Argosy 26 MH highway speeds?

[alhamilton]

How fast do you drive your Motor home on the highway/freeway? Fuel economy difference between 55 and 65 with 454?
Also can you use bigger tires to increase gear ratio?
Thanks,
al

[Boom Sounds]

Negligible difference in mpg

I wouldn't stray from stock tyres. If you do, make sure the duallies don't kiss


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[martin300662]

If you are doing highway miles regularly.....get an overdrive. You wont save the cost with increased fuel mileage but it makes the whole experience much more endurable.

[alhamilton]

Originally Posted by martin300662

If you are doing highway miles regularly.....get an overdrive. You wont save the cost with increased fuel mileage but it makes the whole experience much more endurable.

Thanks Martin, What kind of overdrive? Sounds interesting.
al

[Waipio Rim]

We drive long distances when we are using the coach, 200+ miles per day. We stay off of the interstates as much as possible and get around 7 mpg cruising at 55-60 mph, no Gear Vendors OD unit.

[martin300662]

Originally Posted by alhamilton

Thanks Martin, What kind of overdrive? Sounds interesting.
al

We prefer to get where we are going, then pull off onto the local roads, so less than 500miles is a short day.

I believe your 1975 26ft came with the original 16.5" tires (not the 19.5" found on later models) so the engine/trans is spinning away without the OD.

We have a GearVendors OD, they make a kit specifically for our transmission (need the drive shaft shortened and a 12v supply everything else is included and is bolt on); other brands are available. If you need to change the engine, change both to TBI and 4L80E, as the TBI controller includes the controls for the overdrive trans. You can get a standalone controller for the 4L80E but the swap is not straightforward - ask anyone who has had to remove a trans from an Argosy; you have to cut out the cross-member, so the OD is the easier option unless the whole drive train is coming out.

[OttawaValleyGuy]

I drive my 345 like an old fart
No fast starts, just slow and steady, try to run 55 to 60
I don't push it on long grades, I let it drop to about 2200 rpm
I usually stay in the slow lane
Doing this I get from 10 to 12 mpg

[perryg114]

I think Gear Vendors makes an overdrive that goes behind the transmission that would make the engine last longer and not be revving it to the max. The old push rid V8's last longer at lower RPM's. The valve train has a hard life at high RPM's.

Perry

[Smartstream]

The cheapest route is to change the gear set in the differential. I think most have 4:56 to 1 gears but you can go to 4:11 to drop rpm and or gain road speed. The problem is you lose power.

The Gear Vendor overdrive gives you the choice of direct or overdrive but the cost is probably 3 or more times that of changing the gears.

For those of us with the old Isuzu diesels we have a max rpm of 3300 which gives us max speed of 66 to 67 mph depending on the torque converter slip. Also not a lot of power to spare so the Gear Vendor is the better choice in spite of the cost.

[BentMetal]

Whatever you do, don't increase tire size. I just replaced my axles and found that the tires on the curb side had rubbed a hole in the ABS wheel well. It hasn't rubbed through interior wheel well, but it could have. Also could have caused a giant tire blow out.

[bibbs]

I have the 4l80e and had the rear axle changed to 3:73, I get about 13 at 70+ I don't tow, slows and shifts down, Going up the mountain

[Grosspoluter]

I guess I'm a bit of a lead foot on this forum
If the speed limit is 70 I go 70
But I'll admit 55-65 just feels better
NEVER "hammer down" or jackrabbit starts
I been getting 7-8 mpg on the highway
Also if I can, on hilly ground out where I live (Illinois / Wisconsin)
I try to "pickup" some speed on the down-hills so I don't have to make the engine work so hard on the up coming up-hill