Dynamic Compression calculator?
Thread Starter
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Joined: Dec 2017
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From: San Antonio
Dynamic Compression calculator? I have a calculator for static compression, but I don't know how to calculate the dynamic compression. Does anyone have a link or formula for calculating dynamic compression?
I'm working on hand porting a set of 706 heads, and I want to know if I can still run pump gas if I put them on my LS1. The heads need to be milled due to corrosion. That's why I'm concerned about the compression.
I'm working on hand porting a set of 706 heads, and I want to know if I can still run pump gas if I put them on my LS1. The heads need to be milled due to corrosion. That's why I'm concerned about the compression.
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From: South Carolina
Some of the online dynamic compression calculators require cam specs @ .006 not the @ .050 like on the cam card. Some use the .050 specs minus 15 degrees which is more of a guesstimate.
Thread Starter
12 Second Club
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From: San Antonio
I'm thinking the static will be close to 11.39:1 with a 58cc chamber after milling. I would have to use thicker head gaskets to help out...so maybe .052". I'm assuming the deck height is 0, since I can't measure right now. I have a TSP cam, but the card just has the .050" specs. I guess I could call TSP to get the .006" specs.
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From: St. Louis
You will be just fine, and just use a standard MLS gasket, many of us on here are at a higher static compression than yours will end up being and it's not a big deal at all for the LS just make sure the tune is spot on
My daily is around 11.8 static with my current 706 heads and the little cam I'm running supposedly closes around 65° @ 0.006" so definitely pushing it mathwise but it absolutely runs great it rips those dynamic numbers are just guidelines not absolutes
an absolute would be your piston to valve clearance and also your rocker arm geometry and those are things you should verify with modified heads. What cam do you have?
Also mods this should be in internal engine section
My daily is around 11.8 static with my current 706 heads and the little cam I'm running supposedly closes around 65° @ 0.006" so definitely pushing it mathwise but it absolutely runs great it rips those dynamic numbers are just guidelines not absolutes
an absolute would be your piston to valve clearance and also your rocker arm geometry and those are things you should verify with modified heads. What cam do you have?
Also mods this should be in internal engine section
Last edited by stockA4; Jan 16, 2022 at 10:12 PM.
Thread Starter
12 Second Club
Joined: Dec 2017
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From: San Antonio
I am about 75% done porting one head. I just finished cleaning them today, so now I can continue porting. I'm sure they will need to be milled. My current heads were milled .030", so I shouldn't have any PTV issues with these 706 heads. I still need to contact TSP about the cam specs at .006". My cam is listed in my signature.
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Thread Starter
12 Second Club
Joined: Dec 2017
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From: San Antonio
I just found the Wallace Racing calculator for dynamic compression. I'm assuming the heads will be 58cc after milling. That's how I got the static compression of 11.42:1. Using the cam card specs @ .050". This is what the calculator came up with:
Static compression ratio of 11.42:1.
Effective stroke is 3.28 inches.
Your dynamic compression ratio is 10.44:1 .
Your dynamic cranking pressure is 227.82 PSI.
Your effective boost compression ratio, reflecting static c.r., cam timing, altitude, and boost of 0 PSI is 10.34 :1.
V/P (Volume to Pressure Index) is 214
Static compression ratio of 11.42:1.
Effective stroke is 3.28 inches.
Your dynamic compression ratio is 10.44:1 .
Your dynamic cranking pressure is 227.82 PSI.
Your effective boost compression ratio, reflecting static c.r., cam timing, altitude, and boost of 0 PSI is 10.34 :1.
V/P (Volume to Pressure Index) is 214
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Brett Foote TECH Fanatic
Joined: May 2016
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From: St. Louis
The number would be closer to 9 when using the spec at 0.006. mine calculates out to 9.3 and I have no no issues Even on mid-grade, it's just an estimation of cylinder pressure Don't worry about it you are good to go Just get the tune checked once you get it together