DCR for street?
DCR for street? Hey guys, I searched and couldnt really find what im looking for. From the VE calculator thats on here as a sticky, i entered everything, i came up with a 8.67:1 DCR, will i be able to run 93 no problems and make good power with this? 11.55:1 was SCR, even tho i thought it would be higher, but thats fine. This is on a forged 375ci iron block, with stg 2.5 5.3l heads and ms4 cam. -1cc valve reliefs, 6.125 rods, gm MLS gaskets, jw if i entered anything incorrect of if that looks good! thanks for the help!!
You could but you might have to run reduced timing which will hurt your power. Its the 11.5:1 you need to worry about more than the DCR. I wouldn't run over 11:1 on a street car. I'm running 9.0 dcr on 92 octane but I'm only at 11:1 static compression ratio. Its all in the setup and DCR isn't set in stone limits.
TECH Senior Member
Joined: Mar 2004
Posts: 14,620
Likes: 17
From: BFE
Actualy it is DCR that you look at and yes it is not etched in stone but you have a benchmark idea that way.
To the OP, I would read your plugs to use correct heat range, I would run at least 1 step colder (such as NGK TR6), at your SCR with that cam I would not be worried and premium fuel will be fine.
As for timing on the engine there is nothing set in stone either, you should dyno tune your setup and your tuner will find the sweet spot.
To the OP, I would read your plugs to use correct heat range, I would run at least 1 step colder (such as NGK TR6), at your SCR with that cam I would not be worried and premium fuel will be fine.
As for timing on the engine there is nothing set in stone either, you should dyno tune your setup and your tuner will find the sweet spot.
Actualy it is DCR that you look at and yes it is not etched in stone but you have a benchmark idea that way.
To the OP, I would read your plugs to use correct heat range, I would run at least 1 step colder (such as NGK TR6), at your SCR with that cam I would not be worried and premium fuel will be fine.
As for timing on the engine there is nothing set in stone either, you should dyno tune your setup and your tuner will find the sweet spot.
To the OP, I would read your plugs to use correct heat range, I would run at least 1 step colder (such as NGK TR6), at your SCR with that cam I would not be worried and premium fuel will be fine.
As for timing on the engine there is nothing set in stone either, you should dyno tune your setup and your tuner will find the sweet spot.
listen to this man...DCR is far more important than SCR.
I think the "general rule" is anything above 8.75 is pushing it on pump gas.
Chad
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http://members.uia.net/pkelley2/DynamicCR.html
This is a good explanation of DCR with a calculator download at the bottom of the page.
This is a good explanation of DCR with a calculator download at the bottom of the page.
Mine is coming up a bit high. Im pretty sure all the info is right.
bore 4.0
stroke 3.622
rod length 6.098
static comp 10.9
inlet valve closes at 44* abdc
boost 0 psi
altitude 75 feet (florida)
Here is the cam specs 230 236 .612 .602 111+2 predatorz spec
It comes up 9.84:1 scr. I must be misunderstanding something. Here is the post detailing the cam.
https://ls1tech.com/forums/11501781-post10.html
bore 4.0
stroke 3.622
rod length 6.098
static comp 10.9
inlet valve closes at 44* abdc
boost 0 psi
altitude 75 feet (florida)
Here is the cam specs 230 236 .612 .602 111+2 predatorz spec
It comes up 9.84:1 scr. I must be misunderstanding something. Here is the post detailing the cam.
https://ls1tech.com/forums/11501781-post10.html
Last edited by topher455; May 19, 2009 at 01:56 PM. Reason: sp
im runnin the tr6 plugs, the cam card says 239/242 649/609 111+1, but when it was degreed in it was at 109, which woulda been a 111+2 right? kinda confused here, cuz it will skew your reading if that is different, my deck height is 0 or extrememly close to 0, 4.060 pistons, flat top with a 1cc valve relief, 6.125 rod, factory stroke, gm mls 6.0l gaskets, and the tsp stg. 2.5 5.3l heads, unmilled which the 5.3l heads are a 61.??? cc head correct?? thanks for the help guys its much appreciated!!
