This thread is confusing me.
What kind of dynamometer was Dallas Mustang using? The reason I ask is because the Dynojet actually measures horsepower, then calculates backwards to graph torque, using the formula
torque = hp * 5252/rpm
The Mustang brand chassis dynamometer, otoh, measures torque and calculates to hp, using the formula
hp = torque * rpm/5252.
Engine dynos are the same, measuring torque and calculating hp.
So if Dallas Mustang was using a Dynojet, it makes no sense for them to have reported torque and to have no idea about hp.
Confusion number two is about this 4th gear stuff and lockup stuff. Dynojets should be run in 3rd gear, or whatever gear is closest to 1:1.
A lockup torque convertor will not lock up when under acceleration, and it will only lock up in top (4th) gear. So again it makes no sense to talk about lock up in connection with a dyno run. It seems like people are confusing stall speed with lockup. Stall, or flash, is the point at which the driven turbine in the convertor begins to move in response to the driving turbine's motion. The same TC will have varying stall speeds according to vehicle weight, final drive, traction, and engine torque. A really high stall TC makes it hard to use a Dynojet, because the driving turbine is moving so much faster than the driven turbine through most of the engine's rpm range -- meaning that the wheels aren't spinning the drum, and it's the acceleration of the drum vs. E.T. that produces the hp numbers with the Dynojet.
Third, this "divide torque by .8" to get hp has no basis in fact. It will coincidentally give a correct result at about 6500 rpm, because 6500 rpm is equal to 5252 divided by 0.8. I think this poster is confusing the rwhp to fwhp conversion formula. Assuming a 20% drivetrain loss, you would divide rearwheel hp by 80% (0.80) to get flywheel hp.
Fourth, if your hp and torque curves are graphed with rpm as the "x" axis, if the hp and torque curves do intersect, it will ALWAYS be at 5252 rpm. That's because at 5252 rpm, the conversion factor of rpm/5252, or 5252/rpm, will equal "1," and 1 times hp equals 1 times torque.
Fifth, a gas engine's peak hp will almost never occur at the same rpm as its peak torque. So even if you used the correct conversion formula, hp = torque * rpm/5252, plugging your peak torque number into the formula will almost never give you your peak hp. Looking at the conversion formula, and realizing that torque typically falls off steadily as rpms rise, you can see why. As an example, an engine that makes peak torque of 300 lb-ft at 3000 rpm but loses 50 lb-ft by 5500 is making 171 hp at 3000 rpm and 261 hp at 5500 -- 90 more hp on 50 fewer lb-ft. As long as the rise in rpms exceeds the fall-off in torque, hp will rise. Peak hp occurs when the fall-off of torque exceeds the rise in rpm, when the engine's breathing, cam, and compression ratio just can't make any more cylinder pressure. This typically occurs about 1500 to 2500 rpm north of the torque peak. So it's crazy to talk about calculating peak hp from the peak torque number.
Now what was the original poster's question again?