Modifications To A 400 hp Cat Engine

[api100]

I've had a 2005 Revolution with a 400 Cat for about 5 years. Does anyone have suggestions for possible modifications to the engine to improve power and possibly improve mileage?

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?

Thanks!

Andy

[wolfe10]

Comparing MPG and power between two coaches is a LOT more complicated than it would first appear.

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.

[dickandlois]

Hi Andy, Like Brett said. A little like apples and oranges. The 275 Cummins was likely matched to a Allison 4 speed or 5 speed transmission. From your information I'm thinking thinking an MT 643- 4 speed.The big items are weight, body profile and gearing between the two coaches. Also 125 more HP. More ponies equals more oats. More power is not always a good thing, its how all the parts come together.

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.

Rich.

[desertdeals69]

If I remember correctly the 275 Cummins is a ISB computer engine which for the most part was connected to a Allison MD3060. A 190,230,260 was a mechanical engine and connected to the Allison MT 643. I have installed a ISB 275/MD3060 in my 32 foot coach an get between 10 and 11 mpg towing a 1/2 Silverado.

[dickandlois]

DD you are correct, but a number of Freightliner Chassis had the 275 HP an MT 643 up to the start of the 1999 chassis year and the MD 3060 used from then. The MT-643 is 660flb torque at 70,000 lb load and the MD 3060 is rated at around 750flb torque at a load of around 40,000 lbs.

Close with out looking up the exact specks.

Rich.

[desertdeals69]

My ISB 275 and MD3060 came out of a 98 Freightliner Discovery.

[api100]

Thanks for the comments and suggestions. My coach now has 50k miles. I was not aware of the need for valve adjustments at 30k miles so I'll get this checked , will also check air flow. Thanks! Andy

[southwindtrails]

I would like to know how many miles does it take to break in a 400 Caterpillar. My Cat has 10.000 miles on it.

[wolfe10]

Southwindtrails,

Welcome to the FMCA Forum.

I guess the best answer is that Caterpillar calls for the first valve adjustment around 30,000 miles in an RV application.

[casuall454]

Here is my two cents on this topic and every person has an opinion. Having attended Diesel College and worked on Perkins, Waukesha, CAT 6803 V-8 and Cummins "B" series (that’s the old 5.9 - 12 & 24 valve series) found in Dodge pickups, White & AGCO agricultural equipment.

Remember Diesel engines work on the principle of heat of compression (adiabatic combustion) not external ignition (spark plug) that’s why in warmer air diesel engines get higher fuel efficiency. However to increase gasoline engine power you cool the air (cool can) to make the air more dense so more air (oxygen) can be compressed into a cylinder.

The way you can increase air (oxygen) in any cylinder you can either use a super charger or turbo. Turbo chargers are more efficient at higher engine RPM’s and much smaller that’s why they are used extensively. The major drawback to turbo use is “turbo lag” the turbo charger has to spool up or increase the engine RPM, which then results in increased “boost” or air pressure being forced into the cylinders. Turbo chargers through the use of waste gates and increased manifold air pressure results in increased fuel economy, acceleration this also results in turbo charged engines not suffering from the effects of “thin air” (decreased TORR / atmospheric pressure) at higher elevations.

All combustion engines need air in (oxygen) and air out (exhaust). There are several ways to increase the efficiency of any engine resulting in increased MPG. Below are items for any owner operator to consider for increased efficiency and reliability of their unit.

1. Replace your paper air filter with a cotton / oil filter there are several suppliers including ( K&N, Pro-Guard, Summit and many more ) These filters allow more air to flow through with less restriction. The use of cotton-oil filters can void your warranty, you will have to ask your mechanic or check your state laws.
2. Increase the size of exhaust, larger diameter exhaust decreases engine back pressure resulting in the motor not working as hard to expel the exhaust, this also lowers the engine operating temperature. However the exhaust can’t be so large so as to decrease back pressure or the efficiency of the turbo is effected.
3. Computer Chip, there are several who have well documented increases in MPG (Banks Power, Bullydog, Hyperchip and several others) however they usually require some time to install. Some of these chips will increase HP as well, yet this will result in decreased MPG. (Research, Research and Research your needs and ask others before you buy any of these units)
4. Transmission, shift points, clutch band adjustments, fluid and fluid filter. Maintenance of your transmission will result in a quieter, smoother and higher MPG. Don’t skip the maintenance on your transmission. The current standard from Allison (3000 & 4000 series) is six (6) speed transmissions; expect to see eight (8) speed units in less then 10 years.
5. If your power unit was produced with a catalytic converter installed, don’t remove it (you won’t get a two (2) MPG increase) you do risk a EPA violation citation.
6. Use of motor treatments there are several on the market however they break down into two (2) major groups.
   1. Oil Anti-Friction Treatment TFE commonly called Teflon, Graphite and lastly Moly. The major issue with all of these products are they are suspended in a oil. (Remember basic chemistry suspensions are solid matter contained in a liquid) When these products are used they “build-up” or coat the motor there by potentially taking your motor out of operational tolerances.
   2. Metal Conditioners ( IXL, ER= Energy Release) These products are typically 3-5 microns in size and “condition” the metal on the surface level, that is supposed to result in decreased friction, increasing MPG.

If you decide to use a motor treatment consult with your mechanic or do your own research as both groups have pros and cons.

I am hopeful that at least one person takes something away from this post.

Happy Motor Coaching everyone.

[gaylemarlowe]

I have a 2005 Cat 400 in my 44 ft Newmar and get 8.5 mpg. I did have the valves adjusted at 30,000 miles and they were badly in need of adjustment according to the service shop. This could drastically affect your mpg. Also, my stock paper air filter gets close to max vacuum on the little minder after just 6000-8000 miles. I guess it is just doing its job, but wish it was larger so I wouldn't have to replace it so often. I would suggest getting yours in for a thorough service.

[wildebill308]

1. There are no cotton oiled air filters that pass Cummins or Cat specks for passed dirt. You get more air but way to much dirt.

2. To little Back pressure? The goal is to reduce back pressure to "0" Back pressure reduces the efficiency of the turbo. There is no need for Back pressure in any internal combustion engine.

Bill