Cabriolet MPG and cruising speed

[nc77089]

What should be the avg. MPG for the 6.9 Cabriolet? I have calculated 10-11 MPG unloaded, is this a normal range? What is the normal highway cruising speed range? it has trouble maintaining 65 MPH with hills and flat roads, It seems to handle topping at 63 MPH. Is the C6 3 speed trans granny geared and that's why the slow acceleration from a stop?

[Traveler]

The C6 is kind of a hindrance for the 6.9 engine. Not enough gear selection. So top speed is probably 70mph depending on rear end gear ratio. That will have a lot to do with your fuel mileage.
If you are doing a lot of cruising empty you may want to change the rear end ratio. Or add a gear vender.
Maybe even swap from a 3 speed auto to a manual, or a 4 speed auto.
You can add more fuel to hold those speeds and make it take off faster but it will not help your fuel mileage.
Might want to consider a turbo as well for adding power and economy.

[nc77089]

its equipped with a Banks turbo, but I dont seem to be getting much power out of it.

[Life]

its equipped with a Banks turbo, but I dont seem to be getting much power out of it.

Is the turbo even spooling? These things aren't power houses; they're just dependable pullers for the most part.

[68Mercury250Ranger]

you might need some adjsutment of the Vacuum valve on the injection pump. I can't remember the numbers anymore, but the valve adjusts to get higher line pressures and better shifts. trans shop with some older experienced techs could probably help check it at least.

the 6.9 was only 175hp in stock form. a cabriolet is one heavy MF. you won't have big power even if the turbo is spooling up.
any banks turboed 7.3 idi I saw blew headgaskets and tore threads out of blocks. they must really cause havock with the little 7/16" headbolts in a 6.9?

my powerstroke clubwagon is 7000lbs empty, a cabriolet must run closer to 9000. a 6.9 is not enough!!

diesel C6s have closer ratios than gas ones.

[Life]

you might need some adjsutment of the Vacuum valve on the injection pump. I can't remember the numbers anymore, but the valve adjusts to get higher line pressures and better shifts. trans shop with some older experienced techs could probably help check it at least.

the 6.9 was only 175hp in stock form. a cabriolet is one heavy MF. you won't have big power even if the turbo is spooling up.
any banks turboed 7.3 idi I saw blew headgaskets and tore threads out of blocks. they must really cause havock with the little 7/16" headbolts in a 6.9?

my powerstroke clubwagon is 7000lbs empty, a cabriolet must run closer to 9000. a 6.9 is not enough!!

diesel C6s have closer ratios than gas ones.

Most of the 7.3's I've seen blew up because the wall was too thin. The 6.9 works great, especially with the right gearing, its just not a speed demon. Banks recommended a cruise of 55 MPH for the turbo's they put out. I'm guessing that was based off of a 4:11 rear end.

[nc77089]

it has scaled at around 8,000lbs (11,000 GVWR) I have since thrn have picked up a more modern truck 09 Sliverado 3500, i still have the Cabriolet just dont know what to do with it.

[Life]

Put a 6BT in it!