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View Full Version : Anyone ever measured the COG of their V8 gbody?



rking
05-14-2008, 10:16 AM
Just wondering if anyone has measured the center of gravity of their V8 g-body. All we have complete here at the shop right now are turbo regals :) , but on my personal car, which is in a million pieces, Im going to be running an iron block 402 with 4l80e.

Im going to figure out the COG of one of the turbo regals, and see if I can come up with some creative calculations to figure out what Im needing, but if someone else has the info, I would really appreciate it for comparison! TIA

jackfrost
05-16-2008, 11:33 AM
i'm interested in this is as well...

i saw a method for measuring CG by using corner scales while level, and again while the car is at an angle. alas, I do not have corner scales.

rking
05-20-2008, 09:49 PM
http://www.longacreracing.com/articles/art.asp?ARTID=22

David Pozzi
05-20-2008, 10:03 PM
You can do it at a truck scale. A commercial truck scale will do it cheaper if you don't want a certified weight. Try a local yard that sells rock and gravel, they weigh the trucks as they exit, or try a landfill. Just put two wheels on the scale, and jack up the other end as high as it will go and measure how high it raised, then weigh the whole car. It works far better if you can freeze the suspension that is placed on the scale. Substituting a piece of all-thread rod for the shock works or a supersized turnbuckle.

jackfrost
05-21-2008, 06:13 AM
wouldn't you also need to weigh the front half at level, to get the split?

rking
01-06-2009, 08:21 AM
Im going to bring this back... Im sure that someone has measured their COG at one point or another. Im trying to get some more numbers together before I start building my 3 link rear setup... TIA

terryr
01-07-2009, 10:28 AM
The quick assumption is the height of the cam. [in a V8 with one cam]

rking
01-07-2009, 07:52 PM
But for my antisquat numbers, I need to know the location front to rear also...

David Pozzi
01-07-2009, 09:14 PM
wouldn't you also need to weigh the front half at level, to get the split?
Yes, you need:
the whole car weight
Front weight level,
Front weight rear raised as high as it will go.

To get a more accurate weight, the front suspension should be locked via a "solid shock" arrangement or turnbuckle. If this isn't practical, I guess you just have to live with some error.

rking
01-07-2009, 09:24 PM
Im really surprised that none of these Gbody guys have ever measured theirs... I guess I will have to let everyone know what the COG is when I get my car back together and get it to the scales!

mongoose
01-07-2009, 11:59 PM
try pming mark

Norm Peterson
01-08-2009, 04:27 AM
Excerpted from a NHTSA inertia database spreadsheet. Moment of inertia data deleted. Weight distribution added. Xcg is measured from the front axle line. I'm guessing that the car measured was a V6 model from the weight as I don't have any VIN decoding info handy.

Year . . . . . 1978
Make . . . . . Pontiac
Model . . . . . LeMans
VIN . . . . . 2D27A8P609390
Drive . . . . . RWD
WB . . . . . 108.0
Front Track . . . . . 58.1
Rear Track . . . . . 57.7
Ht . . . . . 55.0
Wt . . . . . 3300
Xcg . . . . . 49.1
Zcg . . . . . 21.6
LOA . . . . . 200.0
Weight Dist . . . . . 54.5 / 45.5


Norm

David Pozzi
01-08-2009, 10:15 AM
Here is a great info page with online CGH calculator: http://www.longacreracing.com/articles/art.asp?ARTID=22

terryr
01-13-2009, 09:55 PM
That's the same link as post #3 above.

David Pozzi
01-15-2009, 06:28 PM
Sorry, guess I need to slow down and read before I post!
David