Big Diesel, MPG increase ideas?

[ps2fixer]

Yes both trucks are 4x4, the 2001 has the push button style, not really a fan of those, I'd rather have the lever and manually do it like the 95 has, my dad's 96 is also 4x4. I saw plenty of 2wd and gas models, but weren't interested. Michigan gets snow and at times 4x4 is really needed. Besides that, it's a truck mainly for wood hauling, and being a diesel, all of the weight is in the front, so it's terrible off road so it really needs the front wheels turning so I don't get stuck on wet grass =). The big mod for the Toyota T100's is manual locking hubs for mpg and less front axle wear, but the 95 came with them stock.

For the propane setup, it would be a proper kit designed for the truck if I tried it. It monitors boost levels and throttle to keep the propane at safe levels. I'll have to read up on the system more, but I think it's pretty interesting. Probably won't be touching anything like that for a while since I'd want to atleast get some miles on the truck to get something for a baseline.

Here's a photo of the truck, not great quality photos, they are from the craigslist page. The push bumper goes down a fair bit, so I guess that gives a bit of an air dam effect. I don't think it has any mud flaps either. The hood latch is rigged up some, I have to bend the hood back down and get a new cable installed. For a michigan truck from 1995, it's in quite good condition body wise. Thinking about painting the custom metal parts black to make them not stand out so much, that or a similar red color to make it blend in more. Not really a big person on looks, but gray and red don't really match too well in my eyes xD.

Talking about trucks, I can't remember which was found to be better on here, a flat topped topper/cap, or a tonneau cover. I'm thinking the topper was slightly better, but for wood hauling, the tonneau cover would probably be more ideal since I can remove it if needed. Catcher is, I have the topper, not the tonneau cover lol.

[Piotrsko]

In my case for the last 21 years, the topper has not been an issue except when the load exceeds 41" tall. I do keep a wrench that loosens the hold downs so I can load 41-45" tall stuff and have a hook in the garage for those loads where I know before that I have to remove it. Takes about 1/2 hour excluding cleaning out the garage.

A sheet of 3/4 plywood and the plastic bedliner make unloading easier.

[Ecky]

To expand on how P&G works to help a diesel:

Consider accessory and frictional losses. If your engine is turning at (for example) 2000rpm, it doesn't matter if it's 20% loaded or 90% loaded, turning the water pump, alternator fan, oil pump, etc. use just about the same amount of energy. Friction goes up a bit with things like piston rings, but it isn't linear.

The way it works out in practice is, that you end up with fewer losses by running the engine half the time at twice the load, and coasting at idle or with the engine off the other half of the time. You're literally cutting all accessory losses in half.

Some modern hybrids do some of this automatically - they have electric water pumps which are not tied to engine speed, and turn themselves on and off as needed, and even the engine itself doesn't necessarily run all the time, but rather, may cycle on and off as the battery is filled and depleted, with the battery carrying the vehicle while the engine isn't running.

Taller gearing always helps with economy because slowing the engine down cuts accessory and other parasitic losses too.

[Isaac Zachary]

To go along with what Ecky said, think of it this way. At 0% throttle (e.g. idle) you're 0% efficient. Close to idle, putting along the road, and you're still pretty close to 0% efficient. The more you lay into the throttle the father away from 0% you get.

[ps2fixer]

Being the bigger diesel, I'd probably avoid the engine off P&G, the traffic on the main roads around here is pretty bad. I've had enough people about hit me when I was going 45mph in a 55mph in the corolla, now the road has even less passing room and such. It went from a 2 line state highway to a 2 lane with left turn lanes and a few right side lanes to pass people turning left, but they removed the option to pass slower traffic. In the main town area the same setup is in town, and they just extended it out about a mile for no real reason, there's no businesses or anything that far out.

Sadly I don't have a garage yet to park vehicles in, so don't really have a solid way to remove a topper easily. For the wood hauling, generally my family runs racks and stacks the wood to the cab height or higher, doesn't matter if it's a little Toyota pickup, mid sized T100, F150, or F250 lol.

