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Calculated and Dynamic C.R. calculator

folkenheath said:
.049 is not really bad, in the range of .040 at least. And extra quench is not good, you want as close to optimal as you can. Without the close quench it doesn't have the same effect anymore. But I would say you are fine where you are at, it's good you chose the .024 gasket, that was a smart move, it put your quench at .049 instead of .064, which wouldn't of been very good quench. Also, I think your smaller chambers and dished pistons are good for some increase in efficiency, assuming the valves aren't shrouded and your pistons have the quench surface around the piston tops.
Click to expand...

Ya the pistons have some quench surface:

355build011.jpg


I guess I should have decked the block, but my $$ was limited and the machine shop took long enough as it was. Hell if I had the money I would have AFR Eliminators on there instead of the Patriot Performance Freedom series.

Thanks for the help and insight though :waytogo:
 
Chevy305 said:
I guess I should have decked the block, but my $$ was limited and the machine shop took long enough as it was. Hell if I had the money I would have AFR Eliminators on there instead of the Patriot Performance Freedom series.

Thanks for the help and insight though :waytogo:
Click to expand...

No problem, and I think even if you decked the block you shouldn't go under .040 quench anyway, so as long as your head gasket sealed fine and you aren't pinging, you will never feel that .009 in the go pedal measurement, don't worry about it. Have fun with it.

76zimmer said:
Heath I added more info to my numbers above. The deck was cut .010 and a couple other things changed a little as well.

I guess I don't see a need for higher RPM (at this point) The pistons are forged for possible abuse in the future, but I'm thinking 5500 is what I'll shoot for if/when I get it that high for a redline/shiftpoint.

Thanks for checking this out Heath.
Click to expand...

Zim, here are the final numbers I get for your engine...

Number of Cylinders 8
Bore (in) 4.280
Stroke (in) 4.250
Connecting Rod Length (in) 6.135
Anticipated Redline (RPM) 5500
Gasket Volume (cc) 9.7
Piston Volume (cc) 23
Comb Chamber Volume (cc) 119
Deck Height (in) 9.800
Extra Quench Height (in) 0.005
Intake Closing(deg) 60
Boost Pressure (lbs/sq-in(psig)) 0
Volumetric Efficiency (%) 90

Outputs
Cylinder Volume (in3) 57.55
Swept Volume (in3) 6.52
Engine C.I.D. 460
Engine Liters 7.54
Bore/Stroke Ratio 1.07
Connecting Rod Ratio 1.53
Compression Height (in) 1.665
CFM Flow 659
Compression Ratio 9.82
Dynamic Compression Ratio 8.17

And yes it says 460, technically your bore is probably ~.005 thousands over that for piston clearance, and even if you change it to 4.281, then it rounds to 461 CID. Compression differences are negligable, .01 difference or something.

Also, for reference, in the gasket volume line, I was looking for the compressed volume of the gasket in cc, not the compressed thickness. Many times they list the compressed volume, if they don't I just calculate it based on the bore and thickness then on the side column gasket calculator in my spreadsheet.
 
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Heath want to build me a motor hahahaha

My somewhat stockish tbi does just fine I would love to have a big output motor, but for the kinda trails and climbs I do gonna stick to efi. I may do a ls swap soon though :whistle::whistle:
 
jekquistk5 said:
Heath want to build me a motor hahahaha

My somewhat stockish tbi does just fine I would love to have a big output motor, but for the kinda trails and climbs I do gonna stick to efi. I may do a ls swap soon though :whistle::whistle:
Click to expand...

An LS swap would be cool, EFI and 15 degree heads factory.

I like building engines, the only problem is they suck up money and time! If you build one and need some help let me know.

EFI is in my future, I don't know how soon, if it's weeks or months, but I definitely want to put EFI on my big block, just need to save some more funds. Ideally I would like to do it the same time I do the rear suspension since I'll probably have to remove the bed for both of them to get to the fuel tanks and fab the rear suspension.
 
Yeah that looks pretty sweet, but there is still several inches of snow, we can't ride motorcycles! :waytogo:
 
folkenheath said:
No problem, and I think even if you decked the block you shouldn't go under .040 quench anyway, so as long as your head gasket sealed fine and you aren't pinging, you will never feel that .009 in the go pedal measurement, don't worry about it. Have fun with it.



Zim, here are the final numbers I get for your engine...

