Now that the warm weather is here, I want to start with the bombs. But before I do I want to do a stock baseline run on a Dyno so I can document my changes. There is a guy with a Dyno near me but he really only does ricers, mostly Hondas.

How do I run a 4x4, dually, diesel, auto on a dyno????

Do I need to remove the outer wheels to run on most Dynos?
How do I actually run it, I know I want to stay in one gear without shifting during the run so should I run it in third (OD off). If I do this how do I start the run at a low enough RPM without downshifting when at WOT? Is it more accurate to run with a mystery switch to keep the TC locked up in a certain gear? If I install the TC lockup switch will I be able to make the run in any gear I want?

I have done dyno runs before but it was with a standard tranny ('87 Thunderbird Turbo Coupe) so this Diesel, Auto thing is new to me and I want to make sure I do it right. Let's hear it from those dyno gurus. Any other hints and comments welcome!!

 

Sidewinder where are you located? There might be someone on this site that can help you with a better location. From what I’ve heard those ricer dyno guys don’t like our trucks, too much torque.
About the mystery switch, it won’t lock in just one gear. Here is a link that will explain how it works and how to use it. I would be VERY CAREFUL using that on a stock torque converter. The setup for your truck is in the second half of the page.
http://www.tstproducts.com/tranny_install.html

For more info on the dyno you can PM DavidTD in this post. He runs a dyno. And would be most qualified to answer any questions.
https://www.dieseltruckresource.com/...threadid=40260

 

BillG

Thanks for the links! I don't think this guy will mind me running on his dyno, and I'm sure the price will be right. I don't have the mystery switch installed and don't really want/need to put one in yet, I was just wondering if it would help on the dyno.

Someone here must have run one of these things on a dyno and have some ideas.

 

i'm in the same boat as you sidewinder ... haven't dyno'd yet but will asap ... from my meager understanding of our trannies i believe you would want to start the run in OD after lockup (about 70mph on my truck) ... if you do it in third you will still have slipping from the third gear clutches ... in OD lockup you won't have to worry about clutches slipping ... can't remember where (gettin' old and have the kids runnin' around me right now ) but i think on DTT's site it stated that in OD lockup the clutches are just "going along for the ride" ie there is a mechanical lockup ... hopefully someone with a greater understanding will confirm or correct me here, whatever you find out let me know

 

That is why I'm asking. If I am going to do the run in OD lockup I will have to:

1)Not start the run at full throttle to avoid a downshift or TC unlock (kind of defeats the purpose of a dyno run)

or

2)Start the run at about 1900 RPM in OD lockup (only get to check the HP/torque from 1900-2700RPM).

From my driving on the street this is how my trans would shift.

 

You are correct in that you will want to run in OD.

You are also correct in that unless you have a lock-up switch you should start your run at around 70mph with 3.5x gears. This is how all of the auto's are done to prevent a downshift.

If you have a lockup switch you can lock it after the shift into OD then let the truck slow down to 1500 - 1600 and it won't downshift. Just remember to unlock the TC before you stop the truck on the dyno.

Your peak HP will probably be somewhere around 2700 rpm and peak tq around 1600 or so.

If you have any questions, I'll do my best to answer them.

 

spoke with Stefan @ DTT today, he said to just rehook the lockup switch for the dyno ... i've had it unhooked since the DTT ... haven't needed it since ... now i've just got to get a biggerer turbo

 

Thanks for the help. Thats exactly what I wanted to know. I will wire in a lockup switch if only for the dyno run. I promise I will never ever use it again on my stock tranny.

My other question was will I have to remove my outer training wheels to run on the dyno (I do not know what model dyno it is). I saw one of those "Hot Rod" shows on TV and when they dynoed a dually they removed the outer wheels. Why???

 

i have run my truck on two different dynos, i did not have to remove the out side duals on either one. but they were less than a 1/4" off the ground. mike

 

Probably the most common dyno is a Dyno Jet 248 and most likely what you will be running on. If the operator takes his time he can get the inner edges of the outside tires on the rollers. IF not and the tires are aired up properly, he can leave one of the outside tires off the drum and therefore above the floor with the other three on the rollers. The only time I have needed to remove an outside tire was on a F350 with six 44's. Tire sidewalls were too soft and the tire off the dyno roller would lay on the floor.

If my memory is correct, the dyno jet is 84" roller width.

Don't forget to report back your numbers.

 

Sometimes even with a TCC lock up switch the tranny will kick down to 3rd. I run 2 lockup switchs, one for Tcc and one for overdrive. I only normally use them on the dyno and can pull all the way down to about 1200rpm like a manual tranny. Gives plenty of time for the turbos to spool. Last dyno I got 62lbs same as I get on the street. Lots of smoke at the bottom though. Tim

 

hmm, my tranny won't kick down out of od at all (with mystery switch) ... even to the point of stalling the truck, buddies '01 is the same way

 

Like I said it is only on some trucks. Mine will drop to 3rd at about 1600 rpm if you floor it with the converter locked. A friend of mine who has a 02 it will not. There was a posting on the tdr about it a couple months ago. Some have the problem some dont. Mine will never drop below 3rd gear with the converter locked so it will stall if I try also. Just shifts 4-3 locked than back up 3-4 locked. Tim

 

whew boy!
how hard does it hit when it shifts down during wot?
bet it puts that billet input to the test

 

It hits hard and I try not to do it thats why I put the 4th gear lockup lockup switch. Had a problem recently with my forward drum seal and it was going from fluid 2nd to 4th lock up if I coasted in 4th gear. You want to feel a hard shift? Glad I had put the billet input and hub in. Tim