A High Mileage Modification Outline
Prepared for Xfi’s Escort Wagon Project
Generally going from the ground up; not listed in order of expected F.E. gains:
*Tread design- More “ribby” than “blocky” tends to have less rolling resistance. Also, shallower tread depths have lower r.r., as do thinner sidewalls and fewer belts in the tread. Worn-out tires have less r.r. than new tires. This is all due to reduced hysteresis- basically, the energy lost to heat from flexing rubber. Tires with a central tread rib generally wear longer at the expense of a bit of traction.
*Pressure- Tires are not supposed to burst even when inflated to 200 psi, so running 50, 60, even 70+ psi is not a danger in that respect for tires in good condition. However, it is possible to blow out older, weather-checked, or otherwise damaged tires with pressures exceeding sidewall maximum- ask me how I know.
Some claim no uneven wear issues with running pressures that high. Personally, I don’t like exceeding 50 psi because the ride quality deterioration made whatever r.r. gains there were not worth it.
*Materials- Rubber with a high silicon content is said to have reduced r.r. Michelin and Hankook are said to be leaders in this area.
*Loading- I came across a Michelin tire site that implied “square” contact patches (where width and length are about equal) offered the least r.r. Various bicycle sites have also made mention of how tires can be too skinny for minimized r.r. Since contact patch is largely a function of weight on each tire divided by tire psi, one can calculate the tire width needed at various tire pressures in order to end up with “square” patches. I think it is safe to say that going narrower than “square” will result in increased r.r., while going wider, within reason, may not. My research has not yet turned up conclusive answers.
*Diameter- supposedly larger diameter wheels and lower profile tires can reduce r.r.- makes sense; they might have less hysteresis. One problem with that strategy is the unavailability of wheels and tires like this that are narrow enough to provide a r.r. benefit.
*Width- within recommended range for the desired tires. I wonder if wheels on the wide end of the range would help tires wear more evenly across the tread when running over max pressure?
*Aluminum vs. Steel- aluminum rims are almost always lighter and this is said to be good for handling and FE. That said, I don’t know if the difference is detectable to the average driver. And fitting some nice moon discs is easier with steelies although they‘re known to have attachment issues.
*Tapered Roller vs. Ball- ball bearings roll easier for sure, but I haven’t recently researched empirical values for how they compare to tapered roller bearings. I know bicycles use ball bearings in the wheels for that reason, and I know Geo-Chevy Metros use ball bearings in the rear hubs too… for that reason? My classic cars have ball wheel bearings and drum brakes and those wheels spin freely like modern car wheels can’t. I’d like to convert the Tempo rear hubs to ball bearings but haven’t researched parts availability.
*Wheelbearing Lubricants- For three years I’ve been running gear oil in one of my rear hubs for bearing lube, with no problems. When I raise the rear of the car and give both wheels a spin, the wheel with the oiled bearings seems to spin easier and keep spinning longer. Haven’t quantified the difference though. I have seen tractor-trailer rigs running oiled hubs on the trailers too. The grease cap needs to be modified with an oil fill if you are to try this mod. Otherwise, the new synthetic greases are said to perform better at lower temperatures than traditional greases. I am trying some Chevron synthetic but don’t have much field experience with it yet.
*Drum- No drag when adjusted properly. I want to fit drums to the front of my car for that reason, but haven’t due to all the fabrication work needed. The wheels would stay much cleaner too.
*Disc- They always drag a bit. Is it feasible to add retractor springs to disc brakes without unduly compromising function? I’ve been thinking of ways to do this; that could be easier to accomplish than converting to drums.
*Ride Height- Several sources have mentioned 3” as an aerodynamically optimal ride height… but don’t ask me why that is. I have two basically identical Tempos, one lowered and one not. They take turns getting better FE, so other variables are greater than this. Still, it makes sense that a lower car can have better aero due to reduced frontal area and less air going past the rough undercarriage. Only you can decide how much compromise on ground clearance and ride quality you are willing to give up. Also, getting stuck in deep snow because your car is too low does NOT help FE.
