Dyno-What is best method ???

[JVolpe]

I am going to a dyno day Saturday and would like input on what is the best method to use on the dyno(DynoJet in ground).



Last time they did one power brake to spool turbo up and then just WOT through all gears. Then did one with OD lockout think went all the way to third and lockup, then WOT.



I really dont have a clue with the diesel and auto trans configuration I have. Any input would be appreciated.



Thanks,



John

 

[Eric_77]

you need to run on an eddy current dyno that will hold a speed and load the engine thus building boost and tell you real power at the real wheel at a RPM. The old Dyno Jets could not do this you needed a Mustang Dyno, I hear Dynojet has made an eddy current dyno but have not used one yet (I think it is a model 250)



Runs should be made in a 1:1 gear for best results but can be done in almost any gear.



my experince is with motorcycles so we are manuals and no turbos but we run a lot of bikes and have a dyno limit so testing must be very precise and repeatable. The Factory (aka Mustang)dyno gave us much more constant results without the correction factors that Dynojet used that I understand to be a certain amount added back in to actuall rearwheel hp to try and give the engine hp.

 

[JVolpe]

Eric 77



They have a Mustang dyno at the performance shop also, but it is rented out for that day. I may go back on my own later after trans upgrade and use the Mustang.



Thanks

 

[RustyJC]

Runs should be made in a 1:1 gear for best results but can be done in almost any gear.

I think that may vary from truck to truck. In my case, 2 runs on a Dynojet 246C in 5th (1:1) yielded approximately 320 RWHP/650 lb-ft. 2 subsequent runs in 6th (OD) yielded approximately 350 RWHP/760 lb-ft. There are a couple of reasons for this:



1. The higher ratio in 6th means that, for a given dyno roller inertia, the engine is working harder to accelerate the roller. This helps to build boost when the throttle is nailed.



2. The fact that it takes longer to accelerate the dyno roller in 6th means that the truck's drivetrain inertia losses are smaller relative to the roller inertia - more power/torque make it to the rear wheel/roller junction.



Those were my results - YMMV!



Rusty

 

[qzilla]

For what you are trying to accomplish the simple, easy and repeatable thing to do is roll through the gears until you are in 4th or OD and you hear the TC lockup. THis should be around 1600-1800 rpm's and around 60mph. You need to roll into the throttle until you hit about 1900 and by that time you can be on the floor. Then hold it until you govern out. The numbers are very similar to 3rd gear, but it gives the turbo a chance to breath a little. It also gives a better sweep.



Hope that helps.



Quad

 

[DaveMorris]

The ones I have been around (and done) run the auto trucks up to 70mph in OD and then pull from there up to 108 mph. The 48re should stay in OD from 70 up so you can get a good constant reading...



I heard the numbers are better in OD, since the RPM range in to short in a 1:1 setting the engine never gets a chance to level out before it redlines (<-just what I have heard, not actual proof).



Have fun, good luck:



Dave

 

[driverno8]

Keep coming with the comments. I was on a dynojet last weekend. At wot the truck was shifting so hard the sensor was coming loose. I couldn't get any torque numbers. Now I want to go back and run in 5th od off like you mentioned.

 

[JVolpe]

Yes thanks for the comments, they will save me a couple of wasted runs to figure it out. I try to learn something new everyday, it's much easier this way than the HARD way I usually go through.

 

[Gary - K7GLD]

I run my truck both empty, and even towing in the hills in 6th gear - and THAT is where my power to the ground is important to me - and as Rusty said above, the heavier loading in OD will likely work the turbo and engine harder, and give a more accurate reading...