TECH Senior Member
Joined: Mar 2004
Posts: 14,620
Likes: 17
From: BFE
Mine is coming up a bit high. Im pretty sure all the info is right.
bore 4.0
stroke 3.622
rod length 6.098
static comp 10.9
inlet valve closes at 44* abdc
boost 0 psi
altitude 75 feet (florida)
Here is the cam specs 230 236 .612 .602 111+2 predatorz spec
It comes up 9.84:1 scr. I must be misunderstanding something. Here is the post detailing the cam.
https://ls1tech.com/forums/11501781-post10.html
bore 4.0
stroke 3.622
rod length 6.098
static comp 10.9
inlet valve closes at 44* abdc
boost 0 psi
altitude 75 feet (florida)
Here is the cam specs 230 236 .612 .602 111+2 predatorz spec
It comes up 9.84:1 scr. I must be misunderstanding something. Here is the post detailing the cam.
https://ls1tech.com/forums/11501781-post10.html
I figured I may have been doing something incorrectly. I was comfortable with all the info up to where it asked for ivc * abdc. I just used the info I had availible to me. I figured with duration in the 230's and 11* overlap the dcr couldn't be that high. I would like to understand what I did wrong though so I can get it right in the future. I assume I messed up the ivc @ X* abdc value correct? Is there a thread or link you could send me to that can explain this? I just used the ivc value I had in the post I linked. Thanks for the help. Im trying.
TECH Senior Member
Joined: Mar 2004
Posts: 14,620
Likes: 17
From: BFE
Use this calc it is very friendly (by pianoprodigy)
http://www.alantripp.com/VE%20calcul...okup%20LS2.xls
Input lobe durations in the .006/.050 and .200
These are your durations respectively: (In the black alphanumeric area)
@ .006 intake (280), Exhaust (285)
@ .050 Intake (230), Exhaust (236)
@ .200 Intake (154), Exhaust (157)
111 LSA, 109 ICL
You'll get 8.40 DCR,
My sheet calculates a bit higher mainly due to the fact that my compressed 6.0 MLS I measured at .052 and not .060 and piston deck height at -.007 (not-.006)
In any case all these calcs are aproximate so yours is in the 8.5 region.
http://www.alantripp.com/VE%20calcul...okup%20LS2.xls
Input lobe durations in the .006/.050 and .200
These are your durations respectively: (In the black alphanumeric area)
@ .006 intake (280), Exhaust (285)
@ .050 Intake (230), Exhaust (236)
@ .200 Intake (154), Exhaust (157)
111 LSA, 109 ICL
You'll get 8.40 DCR,
My sheet calculates a bit higher mainly due to the fact that my compressed 6.0 MLS I measured at .052 and not .060 and piston deck height at -.007 (not-.006)
In any case all these calcs are aproximate so yours is in the 8.5 region.
im runnin the tr6 plugs, the cam card says 239/242 649/609 111+1, but when it was degreed in it was at 109, which woulda been a 111+2 right? kinda confused here, cuz it will skew your reading if that is different, my deck height is 0 or extrememly close to 0, 4.060 pistons, flat top with a 1cc valve relief, 6.125 rod, factory stroke, gm mls 6.0l gaskets, and the tsp stg. 2.5 5.3l heads, unmilled which the 5.3l heads are a 61.??? cc head correct?? thanks for the help guys its much appreciated!!
Use this calc it is very friendly (by pianoprodigy)
http://www.alantripp.com/VE%20calcul...okup%20LS2.xls
Input lobe durations in the .006/.050 and .200
These are your durations respectively: (In the black alphanumeric area)
@ .006 intake (280), Exhaust (285)
@ .050 Intake (230), Exhaust (236)
@ .200 Intake (154), Exhaust (157)
111 LSA, 109 ICL
You'll get 8.40 DCR,
My sheet calculates a bit higher mainly due to the fact that my compressed 6.0 MLS I measured at .052 and not .060 and piston deck height at -.007 (not-.006)
In any case all these calcs are aproximate so yours is in the 8.5 region.
http://www.alantripp.com/VE%20calcul...okup%20LS2.xls
Input lobe durations in the .006/.050 and .200
These are your durations respectively: (In the black alphanumeric area)
@ .006 intake (280), Exhaust (285)
@ .050 Intake (230), Exhaust (236)
@ .200 Intake (154), Exhaust (157)
111 LSA, 109 ICL
You'll get 8.40 DCR,
My sheet calculates a bit higher mainly due to the fact that my compressed 6.0 MLS I measured at .052 and not .060 and piston deck height at -.007 (not-.006)
In any case all these calcs are aproximate so yours is in the 8.5 region.
hmm i didnt know that! well thats ok tho, Mahle said when i ordered the pistons that it was going to be like 11.77:1 with a 62cc chamber thats why i thought it would have been higher but doesnt really make that much difference to me!!
