Modifications To A 400 hp Cat Engine
Posted 28 January 2013 - 10:04 PM
My previous coach had a 275 Cummins which pulled hills just as well if not better than the Cat and got 9 mpg on a 6000 mi trip.
Yes, the previous coach was lighter. My Cat gets 6.5 mpg on a 6000 mi trip.
Also will I have to go to a Cat dealer to have anything done to the engine?
Posted 28 January 2013 - 10:42 PM
Were the two coaches the same weight? Heavier is slower (with same HP) and takes more fuel. Physics is physics
Were they the same HP (producing more HP does require more fuel)?
Were they both compliant with the same emissions standards? Comparing a per-emissions to post-emissions engine?
But, to answer your question, I would start by checking your air filter minder. If air flow is restricted, HP and MPG will suffer on any diesel. Said another way, you can't feed any diesel too much air.
Also, on a hot day with less than 1/4 tank of fuel, check fuel temperature. If more than 10 degrees F more than ambient temperature, consider a fuel cooler (I have used transmission coolers) in the fuel return line from engine to fuel tank. Just make sure you cover it in the winter! But, it is those long hard pulls in the summer that often elicit those "I need more power" issues.
Also, as Caterpillar recommends, be sure to have the initial valve adjustment around 30,000 miles. Valves well out of adjustment affects MPG and HP.
Dianne and Brett Wolfe
2003 Alpine 38'
Moderator, FMCA.com Forums
Chairman, FMCA Technical Advisory Committee
Member, FMCA Long-Range and Development Committee 2007-2009
Moderator, http://www.dieselrvclub.org/(FMCA chapter)
Posted 29 January 2013 - 01:08 AM
Are you driving them the same ?
Was the coach new or a couple years old when you purchased it. Filters, injector pump setup, ECM program, Transmission style and software setup, CAC size, tappet settings, Turbo set up and boost, plus air flow through the engine all come into play.
One could go through the system and get a good shop to check things out to see where you could gain some mileage, no single item will get allot of mpg.
The other is a complete Re-power. replacing the engine with a Detroit 550 and all its required Radiator and CAC changes plus and Allison 4000 transmission might work real good. A friend had this setup installed in his coach and its on its first run. Getting about 18 mpg and all the power one could ever use on a 45ft. coach / 50,000 lbs or so, but at a price.
Note received later this AM, MPG is now 20+. Running the Grapevine at 75 mph.
Re-power also requires the use of DEF fluid. Your current set up is Pre. 07 or 2010 EPA. a lot less involved then to meet the new standards.
Posted 29 January 2013 - 10:20 AM
Posted 29 January 2013 - 11:48 AM
Close with out looking up the exact specks.
Posted 29 January 2013 - 02:11 PM
Posted 30 January 2013 - 06:09 PM
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