I dyno'd today for the first time at a place called Hawks Third Generation in Easley, SC on a dynojet. The guy builds custom street race cars so he was interested to see what a diesel pickup would do . . . so was I. He couldn't measure torque because he didn't have the optical pick-up. He told me he would get one and let me come back to check the torque for free. I thought that was cool. Anyway, with everything in my sig my truck did 336HP to the ground. See the attached file. It's a pic of the printout from my Droid so I apologize for the quality.

Questions:

1 - I'm running the old 4.11 software on level 7. I thought my truck would do way more than 336HP running the 130HP tune. I still have the stock lift pump. Do I have a fueling issue? Do I need more fuel (like a Raptor 150) to see the full benefit of the Smarty?

2 - The guy wanted to know about the fuel/air mixture reading since it was way different than the gas cars he dyno's?

 

I don't know that sounds about right for what I'm reading you have. Last time I dyno'ed I had 375 rwhp and 710 ft. pds. trq. with the jr on SW#3 and that was before I got the Gorend installed.

 

You should be able to push it up to 420-450 unless your LP is totally shot.

How did you make the run? What gear and did you load the engine up before starting the run?

Most Dyno Jets will need the heavier weights to even come close to loading a diesel engine enough for valid readings and even then you have to load it with the brakes to start the run.

If you don't make the run in OD you will never see adequate numbers, not enough load on the engine.

 

The guy did the runs in fifth gear. I always heard that you dyno in direct drive. Should he have used sixth gear? I didn't notice him loading the engine using the brakes. He just ran through the gears until fifth and then rolled on the throttle.

 

Thats how you dyno a gasser and that works for them, not with a diesel.

A diesel is load dependent and will not fuel anymore than is needed to accelerate the load at a predetermined rate. You have to load them hard, over fuel, and trick them into outputting full power.

A 1:1 gear ratio in 5th will load the engine enough to get much more than a 60% load. You need to get into 6th then work the brake and throttle to get the boost over 12 psi and the turbo spooled to start the run or you get numbers like you see.

The operator was wondering about fuel\air ratio and thats what is happening. You start with about a 40:1 mixture at an idle and need to get that down under 20:1 to get full power. The only way to do that is load the engine till it must add more fuel to accelerate.

These CR's have all kinds of fuel management built into them until certain paramters are met. Even the Smarty does not completely over ride them until you get a race type tune. Normal defuel starts at 1800 rpms, at 1600 you are almost 50% defueled. The ECU will not allow full fuel until boost breaks 12 psi and wheel speed is over 5 mph. All emisisons controls.

Best results is build as much boost as possible while holding the rpm between 1700-1800 rpms using the brakes then start the run and data capture. Once you have the steps down you can make changes then do things the same way again to see what happens, particularly what the TQ and HP curves do in response to the changes. Just remember to you need to do the runs the SAME way every time and in the same general conditions to see differences.

A dyno is really a tuning tool to see if you are going the right way with mods and you have to remove as much of guess work as possible with the steps of the run. Your actual numbers may not be as important as the trend you see as you make changes, but, without a solid baseline it is still largely guess work.

 

Thanks. I'll let the guy know next time. I should be going back soon to measure the torque. I'd like to get some realistic numbers next time. Again, thanks for the responses.

 

I don't want to hijack this thread, but it sounds like there's some knowledge and experience with running diesels on dynos.

A local garage got a (mustang, I think) dyno a few months ago and they are very familiar with running gassers on them, but I was the first diesel to go on the rollers. They couldn't figure out how to hook it up to get tq numbers and HP seemed really off too. They (clamped?) onto multiple places, but no success. The other issue was that I have an auto tranny, so it kept downshifting under accell & load.

Any tips on what they were doing wrong...is there another part they needed to hook up to diesels? Also, how can you get a good reading on an automatic?

I have a bully dog GT (plugged into obdII), so they couldn't plug into there. I could unplug the bully dog, but than I can only get the stock numbers.

 

A Mustang dyno is totally different than a DynoJet type. It is more of a load tester than accelerometer like the DynoJet. If they are running a lot of gassers on it its a DynoJet probably.

The optical pickup needs to read the crank and get a signal to get TQ readings. HP and TQ are both calculations based on rpms, wheel speed and acceleration. As far as hooking the dyno up, I drive and let the dyno crew do that. I don't drive, I don't dyno.

An auto is hard to get good numbers because they will downshift under 70 mph and you simply cannot load them hard enough to get a solid baseline. The cure for that is a TC lockup switch. Once your in OD on the rollers flip the switch to keep the TC locked. Unless you have done some different mods to the VB locking the TC will not allow the trans to drop out of OD. In that case you need 2 switches, one for OD and one for the TC.

 

I had my 97 on a dyno (mustang) one time and I won't bother doing that again. The operator had to try several different types of runs before it was obvious (by watching egt) that it really put a load on the truck. Craig

 

I dyno a lot on a Dynojet dyno. I've never had any issues at all. My numbers speak for themselves as well as the many graphs I've posted. If you think it will dyno different on a load dyno then find a Dynojet load dyno 224 and dyno it on there and then go back to the 248 and see the difference. There won't be one.

Your lift pump probably isn't helping you out any. A lower setting on the Smarty would have likely made more power on the dyno with your setup. Your truck stock would have probably been in the 230 ish range. What was the correction factor on your runs? That too is misleading and can cause a big difference in the results. Most people compare corrected numbers but if you got a run that wasn't using a correction factor then that could make up quite a bit of power difference. Corrected runs will always show more power unless you excede the "ultimate" atmospheric conditions set forth by the SAE when they developed the equations for correction factors.

 

I own a Mustang dyno. Just bought it this past November. I threw my truck on there when we first got it to learn the software and did 359@ 789 torque on level 3 on a quadzilla but my trans had an issue. On the dyno we use autotap to get all the info from the truck and we give weight of truck and the system measures humidity, temp, etc to give a fairly accurate reading and applies a load to the truck. When I do decide to make tie to fix my trans il throw her on there again and do a 1/4 mile simulation.