Hypermilers thread

[catfish101]

What fords had the electric vacuum pump? It would be good to know for another discussion/project I'm involved with. Any idea what they cost used? I don't know when Ford made the change on the PS's but 2000 models had electric pumps, or my last service truck did. I don't think they are too bad. I think you would want to wire it up with a signal switch. I don't think they ran all the time, only when the truck needed more vacuum.

[ghunt]

Originally Posted by lartross

I ordered a k&n filter and am gonna fabricate a 4" air input line...just to see if I can get that 2 or 3 mpg...

I doubt you'd get 2 or 3 mpg out of a filter and intake, that'd be a really big gain for something that simple.

[kc8uvu]

Originally Posted by lartross

I've read on these forums a big block chevy blank will fit our engines fuel pump hole.

Yes, the diamond shaped block off plates for small block chevy are a perfect fit.

[David85]

This should make some of you guys feel better.

Did some playing over the canada day long weekend. 3 days of dragging our boat around to all of our favorite places. The lake we go to is 15 km from our house and involves a steep climb up a 10% grade and then another shorter 5% hill on the highway (80 KPH speed zone). About 60% of the last fullup was for towing under those conditions and the rest was short trips to town (mostly getting parts for the GMC in the family!!!). I did not baybe it at all this time around.

The last calculation works out to 12.4 MPG--------OUCH!!

Last I checked gasoline was $1.52/liter and diesel was $1.48/liter. Stupid carbon tax I won't be blowin' black smoke for a while at this rate.....

[David85]

Well I made another trip and I'm back to normal.

Distance was ~202.8 miles and it burned ~10.58 gallons.

= 19.17 MPG Below the 20 MPG mark but still pretty good.

Cruise speed was again 70 MPH average.

The truck was loaded for half of the trip and completely empty for the rest.

There were a couple changes I tried this time around.

The first was to drop the tire pressure from 75 to 60 psi on all corners. Seeing the potential for uneven wear, I can't justify running them any higher unless I'm loaded. More runs will determine for sure if this will cost me significant amounts of fuel.

The other change was to start out early in the morning to see if the cooler air would help. Normally I leave around 10 AM this time I left at 6 AM. No real change it would seem, but winds are more likely to be calm that early and traffic was a little better, especially for a friday.

[David85]

Some more numbers to chew on.

Front tank:

302 km on 44L with 166km towing and the remainder being stop and go short trips around town (302 KM x 0.611=184.522 miles)
that works out to~15.85 MPG

Rear tank: 166 km on 27L. 95% towing on the freeway

All of the freeway towing was averaging 65-73 MPH. I only slowed down where the traffic forced me. (166 x 0.611=101.426 miles)
That works out to~14.2 MPG.

Average = 15.03 MPG

15-16 MPG is what the truck could usually deliver on average during these runs without towing and close to empty before the turbo, engine rebuild and E4OD transplant/upgrade. There was the odd case of getting over 20 MPG, but I was never able to do so consistently. Overall I'm happy with the results so far.

I was also pleasantly surprised to see that overdrive is usable while towing a load like this. If I kept the power low enough (2.5 psi or less) there was no smoke and the EGTs were stable at 700 most of the time. Grades of 4% were about the limit before gearing down was required or lugging would result. Any lower than 70 MPH and gearing down was mandatory.

[M.L.S.C.]

Originally Posted by David85

As for the solenoids in the E4OD, the only one that normally activates once you are up to cruising speed is the TC lockup. The two shift solenoids are off when you are in 4th gear. The solenoid for the IP is very small and shouldn't take much energy.

What about the EPC solenoid - that one runs constantly, loss of power to it will throw you in limp mode, with line pressure ramped up to the skies, with all the shear that causes to the ATF, and all the extra heat that shear in its turn generates. Additionally, the E4OD has a valve in it that controls pressure to the torque converter lockup clutch, if the line pressure at the regular clutches is too high it will cut off pressure to the lockup clutch, thus allowing slip and even more heat buildup! Bottom line, you can easily fry the tranny, what good is then a 2-3mpg gain when you gotta shell out $3500-$4500 for new E4OD?