I haven't seen any hybrid diesels, are they a thing with the auto kill/start like the gas versions? I thought the hybrids put out electrical power to get the vehicle up to speed with less load on the engine (less efficient), then while cursing down the road and brake regen the battery is recharged for the next takeoff. Maybe the newer ones do some different things, I haven't been super active on this site for like 6-8 years.

I think the theory of the engine rpm is a bit backwards for a diesel, the only difference between idle and full throttle is how much fuel is being dumped, there's no throttle plate to cause pumping losses. I'm not sure 100% how the turbo would play into this though since it's an exhaust restriction, but it crams more air into the cylinder for a more violent dentition. Of course this is purely talking about the core engine, accessories clearly would have higher losses at higher rpm.

It would be interesting to test changing the belt to only run the water pump and alt and get an electric vacuum pump for the brakes.

I've messed around a little with the engine off coating with a Camry (mid sized car) and a Corolla (smaller/budget car) and they are no big deal. The truck though, the steering is very hard, not sure if the brake system holds vacuum well or not with engine off. The Toyota's get 2-3 brake hits before it runs out of assistance. The 2001 F250 I flat towed home and the brakes (rusty but not that bad) was barely enough to stop the actual truck against the truck in front coating in neutral (heavier so it seems to coast farther, doubt it's from low rolling resistant tires).

An areo topper might be doable, been thinking a bit on it and since I use side racks for hauling more stuff, if they were shaped to match the cab angle and taper down at a reasonable rate, I'd think it would help slightly. It's already a brick in the air so I think areo mods would be more effective on it than the corolla - passenger mirror delete, mud flap delete, the front end covering, and belly pan, and flat hub caps might have given me 3-5mpg while driving style and tires up to max pressure seemed to give the best gains, 33mpg on the trip home 60mph for ~2hr vs ~39mpg for the same speed with the areo mods and fixed alignment, tires, etc.

I don't have any good photos of the front of the truck, or a solid side profile yet, but the front bumper is a fair bit shaped like an air dam already, it extends down a bit more than I normally build them.

Probably should mention my dad and I both can weld, and my dad was an ASE cert mechanic so I do all repairs on my own or with his help.

For the gearing, I think 3.55 is pretty reasonable for the truck, the overdrive in the transmission is 0.71, so that comes out to 1500rpm for 55mph and 2000rpm for 70mph. The engine red lines around 3250-3500 according to the tach, idle is around 450rpm. It's first gear is basically a creeper gear, so even with the somewhat higher geared axles, it has plenty of gearing for starting off with a pretty good sized load I'd think. The toyota I'm running is 4.10 gearing and with the v6 engine it can struggle a bit taking off, it really could use a creeper gear type of setup. I haven't done it yet, but in theory I could drop it in low range and get to say 2nd gear then swap to 1st gear high range, that truck can be shifted into and out of 4x4 while moving, into low max speed 5mph, into high any speed, and into 4x4 from 2wd 50mph. Have to love owner's manuals. I think the ford manual will say either stopped or under 5mph but I haven't looked for one online yet, the truck didn't come with the manual.

Also I plan to remove the hub caps, they don't look like they are too areo, they are fairly heavy, and the valve stem is hard to get to with them on.

I'm thinking making atleast a short belly pan for the front and seal up the hood a little would be a good benefit since diesels generally don't like the cold, there is excess heat from the turbo that I have to be careful about though so the back side will be the vent for the air that makes it through the radiator.

I'm also reading about the 50mph diesel truck thread to get more ideas. Sounds like 70-80% of the mileage is purely driving style and slow average speed ~30mph. I have nearly zero city driving as I live far out in the country, and when I do go into town, the city driving aspect is about 1-2 miles long. No stop and go traffic, and generally I don't get stuck at the lights more than once.

