DCR: fatally flawed KB-Silvolite-UEM calculator
02-14-2007, 02:18 PM
#1
Le Mans Master
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DCR: fatally flawed KB-Silvolite-UEM calculator
KB Silvolite UEM DCR calculator is bullsheet!
There’s a box labeled “Intake Closing Point (Degrees)
ABDC @ 0.050 lift +15 degrees” where you enter your intake valve closing angle in degrees. The box label instructs you to add 15 degrees to your closing angle at 0.050” lift. That “approximated” ICA is dead wrong! … because 15 is FAR less than reality … and will result in erroneously HIGH DCR.
For example I setup a 9.5:1 SCR w/ 3.48” stroke and 5.7” rod with a clevite aftermarket clone of an L82 cam … clevite P/N 229-1990 (adv dur 291*/287*, v lift .450/.461, 0.050” dur 224*/224*, LSA 114*, ICL 114*, AND SAE ICA 79.5* AND 0.050” ICA 47*).
When I ran the DCR w/ the “approximated” 0.050” ICA of 62* (47* + 15*) … it returned a 7.760 DCR. However, when I ran same combo but with the actual SAE ICA of 79.5* it returned a 6.666 DCR. That 17.5* discrepancy’s one helluva difference boys!
I also took at look at several other cams’ specs … they ALL had a difference between 0.050” ICA and SAE ICA of 27* to 32* … NOT 15* !
So … if you enter 0.050” ICA + 15* into the KB Silvolite UEM DCR calculator … it’s probably gonna return a DCR that’s about 1 whole number TOO HIGH … build/cam it based on that and it’ll be about as sporty as a slug rodeoin’ a turd!
I cross-checked this against another DCR calculator. Other than KB's "approximate" ICA issue, KB's DCR calculator seems reasonably accurate. Regardless, I've never thought much of KB pistons ... SpeedPro/SealedPower as good or better & usually less $.
There’s a box labeled “Intake Closing Point (Degrees)
ABDC @ 0.050 lift +15 degrees” where you enter your intake valve closing angle in degrees. The box label instructs you to add 15 degrees to your closing angle at 0.050” lift. That “approximated” ICA is dead wrong! … because 15 is FAR less than reality … and will result in erroneously HIGH DCR.
For example I setup a 9.5:1 SCR w/ 3.48” stroke and 5.7” rod with a clevite aftermarket clone of an L82 cam … clevite P/N 229-1990 (adv dur 291*/287*, v lift .450/.461, 0.050” dur 224*/224*, LSA 114*, ICL 114*, AND SAE ICA 79.5* AND 0.050” ICA 47*).
When I ran the DCR w/ the “approximated” 0.050” ICA of 62* (47* + 15*) … it returned a 7.760 DCR. However, when I ran same combo but with the actual SAE ICA of 79.5* it returned a 6.666 DCR. That 17.5* discrepancy’s one helluva difference boys!
I also took at look at several other cams’ specs … they ALL had a difference between 0.050” ICA and SAE ICA of 27* to 32* … NOT 15* !
So … if you enter 0.050” ICA + 15* into the KB Silvolite UEM DCR calculator … it’s probably gonna return a DCR that’s about 1 whole number TOO HIGH … build/cam it based on that and it’ll be about as sporty as a slug rodeoin’ a turd!
I cross-checked this against another DCR calculator. Other than KB's "approximate" ICA issue, KB's DCR calculator seems reasonably accurate. Regardless, I've never thought much of KB pistons ... SpeedPro/SealedPower as good or better & usually less $.
02-14-2007, 02:43 PM
#3
Melting Slicks
At the bottom of this page
http://cochise.uia.net/pkelley2/DynamicCR.html
you can download a file that resides on your computer.
Also, here's an online one that calculates DCR w/Boost
http://www.rbracing-rsr.com/comprAdvHD.htm
Jim
http://cochise.uia.net/pkelley2/DynamicCR.html
you can download a file that resides on your computer.
Also, here's an online one that calculates DCR w/Boost
http://www.rbracing-rsr.com/comprAdvHD.htm
Jim
02-14-2007, 02:58 PM
#4
Le Mans Master
The major differences between calcutators drove me nuts a month back when I was figuring for my 406 build.
Never did get two calculators that matched values.
Thanks for the heads up Jack....
Eddie
Never did get two calculators that matched values.
Thanks for the heads up Jack....
