Fuel efficiency...

[MetricMuscle]

And 1000 pounds less with far less rotating mass.

Doesn't this effect acceleration more so than maintaining a cruise speed?

I'm certainly not looking to attain better mpg than a smaller more aerodynamic car rather improve issues the Explorer has and get the best balance between power, driveability and economy.

 

[Mbrooks420]

There’s no free lunch. Moving more weight takes more fuel. Towing a trailer kills your efficiency. It’s pretty much the same idea.

Rotating mass is 4 times the burden of static mass if I recall correctly.

 

[MetricMuscle]

Nobody as yet has corrected the exhaust in any of these 2nd gens, and I might end up being the only one to do it.

What are your plans for exhaust?

More specifically, what do you have envisioned for headers?

I have an exhaust design program which calculates diameters and lengths which correspond to the proper tuning frequency depending on primarily cam specs which dictates the power curve and what rpm peak power occurs. There are lots of other input variables but some will stay the same even on different build specs. I have found that most OE systems are close to the proper overall length but are compromised in most of the other dimensions.

So, do I understand correctly, I can remove the front drive shaft on my 2001 AWD Explorer and drive it without having any issues? I intend to do the 4406 mod eventually but I would like to see how it feels without the front drive shaft connected and if mpg changes.

 

[Mbrooks420]

You can remove the shaft. Mileage won’t increase with any significance. You are still turning the entire front axle assembly and the internals if the transfer case. The only real noticeable difference is the steering will be less heavy.

The truck will tend to creep while in park without the front shaft.

 

[German Engineer]

If you're only interested in MPG at highway speeds 70-ish, then try to get the RPM of the engine at that cruise speed reduced to as low as possible.
There's the transmission and the wheels you can achieve that with.
But when it comes to wheels again, the tires and the width of the wheel have an impact fuel efficiency.
Cars with thinner tires with higher pressures and threading optimized for fuel efficiency on asphalt get better MPG.
Not that it would look any good on an Explorer and if taken to extremes it would negatively affect the handling.
It would cripple off road performance and would reduce performance on snowy roads.
Oh and while we're at it.... getting rid of 4WD reducing it to 2WD could significantly improve MPG as well.

So you might want to consider putting larger, but "preferably" thinner rims on it with performance tires threaded for asphalt performance only (and not off road!). And use summer (summer only not all season) tires unless you live somewhere where it get's cold in winter, then switch the tires to winter tires seasonally. Those changes might make the Explorer look like a car from the nearest ghetto though.

I probably still forgot some things that impact fuel efficiency.

Oh and one last thing to recommend if you REALLY want to improve MPG:
Just sell the Explorer and replace it with a Mercedes A class, VW Lupo, Renault Twingo, Ford Fiesta..... some of those can even do 52 MPG and more when you opt for the most fuel efficient engine they come with.

In that sense cheap rational and realistic alternative to modifying the Explorer might for example simply be, to use the money you're willing to put into a modification and invest it into buying a used Ford Escort wagon or a BMW 3 series wagon (or something similar or smaller from Europe or Japan as suggested above) instead.

If you do enough Highway driving with something like that instead, it could very well pay off relatively quickly even. You can easily do the math on how much fuel you save, by comparing about 19MPG to a used car which gets 32 MPG and more. It can easily be around $1000 and more that you would save on fuel for every 20.000 Miles you drive!
And you would still have the Explorer for other occasions.
Luckily there are quite a few nice and comfortable fuel efficient European cars that can be bought relatively cheap when used.

 

[CDW6212R]

More specifically, what do you have envisioned for headers?

I have an exhaust design program which calculates diameters and lengths which correspond to the proper tuning frequency depending on primarily cam specs which dictates the power curve and what rpm peak power occurs. There are lots of other input variables but some will stay the same even on different build specs. I have found that most OE systems are close to the proper overall length but are compromised in most of the other dimensions.

....

I'm going to build log manifolds for my 98 302, after making the dual exhaust from the back to the front, in three steps. It will be all 2.5", for the intended 306 NA engine. When I get to adding a blower, then I'll do a 3" system, and move the 2.5" parts to my 99 truck with the built 306/4R70W swap.

There is plenty of space for log manifolds, but Ford gets stuck in ideas and concepts, even after they are proven to be bad. So they attempted to make a shorty header, ending up with basically a tri-y POS, paired primaries hitting each other at 90* in three points. I want the equivalent of 1 5/8" primaries going to a 2.5" collector, which will be placed near the OEM collector, but using a v-band clamp. That will flow more air than the tiny TM headers, which are the equivalent of a 1.5" equal length header. Those are horrible to install, and the equal length pipes barely gain any power over a simple shorty design. If they had made a shorty header, 1 5/8" pipes, they could have sold five times as many as they have, for maybe $400 a set.