Anyway, back to that other thread, he mentions about unplugging a heater for quicker warm ups, it's an EGR truck, mine didn't have any of that stuff though. I know the newer truck has a waste gate and it has some sort of exhaust brake setup that helps warm the engine up faster while lowering power to the wheels, I think that truck has some sort of heater system on the turbo area too, not sure what that's for, but if there's any heaters, 100-200amp heater delete would probably be quite a mpg increase I'd think. The mention of his heater is at post #57.

https://ecomodder.com/forum/showthre...tml#post365990

Btw, I went to school for computers, and I've played a little with programming micro controllers. I have a reasonable understanding of electronics (the actual circuits), so I'm keeping that in mind too while thinking of mods. This engine doesn't have much electrical going on with it though, the newer one has a ton of stuff I'm wanting to look into.

I've also been seeing people mention that mufflers on a diesel only makes them get worse mpg, I'm not one to have loud exhaust though (the turbo might be enough, not sure). Pretty sure it still has the factory exhaust, looked to be about 3in. I didn't look over the whole system much, but I remember seeing a muffler. Maybe a cherry bomb style muffler would be the best of both worlds (center wide open, packing material around the outside muffles it a little).

A bit of a side topic, if that 2001 we can't get going within a reasonable budget, it might have some pretty major mods. 2000 Tundra cab (4 door but shorter), custom box (oem one is rusted to nothing). The engine/trans would likely end up being the 2000 Tundra engine, 4.7L v8 gas with auto trans. It would be a bit on the high geared side for the engine/truck since the axles are 3.73 and the Toyota generally comes with around 4.10 gearing. Low range as a creeper gear, I think it would work fairly well. The cab on those trucks are a lot shorter than the fords, a bit narrower and such so I'd think it would do pretty well. I'm looking at hauling ~10,000lbs once in a while, and that's just a bit much for the stock tundra for that era, probably would do it but the suspension, axle, and maybe frame are a bit light duty for that. We've came up with a name for it already if that happened - Tord (TOyota + foRD). Toyota has great engines and electronics, and fords have great axles and frames.

I wish I had photos, but back in the 90's my dad built a truck out of a ton of different parts and made a truck he called the "Ka-truck", it was half "car" and half "truck". Cab was a station wagon front end made into a cab, frame was a heavy 3/4 ton chevy, heavy 3/4 ton rear axle with dually adapter, and powered by an oldsmobile 350 v8. 4.10 gearing, automatic, home made box (very heavy), and home made pipe front bumper. He literately pushed junk cars sideways around the yard. He wrecked the truck into a big pine tree one night, so that truck is long gone, but he still misses it lol. Back then he was a scrapper, lived off scrapping metal. $20/ton and vehicles were either free or the owner would pay a little to get rid of it. If it was something desirable, he might pay $20-50 for it. He had a small collection of Oldsmobile Cutlass cars 1969-1974 era until the township got on him for having too many vehicles in the yard (no junkyard license). The ordnance was changed, before it was fine for unlicensed vehicles to sit behind a fence out of sight from the road, now they want every vehicle to have an active plate or insurance, whichever one. I live a township over and it's no problem here. I like having a parts vehicle encase I need a part, no wait and no running to the store, just have to do the job twice to get it out and put it in the other vehicle.

Anyway, back to some work (self employed) and reading a bit more on that other thread.

[Isaac Zachary]

Did someone say hybrid?
From what I've heard, modern hybrid trucks are usually about power and torque delivery and not so much about fuel mileage, although there can be an advantage.

Consider: all vehicles come with engines that are oversized for your average power consumption. For an example, a lot of vehicles only use some 20hp to cruise along at 60mph, but usually have an engine that's around 10 times bigger since acceleration takes a whole lot more power. A hybrid can help by allowing you to use a less oversized engine, which is better for your average power consumption, like cruising, but still allow you to have the same torque/power/acceleration characteristics by combining the smaller engine with an electric motor.