Eddie
02-14-2007, 07:18 PM
#5
Melting Slicks
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St. Jude Donor '12
here is another dcr calc. i found while looking a few weeks back. all dcr calcs. seem to give dif. numbers. i could not get the other one to download and run on my comp. maybe jackson could use this one and compair it with the other ones that have been mentioned to see how close it is.
http://www.hotroddersauctions.com/Dy...Calculator.php
http://www.hotroddersauctions.com/Dy...Calculator.php
02-14-2007, 07:30 PM
#6
Race Director
I've been saying that since day one, most cam companies will give you a .006" or .016" duration use that and add a couple of degrees or download the one above, I use that one
02-14-2007, 08:55 PM
#7
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Cruise-In IV Veteran
Cruise-In V Veteran
here is another dcr calc. i found while looking a few weeks back. all dcr calcs. seem to give dif. numbers. i could not get the other one to download and run on my comp. maybe jackson could use this one and compair it with the other ones that have been mentioned to see how close it is.
http://www.hotroddersauctions.com/Dy...Calculator.php
http://www.hotroddersauctions.com/Dy...Calculator.php
02-15-2007, 11:44 PM
#8
KB Silvolite UEM DCR calculator is bullsheet!
There’s a box labeled “Intake Closing Point (Degrees)
ABDC @ 0.050 lift +15 degrees” where you enter your intake valve closing angle in degrees. The box label instructs you to add 15 degrees to your closing angle at 0.050” lift. That “approximated” ICA is dead wrong! … because 15 is FAR less than reality … and will result in erroneously HIGH DCR.
For example I setup a 9.5:1 SCR w/ 3.48” stroke and 5.7” rod with a clevite aftermarket clone of an L82 cam … clevite P/N 229-1990 (adv dur 291*/287*, v lift .450/.461, 0.050” dur 224*/224*, LSA 114*, ICL 114*, AND SAE ICA 79.5* AND 0.050” ICA 47*).
When I ran the DCR w/ the “approximated” 0.050” ICA of 62* (47* + 15*) … it returned a 7.760 DCR. However, when I ran same combo but with the actual SAE ICA of 79.5* it returned a 6.666 DCR. That 17.5* discrepancy’s one helluva difference boys!
I also took at look at several other cams’ specs … they ALL had a difference between 0.050” ICA and SAE ICA of 27* to 32* … NOT 15* !
So … if you enter 0.050” ICA + 15* into the KB Silvolite UEM DCR calculator … it’s probably gonna return a DCR that’s about 1 whole number TOO HIGH … build/cam it based on that and it’ll be about as sporty as a slug rodeoin’ a turd!
I cross-checked this against another DCR calculator. Other than KB's "approximate" ICA issue, KB's DCR calculator seems reasonably accurate. Regardless, I've never thought much of KB pistons ... SpeedPro/SealedPower as good or better & usually less $.
There’s a box labeled “Intake Closing Point (Degrees)
ABDC @ 0.050 lift +15 degrees” where you enter your intake valve closing angle in degrees. The box label instructs you to add 15 degrees to your closing angle at 0.050” lift. That “approximated” ICA is dead wrong! … because 15 is FAR less than reality … and will result in erroneously HIGH DCR.
For example I setup a 9.5:1 SCR w/ 3.48” stroke and 5.7” rod with a clevite aftermarket clone of an L82 cam … clevite P/N 229-1990 (adv dur 291*/287*, v lift .450/.461, 0.050” dur 224*/224*, LSA 114*, ICL 114*, AND SAE ICA 79.5* AND 0.050” ICA 47*).
When I ran the DCR w/ the “approximated” 0.050” ICA of 62* (47* + 15*) … it returned a 7.760 DCR. However, when I ran same combo but with the actual SAE ICA of 79.5* it returned a 6.666 DCR. That 17.5* discrepancy’s one helluva difference boys!
I also took at look at several other cams’ specs … they ALL had a difference between 0.050” ICA and SAE ICA of 27* to 32* … NOT 15* !
So … if you enter 0.050” ICA + 15* into the KB Silvolite UEM DCR calculator … it’s probably gonna return a DCR that’s about 1 whole number TOO HIGH … build/cam it based on that and it’ll be about as sporty as a slug rodeoin’ a turd!
I cross-checked this against another DCR calculator. Other than KB's "approximate" ICA issue, KB's DCR calculator seems reasonably accurate. Regardless, I've never thought much of KB pistons ... SpeedPro/SealedPower as good or better & usually less $.
Your right, I have been doing this for the last four hours and my supposed KB close to detonation machine is actually at 10.01 static & 7.78 dynamic when you figure in the actual seat to seat cam timing. Its around a full point lower then the KB crap. If I put in some 7cc FT's I will be at 10.8:1 static and 8.37 dynamic. This will leave me at .042 quench. This site and reading David Vizard's book has convinced me the next engine build is taking place in my house. I think I am going to put this SBC in my Jeep next year to replace the inline 4.0L and build me a killer SBC off of the Dart or Motown block base.
