[HWYSTR455]

The issue here is the OP is not sure if the engine is zero decked.

Also not clear of the exact head cc.

And, he's contemplating a 4.25 stroker kit now.

Using the Butler calculator:

Stock crank @ .030+, .020 in the hole = 10.15

Stock crank @ .060, ,.020 in the hole = 10.27

Stock crank @ .030, zero in the hole = 10.57

Stock crank @ .060, zero in the hole = 10.70

4.25 crank @ .030, .020 in the hole = 10.42

4.25 crank @ .060, .020 in the hole = 10.27

4.25 crank @ .030, zero in the hole = 10.66

4.25 crank @ .060, zero in the hole - 10.79

The available pistons in the Butler stroker kits are -6 and -22 dish.

4.25 crank @ .060, zero in the hole w -6 dish = 10.99

4.25 crank @ .060, zero in the hole w -22 dish = 9.58

4.25 crank @ .060, zero in the hole, -22 dish, and .027 gasket = 9.81

Either the -6 or the -22 would work, with the .040 or .027 gasket.

If you wanted, you could tone down the cam if you'd like even.

Can sell the old rotating parts to offset the new build as well.


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[steve25]

In post 20 if you’re talking about the piston ring land volume that’s a number that the piston manufacturer has to provide.

In general that distance will never be less then .100” because right there you stand a chance of burning through the top of the piston and into the ring groove itself.

Also in consideration of performance and more so tuning, the closer the ring is to the top of the piston ( lesser ring land volume ) the less fuel that gets loaded into the ring land will be left to come out .
This late source of fuel getting up into the chamber makes for a secondary pressure wave when it lights off, and since it always lights off late Acts just like a detonation spike does .

In short, the least amount of ring land height the better as long as your safe from burn through.

[Jay S]

Diamond recently changed the format on their online compression calculator. Last I knew they still had some inputs labeled wrong on the positive and negative inputs. Double check your numbers if you use it.

[performerrpm]

so when you use summit or butlers calculator...theres nowhere to put in the gasket cc. is it automaticaly calculated based off the bore size and compressed thickness?

it would make sense that it does, because otherwise adding the gasket cc of 9.4 of a 1016 gasket to say a 72cc head makes for a helluva drop.

if it does automaticaly figure it by bore size and compressed thickness it seams like the extra .150 or so depending on bore size could still change just a tad bit

[steve25]

On some gaskets for example like the 1016 and the lesser quality 8518 the opening is not round, it bit oval and such it’s bigger then a formula that assumes that the bore is round and the size of the cylinder.

[grandam1979]

With a .040 gasket and all your other info I get 10.57

[HWYSTR455]

Originally Posted by performerrpm

so when you use summit or butlers calculator...theres nowhere to put in the gasket cc. is it automaticaly calculated based off the bore size and compressed thickness?

it would make sense that it does, because otherwise adding the gasket cc of 9.4 of a 1016 gasket to say a 72cc head makes for a helluva drop.

if it does automaticaly figure it by bore size and compressed thickness it seams like the extra .150 or so depending on bore size could still change just a tad bit

Yeah there is, see attached pic:


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[HWYSTR455]

Originally Posted by steve25

On some gaskets for example like the 1016 and the lesser quality 8518 the opening is not round, it bit oval and such it’s bigger then a formula that assumes that the bore is round and the size of the cylinder.

True, but it's maybe a CC or 3 so.

It's just a rough calculator. Some manufacturers not only provide the compressed thickness, they also provide CCs, and you can pump that into the calc under the head volume to make up for it.


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[HWYSTR455]

Originally Posted by grandam1979

With a .040 gasket and all your other info I get 10.57

Some calculations were made with a 4.25 stroke.

To include all variations is why I posted the list of a number of combos.

Some conversations happen in the background....

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[HWYSTR455]

When calculating SCR before a build begins is an 'estimate' for the most part. Generally, you don't have exact numbers to pump into the calculators until after a number of steps of the build are completed.

If you are outside of your' SCR calculations, the best way to adjust (after the fact) is with head gasket thickness. Choose a mid-thickness gasket when making initial calculations so you have room to adjust after the fact.

Yes, it may impact that oh-so-beat-to-death quench, but again, you can always point out other baseline manufacturer's out the door SCRs/quench and performance that were successful, so it's not a game-changer. Yes, wedge chambers do respond to best quench, but the factor is so minimal it's not a go- no go thing.

The quench factor is becomes even less of a factor when you keep SCR within a 'pump gas range', and most are following that recommendation these days.


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[performerrpm]

Originally Posted by HWYSTR455

Yeah there is, see attached pic:


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i knew it had that, thats why i was trying figure out if it calculated automatically basesd off bore and compressed thickness or if you manualy need to add the 9.4cc of the gasket to the combustion chamber volume since the calculator has no way of knowing if your gasket is 4.2, or 4.3 bore.

[HWYSTR455]

Originally Posted by performerrpm

i knew it had that, thats why i was trying figure out if it calculated automatically basesd off bore and compressed thickness or if you manualy need to add the 9.4cc of the gasket to the combustion chamber volume since the calculator has no way of knowing if your gasket is 4.2, or 4.3 bore.

Yes.


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[performerrpm]

Originally Posted by HWYSTR455

True, but it's maybe a CC or 3 so.

It's just a rough calculator. Some manufacturers not only provide the compressed thickness, they also provide CCs, and you can pump that into the calc under the head volume to make up for it.


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this^^^thats what i was getting around to....say for example....1016 head gasket .039 thick 9.4cc volume with 72 cc heads. would u enter it in the calculator as

4.15 bore
3.75 stroke
81.4 cc combustion ' 72cc head + 9.4 cc '
+8 cc dish
.039 deck
8 cylinders