Alternator mod/delete?
There's also the advantage of regenerative braking with a hybrid. Which also throws into my mind alternator mods. I do believe Mazda has an ultracapacitor system that keeps the alternator off most the time, but runs it full blast when you let off the throttle pedal. This then rapidly charges an ultracapacitor bank which in turn is used to charge the 12V battery.

Of course if your drives aren't that long, you could delete the alternator (or just disconnect it somehow) and charge it up with a 12V battery charger at home. But obviously if you're going to be running a lot of electric stuff, like electric vacuum pump for the brakes, you may want to keep the alternator.

Crazy mod
It would be a major mod, but if you have the knowhow and trust a good custom cam company you could get a cam that allows for a atkinson o miller cycle. You'd also might have to change the turbo for another or maybe even a supercharger instead. Of course you'd have to be able to tune it a lot with your tune kit. In the end you'd have less power, but better efficiency and fuel mileage. And if you figure out a way to hook up an electric motor and HV battery you could have yourself a hybrid.

Turbo's effect
Good question about the turbo. A turbo helps efficiency since it allows you to use a higher load, which a higher load in a diesel means better efficiency. A turbo also is able to take advantage of exhaust gas pressure that would have otherwise been lost, unlike a supercharger. (Although the atkinson and miller cycle engines kind of take advantage of that exhaust gas pressure at the piston itself.) But there is also the question of turbo efficiency at different speeds. This isn't the same as engine efficiency, it's how effective the turbo turns exhaust gas pressure into intake pressure.

Engine heat
I had a 1,500W block heater on my 1.6L diesel I'd use for 15min to 2hrs (depending on the weather) before driving and am looking to get that kind of block heaters installed on my current cars. But my dream has always been to make a very large heat storage tank on my cars that works a lot like the 2nd gen Prius' heat storage system, and then to insulate the engine as best as possible.

[BLSTIC]

Originally Posted by ps2fixer

Looking at that truck, it's an aero nightmare. Nearly everything is a sharp edge. Sharp edges have the effect of keeping the air going whatever direction it just was, so for the bumper/air dam and windscreen, that means the air keeps going up, down, and sideways long after the vehicle dimensions have ended. The hole you are punching through the air could be 20-30% larger than it needs to be. It's also going to be a lot of work to fix, and not particularly pretty

Looking at a profile pic of a similar truck, if you were to install a full length flat undertray at the height of the transmission crossmember, side skirts to meet it, make your front air dam with a rounded bottom and sides (about a 6" radius would be a good starting point to try), and taper the undertray up to meet the rear bumper you could largely eliminate underbody drag.
Because the entire exhaust system is above this point height, though, you would need to have cutouts underneath the exhaust to ensure the exhaust didn't overheat anything.
Don't entirely block the bottom of the engine bay or you will not get very far up the road, but keeping the undertray uninterrupted until, say, the back half of the engine can increase cooling airflow by making the airflow where it does join a much cleaner and higher speed thing. You can tune this airflow exit the same way you can tune a grill block.
Ground clearance, departure and approach angles would remain unchanged, but break angle would be reduced slightly and the vehicle would appear visually a lot lower.

Installing a low profile roof box with a curved front would also help a lot. Apply the same 6" radius to the top of the windscreen and see how high it ends up, it will likely be a bit taller than your current lights, but not by much. If you make the front section clear you could mount your lights in it. Increasing the frontal area might seem counterintuitive but it's better than a square edge.

As for the side-front edges, well, you're pretty much screwed on that front.

The wheel gaps, you could fill in with mudguard skirt brushes like they do on semi's, to allow for cleaner airflow and less road spray with full articulation (but they wear out). That's at least a "real truck" thing too.

