Need help. Whats my SCR/DCR
10-23-2007, 06:55 PM
#1
TECH Apprentice
Thread Starter
iTrader: (50)
Join Date: Jun 2007
Posts: 359
Likes: 0
Received 0 Likes
on
0 Posts
Need help. Whats my SCR/DCR I am building a 383 stroker and need to know what cc heads I should get. The short block is not assembled yet so I dont know how far the pistons are out of the hole. The pistons have 6cc reliefs in them. I am running a Comp Cam 238/240 on a 112 XER lobes. The lift is .605/.609. I dont have a cam card so I dont have the other specs.
I am looking at a used set of PRC ported 225 Darts that have been milled to 60cc. What kind of compression will these get me? I was told that will 64cc heads I would be 11 to 1, but I dont know on what gasket. Any help would be very much appreciated.
I am looking at a used set of PRC ported 225 Darts that have been milled to 60cc. What kind of compression will these get me? I was told that will 64cc heads I would be 11 to 1, but I dont know on what gasket. Any help would be very much appreciated.
10-24-2007, 06:23 AM
#3
On The Tree
iTrader: (14)
Join Date: Mar 2007
Location: Central IL
Posts: 156
Likes: 0
Received 0 Likes
on
0 Posts
Assuming .006 out of the hole and a .060 gasket, I'm getting a SCR of 11.23 and a DCR of 8.20
Same deck and .040 gasket gets an SCR of 11.78 and DCR of 8.58
Looks like those heads would work great to me, the deck height isn't going to effect you to much, you have quite a bit of wiggle room with your gasket choices to make up for it. This was also assuming a 112 ICL, but that only changes your DCR about +.1 per degree of advance with that cam.
Same deck and .040 gasket gets an SCR of 11.78 and DCR of 8.58
Looks like those heads would work great to me, the deck height isn't going to effect you to much, you have quite a bit of wiggle room with your gasket choices to make up for it. This was also assuming a 112 ICL, but that only changes your DCR about +.1 per degree of advance with that cam.
10-24-2007, 07:47 AM
#4
I see 11.37:1 SCR and 8.57:1 DCR with stock .052 compressed head gaskets.
112 +4, if you grind at 112 +0 the CR is 11.37 SCR and 8.26 DCR, the DCR drops because the intake @51 abdc
0.006 0.050
Intake Duration - ID (first number) 287 238
Exhaust Duration - ED (second number) 289 240
Lobe Center Angle - LCA (also known as LSA) 112 112
Intake Centerline - ICL 108 108
Intake Valve opens - IVO 35.5 11
Intake Valve closes - IVC 71.5 47
Exhaust Valve Opens - EVO 80.5 56
Exhaust Valve Closes - EVC 28.5 4
Exhaust Centerline - ECL 116 116
Overlap 64 15
112 +4, if you grind at 112 +0 the CR is 11.37 SCR and 8.26 DCR, the DCR drops because the intake @51 abdc
0.006 0.050
Intake Duration - ID (first number) 287 238
Exhaust Duration - ED (second number) 289 240
Lobe Center Angle - LCA (also known as LSA) 112 112
Intake Centerline - ICL 108 108
Intake Valve opens - IVO 35.5 11
Intake Valve closes - IVC 71.5 47
Exhaust Valve Opens - EVO 80.5 56
Exhaust Valve Closes - EVC 28.5 4
Exhaust Centerline - ECL 116 116
Overlap 64 15
10-24-2007, 12:39 PM
#6
This is with .052" gasket
Bore 4.03
ST = Stroke 3.75
RL = Rod Length 5.7
Number of cylinders 8
Deck Height (how much pistons come out of the hole) -0.006
Piston Dome or Dish (- for a dome + for a dish) 6
Compressed Head gasket thickness 0.052
Cylinder Head Chamber Volume 60
Static Compression Ratio 11.37 :1
Dynamic Compresion Ratio 8.30 :1
Rod to Stroke Ratio 1.52 :1
Bore to Stroke Ratio 1.07 :1
Bore 4.03
ST = Stroke 3.75
RL = Rod Length 5.7
Number of cylinders 8
Deck Height (how much pistons come out of the hole) -0.006
Piston Dome or Dish (- for a dome + for a dish) 6
Compressed Head gasket thickness 0.052
Cylinder Head Chamber Volume 60
Static Compression Ratio 11.37 :1
Dynamic Compresion Ratio 8.30 :1
Rod to Stroke Ratio 1.52 :1
Bore to Stroke Ratio 1.07 :1
Last edited by 69LT1Bird; 10-24-2007 at 12:52 PM.
10-24-2007, 12:53 PM
#7
This with a .045" gasket:
Bore 4.03
ST = Stroke 3.75
RL = Rod Length 5.7
Number of cylinders 8
Deck Height (how much pistons come out of the hole) -0.006
Piston Dome or Dish (- for a dome + for a dish) 6
Compressed Head gasket thickness 0.045
Cylinder Head Chamber Volume 60
Static Compression Ratio 11.57 :1
Dynamic Compresion Ratio 8.45 :1
Rod to Stroke Ratio 1.52 :1
Bore to Stroke Ratio 1.07 :1
Bore 4.03
ST = Stroke 3.75
RL = Rod Length 5.7
Number of cylinders 8
Deck Height (how much pistons come out of the hole) -0.006
Piston Dome or Dish (- for a dome + for a dish) 6
Compressed Head gasket thickness 0.045
Cylinder Head Chamber Volume 60
Static Compression Ratio 11.57 :1
Dynamic Compresion Ratio 8.45 :1
Rod to Stroke Ratio 1.52 :1
Bore to Stroke Ratio 1.07 :1
Trending Topics
10-24-2007, 04:33 PM
#8
On The Tree
iTrader: (14)
Join Date: Mar 2007
Location: Central IL
Posts: 156
Likes: 0
Received 0 Likes
on
0 Posts
I guess I should note that my figures assumed a genIII motor with a 3.898 bore and 4.0 stroke. I see LT1Birds given figures for a genIV motor with a 4.03 bore and 3.75 stroke which will effect both SCR and DCR by about .1 equally compared to a genIII bore.
