I have fixed a nagging error in the VE/DCR calculator that I needed to look at for a long time. I needed to convert angle to radians for excel to calculate properly. I had accidentally pointed a cell at the rod length instead of stroke, and I was missing a bracket that was causing a square root to be taken early (threw off the order of operation). So, anyhow, the sheet is broken up into several sections.


EDIT : [link removed, site down] I have uploaded it here as a .zip file

This is my quick and dirty VE calculator sheet with a few add ons:

Sheet 1 - compare two cams (forum post) this was an attempt to put _ in there to keep the spacing right on when posting specs on the forum. I have found a better way now is to use a fixed width font like courier which does the same thing without all the ___. This sheet compares two cams side by side so you can see how they stack up.

Sheet 2 - Compare 4 cams. No underscores in this one. It simply compares 4 cams instead of 2.

Sheet 3 - VE's. Shows where 93 pony was putting a lot of his cams compared to other folks. This was realy there as a reference for me when looking over some cams.

Sheet 4 - Single Cam. Valve Events for one cam.

Sheet 5 - Compare two cams. Compare the valve events, etc... for two cams.

Sheet 6 - Quick and Dirty Cam/SCR/DCR Calculator Spreadsheet. This sheet takes all the cam math and combines it with a bunch of other engine math like DCR and SCR, along with header length math to help you in optimizing your combo, or to give you the details on your combo.

Sheet 7 - Compare DCR. This allows you to compare two motor combos to look at Valve events, dynamic compression ratio, and header length and see where you want to be, or what you're going to end up at with a change...


I'll add sections as they warrant. Anything folks want added, or math they have / want to see.

 

AWESOME MAN!

Thanks for doing this up!

 

I dig this stuff. Very interesting. Neat ways you can manipulate various cam grinds to give you the same desired intake closing points and overlap. It's just a matter of moving things around. I will bookmark this so I can use it to better choose my next cam.

Thanks. Good homework.

 

Why does it keep asking for a user name and password? I tried to save it but could not

 

I don't know. I just tried D/l ing and it worked fine. I can mail it to you if you can't download it.

 

OK, works now. I was opening it, and then trying to save it, and it asks for the info.

 

TTT for new forum

 

Wow, that spreadsheet is pretty damn useful. Any word on whether all of those formulas still apply with the changing times (changing mindset to bigger bore engines, bigger cams, etc).

 

This is still the best spreadsheet I've found for cam timing, and calculating SCR and DCR. Thanks J-Rod.

 

its saying my 468 needs a 2.7" header tube. something tells me its not quite accurate on that one.

 

Great to have all this stuff in one place! Most of the results approach my 'reality check' values, with the exception of intake runner length. The results (e.g. 5"), are about 1/3 of what they should be. I looked in Bell's book, but the formula must be from elsewhere...

 

Does this account for the piston being out of the hole or not. I remember a while back I was trying to play around with excel to get it to do so, but I suck in excel.

 

I didn't have a problem with the piston comming out of the whole but for some reason in mine it does not look at the piston volume no matter what you enter. My solution so far has just been to add the dish and combustion chamber volume (or subtract if you have a dome piston) and go about it that way. From the calculators standpoint I don't see why this would alter the numbers in comparison to correctly entering piston dish and combustion chamber sizes in the appropriate places.

 

Do you have to have Excel to run this program? For some reason I don't have it in my computer and this sheet won't work. If so, where do I get it?

 

find someone who has microsoft office, or buy microsoft office (too expensive if you dont used atleast part of it on a daily basis) You can also look for it on a file sharing program.

 

I believe the piston volume issue is fixed. I had been playing around with one part of the sheet and had fixed values instead of looking at that field. When you change it now, it works. If anyone has a problem, or has other math, etc... you want me to add, post it up, and I'll try to integrate it.

I'm still working on the bottom of the sheet where we get into velocity/runner length/etc...

 

I was running the DCR on a solid roller and have a question. For the advertised duration numbers, they are taken at .020" not .006" for a solid roller according to Cam Motion. They use .006" for hyd. rollers. Will this affect the output of the spreadsheet? Cause I'm getting some bizarre numbers for header length/primary size and a seemingly low DCR. Thanks.

 

How do we find the specs for a particular cam at .006 and .200 so I can use this spreadsheet? Also does it matter what type of lobe it has, is it important in order to use this?

 

Great stuff guys...

I did notice a problem though. When you go under the tab "Compare DCR" there is no formula in cells B42 and G42, clearance volume. This should be the same as in B42 of the "DCR" tab, which is =SUM(0.7853982*(B17^2)*B21) (and for the G column, just substitute G for B in that formula.

If this isn't fixed, it will throw off the SCR and DCR values in this tab.

 

Which book did you pull these equations from?