Dynamic compression ratio on engle W100 & W110?

[APPLEGREENVW]

Where can I find info on DCR on W100 & W110 engle cams?


http://vwparts.aircooled.net/Engle-W100-Type-1-Camshaft-1-1-or-1-25-Rockers-p/e6100.ht

W100, Use a compression ratio of 7.5-8.25:1 *Is this static or dynamic?

W110, Use a compression ratio of 8-8.5:1 ""
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[vwracerdave]

ACN suggestions and recommendations are static.

To get a true dynamic CR you need many measurements to calculate. Most of the internet calculators are for water cooled engines and not accurate for aircooled engines.
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[jfats808]

[ac509]

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[fivelugshortaxle]

[clonebug]

[fivelugshortaxle]

[fivelugshortaxle]

Show me how and why something doesn't work....not just conjecture. Until then, I'll keep doing it.
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[clonebug]

Here's a compression calculator for ya.......

http://www.rbracing-rsr.com/compression.htm

Plug in my numbers.......It's even a W100 cam

7.8:1 static
22.7 lbs. boost....
110 ft. ASL

23,000 miles and counting.....How many miles you got on that 2276????
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[fivelugshortaxle]

[fivelugshortaxle]

[thesatanicmechanic]

I've always put the cutoff for anything aircooled on pump gas at 7.5. CHTs are nothing to be trifled with.

One day, when we're all rolling around with blue tooth enabled pressure sensitive spark plugs that can upload our combustion pressures to the cloud, the empirical data will be reviewed.

Until then, 7.5 is a pretty good Dcr to work with for those of us that do not wish to burn our shit to the ground.


p.s.

we can easily access 93 octane here on the east coast. I like at least that margin of safety.

[fivelugshortaxle]

Yep. That's the same number by all the reading ive9done that I try to stay under.
_________________
Good things come to those who wait.
2332 with lots of goodies....
Rotating assembly balanced by Brothers VW
4340 84mm crank
AA 94mm p&c' s
Total seal 2nd ring, rest are Grants
5.5 h beams
Magnum straight cuts
Steve Long XR310 on a 106
CB 1.4 rockers
CB Magnaspark 2 distributor
NGK D7ea plugs
A1 lowdown 1 3/4 with single muffler
Dellorto 48's with 40 venturies
Kennedy Stage 2 with Daiken disc

[[email protected]]

[ac509]

i have yet to see a compression calculator (dynamic or static) ask for the cooling capacity or cooling type for the engine.

i don't get out much, so maybe someone can point me in the direction of this "aircooled specific" calculator.
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[Floating VW]

If anyone is old-fashioned like me and doesn't trust the algorithms they use on those fancy online calculators, here are the formulas I use to calculate dynamic stroke (which is then used to calculate the DCR):

•Intake Closing Angle @ 0.050" (ICA) = 1/2Duration @ .050” + Lobe Center Angle – 180
•Crank Stoke (CS) = distance the piston travels from TDC to BDC
•Horizontal Rod Displacement (HRD) = 1/2CS × (sine ICA)
•Rod Distance Below Crank Center Line (RD) = 1/2CS × (cosine ICA)
•Rod Length (RL) = length of the rod from journal center to wrist-pin center
•Piston Rise from Rod Distance Below Crank Center Line (PR1) = √(RL² ‒ HRD²)
•Piston Rise from Crank Center Line (PR2) = PR1 ‒ RD
•Dynamic Stroke (DS) = CS – [(PR2 + 1/2CS) – RL]

note: Both the ICA value written on the cam card and the above formula for calculating the ICA don't always match the true ICA of the cam, so whenever possible, I feel it's better to actually clock the cam to find the true value.

P.S. I mentioned this recently in another thread, but I'll repeat it here: For what it's worth, my DCR is set at about 7.64:1 and I run US 89 octane with no problem, and I have used on occasion 87 octane for brief periods, also with no problem. As a fair warning, my intake ports and combustion chambers are a little different, so these results may not be typical.
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[fivelugshortaxle]