There is a calcutator in the stickies that is easy to use and will allow you to tinker and get your desired results by changing gasket thickness and chamber volume.
There is a calcutator in the stickies that is easy to use and will allow you to tinker and get your desired results by changing gasket thickness and chamber volume.
10-24-2007, 07:08 PM
#10
TECH Apprentice
Thread Starter
iTrader: (50)
Join Date: Jun 2007
Posts: 359
Likes: 0
Received 0 Likes
on
0 Posts
2000 LS1 block
bore 3.905
stroke 4.0
rod 6.125
piston 6 cc relief
gasket to be determined (would like to use .040)
deck height unknown, assume -.006
cam 238/240 .605/.609 on a 112 Comp grind (no advance ground in)
cylinder head 60cc
bore 3.905
stroke 4.0
rod 6.125
piston 6 cc relief
gasket to be determined (would like to use .040)
deck height unknown, assume -.006
cam 238/240 .605/.609 on a 112 Comp grind (no advance ground in)
cylinder head 60cc
10-24-2007, 09:10 PM
#12
On The Tree
iTrader: (14)
Join Date: Mar 2007
Location: Central IL
Posts: 156
Likes: 0
Received 0 Likes
on
0 Posts
ST = Stroke 4
RL = Rod Length 6.125
Number of cylinders 8
Deck Height (how much pistons come out of the hole) -0.006
Piston Dome or Dish (- for a dome + for a dish) 6
Compressed Head gasket thickness 0.04
Cylinder Head Chamber Volume 60
Static Compression Ratio 11.80 :1
Dynamic Compresion Ratio 8.60 :1
Rod to Stroke Ratio 1.53 :1
Bore to Stroke Ratio 0.98 :1
10-25-2007, 06:20 AM
#14
On The Tree
iTrader: (14)
Join Date: Mar 2007
Location: Central IL
Posts: 156
Likes: 0
Received 0 Likes
on
0 Posts
I would be happy with it. You will be stuck using premium, of course. But with the quench you'll get from that .040 gasket you should be in pretty good shape.
Keep in mind though, with a DCR that high, if you ever decide to switch to a smaller cam you will probably have to pull the heads to change to a thicker gasket, or possibly different heads too. If you never plan on switching cams you'll be fine, but a 224/224 cam WILL require a head change, a 232/234 would only require a thicker gasket.
I realize since you're a stroker a smaller cam probably isn't going to be an issue, just some food for thought.
Last edited by Thorny; 10-25-2007 at 06:31 AM. Reason: add info
10-25-2007, 12:27 PM
#15
TECH Apprentice
Thread Starter
iTrader: (50)
Join Date: Jun 2007
Posts: 359
Likes: 0
Received 0 Likes
on
0 Posts
Yes I was thinking about that. I dont think I would ever go to a 224. Maybe a 232/234, but that should just take a gasket change. Thanks again!
Still undecided on heads. I think I am going to past on the PRC 225 Darts. Heard on too many possible issues. I wish I could afford the AFR's. Any ideas on a second choice?
Still undecided on heads. I think I am going to past on the PRC 225 Darts. Heard on too many possible issues. I wish I could afford the AFR's. Any ideas on a second choice?
10-25-2007, 04:58 PM
#16
On The Tree
iTrader: (14)
Join Date: Mar 2007
Location: Central IL
Posts: 156
Likes: 0
Received 0 Likes
on
0 Posts
Yes I was thinking about that. I dont think I would ever go to a 224. Maybe a 232/234, but that should just take a gasket change. Thanks again!
Still undecided on heads. I think I am going to past on the PRC 225 Darts. Heard on too many possible issues. I wish I could afford the AFR's. Any ideas on a second choice?
Still undecided on heads. I think I am going to past on the PRC 225 Darts. Heard on too many possible issues. I wish I could afford the AFR's. Any ideas on a second choice?
I'm plenty happy with my Patriot 243's. A little over $1300 shipped gets you upgraded valves, springs, retainers, seals and chambers milled to your request. I'm not sure it gets much better for the money. If you've got the money AFR or T.E.A. Trick Flows are excellent products.
10-25-2007, 05:33 PM
#17
12 Second Club
iTrader: (13)
Join Date: Feb 2005
Location: Gateway International Raceway
Posts: 1,575
Likes: 0
Received 1 Like
on
1 Post
Assuming .006 out of the hole and a .060 gasket, I'm getting a SCR of 11.23 and a DCR of 8.20
Same deck and .040 gasket gets an SCR of 11.78 and DCR of 8.58
Looks like those heads would work great to me, the deck height isn't going to effect you to much, you have quite a bit of wiggle room with your gasket choices to make up for it. This was also assuming a 112 ICL, but that only changes your DCR about +.1 per degree of advance with that cam.
Same deck and .040 gasket gets an SCR of 11.78 and DCR of 8.58
Looks like those heads would work great to me, the deck height isn't going to effect you to much, you have quite a bit of wiggle room with your gasket choices to make up for it. This was also assuming a 112 ICL, but that only changes your DCR about +.1 per degree of advance with that cam.
