JD - Turbo vs naturally aspirated engines

[burnetma]

I had the same exact question. I have the opportunity to buy a 5420 MFD power reverser, but I really want a turbo charged engine for all of the reasons list. So I am doing more research. According to the Nebraska tests:

5520
rated HP = 76.24
Peak Torque = 236 @ 1289
Max Torque Rise = 41.5%
Torque Rise @ 1900 = 35%
Fuel consumption at rated HP = 4.61 GPH or 0.428 lb/HP-hr

5420
rated HP = 65.44
Peak Torque = 204 @ 1094 RPM
Max Torque Rise = 42.5
Torque Rise @ 1900 = 23%
Fuel consumption at rated HP = 4.28 GPH or 0.445 lb/HP-hr

My calculations show 5520 vs. 5420:
HP difference = 16.5%
Torque difference = 15.7%
Fuel economy = -3.8%

Based on this data, at ~ 1200 feet above sea level, the machines seem to be very equal performs when normalized against peak output. It looks to me that you are getting what you pay for when you step up to the 5520, 15% more tractor.

All that said, I still want the turbo, but....

Can anybody else out there shed some light on this subject???

 

[BarryinMN]

Previous posters are spot on.

One thing that was not discussed was that 5420 depending on age & warranty may have a mechanical pump that can be turned up 5-10HP. It is still not a turbo but may be enough to get you over the hill without reducing power train reliability.

The Tier II engines have EGR systems with more sensors to reduce NOX and turbos to bring the power back.

Another point to consider is in 18 months low sulphur fuel shows up which has slightly less BTU content. If your operations use all the power of the tractor you may notice a peak performance drop. Our local refinery in Hastings, MN has stated when they switch over the high sulphur wil be NLA. /forums/images/graemlins/grin.gif