Engine/Transmission (1998.5 - 2002) Dyno ????? - Why boost so low and no high EGT's?

[hammersley]

OK - when I'm on the street I can get 38 lbs of boost and if not carefull 5x5 will get into danger pretty fast on all out go pedal. I went over to http://www.TorqueFreaks.com and ran 431 HP and 808 Ft Lbs BUT I couldn't get the boost above 26 AND the pyro never got above 1000! It wasn't loaded properly IMO. I was running in 3rd ( No OD) and Triple Disk Locked up Manually - I could tell it wasn't working hard. They added 25% brake and no difference. They specialize in rice rocket's so I'm not sure they are up to speed on Diesel's - but they have have ran a couple dozen or so - including RIP's. No my question - are these numbers real world, I mean rolling a roller isn't the same as running a truck - or else the boost and temp would go up... ... how do I get some real world numbers?

 

[DavidTD]

In most all cases, you should run on a dyno jet in top gear. In most all cases you will see more tq and about the same hp as in direct. There are exceptions.



Recently I ran a truck with BIG tires in OD and didn't like the results. I re-ran in 3rd and got more hp but less tq. During the 3rd gear run, I saw 4 pounds less boost. 40 instead of 44, but more HP.



There are ones that say you must load these trucks to get a valid number. This IMO is not always the case. More boost doesn't always mean more power too. I have proven this time after time.



So, in a nut shell, I think your HP is pretty close (not knowing what 2. 4's are rated at) but your torque number low. Closer to in the 900's. One truck I can compare is a 24v with comp and BD IV's (120hp) on a stock 35. 425/9xx, in OD.



Good Luck,

 

[Tcolesanti]

In every case I have ever seen (I have run quite a few cars on a dyno but I've never seen a diesel run on a dyno in person), you always run in your direct gear. Automatic/ 4spd/ 5spd/ 6spd, does'nt matter, always run in your direct gear. Never have I heard of someone running in overdrive/ or underdrive on a dyno.

 

[RustyJC]

I made 4 consecutive Dynojet runs on March 13th to test the "direct versus OD" theory. 2 runs in 5th (direct) gear netted 320 BHP and 650 lb-ft torque. 2 runs in 6th (OD) gear netted 347 BHP and 762 lb-ft torque.



Some of this is a unique situation due to my 4. 10 gearing, but the numbers are the numbers. Whatever the final drive ratio, the engine has to work harder to accelerate the drum in OD than in direct, right?



Rusty

 

[StakeMan]

My truck has always been dyno'd in OD.