need help with scr dcr
Race Director
Joined: May 2005
Posts: 10,674
Likes: 122
From: Millington Illinois
St. Jude Donor '08-'09
Yes and no, niether calculator is different, they both use the same math
to figure dcr, so that much we know is correct.
1). The empire net uses seat timing (advertised duration IVC most cam cards show this as .006 or .004 timing) the kb uses @.050 duration IVC+15.
2). If you entered in the @.50 timing IVC +15 into the empire calculator as your intake closing point instead of the seat timing you will come up with what the KB calculator shows using the @.050 IVC+15 method as I showed above.
3). Now flip it, enter in the seat timing(.004 or .006) IVC into the KB calculator instead of the @.050 and it will show you what the empire calculator shows you with seat timing IVC.
Now, knowing that the math is the same:
KB uses @.050 timing IVC +15
Empire uses .004 or .006 IVC
I talked with the Crane tech and he claims that with there cams you will come up with a more accurate DCR using the .050+15 timing reference then the advertised duration.
So niether calculator is more right then the other it is up to you to input whichever IVC timing point you think is correct.
The real way to solve this is for someone still building there engine with a cam degree wheel to measure the ACTUAL intake valve closing point and see which is closer the adv duration or the @.050 +15.
to figure dcr, so that much we know is correct.
1). The empire net uses seat timing (advertised duration IVC most cam cards show this as .006 or .004 timing) the kb uses @.050 duration IVC+15.
2). If you entered in the @.50 timing IVC +15 into the empire calculator as your intake closing point instead of the seat timing you will come up with what the KB calculator shows using the @.050 IVC+15 method as I showed above.
3). Now flip it, enter in the seat timing(.004 or .006) IVC into the KB calculator instead of the @.050 and it will show you what the empire calculator shows you with seat timing IVC.
Now, knowing that the math is the same:
KB uses @.050 timing IVC +15
Empire uses .004 or .006 IVC
I talked with the Crane tech and he claims that with there cams you will come up with a more accurate DCR using the .050+15 timing reference then the advertised duration.
So niether calculator is more right then the other it is up to you to input whichever IVC timing point you think is correct.
The real way to solve this is for someone still building there engine with a cam degree wheel to measure the ACTUAL intake valve closing point and see which is closer the adv duration or the @.050 +15.
Veteran
Joined: Oct 2005
Posts: 1,284
Likes: 81
From: Nashville, TN
Where is Dave Vizard when you need him?
Last edited by King Lear; Mar 3, 2007 at 05:38 AM.
Race Director
Joined: May 2005
Posts: 10,674
Likes: 122
From: Millington Illinois
St. Jude Donor '08-'09
The Empire does not either, it goes straight off your cam card, I agree but does anyone? have the ramp rate included on the timing card? No! The ramp rate is a guess at that? If someone did I would be a bit skeptical. The rockers change the ramp rate! None of the dcr calc's take into account for the rockers which totally change the cam ramp rate and the internal boost signals sent to the carb.
Where is Dave Vizard when you need him?
Where is Dave Vizard when you need him?
Veteran
Joined: Oct 2005
Posts: 1,284
Likes: 81
From: Nashville, TN
I agree but the only way to know for sure is to take a cam wheel and measure it, in my opinion. After talking to the Crane guy, he said quote"well the advertised duration timing is just an estimate that changes, the @.050 is much more accurate".
Race Director
Joined: May 2005
Posts: 10,674
Likes: 122
From: Millington Illinois
St. Jude Donor '08-'09
With everything you are saying! But the .050 plus 15 to get to the actual closing point would vary drastically depending on the lobe profile. For example if that number is accurate on a mild .450 lift hydraulic flat tappet cam it would be way low on a .700 lift solid roller due to a steep ramp rate in comparision to the hydraulic. Using the actual closing point is the way to go and as you said a degree wheel is probably the best way to find that point.
Veteran
Joined: Oct 2005
Posts: 1,284
Likes: 81
From: Nashville, TN
With everything you are saying! But the .050 plus 15 to get to the actual closing point would vary drastically depending on the lobe profile. For example if that number is accurate on a mild .450 lift hydraulic flat tappet cam it would be way low on a .700 lift solid roller due to a steep ramp rate in comparision to the hydraulic. Using the actual closing point is the way to go and as you said a degree wheel is probably the best way to find that point.
Veteran
Joined: Oct 2005
Posts: 1,284
Likes: 81
From: Nashville, TN
If you want to let go of that 63 split window then you know where to call!!!!!!!!!!!!!!!
I think that is a really ugly car and I am just willing to take it from you to help you out! After all, it is a brotherhood and all! LOL, I will take the C2 from you though if it is a problem!!!!!!!!!!
I think that is a really ugly car and I am just willing to take it from you to help you out! After all, it is a brotherhood and all! LOL, I will take the C2 from you though if it is a problem!!!!!!!!!!
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Race Director
Joined: May 2005
Posts: 10,674
Likes: 122
From: Millington Illinois
St. Jude Donor '08-'09
If you want to let go of that 63 split window then you know where to call!!!!!!!!!!!!!!!
I think that is a really ugly car and I am just willing to take it from you to help you out! After all, it is a brotherhood and all! LOL, I will take the C2 from you though if it is a problem!!!!!!!!!!
I think that is a really ugly car and I am just willing to take it from you to help you out! After all, it is a brotherhood and all! LOL, I will take the C2 from you though if it is a problem!!!!!!!!!!
Veteran
Joined: Oct 2005
Posts: 1,284
Likes: 81
From: Nashville, TN