Also being a diesel, engine intake and exhaust flow is especially important as they are full airflow all the time (varying only with boost). Intake and exhaust flow improvements will result in fuel economy improvements even without fueling changes because at full load it will be running leaner. Even if boost somehow corrects itself load on the turbo will be reduced and you will get slightly better throttle response.
Is it intercooled? If not, do that. 100% do that if you modify nothing else on the engine for this truck.
Check the condition of the injectors and pump (somehow). Spray pattern is much more critical on a diesel than a petrol and you might pick up some (lost) power and reduce smoke emissions.
Google says your downpipe is the best $$$ per performance increase you can do on those trucks, but it requires firewall massaging (probably with a really big hammer)

Also, lose the stone deflector. Replace it with a piece of clear or red vinyl if you're worried about chips on the leading edge of the bonnet.

[ps2fixer]

I defiantly stand corrected on the diesel efficiency at load, the member getting 50mpg was using P&G with engine off to get those figures and it sounds like since his focus went elsewhere he's getting around 35mpg with his current driving habits. Sadly no mention what has changed, but I'm guessing he's not P&G any more.

The coldest week in my area gets down to about -10F at night, so a block heater is basically a must around that time. I already bought a couple mechanical timers a while back for another project (off grid lighting in a shipping container I use for business storage) and the idea was to burn up the excess power from the solar to keep standard car/truck batteries topped up since I have a few spares around that I might recharge once a month or so. I generally get junker vehicles quite often, so I haven't had to buy a new battery except once to get a vehicle home.

The PSD (power stroke diesel) has a static turbo, so the peak efficiency would be interesting to investigate. It has no waste gate, 100% of the pressure is pushed into the intake. I suspect being smooth into the fuel rather than quick jabbing would be more ideal to let the turbo spool up as the load is increased (more fuel to take off for example).

The page I found on the atkinson cycle is quite interesting. Seems like the down falls (low rpm power output) could be offset by increasing the compression ratio for the shorter stroke on the compression stroke, but have the power stroke be the full length. At least the concept makes sense to me for gas engines. Not sure how well it would translate into diesels. Probably a bit more over kill than I'm looking for since the power stroke diesels are an engine designed to have a lot of bottom end grunt.

If I remember right, my corolla was making roughly 14hp to go 55mph. I thought it would be an interesting design to have a small engine,say 20hp for your cursing engine and a larger say 80hp engine for a small car that would lock in and fire up for take off power. Lot of dead weight but weight effects mpg so much less than a lot of other factors.

That reminds me, there was a user on here building a custom car with the ideal tear drop shape, 3 wheeled, and a small diesel engine to power it. I should try to dig up that thread, maybe there's some engine related mods that could make sense for me.

Capacitors and super capacitors are an interesting topic too, over on another forum we were talking about them for atv's with out a battery, but a way to get solid and reliable 12v dc power (technically 13.5-15.5v dc) through a regulator/rectifier. I suspect maxing out the alternator is no big deal as long as it doesn't build up too much heat. In theory, the alternator could be used for the regen brakes and also an electric motor to help with take offs. I'm not sure if there's enough efficiency in the required parts to pull something off like that, but for a 3-4 cyl car I think it could be a fairly large gain. I guess the question at that point would be if it would give better benefits over just deleting the alternator from the get go (or a disable switch).

Poking around some threads and such, it seems like there's only been 2 members that really posted much info about driving full sized trucks with diesels for mpg. Their mods were mainly air dam, grill block, side skirts, and I saw a mention of a belly pan and areo cap. The 2nd member had a 7.3L diesel like me so I have atleast a point of reference. They were getting around 26mpg which isn't bad and it looked like very minor mods. I didn't check but I'm thinking they had an automatic and the manuals are known for better mpg, atleast for the typical driver.

I guess there's two versions of the 5 speed transmission, I have to check the ratios and try to figure out which one the truck has. Basically mine has a creeper gear first, so take off is in 2nd gear.

Power Stroke Diesel Transmission Guide

It's the ZF-S5-47 about the middle of the table. Wide ratio vs narrow. Based purely on rpm and what I've read other people with the transmission had for rpm with 3.55 gearing, it sounds like mine should be the wide ratio (slightly higher geared over drive). 70mpg is dead on or just the tinyest bit above 2000 rpm, the other post I saw the person said they were around 2100rpm.

