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How to dyno a diesel?

7.1K views 8 replies 7 participants last post by  JustinD  
#1 ·
Ok, so I don't know much about how a dyno actually works, so bear with my ignorance here. The local performance shop I use has a dyno, but has never dyno'd a diesel before. He says he can get the HP numbers only, not the TQ. If I remember right, it's because he doesn't have a way to read the RPM like on a gas. Anyway, he said if I could find out how to get the RPM that he would do it. So I guess what I'm sayin is HELP!!!!! lol. He has the only Dyno that I know of around here without driving to Tulsa or something. So if anyone knows what needs to be done so I can get all my numbers, I would appreciate it.
 
#2 ·
I think, and this is a big if, there is a kit you can buy from the dyno manufacturer to run diesels. The dynojet kit allowed for rotory and diesel engines. It was basically an optical pickup and stick on targets. The targets went on the crank pulley and the optical pickup counted how many times it sees the target. Thus you get RPM's. Again, this is all from memory and only applies to dynojets. I haven't gotten to play with one in several years. The local shop bought one to do rotory engines and it would also do diesels.

Later,
Stephen
 
#3 ·
I've never been on a dyno either but have seen them at shows etc. What do you do with a manual? Put it in 4th for a 1:1 ratio? What about an automatic? Do you run up in a 1:1 ratio? How do you get lockup if your not in 5th lockup with the Allison? Just curious as I have no idea the right way to do it. :)
 
#4 ·
You really need a load cell dyno for a turbo'd motor, I ran on a dyno jet made 10psi less boost and no where near as much exhaust heat, DynoJet= no load.
 
#6 ·
I made several runs on a Dyno Jet, T/H mode holding it in 4th gear made about 30 hp less than T/H mode 5th gear. I guess that comes back to the load issue. Regardless of the actual numbers, I now have a baseline to see how any new improvements have worked.
 
#7 ·
I gotta try the 4th gear method, should it make more or less??? I dynoed 458 on a DynoJet and 425 on a Mustang.
 
#8 ·
I've only been on a dyno jet. I used an EFI live tune from othrgrl to lock the truck into 4th gear. The dyno jet didn't load my truck enough though. I only hit 24-25 psi on the dyno and I hold 32-34 psi at the track.
 
#9 ·
Typically this Mustang dyno yeilds lower hp numbers than Dyno jet dynos