diesel performance upgrades

[pschafer]

Hi all, first post on this forum.

We have a 2001 Safari Zanzibar with a CAT 3126B (diesel pusher).

When we were "5th wheelers" I did a few very satisfactory performance enhancements to my Dodge cummins. I installed a Dr Performance 80 hp module, a US gear exhaust brake, and an AFE cold air intake and permanent filter. This all resulted in 11 mpg plus while towing a 36 foot fifth wheel. Since buying the motorhome, I have an average mpg of about 7-8, and that is with an AFE cold air intake installed (came that way).  I have been browsing the internet for stuff I can SAFELY boost the CAT's performance to get a little better throttle response and another mpg or two. There doesn't seem to be much out there for the CAT engine.

Some things I have researched a little are propane fuel injection and a device called the "Vortex Valve". Does anyone out there have any experience with either?

Phil
2001 Safari Zanzibar 38'
CAT 3126B diesel pusher

 

[Gary RV_Wizard]

It's curious that all the improvements on the Dodge got you to 11 mpg. I would have expected around 11 mpg stock when pulling a heavy trailer. Close to that if it was a Ford Powerstroke. What was it before the mods?

As for the 3126, there are a few products but take the performance improvement claims with several grains of salt.  They are almost always exagerated. Edge makes a kit, and so does DR Perfromance. I haven't heard any feedback on either of them.

 

[Jeff]

Phil:

I have a 330HP Cat 3126B in a National Tradewinds that weighs 27,000 plus towing a 3,400 pound Honda CRV. We average 8.5-8.8 MPG and will see 9.5 on calm days if I keep the speed down around 62MPH. At 67 we see 9 MPG on calm days on level terrain.

When we purchased the coach it was three years old with 9,800 miles and I was getting 7.5-8MPG . After attending a couple of Cat and Freightliner meetings and rallies we determined that our side facing fan controller had failed and the fan was running at 100% all the time, using 38HP or so. With the replaced controller the fan runs 25-30% of the time with temps in the 70's. If the temps go into the 90's the fan runs most of the time and our mileage drops 1MPH or so.

I guess I am trying to say check out your coach before you spend money on upgrades, your mileage should be higher.

The second big mileage factor is the driver; keep the engine at low RPM's and use slow acceleration to help fuel burn.

 

[Alaskansnowbirds]

Phil,

We have a '99 Zanzibar with the 330hp 3126B. We have 53K miles and since we have owned it we have averaged 9mpg overall. I keep track of every gallon with Rolling Stock. No jackrabbit starts and I keep it about 62 mph when cruising. No mods other than I had the air intake moved from under the right rear where it was from the factory to up on the right rear side.

 

[pschafer]

Thanks for the info, I appreciate the input.

I have been keeping my speed between 55 and 60, figuring the best mileage would be at a slower speed. I have evidently not found the "sweet spot" yet. It is interesting to note that one of you has gotten 9 mpg at 67 mph. I'm just trying to squeeze all I can out of every gallon.

Phil

 

[Gary RV_Wizard]

I have been keeping my speed between 55 and 60, figuring the best mileage would be at a slower speed. I have evidently not found the "sweet spot" yet.

You may not even be in overdrive at 55 or so.  Your 3126 should do better than that.  I'm getting 7.3-7.6 mpg with a  heavier coach (38,800 lbs combined) and larger (370 HP 8.9L) engine at speeds of 65-70 on interstates. It does not seem to improve below 65 either.

 

[Jim Godward]

You may find with the 3126 that you will do best about 1750RPM, or above about 58/9 MPH as that will usually get you into 6th gear, Overdrive 2.  We do best at the 1750 mark wherever that falls!  BG

2001 Dutch Star.

 

[Jeff]

You may find with the 3126 that you will do best about 1750RPM, or above about 58/9 MPH as that will usually get you into 6th gear, Overdrive 2.  We do best at the 1750 mark wherever that falls!  BG

2001 Dutch Star.

Jim:

I agree about 1750. We get 65MPH at 1800 RPM which is where I seem to end up a good part of the time.

 

[pschafer]

Hi all again, thanks for the additional input. Maybe I was being too conservative with speed, I thought slower = more mpg, but I guess I just need to spend the first month on the road this season finding that "sweet spot" in this engine. It will be a few weeks, but I'll keep you posted..

Thanks,

Phil
2001 Safari Zanzibar
3126B CAT

 

[Ned]

Our 3126 was running at 1650rpm, 58mph, all day today and we averaged 9.7mpg per the VMSpc.  That's just fast enough to keep it in 6th gear and mode on helps on the small grades.  We did make a couple of rest stops where we idled for a few minutes, and one drive through a small town, otherwise we would probably have gotten 9.8 which is our longterm (10 year) average.

 

[Ron]

Looking at the weather where you were at it is probably a good thing you started driving to check your milage. ;D  Hope you have a safe trip.

 

[Ned]

The weather is no better here in La Crosse than it was in Milwaukee.  Flash flood watch through tomorrow morning, with possible more thunderstorms tonight.  Not too hot, in the 70s, but very humid.  Hope it clears out of the Twin Cities before we get there tomorrow.

 

[Ron]

I hope the weather gods will spare you from bad weather.

 

[Ned]

More rain and thunderstorms in St. Paul today, but supposed to start clearing tomorrow.  We'll be parking on grass and it's going to be soggy for a few days

 

[Ron]

More rain and thunderstorms in St. Paul today, but supposed to start clearing tomorrow.  We'll be parking on grass and it's going to be soggy for a few days

Hope you won't need to get pulled out.

 

[Ned]

We're parked and haven't sunk in, thanks to the jack pads we got from Terry B. 10 years ago.  They were in drought up here until a week ago, when the rain started.  They really needed it.  The peddle boats in the pond are sitting on the bottom, even after all the rain.

However, we saw flooding around Red Wing along the river.  Houses were flooded part way up the first floor and a playground under water.

 

[Poltax]

pschafer.........I am in the same sort of situation as you.  97 PSD superchip, air, exhaust, ect.    Just bought a used 2002 HR Endeavor, 330 Cummins with 10,500 miles.  I have been trying to find more info and have come up with this:  Check with BD Perfomance, Edge Products, and also Gale Banks.  Looks like these are the only guys that seem to have come up with some items that will fit our "power fix".  I am looking to check with the local independant diesel shops to see what they have as well.

I am looking to do larger diameter exhaust, maybe straight pipe and also open air element for the intake. 

Good luck keep me posted on what you find out.