Dynamic compression question
Dynamic compression question I'm doing some research about dynamic compression and in my searches it seems a dynamic compression of 9.1:1 or lower is needed for pump gas (93). According to the calculator I'm using it seems an F13 with 5.3 heads will yield too high a dynamic compression, yet I see combinations very comparable to this a lot on this board. Tell me if I'm doing or inputting something wrong.
http://www.kb-silvolite.com/calc.php?action=comp
Here are my input values:
Cyl. head cc: 61.15 (stock 5.3?)
piston head cc: 0 (flat top)
gasket: .053 (Fel-Pro MLS per jegs.com)
gask. bore: 3.945 (Fel-Pro MLS per jegs.com)
Cyl. bore: 3.898
Deck Clear.: -.008
Stroke: 3.622
Rod Length: 6.098
IC ABDC: 58 (43 for F13 + 15 per instructions on calculator)
Results: Static Comp. 11.092 Dynamic Comp. 9.267
Let me know what you guys think. Thanks.
http://www.kb-silvolite.com/calc.php?action=comp
Here are my input values:
Cyl. head cc: 61.15 (stock 5.3?)
piston head cc: 0 (flat top)
gasket: .053 (Fel-Pro MLS per jegs.com)
gask. bore: 3.945 (Fel-Pro MLS per jegs.com)
Cyl. bore: 3.898
Deck Clear.: -.008
Stroke: 3.622
Rod Length: 6.098
IC ABDC: 58 (43 for F13 + 15 per instructions on calculator)
Results: Static Comp. 11.092 Dynamic Comp. 9.267
Let me know what you guys think. Thanks.
Last edited by My90Iroc; Nov 15, 2005 at 07:36 PM.
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I think the problem is the calculated IVC spec. DRC is calculated from actual (~'advertised') degrees, and most cams have considerably more than the 30 degree difference between 0.050" and advertised spec implied by the 'add 15 degrees' instruction. I would try to get the actual 0.006" lift/advertised number, or at least look at typical values for the cam company you are using. For example, I just checked a 5 year old CC and 6 year old Crane catalog, and found many hydraulic rollers to have a 50 to 60 degree longer advertised vs. 0.050" duration. Adding say 27 degrees to your 0.050" IVC of 43 would give an IVC of 70, and a DRC of ~8.4:1
Ahh, so that's why it asks you to add 15 degrees to your .050" ivc. Wow, if that is trying to account for advertised ivc then that is way way off (unless it's attempting to account for the valve train deflection yadda yadda yadda which will make the valve close a little sooner then advertised I think). I've been spending alot of time looking at comp solid roller lobes on their site and the most agressive solid roller lobes I noticed (I believe it was the tk series) took 28 degrees to get from advertised to .050" (I did not look at any lobes with more then .390 lobe lift cause of my 1.95 rockers). And this is solid roller stuff where the advertised number is at .020" or so to account for lash, most hydraulic stuff is at .006" and makes the length to get from advertised to .050" that much longer.
If you use J-Rods calculator (which I've found to be extremely accurate), you will see that your dynamic compression is right at 8.5 to 1. Right where you need to be!
__________________
2013 Corvette Grand Sport A6 LME forged 416, Greg Good ported TFS 255 LS3 heads, 222/242 .629"/.604" 121LSA Pat G blower cam, ARH 1 7/8" headers, ESC Novi 1500 Supercharger w/8 rib direct drive conversion, 747rwhp/709rwtq on 93 octane, 801rwhp/735rwtq on race fuel, 10.1 @ 147.25mph 1/4 mile, 174.7mph Half Mile.
2016 Corvette Z51 M7 Magnuson Heartbeat 2300 supercharger, TSP LT headers, Pat G tuned, 667rwhp, 662rwtq, 191mph TX Mile.
2009.5 Pontiac G8 GT 6.0L, A6, AFR 230v2 heads. 506rwhp/442rwtq. 11.413 @ 121.29mph 1/4 mile, 168.7mph TX Mile
2000 Pewter Ram Air Trans Am M6 heads/cam 508 rwhp/445 rwtq SAE, 183.092 TX Mile
2022 Cadillac Escalade 6.2L A10 S&B CAI, Corsa catback.
2023 Corvette 3LT Z51 soon to be modified.
Custom LSX tuning in person or via email press here.
2013 Corvette Grand Sport A6 LME forged 416, Greg Good ported TFS 255 LS3 heads, 222/242 .629"/.604" 121LSA Pat G blower cam, ARH 1 7/8" headers, ESC Novi 1500 Supercharger w/8 rib direct drive conversion, 747rwhp/709rwtq on 93 octane, 801rwhp/735rwtq on race fuel, 10.1 @ 147.25mph 1/4 mile, 174.7mph Half Mile.
2016 Corvette Z51 M7 Magnuson Heartbeat 2300 supercharger, TSP LT headers, Pat G tuned, 667rwhp, 662rwtq, 191mph TX Mile.
2009.5 Pontiac G8 GT 6.0L, A6, AFR 230v2 heads. 506rwhp/442rwtq. 11.413 @ 121.29mph 1/4 mile, 168.7mph TX Mile
2000 Pewter Ram Air Trans Am M6 heads/cam 508 rwhp/445 rwtq SAE, 183.092 TX Mile
2022 Cadillac Escalade 6.2L A10 S&B CAI, Corsa catback.
2023 Corvette 3LT Z51 soon to be modified.
Custom LSX tuning in person or via email press here.
Originally Posted by Patrick G
If you use J-Rods calculator (which I've found to be extremely accurate), you will see that your dynamic compression is right at 8.5 to 1. Right where you need to be!
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Originally Posted by DAPSUPRSLO
Can you post a link to that calculator? Thanks Patrick.
http://users3.ev1.net/~black_ops/cam...calculator.xls
Enjoy
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Originally Posted by Patrick G
If you use J-Rods calculator (which I've found to be extremely accurate), you will see that your dynamic compression is right at 8.5 to 1. Right where you need to be!
that is the one I use....
Originally Posted by Patrick G
Awesome, thanks for that. I didn't think my numbers were correct.
Originally Posted by Patrick G