Number of Cylinders 8
Bore (in) 4.280
Stroke (in) 4.250...4.00
Connecting Rod Length (in) 6.135
Anticipated Redline (RPM) 5500
Gasket Volume (cc) 9.7
Piston Volume (cc) 23
Comb Chamber Volume (cc) 119
Deck Height (in) 9.800
Extra Quench Height (in) 0.005
Intake Closing(deg) 60
Boost Pressure (lbs/sq-in(psig)) 0
Volumetric Efficiency (%) 90

Outputs
Cylinder Volume (in3) 57.55
Swept Volume (in3) 6.52
Engine C.I.D. 460
Engine Liters 7.54
Bore/Stroke Ratio 1.07
Connecting Rod Ratio 1.53
Compression Height (in) 1.665
CFM Flow 659
Compression Ratio 9.82
Dynamic Compression Ratio 8.17

And yes it says 460, technically your bore is probably ~.005 thousands over that for piston clearance, and even if you change it to 4.281, then it rounds to 461 CID. Compression differences are negligable, .01 difference or something.

Also, for reference, in the gasket volume line, I was looking for the compressed volume of the gasket in cc, not the compressed thickness. Many times they list the compressed volume, if they don't I just calculate it based on the bore and thickness then on the side column gasket calculator in my spreadsheet.
Click to expand...

The stroke is 4.00, and the head gasket cc's is right @ 9.7, does the .010 off the deck make a little difference too.
Looks like I'm right at the ragged edge for Premium fuel huh?
That's what I was shootin for.
 
76zimmer said:
Nice Bill, those are Shovel?
Click to expand...

yes sir....my latest little 80"............i'm looking for the pictures of how i cc'd the whole setup using liquid. when you sink valves for valve to valve clearance it changes the compression ratio as you know. i'm at 11.7 mechanical and had to change the cam to make it kick start friendly. she's somewhere around 9ish:1 dynamic (haven't done the math), but the dual plugs help with detonation. this motor doesn't like to sit in traffic, but does love to run.
 
shovelbill80 said:
yes sir....my latest little 80"............i'm looking for the pictures of how i cc'd the whole setup using liquid. when you sink valves for valve to valve clearance it changes the compression ratio as you know. i'm at 11.7 mechanical and had to change the cam to make it kick start friendly. she's somewhere around 9ish:1 dynamic (haven't done the math), but the dual plugs help with detonation. this motor doesn't like to sit in traffic, but does love to run.
Click to expand...

Very cool Bill, I know when I had my ironhead sporty apart I was surprised to see the hemi type combustion chambers.
I dont know what cams where in that engine, but anybody less than 175 lbs could stand on the kicker and not have it go down, I used to tell people if they could start it they could ride it....Only had 2 people get it started before their leg wore out...:haha::haha:
 
bikeshots002.jpg


this isn't my picture, but the use of the burette is the same...water, food coloring and a touch of dish soap to reduce surface tension.....same concept for the piston, drop it in the hole 1", some grease, and fill away....do the math and bingo, EXACT numbers for calculating.
 
Bill, you know if there is any truth to the need to change lifters on an EVO after 50K?
 
there are recommendations, especially dealer service, but you shouldn't "need" to change them.....not like a timing belt "need to change". evo lifters are automotive style. i've seen men ride well over100K and just do a re-ring and hone, same lifters.....i'd definitely pull them from the blocks and inspect them carefully. if the rollers are nice and tight (up and down) move freely and the lifter bores aren't scored or outta round you should be fine. just clean them up.....depends on the cam too, they don't just beat up the valves and springs. i would replace them on a new engine build for sure though. i was using stock Harley B lifters with limiters in stock '84 cast iron blocks in my .617 lift 89" stroker for almost 50K.....and i was street racing and going cross country with it.....at 11.7:1

make sure you check the witches hat (lifter screen) every oil change and you're good to go. i'm putting a complete hi po evo valve train in my shovel this spring...........use this filter for high performance engines, stock too. the tree hugger stuff is a good byproduct too.

http://www.gopurepower.com/#

stick a big screwdriver handle in your ear and listen to the push rods tubes and lifter blocks with it...primitive stethoscope. if you don't hear/feel ticking down there i'd not worry too much......aftermarket push rods should be checked and adjusted periodically too. hope this helps
 
for sure Bill, I got 40K on my 98 right now, and it runs great. I've had it since 15K, and have only used Mobil 1 Vtwin in the engine, the screen is always very clean.
Thanks for the input.
 
76zimmer said:
for sure Bill, I got 40K on my 98 right now, and it runs great. I've had it since 15K, and have only used Mobil 1 Vtwin in the engine, the screen is always very clean.
Thanks for the input.
Click to expand...

sure thing man.........

just pay attention to the front exhaust, that's the one that will usually give a hint first. steeper geometry. i think i'll go start a Harley thread somewhere.....Lounge? what kind of bike you ride?
 
Ugly Violet Pearl Fatboy, which is a Caddy compared to an Iron head sporty though.

I'll follow your thread when you get one going. Maybe even contaminate it too!
 
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