*Springs, Shocks, and Sway bars- If you want to conserve momentum and take corners fast, lowering the car and/or stiffening the suspension can help. I’ve never bought expensive lowering springs and/or shocks; I’ve cut mine and am pleased. I bet your Escort has a bigger factory front sway bar available- just go to the scrap yard and measure one from an automatic trans equipped car (Tempo a/t cars have bigger bars than m/t models due to all that extra weight on the front end).
*Alignment- In my opinion it is best to stay within factory specifications, although I get as close to 0 toe and 0 camber as allowed.
*Re-gearing- Getting deeper ratios could offer the best potential FE improvement of any of this- 5% or even more. However you can overdo it if your terrain and/or loading is such that you can’t pull top gear often enough. Be ready for an increased workload from downshifting if you go radical and aren’t a flatlander like me. Look here for CO ZX2’s Escort tranny re-gear: Trans gears.
*Lubricants- Ford already uses ATF in the m/ts so…
*Lubricants- Lighter weight oils help FE a very small amount; fuel economy.gov says “For example, using 10W-30 motor oil in an engine designed to use 5W-30 can lower your gas mileage by 1-2 percent. Using 5W-30 in an engine designed for 5W-20 can lower your gas mileage by 1-1.5 percent.” Synthetics may help a bit too under extreme temperature conditions. Don’t expect any miracles though. Follow the manufacturer’s maintenance schedule too- the popular 3,000 mile oil change regimen is obsolete. Consistently running it ? to 1 quart “low” can potentially reduce windage losses safely.
*Air Filter- all the testing I’ve seen that I consider to be unbiased shows a plain old factory-style paper element to be the best at delivering clean air at minimal restriction. I have never fooled with oiled “K&N“ style filters and due to the economics, maintenance requirements, oil contamination of EFI components, and dubious cleaning abilities I probably never will.
*Cold or Hot Air Intakes- “Results” posted on GS and other places are all over the map. Maybe what works on one car does not work on another. Then there is the poor quality of most of the “testing” that was used to report the “results”. I can not in good faith suggest solid improvements here.
*Exhaust System including Headers- I believe the exhaust system can be tuned for FE with long primary headers, fewer bends, better mandrel bends, and smaller tube diameter. Problem is, aftermarket exhausts are tuned for higher rpms operations, not lower. Unless you can build your own, I wouldn’t obsess over it.
*Hotter Thermostat- Some say it works; personally I don’t know.
*Underdrive pulleys- Slowing down all or some of the engine-driven accessories can reduce parasitic power losses somewhat. Biggest benefits are at high rpms, where we shouldn’t be anyway. According to escortfocus.com a 45% under drive pulley leads to a 15% FE increase. But then, they sell pulleys…
*Pre-Heating- Engine heaters are proven FE boosters as well as emissions reducers. Block heaters are the best, followed by “tank heaters”. Auto manufacturers recommend using them at 10 deg. F or less. We know they can be used at any temp to increase FE. If your schedule is consistent put them on a timer so they are on for 1 to 1 1/2 hours before you go.
*Heat Retainers- Feeling inventive? Prius has sort of a Thermos bottle system for retaining some waste heat for later release on cold engine start-up. Even better than electric heaters… if too much time doesn’t elapse between starts. Nothing commercially available especially in N. America that I’m aware of.
*Ignition Timing- Anything with a knock sensor will already have optimal timing.
*Spark Plug Indexing- Very small potential for improvement but if you like tinkering it can’t hurt.
*Grille Blocks- Are they more aero or heat management? My guess is they are both, depending on. They are aero at highway cruise speeds, and heat management especially on start-up, low speed operations, and they help slow heat loss when parked.
