Static & Dynamic Compression Ratio Spreadsheet

The rear suspension is on hold for the moment while I wait on expert help with the trailing arms... I'll post about that later... so meanwhile I've been tearing down my 454 and planning its rebuild.  More details on the tear down to come, but I've also spent a lot of time recently doing research on compression ratios, static (SCR) & dynamic (DCR), to get ahead on the rebuild plans.  Great info out there, in particular...

• http://www.corvetteforum.com/forums/c3-tech-performance/3489278-camshaft-effects-on-compression-and-vacuum.html  (see post #2)
• http://members.uia.net/pkelley2/DynamicCR.html

There are online calculators for SCR & DCR (https://www.uempistons.com/index.php?main_page=calculators&type=comp&zenid=a1229b3d249362b8d9979e2002c74b87 is one example) but they require re-entering numbers into a webpage.  I got bored with that and wrote a spreadsheet that would give me SCR and DCR.  The DCR in the spreadsheet is based on the 'effective' or 'dynamic stroke' remaining using a cam's published intake valve closing point ABDC and some high school geometry/trig.  The sheet lets you change engine parameters and immediately see the effect on SCR and DCR.

When I started this whole restomod process, I would've never guessed that I would be whipping out some trig to figure out engine design!  Thankfully, as a former engineer and current high school physics teacher I'm pretty comfortable with the math and spreadsheets.  If you're interested in making your own spreadsheet, type in the setup you see in the pic below and then there are 4 equations to copy & paste into your sheet...

For engine CID in cell E3 of the sheet...
copy & paste... =((PI()*($B$3/2)^2*$B$1))*8

For dynamic stroke, that starts in B10...
copy & paste... =$B$1+$B$2-SQRT($B$2^2-(0.5*$B$1*SIN(RADIANS($A10))))-(0.5*$B$1-0.5*$B$1*COS(RADIANS($A10)))
then drag/extend it downwards to get the different values for intake valve closing points

For SCR, that starts in C10...
copy & paste... =((PI()*($B$3/2)^2*$B$1)/(($B$4*(1/2.54)^3)+(PI()*($B$5/2)^2*$B$6)+(PI()*($B$3/2)^2*$B$8)+($B$7*(1/2.54)^3)))+1

For DCR, that starts in D10...
copy & paste... =((PI()*($B$3/2)^2*$B10)/(($B$4*(1/2.54)^3)+(PI()*($B$5/2)^2*$B$6)+(PI()*($B$3/2)^2*$B$8)+($B$7*(1/2.54)^3)))+1
then drag/extend it downwards to get different answers at different intake valve closing points

Hope the spreadsheet helps someone out.  I'm using it as tool to help select an appropriate camshaft for my build.  Let me know what you think!

Front Suspension & Brakes

It's been quite some time since the last post.  Some minor work was accomplished such as restoring the front spindles, hubs, steering knuckles, and rear half shafts.  Nothing too interesting and should've been able to do more over that time, but laziness & work (mostly laziness) got in the way.  Back at it now though and hopeful to have a rolling chassis soon.  Excited to get that phase behind me, so I can dive into the engine next.

The front suspension recently came together...

Some info on what you see in the pics...

• The upper and lower control arms are part of Vette Brakes & Products Performance Plus System.  It was a tough decision on which direction to go here... stock vs aftermarket, and then which aftermarket.  I liked this system for its adjustable ride height and ride firmness, plus appreciated the experience of other users who reported better handling on the road.  It utilizes a dual-mount transverse spring that does away with the coil springs between the control arms.  Coil-overs were an aftermarket thought too, but far too expensive for my overall budget plans.
• Installation of the whole system went fairly smoothly following the directions and using the pictures I took during dis-assembly.  Also having the original suspension partially mocked up immediately after it came off the frame served as another good visual reference.  I did have to do some minor grinding on the bottom of the frame on a small area of the vertical lip where the RH side lower control arm cross shaft fits to get it mounted flush.  These cross shafts are much wider than stock.  Then I touched up the grinded area with POR15.  (yes, the frame is dusty!)

• The system requires you to reuse some original fastening hardware.  Rather than restore every nut/bolt/etc right away, I just tackled each one as I needed it.  This helped me to not get things mixed up or misplaced.  I just used a wire wheel on my bench top grinder to restore them.

• For the upper control arm shims, I cleaned up and put back what was initially there.  This will have to be fine tuned later at an alignment shop.
• For front brakes, I'm using Wilwood 14" slotted rotors and 6-piston calipers fitted for C2 & C3's.  The installation went smoothly just following the supplied directions which was nice since it was another first in a long list of firsts for me on this project.  There is some trial & error built into the process in centering the caliper over the rotor and spacing it far enough way radially, but all the required shims were included in the kit.  My research revealed that the stock C3 braking system is still pretty good even by today's standards, but I liked the reduction in unsprung weight these brakes offer that I read about and the aesthetic is pretty cool too.  I did not get drilled and slotted rotors because some of the research I did showed that the holes can represent a weak spot in the rotor.  Once installed, I measured the rotor runout at ~0.010" on each side after torquing them down with lug nuts.  I'll have to use some shims between the hub and the rotor hat to get that in spec, but don't have any yet so perhaps I'll put that step in a future post.
• The sway bar is not attached because the end links don't quite fit nicely with the mounting points on the lower control arms yet since there is no weight on the suspension.  I'll have to remember to attach those when I get to that point.
• I'm impressed with the overall sturdiness of the components and hopeful it helps improve handling on the road.  The sway bar is 1 1/8" in diameter, 1/4" larger than what came off the car.  The control arms are made from box tubing which should be sturdier than the stock stamped steel.  The cross shafts for the lower control arms are much larger than stock as you can see in these pics...

• I  cleaned up my stock spindles, hubs, and steering knuckles with a wire wheel and then gave them the POR15 treatment with a final coat of Seymour Cast Blast to get the color, being careful to not get any paint inside the hub or on the rotor mating surface.  I put new Timken bearings and races in the hubs as well.  I think the before/after pics are pretty obvious!

That wraps up where I'm at with the chassis as of this moment.  Next post will talk about what's installed in the rear in the pic below along with some rear suspension work.  Thanks for reading!