Anyone that can, can you E-mail or PM me and run it for me? I am interested in getting correct info on my DCR. Thanks Kevin
need help with scr dcr
Le Mans Master
Joined: Sep 2001
Posts: 7,739
Likes: 630
From: Unreconstructed, South Carolina
verified: KB calculator fatally flawed
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!
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!
Thread Starter
Pro
Joined: Dec 2006
Posts: 665
Likes: 0
From: wilmington nc
Yall making me nervious this morning so i downloaded this calculator
http://www.empirenet.com/pkelley2/DynamicCR.html
I got 10.44:1 scr and 8.12:1 dcr , carry on I"m not nervious anymore!
enter negative numbers for postive pistons whoever woulda thunk that...
http://www.empirenet.com/pkelley2/DynamicCR.html
I got 10.44:1 scr and 8.12:1 dcr , carry on I"m not nervious anymore!
enter negative numbers for postive pistons whoever woulda thunk that...
Veteran
Joined: Oct 2005
Posts: 1,284
Likes: 81
From: Nashville, TN
Yall making me nervious this morning so i downloaded this calculator
http://www.empirenet.com/pkelley2/DynamicCR.html
I got 10.44:1 scr and 8.12:1 dcr , carry on I"m not nervious anymore!
enter negative numbers for postive pistons whoever woulda thunk that...
http://www.empirenet.com/pkelley2/DynamicCR.html
I got 10.44:1 scr and 8.12:1 dcr , carry on I"m not nervious anymore!
enter negative numbers for postive pistons whoever woulda thunk that...
Race Director
Joined: Apr 2000
Posts: 17,676
Likes: 201
From: Who says "Nothing is impossible" ? I've been doing nothing for years.
You should be OK with that, providing the numbers are correct. Before anyone jumps on the quench, that is where mine is and I have no detonation problems with a 550HP small block runnning 91 octane. I have 11:1 CR and about 8.7:1 DCR 
Le Mans Master
Joined: Sep 2001
Posts: 7,739
Likes: 630
From: Unreconstructed, South Carolina
Yall making me nervious this morning so i downloaded this calculator
http://www.empirenet.com/pkelley2/DynamicCR.html
I got 10.44:1 scr and 8.12:1 dcr , carry on I"m not nervious anymore!
enter negative numbers for postive pistons whoever woulda thunk that...
http://www.empirenet.com/pkelley2/DynamicCR.html
I got 10.44:1 scr and 8.12:1 dcr , carry on I"m not nervious anymore!
enter negative numbers for postive pistons whoever woulda thunk that...
Race Director
Joined: May 2005
Posts: 10,674
Likes: 122
From: Millington Illinois
St. Jude Donor '08-'09
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. Its not the DCR program, just a bs windows program used to run it.
Race Director
Joined: May 2005
Posts: 10,674
Likes: 122
From: Millington Illinois
St. Jude Donor '08-'09
I think I tried this when I originally was designing the engine. That trial program is probably expired. Can anyone that has this help me out? I have all the info to input. I noticed it takes into account ICL and LSA. Sounds like it would be much more accurate.
Burning Brakes
Joined: Oct 2004
Posts: 904
Likes: 0
From: Murphy NC
Sure. Just PM me your specs and ill run it. Need stroke, rod length, adv. duration, lobe separation, intake lobe centerline, combustion champer ccs, head gasket thickness and bore, cylinder bore, piston to deck clearance, and piston cc (dome or dish)
Le Mans Master
Joined: Sep 2001
Posts: 7,739
Likes: 630
From: Unreconstructed, South Carolina
That calculates what the ICA is based on you input SAE duration, ICL & LSA. If your cam card has the SAE ICA ... that part of the program is handy to see if it matches & to learn how it all "meshes" together. As in measuring & cutting ... calculating w/ new calculator is same ... run it MANY times ... checking that you've updated everything ... then change some stuff ... then verify that it does return a change ... do many times until you're sure.
Veteran
Joined: Oct 2005
Posts: 1,284
Likes: 81
From: Nashville, TN
Veteran
Joined: Oct 2005
Posts: 1,284
Likes: 81
From: Nashville, TN
I used the empire net dcr calc and when entering in the adv dur and lobe points it actually says my IVC is 69 not the KB of .050 38+15=53. Made quite a difference on dcr. KB says I am at 8.7dcr with the actual cam timing on the empire net dcr calc I am at 7.79dcr. HUGE difference.
Le Mans Master
Joined: Sep 2001
Posts: 7,739
Likes: 630
From: Unreconstructed, South Carolina
I used the empire net dcr calc and when entering in the adv dur and lobe points it actually says my IVC is 69 not the KB of .050 38+15=53. Made quite a difference on dcr. KB says I am at 8.7dcr with the actual cam timing on the empire net dcr calc I am at 7.79dcr. HUGE difference.
Le Mans Master
Joined: Sep 2001
Posts: 7,739
Likes: 630
From: Unreconstructed, South Carolina
That difference is probably because ... either ... they expect you to install it 4* advanced at 69* or it is ground w/ 4* advance.
Please state ALL adv/sae cam specs from mfg ... and separately
ALL adv/sae cam specs that you input and were returned from the "good" dcr calculator.
Please state ALL adv/sae cam specs from mfg ... and separately
ALL adv/sae cam specs that you input and were returned from the "good" dcr calculator.
Racer
Joined: Oct 2004
Posts: 285
Likes: 0
From: Stockholm
Like dmaaero I have some concerns about my cam choice.
The cam I'm sitting with now is a XE274 IVC 63* @0.015.
This cam was perfect for my Ross pistons (10.8 scr) but as my block didn't clear up I bought new Probe SRS pistons (11.2 scr) which was a misstake, should'n have bought them at all, but now I have them.
If I use the KB calculator I get the dcr to 9.1 which is to much.
I can retard the cam 4* but I'm not shure I will be enough.
If doing that I will still have 8.8 in dcr.
I also talked to a guy from Comp Cams this evening, and he said it's better to go for a XE280 instead, just to bleed of some of the dcr.
But is IVC 63*@0.015 the real closing time?
To me it looks like the valve is still open 0.015?
Shouldn't it be seated a few degrees later than 63* ??
The cam I'm sitting with now is a XE274 IVC 63* @0.015.
This cam was perfect for my Ross pistons (10.8 scr) but as my block didn't clear up I bought new Probe SRS pistons (11.2 scr) which was a misstake, should'n have bought them at all, but now I have them.
If I use the KB calculator I get the dcr to 9.1 which is to much.
I can retard the cam 4* but I'm not shure I will be enough.
If doing that I will still have 8.8 in dcr.
I also talked to a guy from Comp Cams this evening, and he said it's better to go for a XE280 instead, just to bleed of some of the dcr.
But is IVC 63*@0.015 the real closing time?
To me it looks like the valve is still open 0.015?
Shouldn't it be seated a few degrees later than 63* ??
Last edited by gbak; Feb 16, 2007 at 05:57 PM.