*Engine Blankets- I like to insulate the top of the engine bay to help heat retention when parked after a bit after running, and also it might help warm up the engine compartment when it’s plugged in? (Not tested)
Cylinder Head Modifications
*Compression Ratio- Higher C.R. = better thermal efficiency. However, with our desire for tall gears and low rpm operations, all the lugging and near-lugging we do coupled with the higher temps from our grille blocks and whatnot increases the engines’ propensity to detonate… so we can’t go overboard on this or the engine management computer will do naughty things like pull timing advance. However, ethanol mandates are becoming more widespread in the U.S. so higher octane fuels are now readily and "cheaply" available. I’d increase C.R. if committing to ethanol blends.
*Somender Singh Grooves- I like the story; I like the theory; but do they really work? It sounds like, in order to work best the combustion chambers need big ol’ quench zones, like old small block Chevys had. I don’t think your Escort chambers have much, if any, quench.
*Camshafts- I’m sure any of the big cam companies (Crane or Comp Cams come to mind) could come up with a custom grind that would help to move the power band lower. This would be especially useful if you regear the transmission. They may also be able to come up with estimates of efficiency gains. They have access to powerful simulation formulas and years and years of dyno experience. I don’t.
*Camshaft timing- One source says “Advancing the cam leads to slightly improved low rpm torque, slightly reduced peak power, imperceptible change in emissions, idle & fuel consumption”. Well if you’re geared way up and you can improve low rpm torque, allowing you to better short-shift and use the taller gears, it might increase FE… right?
*Coatings for Internal Engine Components- There are many (Swain comes to mind); some for piston skirts that retain oil and are “slipperier”, some for piston tops that claim to reduce hot spots and overall temps for increased detonation resistance, still others for cranks, rods, and blocks to promote oil being flung off, reducing “windage losses”. Do you want to tear the engine down for that?
*Engine Cleanliness- Seafoam users claim good things from top-end cleanings. Of course, it won’t improve anything if the engine is already clean! On that note, if your injectors are old they may benefit from an out-of-the-car cleaning or replacement.
*Throttle Locks & Cruise Controls- Not going to P&G all over the place? I don’t blame you. The next best thing is a very steady throttle. G.S.rs have done throttle locks and hacked cruise controls to maintain constant throttle settings. I don’t know the FE results of these mods though- have they ever been reported?
Electrical Load Reduction
*LEDs- reduced wattage draw on the electrical system. Won’t pay back for a long, long time though… if ever.
*Alternator Delete- Definitely improves FE (up to 10%!) but do you want to do all that battery-handling work? Also you are basically transferring power supply from the gas in the tank to the national grid. It is more fuel efficient though.
*Alternator Disable- Cutting out the field so that the alternator doesn’t charge under acceleration and maybe even cruise can improve FE a claimed 1-10%. It could be done manually via dashboard switch, or perhaps a vacuum switch of some sort could disable it under high loads. The real deal would be for the engine management computer to have an algorythm to take care of it- beyond my skillz at this point and I know of nothing commercially available.
*A/C delete- Definitely can improve FE… by how much depends on how much, and how you use the A/C. I've seen figures for up to 20% FE improvement, but I don't know how accurate that may be.
*Interior Cooling Strategies- Reflective window shades, white exterior and interior colors, crack a window open slightly when parked, find a shady spot, etc.
*Power Steering Delete- Big guys driving little light cars shouldn’t need power steering. It doesn’t consume much power, but it’s a parasitic loss nonetheless. There are manual steering racks that swap right in our cars. Failing that, I have considered running the lines from the rack into a reservoir and removing the pump- perhaps almost as good "feel" as a real manual rack?
