Ccr and ccp
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Cruiser
Joined: Oct 2009
Posts: 116
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From: Pittsburgh
Ccr and ccp
I'm currently doing a 98 build and am conflicted on numbers from bigboyz calculator. many threads on the subject mention baggers 9.6 ccr but this on my buid at 9.51 ccr is showing ccp of 197. other threads say stay around 190 ccp. i don't mind using comp. releases if the power is worth the install. just wanting some input from people who are knowledgeable in this area.
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Cruiser
Joined: Oct 2009
Posts: 116
Likes: 0
From: Pittsburgh
thanks guys, I currently am running a new 203 cam in the 88 stock heads with the cam plate upgrade. my heads i'm doing a port and polish on late model stock heads with a 1.90 intake upgrade at stock 85 cc or 86 haven't checked yet, 10:1 wisecos already purchased and fitted to cylinders. of course a PC5. this combination is giving me 201 ccp, have plugged in a tw-555(which I plan to switch to if the 203's don't feel right) and it lowers to 197ccp.
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Cruiser
Joined: Oct 2009
Posts: 116
Likes: 0
From: Pittsburgh
sorry should have included riding style. mostlt ride single, and like bottom torque but but also like highway, planing a 34 tooth sprocket install, so enough torque to leave the line ok and stay strong.
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Cruiser
Joined: Oct 2009
Posts: 116
Likes: 0
From: Pittsburgh
hmmm, no responces, i just dont under stand the ratio of ccp to ccr. is it a fixed number or can it be manipulted. is ccp a set number that coincides with ccr. my evo with ccp of 189.0 requires a full battery to start without releases. furtunately it always starts quick cause to many tries and i'm pushing it.
Road Warrior
Joined: Apr 2011
Posts: 1,443
Likes: 9
From: North Carolina
One is cylinder pressure and one us compression ratio, corrected not advertised a puston mfg stating comp of 10:1 does not mean installed ratio. Pressure is varried on cams, head cc and overall volumetric efficiency. You could get a corrected ccr of 10.5:1 or 9:1 depending on other parts of the build.
Although I kinda see what you are getting at I just cant work it through a keyboard.
Although I kinda see what you are getting at I just cant work it through a keyboard.
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Road Captain
Joined: Nov 2008
Posts: 537
Likes: 2
From: Ohio
Your compression
The advertised compression is different than the actual compression..Your pistons may be 10 to 1 advertised..Now consider the components that make up your "stack".. Have the heads been milled?, cc volume of the combustion chambers , dome of the pistons, and yes even a flattop can have a plus cc here, Are the pistons set to zero deck height, stock typically run in the hole 5-7 thousandths, head gasket thickness .028 thru .060, event sequence of the cams play a major role in when the compression is made and how much..All things considered, and I prob missed a couple..this is your corrected compression,CCR, which generally is lower than advertised..The amount of compression, measured in ft lbs, made in your individual combination, ie all of the above, can be checked with a gauge know as a compression tester. This gauge will tell you your cranking compression, in ft lbs., with your combination, that your starter will hve to overcome to start..much over 180 and I would advise releases...Screw in the gauge (sparkplug hole) with throttle open, ground the sparkplug leads, crank the motor, note the pressure. Cranking compression..CCP Scooter
Last edited by scooter_trash_1; Feb 18, 2013 at 09:27 PM.
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Stellar HDF Member
Joined: Dec 2009
Posts: 2,561
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From: North Cental Iowa
On the Bigboyz site you have to enter the cam you'll be using to get your ccp, the later the cam closing the more it will lower your ccp. I don't think you've entered a cam selection so far.
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Cruiser
Joined: Oct 2009
Posts: 116
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From: Pittsburgh
ok thanks guys, i have a pretty good understanding of all your replies. this is the first time I used a calculater for a build and needed to get a grasp on understanding it. knowing I put 10.5 pistons in my evo and knowing it was borderline needing releases. i couldn't believe that this motor build had such a high ccp with only a 9.5 ccr. it wasn't until I plugged my evo numbers into the calcuator and found out that its ccr was only 9.1 then it registered. guess i'm definately installing releases. anyone got a Jims tool they want to sell,lol. the build I thought I wanted is about 205 ccp with the se203's but drops to 199 with the tw-555's. hope i'm not building to much pressure for the 98" bore cylinders.