 

[MetricMuscle]

If you're only interested in MPG at highway speeds 70-ish, then try to get the RPM of the engine at that cruise speed reduced to as low as possible.
There's the transmission and the wheels you can achieve that with.
But when it comes to wheels again, the tires and the width of the wheel have an impact fuel efficiency.
Cars with thinner tires with higher pressures and threading optimized for fuel efficiency on asphalt get better MPG.
Not that it would look any good on an Explorer and if taken to extremes it would negatively affect the handling.
It would cripple off road performance and would reduce performance on snowy roads.
Oh and while we're at it.... getting rid of 4WD reducing it to 2WD could significantly improve MPG as well.

So you might want to consider putting larger, but "preferably" thinner rims on it with performance tires threaded for asphalt performance only (and not off road!). And use summer (summer only not all season) tires unless you live somewhere where it get's cold in winter, then switch the tires to winter tires seasonally. Those changes might make the Explorer look like a car from the nearest ghetto though.

I probably still forgot some things that impact fuel efficiency.

Oh and one last thing to recommend if you REALLY want to improve MPG:
Just sell the Explorer and replace it with a Mercedes A class, VW Lupo, Renault Twingo, Ford Fiesta..... some of those can even do 52 MPG and more when you opt for the most fuel efficient engine they come with.

In that sense cheap rational and realistic alternative to modifying the Explorer might for example simply be, to use the money you're willing to put into a modification and invest it into buying a used Ford Escort wagon or a BMW 3 series wagon (or something similar or smaller from Europe or Japan as suggested above) instead.

If you do enough Highway driving with something like that instead, it could very well pay off relatively quickly even. You can easily do the math on how much fuel you save, by comparing about 19MPG to a used car which gets 32 MPG and more. It can easily be around $1000 and more that you would save on fuel for every 20.000 Miles you drive!
And you would still have the Explorer for other occasions.
Luckily there are quite a few nice and comfortable fuel efficient European cars that can be bought relatively cheap when used.

I'm gonna put you down as a "Valued Contributor". Not only for all of your brilliant ideas but also the way you present them which magically motivates us to strive for perfection.

 

[MetricMuscle]

I'm going to build log manifolds for my 98 302, after making the dual exhaust from the back to the front, in three steps. It will be all 2.5", for the intended 306 NA engine. When I get to adding a blower, then I'll do a 3" system, and move the 2.5" parts to my 99 truck with the built 306/4R70W swap.

There is plenty of space for log manifolds, but Ford gets stuck in ideas and concepts, even after they are proven to be bad. So they attempted to make a shorty header, ending up with basically a tri-y POS, paired primaries hitting each other at 90* in three points. I want the equivalent of 1 5/8" primaries going to a 2.5" collector, which will be placed near the OEM collector, but using a v-band clamp. That will flow more air than the tiny TM headers, which are the equivalent of a 1.5" equal length header. Those are horrible to install, and the equal length pipes barely gain any power over a simple shorty design. If they had made a shorty header, 1 5/8" pipes, they could have sold five times as many as they have, for maybe $400 a set.

There are so many OE headers/manifolds designed in really ugly ways. I'd love to know what led engineers to these final designs other than cost, manufacturing simplicity and fitting where they need to.

 

[Mbrooks420]

There are so many OE headers/manifolds designed in really ugly ways. I'd love to know what led engineers to these final designs other than cost, manufacturing simplicity and fitting where they need to.

Those are the only three driving factors of any mechanical automotive design.

 

[MetricMuscle]

Those are the only three driving factors of any mechanical automotive design.

It also has to work well enough for the engine to run well enough. Maybe these wonky exhaust manifolds work better than they look.

 

[CDW6212R]

It also has to work well enough for the engine to run well enough. Maybe these wonky exhaust manifolds work better than they look.

No, no, these manifolds are the worst things ever made. I'd have shot the engineer/designer if I had a say when they first made them.

 

[German Engineer]

No, no, these manifolds are the worst things ever made. I'd have shot the engineer/designer if I had a say when they first made them.

View attachment 161474

They might be, but I guess they're probably really not.
Exhaust manifolds are not only designed with maximum power and fuel efficiency in mind but - and this is actually extremely important to meet the norms on pollution - to deliver the exhaust to the catalytic converter(s) in the way such that it can reduce the vehicles pollution as effectively as possible.

