Does anyone have the web adress for the compression calculator? I tried a search on the web but get different answers on them for Static and I cant find a good dynamic compression calculator. Need to figure out what thickness head gasket I need for my new motor.Thanks!

 

how about this one http://www.kb-silvolite.com/calc.php?action=comp

 

Post all your data and I'll post your compression ratio calculation. If you want an excellent tool for doing this take a look at Performance Trends Compression Ratio Calculator.

 

You do not need a calc to find that out. gasket thickness is related to quench and piston deck height (in or out of hole). That should be more the concern.

But just in case, here is a link to a good SCR/DCR calc from the advanced tech section.

https://ls1tech.com/forums/advanced-...readsheet.html

 

Thanks, I tried this one but it gave me a really weird reading for DCR so must be doing something wrong

 

Its a stock stroke, 3.903 bore, 6.125 rod, -3.2cc valve releifs, 62cc chambers. Trying to figure out if using a .040 gasket will get me to 11:1 compression or if I need to mill my heads. Cam is a 235/240 112+4

 

Here is your SCR with the information your provided.
Assumptions:
1. 0 piston to deck height, supply piston compression height for a more accurate calculation
2. Head gasket is a Cometic .040/3.910

I need advertised cam duration numbers to calculate DCR . I wouldn't worry about DCR , it doesn't mean anything.

 

DCR is what will determine your probability of detonnation according to fuel octane used. Meaning that you need to keep an eye on it. It matters more than SCR.

 

I'm sorry but I don't believe in the DCR myth. No one can establish an absolute method for calculating it, nor is there any quantifiable data to establish ANY correlation between DCR and ANYTHING. It's just another specification that can be used as a reference point, but that's all.

 

So true dont worry too much about DCR. I am running 8.8:1 DCR and most people would say its not possible. Runs fine on 92 octane. Maybe thats why I'm getting 114% volumetric efficiency at 3600 rpm

 

Yeah right. I run 12:1 SCR and 9 DCR on 93 octane but 26* max timing with TR6 plugs.
Any more advance and it detonates. If I run race fuel mix, I can go another 2* with no issues.
So I guess you guys do not believe detonnation exists either.
The thing is it is not the same for all motors (depending on chamber design, quench etc...) so I do agree that there is no real rule of thumb, but there are limits which you do not want to cross.
One important aspect of running high compression and controling detonnation are cam specs, and the valve event to watch is IVC.
Late IVC will fight of knock better than early IVC cams. The ratio of the cylinder volume at IVC over the volume above the piston at TDC represents the dynamic compression ratio. That is the corrolation of DCR/octane and detonnation.
That is why I designed my cam with 49 IVC and that I have little issue even in hot weather.
224/222 making 463rwhp of neck snapping throttle response (370cid)

So yes DCR matters.