My DCR Calculator - If you have a Comp grind, it doesn't get any easier than this...
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Joined: Dec 2001
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From: Bergen County, NJ
Originally Posted by pianoprodigy
Well, from what I've read, Patrick G recommends 8.8:1 as the "limit" on 93 octane; however, if your combo works and you were able to run good timing with no knock retard, then you're fine. I imagine the midrange power and low-end response feels phenomenal on your car with that "small" cam, great DCR, and high velocity runners on the AFRs.
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From: Tampa Bay Area, FL
Originally Posted by LS1Formulation
When you bring the calculator up it lists "0" for piston dish on a stock LS1. As far as I know, LS1 pistons have valve reliefs in them which would account for at least 2-4 cc's . When I put 3 cc's in it gave me 10.01:1 . Just thought I'd add that in there. Correct me if I am wrong.
Joined: Apr 2006
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From: Grand Rapids, Michigan
And no, I haven't seen a stock LS1 piston. These engines are still new to me and I have yet to have one apart. I was just trying to account for the discrepancy between what most people say these engines have for compression (10:1) and what the calculator shows (10.37:1)
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Joined: Apr 2006
Posts: 1,875
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From: Naperville, IL
it doesn't work. I entered my cam specs, and it said DCR is N/A. got it on the manual calculator tab, but it kept giving me a +4 advance value, not the value I entered.
oh well, good try though!
edit:
going off the lobe specs worked, but going off what the cam doctor gave me (my EXACT specs, with decimals and everything) did not work.
any chance you can change that so anything I enter works?
oh well, good try though!
edit:
going off the lobe specs worked, but going off what the cam doctor gave me (my EXACT specs, with decimals and everything) did not work.
any chance you can change that so anything I enter works?
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Joined: Apr 2006
Posts: 1,875
Likes: 1
From: Naperville, IL
the smaller the intake lobe I used, the higher my DCR got. however, I know that a bigger intake lobe is going to make more power, so I've come to the conclusion that DCR is not the definer of how much power an engine will make. It makes sense. a 454 with 9:1 compression is still going to make more power than a 350 with 11:1 with all other things equal. likewise, a 346 with a 8.8 dcr with a 216/228 isn't going to make the same power as a 346 with a 8.1 dcr with a 236/242, all other things equal.
but this does help maximize what we all have and I am very glad you came out with this!
but this does help maximize what we all have and I am very glad you came out with this!
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DCR is a direct calculation of how much actual compression occurs after the intake valve closes. The reason DCR goes higher and higher as you go to shorter durations is because the intake valve is closing earlier. What you've seen is the exact reason why SCR needs to be higher to get better performance when going to a longer duration cam. It seems the greatest benefit is on the low end, but getting the proper SCR for the cam you select will improve power all around.
Said another way, a max effort cam like the MS4, which is still designed for cam only clearance, leaves a pretty low DCR. It works well up top simply as a result of the durations used, but it still only acheives a 7.67:1 DCR in a stock LS1 - a full point off of optimal for 93 octane pump fuel. Use 240/242, .649/.610, 111+2 in the calc to see for yourself.
Now use a .040 thick gasket and mill the heads enough to get 57cc chambers (a lot, would definitely require notching the pistons, so add 2cc for the piston dish) and you'll see a 11.8 SCR and 8.69 DCR. That setup would rock all the way around, and still make even more power on the big end.
Said another way, a max effort cam like the MS4, which is still designed for cam only clearance, leaves a pretty low DCR. It works well up top simply as a result of the durations used, but it still only acheives a 7.67:1 DCR in a stock LS1 - a full point off of optimal for 93 octane pump fuel. Use 240/242, .649/.610, 111+2 in the calc to see for yourself.
Now use a .040 thick gasket and mill the heads enough to get 57cc chambers (a lot, would definitely require notching the pistons, so add 2cc for the piston dish) and you'll see a 11.8 SCR and 8.69 DCR. That setup would rock all the way around, and still make even more power on the big end.
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Joined: May 2006
Posts: 631
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From: Metairie, LA
Can anyone help me with calculating DCR on an LT1? I don't know much, if any of the vital info. I have flow #s, but no cc's on my GTP LT4 heads. Don't know bore, stroke, head gasket thickness, cylinder head chamber volume, etc...I'm trying out ideas for a custom cam. Thanks for any help.
holy cow
i think i found why my car is a dog
7.60dcr
what is the difference between the ls1 and ls6 numbers. if you put in the same info(head cc and all ) the ls6 still comes out higher
i think i found why my car is a dog
7.60dcr
what is the difference between the ls1 and ls6 numbers. if you put in the same info(head cc and all ) the ls6 still comes out higher
Last edited by 1BADAIR; Dec 31, 2006 at 10:59 PM.
Ok , say I go from a 246 248 114 to a 246 248 110+4. How would that cam do on a 200 shot?
or should I go with say a 238 242 or something
or should I go with say a 238 242 or something
Last edited by 1BADAIR; Jan 7, 2007 at 05:54 PM.
Awesome calc. Any reason it is protected? I tried to move the part where you enter cam specs to the DCR page to make it easier to "play" with and it is locked. Mind posting the password?
Thanks.
-Geoff
Thanks.
-Geoff