I realize this is probably a dumb question,but figuring its about time I put my truck on the rollers.I went and talked to a local machine shop owner that has chassis dyno (that I have had do machine work on gas motors in the past for me),about put my truck on the dyno.During ower conversation he asked me what it would mile in hour at,I told him close to 130 (speed limiter raised to 150 and Ive seen 120 and climbing).He then said you mean in overdrive,because you absolutely can,t dyno in overdrive,you,ll break the trans.I then explained that I got a full billet DTT with triple disc coverter.He still wasn,t convinced.Keep in mine were I live is definately not diesel country,so this is new to him,and I have never been on the dyno myself.So I believe I know the answer but for all of you with actual experience do you or dont you dyno in OD with an auto,because that I,m aware of on the third gens you cant lock out OD other than to put in second (and ya I know sticks dyno in 5th not 6th but what about autos).Thanks for your responce.

 

I can lockout OD, so its drive for me.

 

OK, I wont bash him since he is new to diesels...

Dyno in OD. Bring the truck up and let it hit OD with the converter locked. Start the run around 60mph and have him load the dyno to make sure you have around 10-12psi before you start the run. Some trucks need more load and higher speed (say 70mph with a heavy load).

If he doesnt have ability to load the truck, you can drag the brakes with your left foot to get the boost up before you start the run.

 

Wow that was fast.Other than using brake thats about what I was thinking.Ya I asked him about how much he could load it (since I have a 62/71/13 over a S480 that will hit 70 psi on the street)and he told me he could stall a 400 hp gas car on the dyno.thanks again.

 

If you don't dyno in overdrive the dyno won't load the truck as much and you'll get less boost. When I dyno'd my truck last it will hit approx. 52psi on the street but would only hit about 45 on the dyno.

 

heck that gasser might make 300lb/ft..you do that at idle. Just have him load it when you are at 60-65 until you hear the turbo light and see some decent boost. Have him leave the load on for the whole run.

 

What kind of dyno should be the first question...

I personally don't need to drag the brakes to hit within 1-2 psi of street boost on a Dynojet...

 

Have him leave the brake on for the whole run also, that will help the load and you will drive right thru it. Stall a diesel on dynoJet type dyno, THAT is hilarious.

You will be lucky to get enough load to see what you do on the street but try it and see what happens.

Unless you start the run over 70 mph you may not be able to keep the trans from downshifting. They all react a little different so you may need a lockup switch to start the run aroung 55 or 60.

 

I have never dyno'd either so Im clueless on how to.

 

I thought you dynoed with od off and in lockup?

 

Nobody said I was trying to stall the truck on the dyno,just get enoph load to make boost.And the tow/haul doesnt lock out OD just changes shift points.

 

Sorry, on your truck it locks out OD.

You won't stall the truck, thats what we are laughing about. A Dynojet type dyno is nothing more than an glorified accelerometer used to tune gas engines. It has neither the capability or design to efficiently measure the type of power a diesel is capable of making. For that you would tune the diesel engine on a load type dyno like a mustang.

As I pointed out before, you will more than likely need a TC lock switch to keep it OD.