Well...I first want to say the people at the dyno shop I went to were great and went out of their way trying to get good results.

That said, it was a dynojet inertia dyno with a 4000lb roller. They didn't have an optical tach because they normally only dyno cars. I knew that going in which means no RPM...which means no torque readings. If you look out the back door of their shop you see where I work. I figured I'd give it a try.

Well just getting the truck, which was sitting up on a 4 post lift, to back up onto the rollers was a task. It was spinning the roller with the rollers brake engaged. We had to rachet the truck up onto the roller and then run 2 straps in the front to keep it on there.

Once it was there the guy was trapped in the truck because of the post and we decided to just let him make the runs. This in the long run wasn't a good idea. Not that he wasn't capable to do it, he just didn't know the truck and how it boosts/shifts/defuels etc. Like sitting me in a plane and telling me to test it

So. We start and the 1st run is like 150 hp. Ummm..no. I let them make a few more runs and then I ask about the boost. He says it's going to like 17 and dropping off fast. I can see the truck is just whipping the roller up really fast and defueling. I tell him I can get 24-25 on the street. We talk about the roller weight a bit and I tell him to go to about 30-35 really slowly, lift on the pedal and get the trans to shift into 3rd and hammer it. More runs..he's getting the hang of trying to get the thing to load a bit and we get to 21psi. Never got higher that that. Also the rpms were flying up to 3000 and defueling, I never see more than 2600 driving. Also the EGT were real low.

Results after 15! runs. 186hp. Not a happy camper because I could see the thing was running like a free rev sitting in the driveway. It would boost up and just whip the roller from 35-55 and the truck would be almost like a free rev and defuel.

If you plan on dynoing your truck find a shop that does diesel trucks, or a shop with a load dyno or that has the ability to apply load to an inertia dyno. Some of the newer dynojets are capable of this now. Also make sure they have the optional optical tach that plugs into the dyno's computer stack (been researching )

The cool thing is they only charged me the 3 run $75 fee. With is fine with me. It was a learning experince for me and them. Everybody should be paid for their time regardless. I also let him take it for a drive to see the difference. He came back and I could see that he understood what I was talking about.

Now I need to find another dyno to get some real results.

Den

 

Looks like you paid $75 for nothing, you have any more money laying around that you don't want?

 

You want to run it in overdrive on the dyno. That's the only way to get a good enough load on the engine.

But you're right, the dyno doesn't load the engine anywhere near the way the truck can load it. When I dynoed EGT was low as well.

 

DEN check southeast power systems theres one right here in tampa im pretty sure they have a dyno and they specialize in diesel trucks they have a website but i dont have it right off hand

 

I have a Southeastern Power over here in Ft Myers. Don't know if they have a dyno or not. Have to check.

Den