Gas mileage when towing with big motors

[NiceAft]

but to compare apples to apples, we have to peg some variables like tow speed, single axle versus double, diesel versus gas and probably A/C versus no A/C as

You left out mountain/hilly driving vs flatlands. How much flatter can you get get than the keys? Well, maybe Kansas

Ray

[Baerkanu]

Here are two pics after finishing the trip.



Obelix

Obelix, how does your cover handle highway travel? I just bought the same one to cover the 26M for the winter - it fits well and certainly seems weel-designed and strong enough to handle road use, but I worry about the hold-down lines chafing the hull or stripes. Has that been an issue for you?

I also need to figure out an easy way to access the cockpit without undoing all the lacing -

- Clay

[1st Sail]

We need Chinook's data from his x-country USA trip from Wash to FL. He cut the US diagonally. IIRC he avg 10-11 with his GMC. Chinook where are you. Come up for air while planning your Great Loop trip!

[Sumner]

.....another variable that certainly makes a big difference when towing is speed. ...so slowing down 5-10 mph very well could be saving 1-2 mpg.

That might be a big part of the 1-2 mpg loss with the tandem axle trailer as before we towed right around 60 and run around 65 now.

It is interesting to compare mileage, but if you are looking at that to determine which vehicle to buy to tow your boat with I'd put that down the list as far as the most economical solution. First I would only consider a diesel if I was pulling heavy loads and the Mac is not a heavy load. If I was pulling 6000 lbs. plus on a regular basis then I'd look at a diesel truck. Less than that and you don't need the cost of the diesel in the first place and the potential costs down the road if it ever needs repair.

How many on here tow their Macs long distance on a year to year basis. We've been to Canada and Florida and a couple other places with ours over 4 years or so. About 8500 miles. I just looked up average gas/diesel prices last week (gas $3.58 and diesel $4.02). So right there you had better be averaging about 12% better mileage with the diesel to break even. At our 11 mpg the 8500 miles would cost us $2766.00 for fuel. At Matt's higher than I've seen 21 mpg the 8500 miles would of cost $1627.00. $1139.00 difference or about $284.00 a year. Our vehicle cost $3900.00 and we put a new engine and had the transmission rebuild this last year for $3500.00 so have about $7400.00 in it. It should now easily go another 150,000 miles with no major expenses. Not sure how much Matt spent, but I'd say it was considerably more than what we did.

How many of you have towed your boat 8500 miles in the last 4 years. If you figure a more normal diesel mileage of say 17 mpg then the savings over our gas motor would be $189.00 a year.

If you have the money and want a certain vehicle go for it, but using the mileage as a decision maker for a vehicle that isn't used that much might come after the suitability of the vehicle for towing and comfort while doing so. It is a lot more comfortable driving a vehicle that is rated for about twice the load vs. right at the load limits. For your daily driver I'd for sure look at gas mileage as a decision maker. For trips without a trailer we use the Buick at 30 mpg, but if we are towing even the smaller trailer we will use the Suburban as it only gets 1 mpg less and even though the Buick came with every comfort option for that year the Suburban is much more comfortable going down the highway,

Sum

===================================
Our MacGregor 26-S

Our Endeavour 37

Our Trips to Utah, Idaho, Canada, Florida

Mac-Venture Links

[Obelix]

Clay,

The two pictures were taken just after completing 2850 miles highway travel, no cleaning or re-rigging. There was no visible wear or rub-throug since we put cut tennis balls over all the stanchions and pipe insulation over the back rails on the rear seats to prevent chaving. We modified the lacing by using a separate rope for the rear vertical closure, not to have to undo the main cover. All in all the cover worked well.

Obelix

[Tomfoolery]

It is a lot more comfortable driving a vehicle that is rated for about twice the load vs. right at the load limits.

I'm in the early stages of planning a trip to Florida for next winter (all winter), and my leased Highlander with 5 kip factory tow package is giving me pause. But buying a used Suburban or Excersion just for that sort of service may make the most sense of all. Diesel, while nice, probably won't be worth the trouble. And new is pricey, at least a lot more than the Highlander. I also need the extra room for the Admiral, dog (Lab), my office (still have to work), and lots of boat gear, though much of that could be stored in the boat, along with clothes and such. And then there's driving a tow vehicle with much higher capacity than the minimum, with its longer wheelbase and (probably) wider track.

