I Might Have Hit The Wall Today

[meemooer]

taller rear tires?
Maybe a different Sterling or a Dana axle has higher gearing available

[Duffman]

Dave what did you do to lower your truck in the front, springs from a 5.4? Any issues with re-alignment?

[Big Dave]

I used drop I-beams and shackles to accomplish the drop. Same springs. The truck re-aligned with no issues.

The 3.08 is the best I can do without putting a GM axle under the truck.

I've tried larger and smaller diameter tires. The current tires (235-85x16E at 105 psi)are optimum.

[MazdaMatt]

I've got a 94 f350 cube van with a 20 foot box and 7.3L NA deisel. I get HORRIBLE mileage in this thing. Especially over 90km/h (my consumption doubles when i get to 115km/h, but that's full throttle). It has a THREE speed auto tranny that shifts by RPM, NOT engine load! What the hell can I do to my truck to get reasonable mileage? I will continue to drive 90, so that's no biggie. What would a better tranny cost me?

[SuperTrooper]

Originally Posted by Big Dave

I've tried to keep the truck true to its mission. It can tow and haul just like stock. But a lot of these heavy-duty components limit my options.

Maybe its time for a different vehicle. Two options would be either a Chevy 4x2 half-ton or a 1994-96 Caprice. Both use the same drive train.

I can get either of them converted to T-56 Corvette six-speed. The T-56 has two overdrive gears. Fifth is 0.71:1 (about what most overdrives are) and sixth is a whopping 0.5:1.

The light-duty GM axles host gears from 2.47 to 4.88.

There are a ton of slam kits for both vehicles.

The engine choice would be either a GM 6.5 or a Cummins 4BT3.9 diesel.

Both offer some scope for aero-mods.

I can get either vehicle fairly cheap - $3,000 to $6,000. The low cost allows making exotic moves.

With either, I think 35 is possible and a project done for under $12,000.

The Caprice might be the better choice. Cd of 0.34 is a major bonus. On the other hand, the parts for the diesel conversion of the truck pretty much already exist. Lots more fabrication involved with the Caprice.

[Big Dave]

The GM 6.5 is almost a bolt in but gives a more crowded engine compartment. The GM 6.5 and the Cummins 3.9 are about the same weight - 700 pounds.

The Cummins is taller and may require some hood mods, but I'd just do the same hood reslope that Phil (Aerohead) did on his T-100. The Cummins would require the motor mounts to be relocated.

Either engine will require body sound deadening material.

Not only does the Caprice have a better Cd, but also a slightly smaller frontal area. The pickup has a roomier driver's position and a more upright seating position.

Much to consider.

[LUVMY02CREW]

Keep setting the bar high for the rest of us "truck junkies".

I've gotten 25mpg on a few commutes home from work and that is just with driving changes. When I get up off me ars and get some aeromods done, I hope the numbers will bump up.

[Big Dave]

What killed me is the very configuration that helps me out-MPG most trucks: 4x2 and stick shift.

The adapter kits for 4x4 automatics are pounded out in quantity (probably in China) but they have to make up 4x2 kits individually. To add insult to injurt the 4x2 manual setup does not bolt the tranny but is "divorced" - the overdrive hangs off an additional ctossmember on the frame. It is nicely engineered but saltier than something from Gale Banks.

It shows the degree to which 4x4 and automatics (two MPG-killers) have become the standard in the industry.

Maybe I should quit fighting the mechanical battle and go at it from a bodywork angle. Do like Red and get a fugitve-from-the-junkyard Insight, and take it to a custom body maker and have the roof raised five inches.

[SuperTrooper]

I guess I'm confused with your goal Dave. Since you are "Big Dave" I'm going to assume that you are tall and that's why you buy larger vehicles. My BIL is 6'4" and loves his Scion xB. The headroom is truly amazing and the seat goes back pretty far. True, it's a little pokey, but with a 5-speed he has no trouble getting on the highway. Do you have other needs to be addressed by your daily driver?

[Big Dave]

Think 6'10". At least thats the headroom I need.