There are also electric powersteering pumps that only run when you need the power assist (toyota). So again in my case at least, I don't really need the powersteering belt spinning all the time once I set the cruise control at 70 MPH on the freeway.

Maybe tis just me, but I ain't never installing import parts on my domestic truck - call me a stupid redneck if you will (even tho I'm Russian), but imports are imports and domestic are domestic, and there's very few import vehicles I have respect for, none made by Toyota. However, if you want on-demand steering assist - the GM hybrid SUVs (Tahoe and Yukon) have it, electric rack and pinion contraption, so you will technically get rid of huge steering box as well - only problem would be how you attach this thing to our steering, and more important, what electronic doodat you use for controlling it?

Truth be told if there was a way to recover the lost head of our engines instead of just radiating it to the environment around the vehicle, there would be a significant improvement in efficiency. Most of the loss is in heat after all. Maybe a micro steam turbine under the bed of the truck

Oh well maybe a little too much thinking out loud.....

Well ain't that just what turbochargers do, recover some of the exhaust heat energy and turning it into useful mechanical energy. Is your truck still n/a?

[David85]

A lot of that is just thinking out loud. Its unlikely I'll ever do any of it. The turbocharger does recover some of the lost heat, but not much of it. Your mainly just using the back pressure. Most folks don't realize this, but if you were to take an engine like the 6.9 and run it underwater (impossible, I know), the heat generated by the engine would actually be more energy than the energy off the crank shaft. We're talking peak efficiency of 40% at the crank at best and that before accessories and powertrain losses.

If there were indeed a way to recover the energy lost to the radiator and exhaust system, than it is possible to pass 40 or even 60 MPG in a truck this size. The technology exists, but its never been deloyed to a production vehicle. Gas turbine powerplants use it. But again this is mainly hypothetical, and I certainly don't have the resources to try any of it.

Yes, my truck is turbocharged.

As for limp mode. Thats not gonna happen with my aftermarket setup, it does what its told to and nothing more. But cutting power to the EPC will max the line pressure no matter what computer runs the tranny. I was mainly thinking that the energy needed to run the solenoids in the tranny would be minimal, since only two are powered once you are in overdrive and cruising. Not really sure how long the batteries would hold up without the alternator before a restart of the engine would become difficult.

[Dodge/Cummins]

David 85,
Never thought about the heat-energy-loss before. Makes you think!
I think you've got some good ideas, keep "thinking out loud".

[M.L.S.C.]

Originally Posted by David85

If there were indeed a way to recover the energy lost to the radiator and exhaust system, than it is possible to pass 40 or even 60 MPG in a truck this size. The technology exists, but its never been deloyed to a production vehicle. Gas turbine powerplants use it. But again this is mainly hypothetical, and I certainly don't have the resources to try any of it.

Oh yes, gas turbines are the cat's meow when it comes to fuel efficiency, too bad they don't go in regular vehicles.

As for limp mode. Thats not gonna happen with my aftermarket setup, it does what its told to and nothing more. But cutting power to the EPC will max the line pressure no matter what computer runs the tranny. I was mainly thinking that the energy needed to run the solenoids in the tranny would be minimal, since only two are powered once you are in overdrive and cruising. Not really sure how long the batteries would hold up without the alternator before a restart of the engine would become difficult.

If tis any clue, the resistor I have in my EPC feed line is a 10-watt unit, it don't get hot so I assume it handles the current just fine, but another guy with a 3-watt rheostat (to tweak line pressure on the fly) says his gets heal hot real quick. Also, why did you install an E4OD, I think if you're looking for best fuel economy a 5-spd makes more sense since it has no electrical power demands and it gots a whole lot less drivetrain drag than the slushie...

[David85]

I went with the E4OD for a lots of reasons.

For one, it has a wider overdrive ratio than the ZF5, so I feel this can make up for the extra losses from the hydraulics. The geartrain on the automatics also have less mass and this makes the mechanical hard parts more efficient so the difference in efficiency between the manual and automatic transmissions is not that big once you lock the torque converter.