So it looks like a big gas engine would be the most cost effective, especially in a vehicle someone else took the biggest depreciation on already. 3000 mile round trip at today's prices (regular) and 12 mpg (a guess) is only 250 gallons, or less than $1000 in fuel at $3.75/gal (another guess). The mileage would have to be super good with a diesel to make any real difference in total fuel cost.

Very interesting thread so far.

[moondancer]

Dimitri
I tow with a '11 Ram pick-up, 2500, 5.4l. When I know I am going to tow I will use premium gas, for the octane and fill up the boat's tanks, I get 10 miles to the gallon going up and down hills on the back roads of CT. Lots of stop and starts and usually with O.D. off. Once on the interstate where it is mostly flat the computer tells me I am towing at 18 mpg at 65-70 mph. Of course I do turn O.D. off when highway gets hilly. One trip, not towing and on flat interstate, lightly loaded ( alright medium loaded, I was driving) I did hit 20mpg at 70mph for a few hours. My truck gets really thirsty when the revs come up above 2000 rpms though.
So I think you are right where you are supposed to be when towing.
Moondancer waiting for the spring thaw.
Mike

[u12fly]

Seams like 10 or 11 is that magical number, we see the same thing. We are towing our Mac with a 1999 Ford Expedition. In normal highway driving we get about 17 MPG (I think the vehical has the 4.6L V8). When we tow we usually get right around 11 MPG. With all the mods on our boat and the double axle trailer we are hitting just over 5000 lbs of tow weight. Our expedition can tow 6000 lbs (by the book), we never really notice the boat back there unless it is real windy out. - Or we look in the mirror

[dlandersson]

That's what I did - found a very nice 1998 Jeep Grand Cherokee Limited Ed (5.7 engine, 7,000 lbs towing) for a few thousand. It's our tow and backup vehicle - doesn't get used much.

It is a lot more comfortable driving a vehicle that is rated for about twice the load vs. right at the load limits.

I'm in the early stages of planning a trip to Florida for next winter (all winter), and my leased Highlander with 5 kip factory tow package is giving me pause. But buying a used Suburban or Excersion just for that sort of service may make the most sense of all.

[Sumner]

Most of the GM vehicles (Suburbans, trucks) with the 5.7 engine, up to about 2000, or the newer even better engines will go 250,000 miles on the engines/transmissions. They are extremely reliable except for one weak link and we found it. They all use the plastic tank radiators now (Maybe Ford and Dodge does too, don't know).

Our radiator went out in 108 degree heat in Arizona and broke wide open dumping most all of the water in a few seconds. By the time I got over to the side of the road the engine was damaged. We bought a new GM motor (3 year -- 100,000 mile warranty) for $1900 and that is for a long block. You can't find a new motor for anything else that cheap. While the motor was out I figured maybe get the transmission rebuilt even though it was having no problems at 175,000 miles so that was $900 and included a new convertor. New water pump, gaskets, distributor cap, plugs, etc. brought the total to about $3500.

I've found out since that 3 of my friends have also had radiator problems after 150,000 miles. Theirs didn't let go all at once so they didn't hurt their motors. The moral of the story is that if you have a vehicle with over 150,000 on it with a plastic radiator I'd change it out. Lots cheaper than the alternative.

I have a friend that has had a number of Suburbans and he looked at ours for us on Craigs list in Phoenix and we went down and got it after he looked at it (same friend that looked at our Mac also in Phoenix). He said we would love it and we do. I like it better than anything I've ever driven down the highway. I'm long legged and it is comfortable and you sit up high and see everything. I'd get another if something bad happened to this one and it is the reason we put the money into the new engine and trans. rebuild. We couldn't of found another vehicle for $3500 with a new engine and such in it. We will keep it at least as long as we own the Mac.

I'm an old MoPar fan, but a lot of them seem to loose the transmissions between 120,000 and 150,000 miles (happened with a Dakota we had) and some of the Fords also (on the other board a Mac owner with a 2000 Expedition, I think, lost his transmission in that mileage range.

