need help with dynamic compression ratio

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trbodrt

trbodrt

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Need help figuring out my dynamic compression. Only number i'm not sure of is this, intake Closing Point (degrees)ABDC @ 0.050 lift plus 15 degrees using a comp cams xe275hl, any help would be appreciated.
 
so do i just use the the intake valve closing # plus 15 degrees, that's the part i'm not sure of.
 
I see what you're trying to do now. The number you use is 64 ABDC. Don't use any numbers @ .050 (the valve is still open).

Southernman
 
Southernman said:
I see what you're trying to do now. The number you use is 64 ABDC. Don't use any numbers @ .050 (the valve is still open).

Southernman
Click to expand...

He wasn't going to use .050" figure - KB Silvolite's calculator recommends using that figure plus 15 degrees rather than advertised seat timing. It gives DCR on the high side in most cases, especially if you're using an Edelbrock grind! :toothy7:
 
so as said i should use the # 64 without adding 15 degrees to it.
 
MoparAnglia said:
He wasn't going to use .050" figure - KB Silvolite's calculator recommends using that figure plus 15 degrees rather than advertised seat timing. It gives DCR on the high side in most cases, especially if you're using an Edelbrock grind! :toothy7:
Click to expand...

Well, mate, I must have misread where he stated:

"Only number i'm not sure of is this, intake Closing Point (degrees)ABDC @ 0.050 lift plus 15 degrees using a comp cams xe275hl, any help would be appreciated."

Run your number both ways. , and then verify it once you install the cam.

I'll ask the question I asked yesterday:

Are you running a split pattern cam ?

If no, then you only need to plug in the mfgs advertised duration (not at .050) and the mfgs lobe seperation angle. That's it.

If the cam is a dual pattern then you default to the intake valve closing angle and any advance or retard of the cam measured in CRANK degrees. Therefore, if a cam has 7.5 degrees advance/retard built into it, the number you would use is 15 degree.

And, yes, I've read the cam specs...

I hope this helps.

Southernman
 
Not sure what a split and single pattern cam refers to, is it a difference in duration from intake to exhaust , although i've been working on cars for a bit i'm still fairly new to the performance engine building side of it and trying to learn as much as possible.
 
Sorry trbodrt, heres some info that may help.

Split pattern, or dual pattern, cams translate to different lift values for the intake and exhaust (I.E. 525 on the intake and 540 on the exhaust, and so on).

The specs for your cam indicate it's a "single" pattern cam - both intake and exhaust lift is the same.

I also couldn't help but notice your handle (turbo). Are you planning to use this cam in a turbo application ? If yes, your turbo may not like the 106 centerline... This is a hot little street cam, but it's definitely oriented toward a conventional carb setup.

Just a suggestion.

Southernman
 
no turbo, one was in the works but it feel through. That threw me off because you said earlier that you had read the specs, it makes sense now.
 
trbodrt said:
no turbo, one was in the works but it feel through. That threw me off because you said earlier that you had read the specs, it makes sense now.
Click to expand...

If you use the link to the Wallace calculator I posted...you don't add the 15 deg.
 
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