A518 gear lock for dyno?

[young_gun17]

93 LE d350
I stopped in at the dyno shop here locally and asked what the procedure was for a dyno run. He said for an auto I need to find some way to keep it locked in 3rd gear and let it idle all the way down and then stomp it and let it accel all they way up to get numbers. he said if it shifts into second then the numbers wont be right. Is there any way to keep it in 3rd on my 518? I want to get base numbers before I start my build.

 

[cerberusiam]

Not 3rd gear, OD. Direct drive will not get you solid actual numbers, not enough load on the engine. Mystery switch grounded on the OD sense wire and it will lock it into OD. Ride the brakes to get as much boost up as possible at around 1700 rpms, give them a nod to start the capture and wood.

 

[young_gun17]

Not 3rd gear, OD. Direct drive will not get you solid actual numbers, not enough load on the engine. Mystery switch grounded on the OD sense wire and it will lock it into OD. Ride the brakes to get as much boost up as possible at around 1700 rpms, give them a nod to start the capture and wood.

Where is the sensor wire located? By mystery switch you mean run a hot wire to a switch and run it to the sensor wire? And the guy told me to let it idle all the way down and stomp the pedal until it tops out. Are you saying to have my boost built around 1700 rpm before engaging the dyno?

 

[cerberusiam]

There is a 2 wire connection on the transmission almost right above the rear cooler line attachment. It has 2 wires, a slightly larger one that should have 12 volts on it when the key is on. the smaller one is the OD sense circuit the PCM grounds to activate OD. Tap into the smaller wire with a scotch lock then run the wire to switch and the other side of the switch to ground. Activating the switch grounds the circuit activating the OD solenoid which activates OD.

You need fuel to make boost and that will take some rpm to get boost up enough to override the diaphragm spring to allow full fueling. Run the rpms up enough on the rollers to get the trans into OD, flip the switch, start braking and feeding throttle till you have a balance and boost is staying around 10 psi. Hopefully you can get that balanced out around 1700-1800 rpms to start the run. The graphs will give you an idea of the TQ the tuning is capable above in the normal operation range 1800-2100 rpms, and total HP at the poijnt the governor starts shutting the it down.

You are looking for a base line to start making changes from, but, you have to be able to get full fuel at the start of the run or it skews the numbers jut like trying to dyno in 1:1 ratio. Assuming you will be using a DynoJet they typically cannot load a diesel engine enough to get comparable numbers so you have to help it out to get useful chart.

 

[Gumby79]

If possible post up the results . Ive been trying to find a chart of a stock 1st gen. Aswell as BSFC ( brake specific fuel consumption) curve if that can be gotten.
3-4 shift 32.5 - 60mph
Thanks in advance.
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