 

[MetricMuscle]

I'm going to build log manifolds for my 98 302, after making the dual exhaust from the back to the front, in three steps. It will be all 2.5", for the intended 306 NA engine. When I get to adding a blower, then I'll do a 3" system, and move the 2.5" parts to my 99 truck with the built 306/4R70W swap.

There is plenty of space for log manifolds, but Ford gets stuck in ideas and concepts, even after they are proven to be bad. So they attempted to make a shorty header, ending up with basically a tri-y POS, paired primaries hitting each other at 90* in three points. I want the equivalent of 1 5/8" primaries going to a 2.5" collector, which will be placed near the OEM collector, but using a v-band clamp. That will flow more air than the tiny TM headers, which are the equivalent of a 1.5" equal length header. Those are horrible to install, and the equal length pipes barely gain any power over a simple shorty design. If they had made a shorty header, 1 5/8" pipes, they could have sold five times as many as they have, for maybe $400 a set.

What diameter will the primaries from the head be? Log diameter? Will the log be a tapered cone shape?

No, no, these manifolds are the worst things ever made. I'd have shot the engineer/designer if I had a say when they first made them.

View attachment 161474

Ok, maybe not those particular exhaust manifolds. Ya do gotta wonder what folks were thinkin' sometimes.

What about the cast exhaust manifolds found on the later models? I know they didn't have the structural failures the earlier ones did but do they flow better than they look?

 

[MetricMuscle]

They might be, but I guess they're probably really not.
Exhaust manifolds are not only designed with maximum power and fuel efficiency in mind but - and this is actually extremely important to meet the norms on pollution - to deliver the exhaust to the catalytic converter(s) in the way such that it can reduce the vehicles pollution as effectively as possible.

I think the priority would be meeting emissions then cost. Not sure if power or fuel efficiency was much if any concern since an aftermarket design can so easily improve on exhaust manifold/header flow efficiency. So many other areas have been optimized by OEM's over the years, they leave less and less on the table anymore, especially compared to the miserable stuff the late 70's and early 80's. I haven't seen an OE intake system lately which wasn't already pulling cold air from a high pressure area. Most cat back systems only change the sound of the vehicle, they don't improve the exhaust flow except at WOT redline rpm range, if that.

 

[MetricMuscle]

So lets look at just the engine and what mods increase fuel efficiency at highway cruise speeds of say 70mph. These are just my thoughts.

I used to think that a tall top gear was the key to best mpg but it is actually Throttle Position. One way to monitor this is intake manifold pressure/vacuum. The smaller the throttle opening is, the higher the manifold vacuum will be. If an engine has enough power to turn a taller gear then rpm will be lower but more importantly, small throttle opening. If the engine doesn't have enough power for a taller gear then mpg will suffer because it will take more throttle to pull it. This is especially obvious with small 4-cylinder engines, they have to be in the right rpm range to pull the gear with small throttle opening.

For an engine to make power at low rpms and small throttle opening, it's got to have compression. Compression helps everywhere but has to be managed properly. Combustion chamber design is probably the most critical and the GT40P heads are designed with this in mind by locating the spark plug more centrally and smallish chamber volume for better faster burn . They also flow very well for their intended power range.

Cam specs, like Lobe Separation Angle, can help manage higher compression. Timing can too but it has a different priority, peak cylinder pressure.

So imagine you are on a reality show and your team has to modify a 2001 Explorer 5.0/302 engine for best mpg at 70mph. How would you go about it? The rest of the truck has to be left alone, even the low hanging fruit like roof rack, etc. Just mods from the airbox to the tailpipe tip, Intake, Engine, Exhaust, including a proper tune if necessary.

 

[MetricMuscle]

I higher compression than 9:1 would help quite a bit. I'm aiming at the 9.5 range or whatever my cam designer tells me, that he can make work with regular gas. Look at the KB hypereutectic pistons, there are $315 sets that can get you in the 9.5 to 10:1 range. Set the quench in that .035" range with adjusting the pistons and gaskets, that should make good power.

The exhaust is horrendous, that's a cause for a big loss of power and fuel economy. If you could correct the exhaust, and make the compression/cam/intake ideal with PCM programming for proper A/F and timing, 21-23mpg should happen with the 302. But without all of those things right, you'll be lucky to get close to 18mpg. Nobody as yet has corrected the exhaust in any of these 2nd gens, and I might end up being the only one to do it.

Who is your cam designer?
Are you referring to the KB Step Dish design? I like what he has written on how/why these were designed the way they are.

