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36hp Compression ratios
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Daniel hunt
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PostPosted: Tue Dec 12, 2017 12:24 pm    Post subject: 36hp Compression ratios Reply with quote

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
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PostPosted: Tue Dec 12, 2017 8:30 pm    Post subject: Re: 36hp Compression ratios Reply with quote

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
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PostPosted: Wed Dec 13, 2017 5:47 am    Post subject: Re: 36hp Compression ratios Reply with quote

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
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PostPosted: Wed Dec 13, 2017 9:06 pm    Post subject: Re: 36hp Compression ratios Reply with quote

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
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PostPosted: Wed Dec 13, 2017 11:49 pm    Post subject: Re: 36hp Compression ratios Reply with quote

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
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PostPosted: Thu Dec 14, 2017 6:19 am    Post subject: Re: 36hp Compression ratios Reply with quote

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
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PostPosted: Thu Dec 14, 2017 4:00 pm    Post subject: Re: 36hp Compression ratios Reply with quote

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
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PostPosted: Thu Dec 14, 2017 6:29 pm    Post subject: Re: 36hp Compression ratios Reply with quote

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
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PostPosted: Sat Dec 16, 2017 1:07 pm    Post subject: Re: 36hp Compression ratios Reply with quote

How would i check the valve to piston clearance?
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Danwvw
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PostPosted: Sat Dec 16, 2017 3:46 pm    Post subject: Re: 36hp Compression ratios Reply with quote

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.

Image may have been reduced in size. Click image to view fullscreen.

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Daniel hunt
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PostPosted: Sun Dec 17, 2017 1:16 pm    Post subject: Re: 36hp Compression ratios Reply with quote

Oh brilliant . I never thought of that . Thank you for your help and wisdom
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JeeWee
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PostPosted: Thu Dec 21, 2017 2:20 am    Post subject: Re: 36hp Compression ratios Reply with quote

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
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PostPosted: Thu Dec 21, 2017 2:41 am    Post subject: Re: 36hp Compression ratios Reply with quote

Oh ok fantastic . Il have a look into one of them. What is the rest of your engine set up? .
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