Help with DCR
Thread Starter
TECH Resident
Joined: Aug 2005
Posts: 980
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Help with DCR I am trying to finish up my 434 ls7 but ive come to an inpass with my DCR vs quench.
I have a zero decked ERL 434
4.155 bore
-3.0cc dished pistons
factory volume heads (70.0cc)
and a katech torquer 116 cam
ideally for quench i need to run a 0.041 head gasket but that brings my SCR to 11.82:1. I am not exactly sure what that will bring my DCR to with this cam because im not sure how to calculate it but i believe its close to boarder line for running 91 octane pump fuel. Can anyone help me calculate the actual number and then I can determine what to do. Currently i have a set of 0.051 head gaskets with 4.16 bore making my SCR a little under 11.6:1 but that leaves my quench high. Is 0.051 too high?
I have a zero decked ERL 434
4.155 bore
-3.0cc dished pistons
factory volume heads (70.0cc)
and a katech torquer 116 cam
ideally for quench i need to run a 0.041 head gasket but that brings my SCR to 11.82:1. I am not exactly sure what that will bring my DCR to with this cam because im not sure how to calculate it but i believe its close to boarder line for running 91 octane pump fuel. Can anyone help me calculate the actual number and then I can determine what to do. Currently i have a set of 0.051 head gaskets with 4.16 bore making my SCR a little under 11.6:1 but that leaves my quench high. Is 0.051 too high?
TECH Junkie
Joined: Dec 2005
Posts: 3,092
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Exactly, you need to know the specifications of your camshaft in order to calculate your DCR. With my setup I have been running a DCR of 8.5 and 91 octane gasoline. My SCR is 11.2:1. With 93 octane you could go a little higher. There are other things to consider such as a cold air intake and how hot your motor runs.
Thread Starter
TECH Resident
Joined: Aug 2005
Posts: 980
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yah i understand i need to know the closer degree of the intake valve but i dont have the cam card in front of me. was kind of hoping someone knew it. I have seen a thread about the DCR of the 110 LSA version and it gives a 9.1 DCR with the factory compression of 11.0:1 and 9.7 with 12.0:1. is 0.051 quench too high?
Thread Starter
TECH Resident
Joined: Aug 2005
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269/2 = 134.5-(116+4 advance so 112?)=22.5+180=202.5...269-202.5=66.5 IVC
that give it a 8.7 on factory SCR of 11.0:1 AND 9.15 on mine of 11.58:1
I would run it. If you're that worried, maybe you could retard the cam a couple degrees, delay that IVC and probably make a little better power up top with minimal loss in the low end.
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Thread Starter
TECH Resident
Joined: Aug 2005
Posts: 980
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That was kind of what i was thinking, katech says if u retard the cam the 4* thats built in you trade about 5hp for 5tq, id then be running 0.041 quench which seems a more universally accepted number and my dynamic comes out at 9.0:1. I have 93 octane here and will probably run E85 on it when i can but i never know where i will end up and want to be able to run 91 octane if i have to
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