Sum

===================================
Our MacGregor 26-S

Our Endeavour 37

Our Trips to Utah, Idaho, Canada, Florida

Mac-Venture Links

[Don T]

Hello,
I have a 1984 GMC G2500 van. With the original 5.0L HO w/carburetor and 700R4 trans, I got 12.5 mpg towing or not. That trans was horrible, by the time the van had 140k miles it had 3 trans rebuilds. SO, it now has a vortec 5.7L FI motor w/4L80E trans and gets 12.5 mpg towing and about 15 mpg hiway not towing. I do like the extra HP and torque of the vortec though the 4L80E trans was the best part of the upgrade.

[Sumner]

Hello,
I have a 1984 GMC G2500 van. With the original 5.0L HO w/carburetor and 700R4 trans, I got 12.5 mpg towing or not. That trans was horrible, by the time the van had 140k miles it had 3 trans rebuilds. SO, it now has a vortec 5.7L FI motor w/4L80E trans and gets 12.5 mpg towing and about 15 mpg hiway not towing. I do like the extra HP and torque of the vortec though the 4L80E trans was the best part of the upgrade.

'84 was the first year for the 700R4 and yes they had problems the first 3 1/2 years like most other transmissions before them including the 350 and the 400. The 4L80E is the overdrive version of the 400. I have two, but none in a vehicle at the moment. The 700R4 since mid '87 has been a good transmission. I have one in my .....



...'48 GMC and have over 140,000 miles on it and about 60,000 was towing the teardrop that weighs about 1700-1800 lbs. A lot of those miles at 75-80 mph. The 700R4 was originally controlled by at TV cable (throttle valve cable). If the TV cable is not adjusted right the transmission will not live long. I wonder if that was the problem with the other 700R4's you had. I have the info on doing that adjustment on my site. The 700R4 is now the 4L60E and 4L65E and controlled by the computer. It is a good transmission now and will go well over 200,000 miles if cared for. I'm aware of some with over 300,000 miles on them. It can be modified now for applications in excess of 700 HP. It does also have a couple good points over the 4L80E in some applications. It has a lower first gear of 3.06 vs. about a 2.48 for the latter and the overdrive is .70 vs. .75 so in some instances gives better gas mileage but you shouldn't tow heavy loads in overdrive so in 3rd they are the same. The 4L80E is stronger though and a modified one will take over 1000 HP. I have one like that which I was going to put in my GMC when I was going to turbo it, but that is on hold now (darn boats!).

Probably more info than anyone wanted to know ,

Sum

P.S. If you type "700R4 info" into google the info on my site will come up at or near the top of the first page.

===================================
Our MacGregor 26-S

Our Endeavour 37

Our Trips to Utah, Idaho, Canada, Florida

Mac-Venture Links

[bartmac]

Smaller motors seem to do the similar....our Ford Transit LWB truck....2.4Litre 4 cylinder Turbo diesel c/w chip 145kw does about 11.5-12 litres 100km...about 20miles/ US gal empty....put a slide-on camper on it or a Mac behind it and it jumps the fuel consumption to 13.5-14litres/100km...or about 17miles/US gal at 85-90km....BUT jumps major if you go 100-110KM/h ie 15-16 litres/100km

[Baerkanu]

I am interested in getting a new F150 with the 3.7 liter V6 , 302 hp. Empty it gets 17 city and 23 highway, compared to 15 city and 20 highway on 4.2 liter truck.
Dave

I know that engine/tranny combos have changed greatly, but my experience both with an '89 and '04 F150 with the smaller V8 was that they weren't suitable for towing anything heavy. The gearing was such that the tranny hunted at seemingly the smallest hill - put a trailer behind it of any weight, and they were useless. Bigger tires was about all they could handle, albeit unwillingly. OTOH, my ex's '94 Bronco with the big V8, big tires and E4OD was a beautiful towing rig - geared just right and wonderful (though a longer wheelbase would've been better).

Again, this is outdated info, and newer engines/trannies are probably very different -

- Clay

[Baerkanu]

Clay,

The two pictures were taken just after completing 2850 miles highway travel, no cleaning or re-rigging. There was no visible wear or rub-throug since we put cut tennis balls over all the stanchions and pipe insulation over the back rails on the rear seats to prevent chaving. We modified the lacing by using a separate rope for the rear vertical closure, not to have to undo the main cover. All in all the cover worked well.

Obelix

Thanks Obelix - the tennis balls and the extra lacing are a great idea. As soon as the wind/snow stop, I'll have to reconfigure it and then see how it tows this spring!

- Clay