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Daniel hunt Samba Member
Joined: September 28, 2015 Posts: 15
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Posted: Tue Dec 12, 2017 12:24 pm Post subject: 36hp Compression ratios |
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Hello all,
Ive been reading discussions on the forum and have found loads of usefull info. But bee unable to get the question of compression.
Ive been getting ready for my 36 horse build im going to run
- 69.5mm counter weight stroker crank from ww
- 80mm big bore kit from aa pistons
- 36hp preformance cam from ww
- fram oil filter
- okrasa twin carb kit from ww
- 21mm oil pump
- abarth 4 tip exhurst
So in all it will be just shy of a 1400cc
Iv been measuring and figuring out the compression ratios i could have.
If i keep to the standard 0.040 to 0.045 inch deck height il end up with 8:1 compression ratio
So the question is .. is this ok for an 36hp engine for street use?.. i know from articals from ww when they were talking 36hp preformance they ran 7.5 ratio that made 52hp with standard deck height
So whats healthly . Im looking for experiance and abit of guru know how on this .
Ive worked oit deck heights for other compression ratios. Just dont know where to go |
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slalombuggy Samba Member
Joined: July 17, 2010 Posts: 9131 Location: Canada
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Posted: Tue Dec 12, 2017 8:30 pm Post subject: Re: 36hp Compression ratios |
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Are you using a cam with longer duration or a stocker? But, 8:1 is an easy compression ratio to run.
brad |
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Daniel hunt Samba Member
Joined: September 28, 2015 Posts: 15
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Posted: Wed Dec 13, 2017 5:47 am Post subject: Re: 36hp Compression ratios |
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Thank you for the reoly.
This is what the website on wolfberg west says
234 degree duration at .040" (or 227 degree duration at .050"), .345" lift, 24 degree overlap.
Should i not be worried about heat increase caused by the higher compression?
Im making all the preformance changes as i want more power but also i want it reliable as a street car il be driving on weekends |
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slalombuggy Samba Member
Joined: July 17, 2010 Posts: 9131 Location: Canada
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Posted: Wed Dec 13, 2017 9:06 pm Post subject: Re: 36hp Compression ratios |
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By running a tighter deck height you are moving the combustion into the head that sheds heat better than the piston and cylinder. A more efficient engine will actually run cooler and 8:1 isn't a huge jump, it really isn't that high of compression. If you are really worried about cooling you could replace the 36hp fan with a newer flan with more blades to increase airflow.
brad |
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Daniel hunt Samba Member
Joined: September 28, 2015 Posts: 15
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Posted: Wed Dec 13, 2017 11:49 pm Post subject: Re: 36hp Compression ratios |
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Oh right ok . Well that eases that worry .. how small of a deck heigh can someone go? Because i know a deck height of 0.026 will give compression of 8.6
I hadnt thought a newer fan would have fitted but that sounds great and il stary looking i to that right away.
Dan |
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slalombuggy Samba Member
Joined: July 17, 2010 Posts: 9131 Location: Canada
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Posted: Thu Dec 14, 2017 6:19 am Post subject: Re: 36hp Compression ratios |
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You are already pushing the limits for deck height with stock rods and a relatively weak case. I wouldn't run any tighter than you are already..most people run .060 eith stock parts.
Brad |
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Daniel hunt Samba Member
Joined: September 28, 2015 Posts: 15
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Posted: Thu Dec 14, 2017 4:00 pm Post subject: Re: 36hp Compression ratios |
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Im aware of the wearer stock rods and have been lookig at h bean 36hp rods that aapistons have started making .
Ok well its settled then il run stock deck height.
Il get a better fan.
Any more advice would be amazing but as for the moment thank you so so much for your replies |
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txoval Samba Member
Joined: January 23, 2004 Posts: 3540 Location: The Woodlands, TX
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Posted: Thu Dec 14, 2017 6:29 pm Post subject: Re: 36hp Compression ratios |
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You can go tighter, I run .037...originally wanted .040
Just ensure you have proper valve to piston clearance |
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Daniel hunt Samba Member
Joined: September 28, 2015 Posts: 15
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Posted: Sat Dec 16, 2017 1:07 pm Post subject: Re: 36hp Compression ratios |
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How would i check the valve to piston clearance? |
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Danwvw Samba Member
Joined: July 31, 2012 Posts: 8892 Location: Oregon Coast
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Posted: Sat Dec 16, 2017 3:46 pm Post subject: Re: 36hp Compression ratios |
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I used modeling clay, Did a engine assembly mock up, turned the engine over a couple of times then took a look measuring with digital calipers.
_________________ 1960 Beetle And 1679cc DP W-100 & Dual Zeniths! |
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Daniel hunt Samba Member
Joined: September 28, 2015 Posts: 15
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Posted: Sun Dec 17, 2017 1:16 pm Post subject: Re: 36hp Compression ratios |
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Oh brilliant . I never thought of that . Thank you for your help and wisdom |
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JeeWee Samba Member
Joined: February 05, 2011 Posts: 120 Location: Garijp, the Netherlands
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Posted: Thu Dec 21, 2017 2:20 am Post subject: Re: 36hp Compression ratios |
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in regards to cooling, I run a 58hp 1192cc WW okrasa engine and CR1:7,7 and using this http://www.awesomepowdercoat.com/Venturi_Ring.html part. No additional oil coolers etc. runs perfect also on hot days, no problem.
I always used this setup so I can not compare to with or without this venturi ring.[/url] |
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Daniel hunt Samba Member
Joined: September 28, 2015 Posts: 15
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Posted: Thu Dec 21, 2017 2:41 am Post subject: Re: 36hp Compression ratios |
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Oh ok fantastic . Il have a look into one of them. What is the rest of your engine set up? . |
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