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Thread: 20V + 16VE pistons CR

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Posts: 31-40 of 45
2009-10-28 11:18:32
#31
Originally Posted by src
jonwepa, "+1mm notched pistons" I mean deeper for 1mm valve reliefs.

Thanks guys for taking this thread live. I really don't want to post if I don't get feedback from you. This is a place to share our knowledge and to discuss things like that.


Can you show me a diagam of some sort because this whole notchng pistons is new and different for me. I JUST PUT THINGS TOGETHER. Sorry:o
2009-10-29 07:51:25
#32
jonwepa,

Will post some photos as my pistons will be ready.
2009-10-29 13:22:44
#33
Originally Posted by src
jonwepa,

Will post some photos as my pistons will be ready.


Thanks man. i really need visuals, but once i see it I got it!
Cant wait.
2009-10-29 17:25:18
#34
Originally Posted by jonwepa
Can you show me a diagam of some sort because this whole notchng pistons is new and different for me. I JUST PUT THINGS TOGETHER. Sorry:o

More compression for my B11 - SR20 Forum
2009-10-29 18:27:06
#35
Do u mind pming your phone number i am a question guy and i have alot for about your whole set-up.
2009-10-31 19:11:21
#36
SR16VE piston notched 1mm (valve reliefs are deeper for 1mm.
This is done by machine.



Some polishing by hands. Also sharp edges are cut and softened.






I think with this handwork compression falls down a bit too. I will measure these pistons volume in a days.
2009-10-31 21:17:01
#37
good stuff src it always good to get rid of sharp edges sharp edges get hot
2009-10-31 22:16:43
#38
AWESOME! Definitely let us know what the compression comes out too!
I have a set that will be heading to the machine shop if this works on 93 pump gas.
2009-11-04 14:21:08
#39
Ok, just measured them. I came to 3,3cc piston dash volume (in bore) with these modified notches.

They are +0,5mm in diameter and +1mm deep, cut sharp edges.

So, summarized:

if we take into consideration 40,5 сс volume (more_fasterer's data) for stock 20V head, we will get 12,3:1 CR using 16VE notched pistons like mine.

if we take into consideration 41,8 сс volume (Andreas' data) for stock 20VE head, we will get 11,97:1 CR using 16VE notched pistons like mine.

My modified 43,15cc combustion chamber will bring me 11,65:1 CR using mine 16VE notched pistons. Safe enough I think!

The one thing which must be corrected is gasket volume. I will measure my compressed gasket as soon as my engine will be assembled.
2009-11-04 14:43:26
#40
bugger me 1mm off each one takes the comp down that much! what if you take them down .5 of a mm will that keep it closer to 12.5:1 in a 20VE

on a side note.. are the pistons coated on the top from factory? i know they have a coating on the skirts but are they coated on the top? will they need re coating if they are?
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