The truck is at my dad's place since he has an area to work on it, so I'm not 100% sure of the tire size. I know it's slightly wider than stock, something like a 265 75 R16. Yay math time lol.

1 mile = 5280 ft
70mph = 369600ft/hr, 6160ft/min
Tire diameter: 31.6in, circumference: 99.4in

wide ratio 5th gear, 1 rev of the engine = 0.3706 turns of the tire, or 36.8421 inches -> 3.0702ft. 6160/3.0702 = 2006.4rpm

close ratio 5th gear, 1 rev of the engine = 0.3658 turns of the tire, or 36.3636 inches -> 3.0303ft. 6160/3.0303 = 2032.8 rpm

They are so close, can't really tell the difference in 5th gear . I guess the best test would be speed at 2000 rpm in 1st gear or if there's some sort of markings to id the two apart. I think that kind of confirms my rear axle must be 3.55 since the math lines right up with the tach and speedometer.

The heat storage system sounds interesting, I suspect it must use a fluid that has high heat capacity (generally highly corrosive with salts etc) and the bulk of the stored fluid is in a highly insulated box/container? This crosses over with some of the research I've done for rocket mass heaters, water is great, but adding a type of salt in it increases the capacity more, I think it has a lower freezing point too.

For the hybrids, my reading dates back to around 2012ish, so maybe in 8 years there's been some pretty major design changes and marketing focus. Newer vehicles always have to put out higher hp numbers to keep the average person wanting to "upgrade" their vehicle. I'm perfectly content with ~450ft-lb of torque at the flywheel on this diesel, I don't need the near 1000ft-lb of torque that the newer trucks have. If they took the updated tech and put it in half the size of engine to match the old machines, I bet some pretty impressive mpg figures could come out of them while still being a very solid power house for work. I've seen the same trend while researching GVWR. A 1 ton truck used to have a payload of 2000lbs, now they are something like 3 1/4 ton (7000lb) or more. In the 80's Toyota made a couple trucks that were badges as a "1 ton" but I suspect they were meaning it's payload capacity was truly 1 ton instead of the 1 ton "class" of truck.

Anyway, my wheels are turning in my head lol. If I can hit over 25mpg, then it would almost make no sense for me to have my car on the road. Not really an ideal mpg car, a 1990 Lexus LS400 with a V8 gas engine, RWD. I wanted to try one out and they are an awesome car, it's like 5x the quality of a Corolla if not more. I've been thinking of maybe getting a newer Lexus with a hybrid system, something around 2006ish. One guy I talked to with one was pulling pretty impressive numbers for a fair sized car, it was around 35-40mpg. With me driving it I'd think I could hit 45mpg pretty easily and make the corolla pointless to get going again lol. Of course the cost of the car isn't cheap, so the fuel savings won't pay for the car for an extremely long time. The corolla is rusted pretty badly, so it's only got probably 2-3 years for the body left.

[BLSTIC]

I can't believe I'm saying this (because it's EcoModder.com not TightwadDriver.com), but how much spare cash have you got and how much load-free driving do you do?

A 2010 Prius gets 51mpg according to the EPA. If you sell the Lexus and the Corolla you shouldn't be too far off buying one.

Your F250 probably gets 17mpg, or 5.88 g/100mi, at $2.44/gal that's $14.35/100mi
A Prius gets 51mpg, or 1.96g/100mi, at $2.05 for regular that's $4.02/100mi

At $10/100mi price difference that's 50,000 miles in total to pay for the entire cost of a 2010 Prius, and that's only considering fuel costs. The rest of the operating costs are so much smaller too

[oil pan 4]

The propane just needs a pressure switch so it cuts off above a certain boost level.
Oh and get an intercooler if you dont have one and a bigger turbo charger.
One from a powerstroke would be sufficient.