DCR numbers

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The claculators I use do it at .050. This does technically skew the result a little, but I feel it gives me a little cushion and it removes the variables of the take up and closing ramp design differences between lobes. Others want the actual IVC point.
 
moper said:
The claculators I use do it at .050. This does technically skew the result a little, but I feel it gives me a little cushion and it removes the variables of the take up and closing ramp design differences between lobes. Others want the actual IVC point.
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well it really tanks my numbers if i go seat to seat, obviously, down to like 7.45... from @ .050 of 8.37
 
Yup. plus, different grinders use different places (in terms of lift) as the actual closing point, and have different rates of take up andd closing speed. KBs calculator avoids this by simply saying "add 15°". I've found that being pretty close. Whose cam are you playing with?
 
moper said:
Yup. plus, different grinders use different places (in terms of lift) as the actual closing point, and have different rates of take up andd closing speed. KBs calculator avoids this by simply saying "add 15°". I've found that being pretty close. Whose cam are you playing with?
Click to expand...

its the erson solid flat in my slant... i think my springs are gone and was thinking if i have to pull it to change i might as well get a final comp increase...

but here are the specs...

3.480 bore
4.125 stroke
6.7 rod
static is 10:1
IVC @ .050 is 51 and seat to seat is 67
no boost
2K elevation

all we have is junk 91 so i need to be able to street drive it even though i have 100octane leaded in it most the time... so i want at least an 8:1 if not 8.4
 
Well, by the KB one, you're at 66° to input... What is the chamber volume and gasket thickness?
 
The elevation will hurt you too. With no work to stop detonation, I use 8.25 as a maximum for the pump fuel we have here. I'm at sea level, and have 10% ethanol fuel. You could advance the cam to help, but I think something smaller, or a jump of 3/4 pt of static will help. Play with the closing point by reducing the figure by 4 or 8°. Whatdoes that do for it?
 
moper said:
The elevation will hurt you too. With no work to stop detonation, I use 8.25 as a maximum for the pump fuel we have here. I'm at sea level, and have 10% ethanol fuel. You could advance the cam to help, but I think something smaller, or a jump of 3/4 pt of static will help. Play with the closing point by reducing the figure by 4 or 8°. Whatdoes that do for it?
Click to expand...

changing it to 60IVC it went up to a 8.27... same gas but 2K elevation most of the time (corrected with DA) but as high as 4 in the summer...

and i was thinking of that 3/4 pt increase...
 
It's a big move. My own feeling is once you have to move the cam more than 4° you need a new cam, but I know the slants are not quite so blessed with options.
 
moper said:
It's a big move. My own feeling is once you have to move the cam more than 4° you need a new cam, but I know the slants are not quite so blessed with options.
Click to expand...

yea its already from a 106LSA installed at 102... but i was looking into a 1" lifter cam with a 246@ .050 but .550 lift... but would still have the same issues...

so it looks like it could really use 10.5:1
 
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