Troy Patterson wrote:
This is just a random graph I pulled up of a drag car launching and making a 1/8th mile pass which shows G-Force. This car was launched at 3000 RPM (with a 1050 on a 406 SBC) and shifted at 7000 RPM. That's 4000 RPM this engine is working.
I happen to know this engine makes peak torque at 5100 RPM with a different, smaller carburetor and peak horsepower at 7000 RPM. Interesting that this drag racer launches 200 RPM below peak torque - isn't it
Makes you wonder what would happen if he launched at peak torque!
As one would expect when launching from a standing start, measured G-Force will be very high initially, then as RPM increases - once the vehicle is under way measured G-Force slowly declines:
Hey, look how uniform the EGT numbers are with that thing reving up
Poorly tuned carburetor / engine aside (and not by me) - the owner stated this poor tune represented the highest G-Force measured from his car at launch (with a Weber Power Plated carb) - clearly he's left a bunch on the table yet still exceeded his own carburetor's performance by an impressive margin.
Back to topic, using the G-Force trace after launch and once the vehicle is in motion, you can choose RPM points or ranges to make comparisons between where and how much energy is present to generate the greatest amount of acceleration. If a person argued wind resistance was a factor, then two points could be chosen within say a 200 RPM of each other so differences in wind resistance would be insignificant.
Some would argue there is a greater amount of stored energy in the engine's reciprocating assembly, flywheel and so forth at a higher RPM and therefore a stronger launch / reduced 60' and ET can be achieved as a result - which would require the engine to already be operating at WOT when the load is applied. If the engine is not at WOT when load is applied, the engine is not producing a maximum amount of torque or horsepower defeating and negating any gains launching at red line for example, is claimed to produce.