Engine Mods for the V10 Ford what have you done

[Chance]

E350, the thing about cruising on flats with a stock van that isn't towing is that it really doesn't take much power. I'm more familiar with my own van so I'll use it as an example to make the point.

At 70 MPH I'm running around 2200 RPM on my V10. If the engine was operating at rated "continuous" power, per curve above, it would be making 140 HP. And at a BSFC of .41 pounds per HP-HR, it would be burning around 57 pounds of gasoline per hour, or 9.5 gallons per hour. And if traveling 70 MPH then I'd only get 7.3 MPG at best.

The above rough estimate shows that a V10 is way oversized for a stock Econoline to cruise at 70 MPH on flat roads. I put my cruising power requirement at about 50 HP, which makes my engine about 3 times too large to hold speed with present gearing. However, since engines run very efficiently from about 60 to 70 percent load and up, downsizing my 6.8L in half to about 3.4L or so would make it much more efficient while still leaving a little excess power on tap.

It's no surprise that new Ford Transits, which can be bigger than Econoline, will come with a 3.7L V6 as standard. Albeit with slightly lower gearing. Still, the standard engine won't have that much reserve torque before it needs to downshift for hills or passing.

[E350]

Chance: Thank you for your continued replies. To my less astute brain, I think we are somewhat in agreement. I was able to place the torque table inline (see two posts up). At 1400, the 7.3L reaches its max torque. IIRC, Dave Whitmer cruises between 1300 and 1400 rpm with his manual transmission and 308 gearing. I just want to cruise on the flats at 70 mph in the sweet spot of the 7.3L's torque band, i.e., 1300 to 1400 rpm. With my current gearing, my guess is I am likely over 2000 rpm at 70 mph on the flats (yes, I will check for T.C. slippage) which I believe just wastes fuel.

FYI, there are times when I need a one ton truck (like pulling a 10K trailer up Kingsbury Grade in the Summer), so I like my big engine, but there are times it is spinning way too fast for the relatively little power I believe I need. In my ideal world, I would want gearing that will span my entire range of needs. That is what all truck engines are moving to I think (in truck tractors it has been there forever). I am sure that the Transit has many forward gears and I have heard that some of the new Jeeps have nine gears.

BTW carringb: Is it possible to install a Gear Vendors in between the trans and the engine so that the additional gearing would be available in 4x4?

[BajaSportsmobile]

Originally Posted by E350

Is it possible to install a Gear Vendors in between the trans and the engine so that the additional gearing would be available in 4x4?

No, not an option.

[Chance]

Originally Posted by E350

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FYI, there are times when I need a one ton truck (like pulling a 10K trailer up Kingsbury Grade in the Summer), so I like my big engine, but there are times it is spinning way too fast for the relatively little power I believe I need. In my ideal world, I would want gearing that will span my entire range of needs. That is what all truck engines are moving to I think (in truck tractors it has been there forever). I am sure that the Transit has many forward gears and I have heard that some of the new Jeeps have nine gears.

........cut.........

As far as I know the new Transit will have the 6R80 automatic, which has six forward speeds. The gear spread between low and high is "about" 6:1.

Chrysler / Jeep has a new 9-speed front-wheel-drive transmission with an even wider gear spread. That is the future trend in order to provide low-enough pulling gears for towing and also high-enough for cruising while empty. And of course RAM has been using 8-speed rear-wheel-drive transmissions on some pickups.

Of greatest interest to me in this area is the new GM/Ford partnership to develop a 10-speed RWD transmission. I'm sure the goal is to increase total gearing spread while maintaining small jumps between shifts. According to reports we may start seeing info on these in the next year or so.



By the way, if you were to change your van's gearing from 3.73 to even 3.08 it won't drop your RPMs from over 2000 to the 1400 RPM range you want. And even if you could, have you considered what you'd be giving up for such little gains in fuel economy?

[carringb]

GV says they can special build a GV unit to mate between the trans and T-case. But you would need a shorter fuel tank to make that fit, and have to remount the crossmember. And unless you are planing on doing tractor pulls, there probably isn't much good reason to use it in 4x4. It has a lockout so you can't accidentally enable the GV while you are in 4x4.

[carringb]

Originally Posted by Chance

Chrysler / Jeep has a new 9-speed front-wheel-drive transmission with an even wider gear spread. That is the future trend in order to provide low-enough pulling gears for towing and also high-enough for cruising while empty.

Except with their current powertrain, reviews are saying it only hits 9th gear when coasting downhills and under most conditions can't even cruise in 8th.

[BroncoHauler]

8th and 9th are probably only there to help them meet MPG requirements.

[E350]

carringb: Do you know about this? Last post was yesterday:

http://www.bangshift.com/forum/forum/ba ... ge-revival

http://www.ebay.com/itm/Doug-Nash-Overd ... c3&vxp=mtr

[carringb]

Originally Posted by E350

carringb: Do you know about this? Last post was yesterday:

I had not seen that. I looked into US gears before, and I was turned off my the shifting method. It's just like a splitter on a big-rig, where you have to shift under no-torque (You can move the switch, then it will just shift when you lift the throttle). For an auto trans, I just think the Gear Vendors unit is a better match since it can shift under full load. It does have some reverse-HP limitations (i.e. no heavy engine braking with the GV engaged) but that would not be a show stopper for me, since I can use 2nd up to 70MPH. Really I think a GearVendors is just about the next best thing to a true 6-speed conversion. At least the controls for it are already established, even if it won't do everything the new 6-speeeds do.

Would a GearVendors even pay for itself? Maybe. I passed on it previously because it would have taken about 120,000 miles to pay for itself. I didn't really realize I'd be putting on another 200,000+ miles at that point. And now that I'm shopping for another huge trailer, that those in-between gears will allow me to make use of the HP I have now. At this point I cannot really make more HP without either major internal changes (bigger valves and different cam profile) or slapping a turbo on. Neither of those options would net any fuel economy benefit, while more gears would.

[carringb]

Originally Posted by BroncoHauler

8th and 9th are probably only there to help them meet MPG requirements.

Yet the (3-yr old?) 6-speed Mazda CX-5 still does quite a bit better in EPA testing, and probably more so in the real world since it can actually use its gears.