Engine Power and Fuel economy with a FL chassis

[tqqest]

My experience is the same as Stuart.

My 2020 DS4369 was on a Spartan chassis, and my 2022 DS4369 is on a Freightliner chassis. Both pulling our Jeep Wrangler Rubicon Unlimited. Both traveled regularly between SLC and Palm Springs. Tons of passes and long hard climbs each way. I don’t see any measurable difference between them. Both average about 6.5 mpg overall. 7.5 mpg in California as the speed limit while towing is 55 mph, I usually do 60. And 5.5 mpg in Utah running 75 mph in the 80 mph zones.

I know that Tom won’t agree, but so far I definitely prefer the Freightliner. Although I do prefer the hydraulic cooling fan on the Spartan.

Fuel mileage wise, in my case, running at high altitude in mountainous areas at high speeds, I really couldn’t say which one had the best mpg. It isn’t surprising to me at all that the big X15 gets better fuel mileage, as it is not working nearly as hard as the L9 is. When running in the mountains, my gauges always show me at 80%-100% power & torque, with the the turbo boost at 30-35 psi.

[sramer]

Originally Posted by Stuart W

How much does your 19 LA weigh ?

I am right there with Tom on my LA at 51,000 lbs with full fuel and tow a Grand Cherokee at 4750 lbs.

[tom chelbana]

Can't tell you how please we are on our travel from Cal. to Newmar and then on to TN with the LA. On the last fill up here in NE., using the TSD card at Love's we ended up paying 3.04 with a posted 3.49 price cash. But it gets better when the LA fuel millage was 7.7 running around 65 to 70. What not to like about this trip back east with those sets of numbers.
Newmar Man

[Dutch Star Don]

After all is said and done, this post didn't reveal anything unusual. The Dutch Stars (comparing apples to apples) on either a Freightliner or Spartan chassis got the same mpg. My fan works as it should. When the AC is on, the higher fan speed keeps the condenser cooler, hence better cooling.

Mileage depends a lot on where you live, NOT the chassis that is under your coach. We live out west, no matter what direction I leave home, I'm either hitting big grades or driving against the wind in the desert.

[tom chelbana]

There is a difference with our 2018 LA getting over 7.2 MPG over 40K miles and a 2020 LA travel together getting 6.5 MPG. After taking his coach to FL and having FL tell him his engine fan drive was missing a switch which they added (600$ labor 200$ parts) the two coaches are getting the same MPG. That is a difference and when owners are looking for best MPG and this fan drive being on high is going to make a difference. FL said there was a problem because the coach didn't have the switch which they say Newmar should have added and Newmar says FL should have. FL did do a good will price adjustment by cutting the bill in half. FL said there was a problem so there is a issue and that was why the added the switch.
Newmar Man

[Stuart W]

Tom is it possible that this is a LA issue and does not make the same difference on a DS ? The DS on a Spartan has a hydraulic driven fan and the Freightliner has a shaft driven fan much like what both the LA Spartan and the LA FL have.
It would seem like the two LA’s are more of an equal comparison to me.
Again now having owned one of each on the exact same floor plan I have found no difference in MPG.
Also wanted to add that I believe your LA getting slightly better fuel economy compared to DS’s is more of a Power to Weight Ratio situation

[Stuart W]

Tom
LA specs vs DS 43 footer
Both approximate weight empty
LA 46,000 LBS vs DS 40,000 LBS
The LA is 13% heavier

Torque:
LA 1,950 vs DS 1,250
The LA has 36% more torque

HP:
The LA has 605 HP vs the DS 450 HP
The LA has 26% more HP

These numbers are not exact put reasonably close
The LA is only 13% heavier but has 36% more torque and 26% more Horsepower!
I’m willing to bet that the LA with the same aerodynamic shape and these very impressive engine specs accounts for your .5 miles per gallon increase over the DS

[Stuart W]

[redbaron73]

My 2022 LA on a spartan chassis gets 6.5mpg out west average.

I think the difference is Tom has a different engine / epa spec than the newer coaches.


2018 EPA spec was first 605hp x15
2020 EPA spec was 2nd and most likely on a freightliner.
2021 EPA Spec is current and what I have.

[tom chelbana]

The coaches that have their engine fan drives on high speed only are going to get poor performance which then ends up with lower MPG. It doesn't mater which chassis or which engine. The key point here is just like 2020LA on a FL going to a FL service location and being told that his coach was missing the fan switch so that he has a 2 speed fan and when installed gets over a 1/2 more miles per gallon. There is a issue here and being aware of it might apply to your coach is good to know. Who doesn't want a half more mile per gallon improvement.
Newmar Man

[Stuart W]

Originally Posted by tom chelbana

L series 450HP in a Dutch Star 4369 should be getting 8 MPG. Our LA which is close to weight and size is getting 7.2 on average with a X-15 605 and many of those owners with the 4369 FL are reporting 6.5 or less. Would be interesting if we could get Newmar owners information on difference in MPG between Spartan and FL chassis with same year and model.
Newmar Man

I’m not disagreeing with your LA to LA references
This post is where I don’t agree

[RVStitchy]

Originally Posted by Stuart W

I’m not disagreeing with your LA to LA references
This post is where I don’t agree

Getting 8 mpg would be a dream right now. We are getting 6.2-6.5 mpg. Driving 66-68mph towing 7,000 lbs (toad + golf cart) on flat Florida highways.

As my signature states - 2022 4369 on FL chassis.

[tom chelbana]

Fl chassis for the LA 605 should have a 2 speed fan. The 2020 LA with FL chassis didn't have it and that was the difference in MPG. That is the point of the post. Newmar owners wanting the best MPG might want to check if they too don't have the 2 speed.
Newmar man

[Gary More]

Originally Posted by RVStitchy

Interesting topic. Whenever I am hooking up the toad or in a camp ground setting up to leave I turn the dash AC off and tap the brake to dramatically drop the engine noise to be polite to others. Is that a sign that it is working properly? That engine screams at high idle with AC on. Our 450hp/8.9L with 12,000 miles is still averaging 6.2-6.5mpg with no generator which I think is a little low based on other reading.

What’s with no generator running. In the mountains I go down to 6.0 mpg. I’m always pulling a vehicle.