The E4OD was also designed for towing in overdrive, but the ZF is not, I like having the choice of 2 cruising RPMs at 70 MPH. Now I know that this may be in dispute in some circles, but having seen the parts for myself, I see no reason why E4OD overdrive can't be used as long as you are in the powerband. In fact the overdrive planetary is stronger than the forward planetary. All of the power of the engine hits the OD planetary before any other hard part after the input shaft (I have the steel upgrade).

I can drive stick as well and I find that fun sometimes, but for what I use my truck for, I prefer auto. At the end of a long day on site, I really would rather just get home and not have to worry about timing my shifting perfectly. We also have a rather lousy steep gravel driveway and while it may be possible to get good enough with a stick shift to not dig in with my 2wd truck, I find it easier to control an auto going up that hill to get out, especially if I am towing a trailer. The cost of paving that driveway made the E4 conversion look economical.

Then theres the 3.08 gears. The ZF is supposed to have a granny first gear, but with such tall gears in the differential, I can't help but wonder what kind of clutch problems that would develop over time on our driveway or on boat launches. Then theres the problem of converting to SMF since the DMF on the ZF would have probably caused problems eventually. Fitting the hydro clutch....cutting the hole in the floor....removing the column shifter.... and it goes on to convert to stick shift.

Whats interesting about gas turbine engines is that while they are powerful, compact and have along service life due to no reciprocating parts, they are actually not very fuel efficient. Usually no better than 30% thermal efficiency. Most of the remaining energy is blasted out the back and wasted in the form of heat, just like most any other heat engine, except maybe the sterling engine. The trick with advanced gas turbine powerplants is that they use that normally wasted exhaust to power steam generators. So even though its technically a gas turbine powerplant most of the power comes from steam.

There were a few gas turbine powered cars from the late 50s up to the late 60s that were tested, most notably being GMs jet age "dream car", ford tried a more conventional approach with something that could actually be driven on streets. But these cars made the big block powered land boats of the era look fuel efficient so when the fuel crisis of the 70s rolled in, they were history, along with lesser known plans for rotary engines in american built cars. Instead, we got the pinto, K-car, and chevett. All powerd by a mysterious device known as the "4 banger".

[David85]

Been a while, but I'm still keeping track of my MPGs.

Latest data:

Distance: 360 KM
Fuel : 56 Liters
Works out to roughly 14.66MPG

Conditions:

45 Km were short empty trips around town,
The rest was averaging 70 MPH with a flatbed trailer behind me in the rain.

As mentioned earlier, rain is not good for MPGs at freeway speeds.

Miserable drive, actually.......

This is the trailer I was towing. Very light, but there is still some wind drag from the overall size.

[M.L.S.C.]

Dave, I average about 15mpg towing as well, I haul a 30ft enclosed racecar trailer and keep it steady at 55mph, as I have 4.10s and at 70mph like you I'm winding way past 2000 rpms so well out of the fuel economy range.

[David85]

I have been meaning to make a test run at lower speeds but to date all of my runs are at 70 MPH. After the engine rebuild and some tweaking with the timing, I can leave it in overdrive most of the time even towing without bogging the engine and EGTs are just over 600 most of the time. At 70 MPH My tach reads 1550 RPM, but its probably closer to 1650 RPM in reality. When I gear down it gives me roughly 2250 RPM.

If I were to tow at 55-60 MPH it would be 3rd gear all the way. It certainly would be interesting to see if there is a significant gain in MPGs. Logic would say yes. Either way, you and I are ahead of the latest diesels that are being sold right now. 15 MPG towing is not bad at all IMO, and you are definately moving more weight and air than I am.

[David85]

Latest data:

430 kilometers with 57 liters of fuel

works out to 17.4 MPG.

This round was a real mixed bag and since mine is the only running truck at the moment others are driving it as well, so I can't really say for sure all of the things its been doing or how its being driven.

What I do know is that there were a few short trips in town as usual,
A brief 30 kilometer sprint at 84 MPH to catch an appointment,
and a family road trip of about 250 miles, most of it at 75 MPH with AC on most of the time.
No towing this time.

A little dissapointing to see a number below 20 MPG actually.

Oh well, better next time.