

if I find the time and energy, I might add pages for conical heads.
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Re: MJ's and now also Janbros' cyl-heads calculator

Post by fred » Wed Jan 17, 2018 11:21 pm

Hi Jan ,i made a one piece cutter to fit in a fly cutter to reprofile a x7 suzuki head ,it worked fine ,that`s 29 yrs ago tho when i was in college at 16. can we make this thread a sticky and save it ?

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Re: MJ's and now also Janbros' cyl-heads calculator

Post by JanBros » Fri Jan 19, 2018 1:43 am

had made an error with securing the "choice rounds", solved now.

and added conical combustion chamber.
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Re: MJ's and now also Janbros' cyl-heads calculator

Post by JanBros » Mon Jan 22, 2018 9:46 pm

apparently there was another problem with the "Auto Adjust Graph" buttons after securing the pages, should be solved now. can somebody test and confirm ?

it's possible you have to change the macro-settings in Office, of better, save the file in a "secured location" (see Office help) for all the macro's and Active-X elements to work.

the pasword is also inbedded in the "Auto Adjust Graph" code (page needs to be un-secured and re-secured for it to work), so if you want to use another pasword, you have to change that to.

http://users.telenet.be/jannemie/JanBro ... 0Calc.xlsm
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Re: 2 stroke software

Post by JanBros » Sat Feb 03, 2018 4:01 pm

finished my exhaust calc :

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http://users.telenet.be/jannemie/FOS%20 ... black.xlsm

it calculates FOS-pipes (from Frits Overmars), with the possibility to ad a Wobbly Exhaust Duct.
You can also make 2/3 stage variants, and plot all 3 pipes ogether in the graph which makes it a lot easier to see the differences.

more explanations inside the excel.

latest versions will always be available in the first post.
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Re: 2 stroke software

Post by Binetta Steve » Sat Feb 03, 2018 11:30 pm

Jan have you read Stealing Speed by Matt Oxley? He talks about Ernst degners defection from MZ east germany to Suzuki after WW2. Part of the book talks about his colleague Walter Kaardens work on expansion chambers and extracting power from two strokes .
Kaardens previous occupation was a rocket scientist working on pulse jet exhausts on the german V1 doodlebug!

You would / will love the engineering in the book. Its available on kindle about €7 I think

Steve

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