I don't understand the point of your question. If you don't count the body, wheels and axels the only thing left is the weights you add to get to 5 oz. The best total weight is still 5 oz but where it is located is the important issue. You want the weights placed to get the center of mass (C.0.M) just forward of the rear axels. A range of 0.6 to 1.0 inches is the target range for best performance. Maybe you can clarify your question.
Are you basing your question on the assumption that you can enter a race with a car heavier than 5.0 oz? Adding weight would add speed but what is the point if you are illegal? I don't know of anyone who has conducted tests of this nature since you could not take advantage of the test results in regular race!
Another comment regarding maximizing weight. Once you get to 5.0 oz the best performers are not there because of weight, it is most likely because they have fine tuned the rail riding technique and minimized friction. Are you rail riding? I have a 39 foot track at home that all my cars are tested on prior to racing. I can tell you for sure that once you have done your best to reduce friction of the axels and wheel bores the best thing you can do is deal with car alignment - your car must run as straight as possible down the track without any deviations due to bouncing against the center rail. There are several threads on this forum that deal with this issue as there are on the PWDproboards forum. You can gain or loose a huge amount of time by the way the car runs down the track. You can't overcome a poor tracking car with adding weight, in my opinion!
What I am trying to ask is my son and I made a car that if you weighed the Body, Axles, and wheels by itself, the weight came up to 1.16 OZ
That gave me the weight of 3.84 OZ of Tungsten weights to use... Yeah... (I thought)
My Son destroyed all the cars at his Pack PWD Race of 40 cars and advanced. Then went to the Regional race got third.
The car made it to the Championship Finals. We placed sixth overall out of 132 cars. The winner had a top speed of 233 MPH.
My question is to win a race at that level. What is the ultimate weight needed?
I thought 3.84 ounces of Tungsten would give my Son a shot.
I agree with CycRunner on this. I think you are just fine with your body, wheel and axle weight. Getting 3.84 ounces of "motor" in your car is good. I would start looking into other areas for improvement...rail-riding, axle prep, wheel prep, com, etc...