DEF and Regans

[Catchad81]

With most if not all tractors over 75 horsepower now having def in addition to the dpf, these users in the 70-100 hp range, has anyone seen or done comparisons on whether a tractor with only a dpf will regen more then a tractor with bothe def and a Dpf of if their are any performance differences? A Deere salesmen tells me that the def will make the gaps between Regens longer especially when doing light work.

 

[moriboy]

I would not buy a new diesel anything if it didn't have a DEF system. I replaced a 2008 Dodge pickup with a new one, and the number of regens, reliability, and mileage are much improved over the old one.

 

[Bavarian]

That's true.
The reason is, engines equipped with DEF recirculate less exhaust gases, produce less soot which needs to be burned off in the DPF.

 

[MHarryE]

There is a little bit of data on this from Nebraska tests on JD's although not many tractors in the 75 to 100 HP range have T4 interim and T4 final test comparisons.

John Deere 5085 and 5115 have tests of both. Testing was not long enough to measure time between regens; however, the reports state the average time between regens is 100 hours for both T4 interim (dpf only) and T4 final (dpf and scr)

The test reports state they measured a 3% power increase for the 5085 T4 final during regen and a 3% power decrease for the 5115 T4 final. Curious as to whether this is a mistake

The reports show a 1% fuel economy increase for the 5085 final and 2% increase for the 5115 final. Torque backup was 34% for both although the JD literature states one reason for using SCR and DPF togetehr is to optimize enigne performance in transient conditions which I take to be primarily torque backup - when lugging down the dpf will eliminate the soot created in that condition.

So by the numbers, the tier 4 final solution does not appear to reduce hours between regens (according to Deere) and tractor performance is little changed. It will be interesting to see similar comparisons for other manufacturers.