Honestly I didn't think you did, but I got an e-mail from somebody asking why I was picking on Quad?!?!? Told him I wasn't, but even if I was, Quad can hold his own.

That's what I've been looking for. I've found at least three different methods for converting TQ to HP, but none for the other way.

 

Wouldn't you be able to reconfigure your formula and come up with the calculation for TQ from HP?

Torque x RPM / 5252 = HP

HP x 5252 / RPM = Torque

 

in the start of this thread you guys were looking for a tach. signal. i read in another thread that there is a clean tach signal bundled with those"courtesy wires"under the dash, that ford runs through the fire wall. the other post said it was the pink wire under the dash with the other wires and it was put there to help with installing a remote start...dont know, but it might be worth checking out.

 

It's a similar formula, but slightly more complex. You need to determine what rpm you produce peak torque at. In the computer at B-D, it's 2100. You measure the hp you're making at that rpm, multiply it by some constant number, and divide the answer by 2100 to determine torque. Since the formula calls for you to multiply by a constant, and divide by a constant, the formula could be simplified a lot by merely multiplying by one constant. I reduced the equation, and found the simpler version of the formula. Then, I sat and played with trying to find a simpler formula altogether, using a number of different dyno slips from different trucks, and found that since the power curve of all the trucks I used in my sample, (all were pre-99 models), a decent approximation can be arrived at by multiplying your peak hp by 1.8-1.9. All the trucks in my sample fell within that range. Using that crude formula, my truck makes 290hp X 1.85 = 536.5ft/lb at the rear wheels.
Using the B-D formula, and my crude formula, all the trucks in the test group had resultant answers within a few ft/lb, regardless of mods, etc.
One variable that wasn't included in the test group was a truck with a different turbo housing. The power curve is steeper in the midrange for a truck with a 1.0AR housing, so the crude formula wouldn't be as accurate for my truck as it sits now.

All this is assuming that the formula that Brian gave me was accurate for Powerstrokes. At least it gives you someplace to start.
I hope you find this somewhat useful.

 

Back to the tach wire, I pulled mine from the block of wires under the hood, its a big block looking thing on the drivers side valve cover. I believe the wire is kind of goldish/yellow. Truck is at my friend house now, i can look tomorrow and give an exact #, or at least be more specific.

 

I PERSONALLY OWN A DYNOJET DYNO. It is a mobile chassis dyno. The way you get a tac reading off of a diesel motor is to place a peice of reflective tape on the harmonic balancer. You then place a pickup sensor that looks at the balancer and every time the motor tunrs over it reads it. The pickup plugs into the computer, if your speed shop has the pickup that is. Any questions go to www.dynotex.net or call me at 940 - 902 - 3445. I will be happy to answer any dyno questions. Bryce.

 

That's the way what I consider my most accurate readings have come. Evidently there are other ways, but I still consider that one to be the most accurate.

Will a 172" wheelbase fit on the mobile dyno? I know a guy up in Springfield MO. that has one, he's pretty sure my truck won't fit.

 

Dont worry, I have a full size F-350, 4-door long bed dually and it fits. It uses up every bit of trailer but it does fit, although you have to take off the outer set of tires to make it work. If you want I can get pictures of some full size trucks that have been on it so far.