dinamic compression

[Nacho-RT74]

How good or bad is  03.419 dinamic compression ratio ? ( Unless I'm filling something wrong on boxes )

http://kb-silvolite.com/calc.php?action=comp

[supserdave]

I think you missed a decimal someplace, should be around 8.5-1 or so.

[Nacho-RT74]

ok, then... what's the value I have to fill here ?
Intake Closing Point (degrees)
ABDC @ 0.050 lift plus 15 degrees

rest I have them

bore, stroke, rod lenght, finally got the piston to deck height ( deck clearence ) based on stock unmodifies values as a guess, to get an aprox 0.026 http://board.moparts.org/ubbthreads/showflat.php?Cat=0&Number=3902967&an=0&page=5#Post3902967, piston dish volume, gasket related values and I'm playing with heads volume ( around 75-80 )

[Nacho-RT74]

so?

[aifilaw]

really confused...

if you want us to tell you your static compression ratio, then we need:

bore
stroke
cc's added to the dish
cc's subtracted from the dome
gasket bore
gasket thickness
cylinder head cc's


if you want your dynamic, we need all that, plus the exact specs of the camshaft.. then it can be calculated pretty close.

Or you can run a compression test and we can guess pretty close from psi

[Nacho-RT74]

I'm looking for predictions I'm playing on that calculator with static compresion values between piston to deck clearence and combustion chamber ccs. On that link I'm able to make that and I have got from 9 to 10 static CR values playing. On Moparts thread link, got from a member how to calculate the piston to deck clearence, and KB website provides how to calculate everthing from every number

I went definitelly with MP Cam  http://store.summitracing.com/partdetail.asp?part=DCC%2D4452993&autoview=sku what I know MOSTLY OF YOU don't like ( what is PRETTY similar to the engle  K 58 cam, that mostly of you like, but lower lift factor and able to drive between 9 and 9.5 compression, and I'm on those numbers )

http://kb-silvolite.com/performance.php?action=details&P_id=22

there all values, except I will drive standart bore.

[aifilaw]

Valve lift isn't going to change your dynamic CR in any real way. What does change it is the valve timing, and the reason we don't like the old Mopar Performance cam grinds is that they are just that, "old". There have been vast improvements made by every aftermarket manufacturer over the MP grinds, you will get better power grind to grind in a MP vs anything else on a dyno and on the 1/4, that I gaurantee...

Regardless, I'm still confused as to what question you are actually asking. 9-10 static is a good spot to be on an iron head

[Nacho-RT74]

the question is what I don't know what I'm filling wrong to get what I stated on first reply:

How good or bad is  03.419 dinamic compression ratio ? ( Unless I'm filling something wrong on boxes )

http://kb-silvolite.com/calc.php?action=comp

[aifilaw]

well, I think most of us are confused because 03.419 has nothing to do with compression ratio's....

10:1
10.4:1
10.5235234124:1
yes

03.419 ?? were all clueless what that means

[Nacho-RT74]

well, I think most of us are confused because 03.419 has nothing to do with compression ratio's....

that's what I'm saying and that why I'm asking whats the value must be filled on:

ok, then... what's the value I have to fill here ?
Intake Closing Point (degrees)
ABDC @ 0.050 lift plus 15 degrees

rest I have them

bore, stroke, rod lenght, finally got the piston to deck height ( deck clearence ) based on stock unmodifies values as a guess, to get an aprox 0.026 http://board.moparts.org/ubbthreads/showflat.php?Cat=0&Number=3902967&an=0&page=5#Post3902967, piston dish volume, gasket related values and I'm playing with heads volume ( around 75-80 )

Have you clicked on links I'm posting ?

[Nacho-RT74]

Ok, lets state I'm playing but there is SOME VALUE is wrong, And I think is the:
Intake Closing Point (degrees)
ABDC @ 0.050 lift plus 15 degrees

Piston to deck clearence was provided based on KB piston specs and blue printed Mopar block values. Everything calculated on Moparts board

so, whats the value should be there ?
Again, cam specs are 110º 280/.474, 238 @50

[supserdave]

Why did you type in 238, when you said the intake closing point is 15. I type in 15 and get 9.5.

What heads are you using that are 80 cc's?

[Nacho-RT74]

I said? I didn`t say anything... I just copied and paste what box says to fill. and that's the point. I don't know what to fill there, just filled with duration at 50 cam value

80ccs, not by the moments, I'm using 452 heads what I can mill down up to 80ccs whatever they have. I just posted that value to play

[supserdave]

Intake Closing Point (degrees)
ABDC @ 0.050 lift plus 15 degrees

I used the values you plugged in, but I used the value above that you stated.

[Nacho-RT74]

once again, I'm not stating anything, I'm asking since I have not idea what is that... I'm coping and pasting what does says the box on yellow circle. I thought there should be filled with the Cam duration at 50 and that what I posted ( thats why fill with 238 )

[supserdave]

I got ya know. Not sure what that value is on the mp cams. On the Lunati voodoo we used the closing point was 39 degrees I think.

[Chatt69chgr]

You are going to have to call the cam manufacturer to get that number.  I looked at cam manf websites and never found it.  The Dynamic Compression Calculator being referred to is found on the KB Silvolite (Keith Black Pistons) website.  I called Engle to get the number for their K56.  The guy there was real nice but I never did get the number.  He told me a lot of stuff but never that specific number.  He did say that it was more or less a waste of time to worry about it.  I told him I was looking to build a engine that ran on pump gas and would like to get the best power and a little lope and that I was going to use stock ex manifolds.  He said not to waist my time worrying about the dynamic compression ratio.  Just shoot for around 9.4:1 or so Static with iron heads and that I wouldn't have any problem with the pump gas. 

[aifilaw]

You are going to have to call the cam manufacturer to get that number.  I looked at cam manf websites and never found it.  The Dynamic Compression Calculator being referred to is found on the KB Silvolite (Keith Black Pistons) website.  I called Engle to get the number for their K56.  The guy there was real nice but I never did get the number.  He told me a lot of stuff but never that specific number.  He did say that it was more or less a waste of time to worry about it.  I told him I was looking to build a engine that ran on pump gas and would like to get the best power and a little lope and that I was going to use stock ex manifolds.  He said not to waist my time worrying about the dynamic compression ratio.  Just shoot for around 9.4:1 or so Static with iron heads and that I wouldn't have any problem with the pump gas. 

I'll look at this more in depth later tonight...

but in short, that guy and his advice has the same mentality I really dislike.
Truly engineering an IC engine comes down to common sense, science, math, and finally experience in that order. I've built a couple engine combo's in my time that went on an engine dyno and got an "oh my god... how the hell is that engine making that much torque there and not running on 110 octane?"
And it really came down to turbulence, quench, and dynamic compression.
I've run a 12.5:1 static CR engine on 93 octane without detonation on open chambered 452 iron heads. That's how I made it back and forth to Ardmore, OK (500 miles one way) in my charger twice.
The impossible is achievable.. (granted I wasn't making near the power I could have been, but it ran without detonation)