Help with DCR
08-30-2005, 01:09 PM
#1
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Help with DCR I'm again searching for cam. Now i've been punching in lots of cam profiles to figure the DCR of the engine and i have some questions. Now I'm trying to figure out what afffect the DCR has on detonation. For example the cam I'm looking at is a 222/228 272/278 103/109-this is one of Lunati's new Voodoo grinds. The DCR on a motor with a 64 CC head, 040 gasket with the piston .008 out of the hole is 8.8 SC is 11.01 and then 9.3 with 11.5(59cc). Now isn't 8.8 DCR very hi to begin with? So I'm confused-I'm trying to find a cam that has alot of "power under the curve" but I'm afraid of running into detonation problems with my heads being milled(.040). Can you guys explain to me what's going on in "english", I'm confused.
thanks!
thanks!
08-30-2005, 01:33 PM
#2
Ideally, you'll want to stay at or near 8.5 DCR for running 91-93 octane. If you have 94 octane, then you can push it a little higher.
Dynamic compression is based 100% on intake valve closing point...no two ways around it. If we try to hit 8.5 DCR and less, I'm afraid your IVC will be too late. I don't like going past 46 degrees on a street/strip 346. Based on your excellent heads and your upcoming long tubes (with factory cats), I'd say you still need a little bit of a split to your exhaust.
Based on your desire to stay emissions compliant, we'll need to limit overlap to less than 46 degrees at .006 lift.
To keep horsepower at its highest, we'll need an intake valve closing point of 45-46 degrees ABDC (at .050").
Keeping all those figures in mind and a desire to keep DCR as low as possible, here's what I'd recommend:
0.006 0.050 0.200
Intake Duration - ID 273 224 146 3722 XE-R
Exhaust Duration - ED 279 230 148 3725 XE-R
Lobe Center Angle - LCA (also known as LSA) 116 116 116
Intake Centerline - ICL 114 114 114
Intake Valve opens - IVO 22.5 -2 -41 BTDC (- indicates ATDC)
Intake Valve closes - IVC 70.5 46 7 ABDC
Exhaust Valve Opens - EVO 77.5 53 12 BBDC
Exhaust Valve Closes - EVC 21.5 -3 -44 ATDC (- indicates BTDC)
Exhaust Centerline - ECL 118 118 118
Overlap 44 -5 -85 degrees
Dynamic compression is based 100% on intake valve closing point...no two ways around it. If we try to hit 8.5 DCR and less, I'm afraid your IVC will be too late. I don't like going past 46 degrees on a street/strip 346. Based on your excellent heads and your upcoming long tubes (with factory cats), I'd say you still need a little bit of a split to your exhaust.
Based on your desire to stay emissions compliant, we'll need to limit overlap to less than 46 degrees at .006 lift.
To keep horsepower at its highest, we'll need an intake valve closing point of 45-46 degrees ABDC (at .050").
Keeping all those figures in mind and a desire to keep DCR as low as possible, here's what I'd recommend:
0.006 0.050 0.200
Intake Duration - ID 273 224 146 3722 XE-R
Exhaust Duration - ED 279 230 148 3725 XE-R
Lobe Center Angle - LCA (also known as LSA) 116 116 116
Intake Centerline - ICL 114 114 114
Intake Valve opens - IVO 22.5 -2 -41 BTDC (- indicates ATDC)
Intake Valve closes - IVC 70.5 46 7 ABDC
Exhaust Valve Opens - EVO 77.5 53 12 BBDC
Exhaust Valve Closes - EVC 21.5 -3 -44 ATDC (- indicates BTDC)
Exhaust Centerline - ECL 118 118 118
Overlap 44 -5 -85 degrees
__________________
2013 Corvette Grand Sport A6 LME forged 416, Greg Good ported TFS 255 LS3 heads, 222/242 .629"/.604" 121LSA Pat G blower cam, ARH 1 7/8" headers, ESC Novi 1500 Supercharger w/8 rib direct drive conversion, 747rwhp/709rwtq on 93 octane, 801rwhp/735rwtq on race fuel, 10.1 @ 147.25mph 1/4 mile, 174.7mph Half Mile.
2016 Corvette Z51 M7 Magnuson Heartbeat 2300 supercharger, TSP LT headers, Pat G tuned, 667rwhp, 662rwtq, 191mph TX Mile.
2009.5 Pontiac G8 GT 6.0L, A6, AFR 230v2 heads. 506rwhp/442rwtq. 11.413 @ 121.29mph 1/4 mile, 168.7mph TX Mile
2000 Pewter Ram Air Trans Am M6 heads/cam 508 rwhp/445 rwtq SAE, 183.092 TX Mile
2018 Cadillac Escalade 6.2L A10 Pat G tuned.
LS1,LS2,LS3,LS7,LT1 Custom Camshaft Specialist For custom camshaft help press here.
Custom LSX tuning in person or via email press here.
2013 Corvette Grand Sport A6 LME forged 416, Greg Good ported TFS 255 LS3 heads, 222/242 .629"/.604" 121LSA Pat G blower cam, ARH 1 7/8" headers, ESC Novi 1500 Supercharger w/8 rib direct drive conversion, 747rwhp/709rwtq on 93 octane, 801rwhp/735rwtq on race fuel, 10.1 @ 147.25mph 1/4 mile, 174.7mph Half Mile.
2016 Corvette Z51 M7 Magnuson Heartbeat 2300 supercharger, TSP LT headers, Pat G tuned, 667rwhp, 662rwtq, 191mph TX Mile.
2009.5 Pontiac G8 GT 6.0L, A6, AFR 230v2 heads. 506rwhp/442rwtq. 11.413 @ 121.29mph 1/4 mile, 168.7mph TX Mile
2000 Pewter Ram Air Trans Am M6 heads/cam 508 rwhp/445 rwtq SAE, 183.092 TX Mile
2018 Cadillac Escalade 6.2L A10 Pat G tuned.
LS1,LS2,LS3,LS7,LT1 Custom Camshaft Specialist For custom camshaft help press here.
Custom LSX tuning in person or via email press here.