 

[CDW6212R]

FTI, Ed Curtis is my choice right now for a cam. He's very good and well known on the big Ford forums. The cam tech lines are manned by people who's job it is to sell callers one of their cams. They use computer software that selects a cam of theirs which should be close to what a buyer wants.

Real cam guys use the actual valve springs available to optimize what can be done with a given vehicle, and the obvious details like heads, intake etc. As an example, EC can make a cam for an engine to work at higher rpm's than the parts may be thought to be best for, as requested by the buyer, or a lower rpm band, or with existing valve springs etc.

The best results come from very good parts selection, plus the cam designer, which usually also includes valve springs not installed in new heads available commonly from Summit etc. More can be had from the best parts for a given combination, and the right cam guys know what those are in most cases. They can be invaluable for helping to select parts, though that's not their primary function. On the Corral forum it is common to see Ed's suggestions for heads or intakes etc, in threads discussing parts combinations.

I haven't asked Ed about any parts choices, except for valve springs for heads I was about to buy. I also asked him once about compression ratio for general street use etc, and that's where I got the idea that I can use 87 octane for work with a compression higher than 9.0 for a 306 SBF.

The heads I have to build a 306 now I got are a ported knock off set of GT40X's. I was wanting a used set of TFS 170's, but those are rare in solid trusted unmolested form. If those can be had for $1000 or less already prepped, that's the best choice for a mild level SBF. But given the $250+ cost of the best valve springs(kit) that a custom cam needs, and the common rebuild cost of used heads, I didn't find any. In the end the TFS 170's used would end up costing very close to their new price, say $1250 or more.

So I settled on these FloTek 180's, being ported by a well known head guy, I expect any defects from being knock offs are corrected. I have the proper springs Ed suggested, and I'll ask him for a specific compression ratio(and quench) to use when I'm ready to buy pistons.

The GT40 heads(all of them) are not high flowing heads, but they are very competitive in normal street rpm's for efficiency. So a TFS 170 head will outrun all GT40 heads above say 3500rpm, but below that it's not a big enough difference to worry about. GT40(and P) heads on Explorers flow under 200cfm typically, and max ported may get 225cfm. The best GT40 FMS heads might get close to 245cfm ported, but all aftermarket heads worth having, start above that.

 

[MetricMuscle]

I'd like to find a way to get a proper 0.040" squish by just replacing head gaskets but we'd need one with installed thickness of 0.020" and the only way I've seen this done is with solid copper and an o-ring. Not sure this is doable without machining heads and block prior.

So I settled on these FloTek 180's

What kinda power are you after? What rpm range?

 

[CDW6212R]

I'd like to find a way to get a proper 0.040" squish by just replacing head gaskets but we'd need one with installed thickness of 0.020" and the only way I've seen this done is with solid copper and an o-ring. Not sure this is doable without machining heads and block prior.



What kinda power are you after? What rpm range?

The stock cam is really intended for the stock 9:1 compression, who knows how changing just the head gasket would work. I think you can get them from Comotec in the .025" range, but yes they are probably virtually a solid metal, and high too.

I'm aiming for a 5500rpm shift, stock 4500lbs weight plus few hundred pound load. My 99 4WD has 4.10 gears and I think that will be very good for my work use. I'd like it to shift at around 3500rpm normally, with my typical half throttle effort. I'm not easy on the gas in anything I drive.

My 98 302 4R70W is stock but the shifts are rather high for a given throttle. It's shifting easily above 3500rpm as I drive it, kind of letting off to make it shift when I think it should(not let it push to 4000 or more until it wants to). So my 98 being stock isn't the perfect example of how I want it to shift. Some adjustments to the software may be in order, after replacing the solenoids, accumulator springs, J'Mod attempt, and Sonnax upgrades.

In a Mustang I'd expect 300rwhp and more with the 306 I have in mind. But our automatic and transfer case cost an easy 40hp versus a Mustang/manual. So I'm after say 250-275rwhp. I don't expect to gain fuel mileage with it, I've lived with V8's my whole life and don't have allusions about seeing 25 or 30mpg. I'd be satisfied if it could do close to 20mpg at a steady 60-70mph.

My route takes five hours to drive 83 miles, I might be getting 10mpg, due to about 30 miles of commuting distance. So a gain or loss of 1mpg can mean a lot to me over a year etc.

 

[Centaurus5.0]

So I'm after say 250-275rwhp.

So put an e cam in the stock engine with tfs 1 springs and there you go.. no aluminum heads, no port work, no 1k valvetrain and no name dropping needed.

The money you saved could be spent taking your rig to an exhaust shop..