Radical Engine Mods
*Engine Swaps- You know you can do a diesel swap! Or any other engine that presumably has some combination of less power/more efficiency than what it came with… Howaboutta D15Z1??? LOL
*Deactivating Cylinders- Forget about merely cutting the injectors and/or disabling the valves- those ain’t gonna cut it. I do believe removing two pistons and rods would work though. I haven’t done it thus far because of the time-honored principle I try to adhere to: “If It Ain’t Broke, Don’t Fix It“. I do know that cutting air-cooled VW 4-cylinder boxers down to 2 cylinders has been done many times successfully.
*Acetone- Some swear by it, others swear at it. IMHO it doesn’t pass the smell test, although if you are starting with a dirty fuel system and if this stuff has some cleaning action I suppose it can help on occasion.
*E85- Some swear by it, others swear at it (d?j? vu?). I like it even though it does sometimes show a reduction in FE… but in my experience, rarely as big a drop as many others claim. It has good cleaning properties too, and since I haven’t experienced major FE drops and the price differential between it and regular is big, I come out ahead using it. Don’t use it full-strength when it’s below freezing out; you will experience cold-start and driveability problems. Were a guy to dedicate himself to running E85, raising the compression ratio far above what regular gasoline will tolerate gets back much if not all the efficiency losses caused by ethanol’s lower BTU content.
*Weight Reduction- 1-2% FE increase per 100 lb reduction. Ask yourself if gutting the car of seats and interior is worth more than a 2 mpg FE gain is.
*Air Dams- Vehicles with really rough undercarriages like pickups benefit more from deep air dams. Vehicles like Escorts that aren’t so rough underneath, or have bellypans, should not need air dams that extend closer to the road than the lowest point on the undercarriage, and some designs may not benefit from an air dam at all.
*Rake- A few degrees nose-down reduces aero drag.
*Mirror Removal- Potentially reduces drag but on some designs mirror removal actually increases drag. Those of us without access to wind tunnels can do yarn testing on mirror mods, or removal. If mirror removal looks to be beneficial, some G.S.ers say mounting convex mirrors on inside on the A-pillars works well.
*Antenna Removal- Antennas can be relocated to somewhere in the interior, usually under the dash, with mixed results. Reception never gets better than stock; it is a question of how much it deteriorates. I rarely listen to the radio in the car anyway so antenna removal didn’t inconvenience me, the car looks a little better to my eye, and one source of wind noise is removed. As far as FE goes, my testing isn’t fine enough to detect whatever improvement there may have been.
*Wiper Removal- The base of the windshield doesn’t have the fast-moving air everyone thinks it does. I’ve removed wipers and it results in more inconvenience than anything. I've removed the passenger wiper and it results in the passenger feeling like a second-class citizen. Now, they are both back on.
*Roof Rack Removal- Luckily you don’t have one. Don’t add a permanent one.
*Wheel Skirts- Intuitively they should reduce aero drag but out in the real world the FE benefits have been tough to assess. And, many low-drag designs do not rely on skirts. I had some, then took them off, and the gas logs aren’t showing a conclusive difference. Put some on if you want, but know that checking tire pressure gets a lot more difficult. Tire pressure has a far greater influence on FE than skirts.
*Belly Pans- Properly executed pans definitely reduce aero drag- up to 10%, which equates to roughly a 2% FE increase. So if your Escort gets 37.00 mpg highway it could possibly go to 37.74.
As with all things aero it involves compromise. The faster your average speed, the more potential FE benefit.
*Spoilers and Wings- Usually wings are for looks and/or down force and actually increase aero drag. Properly designed spoilers can reduce drag. How can we tell what reduces drag and what doesn’t? If there are any published wind tunnel test results, great. If not, I assume a factory spoiler affixed to a trailing edge reduces drag while all others probably increase it.
*Radical Aeromods- there are many ways to chop, section, and reconfigure vehicle bodies to improve aerodynamics. The most likely to succeed would be mods that reduce frontal area. Of course, one has to evaluate their utilitarian needs from the vehicle first so as not to overly compromise or ruin it’s usefulness. And, it’s a major undertaking, requiring either above average fabrication skills or a large investment. I’d say if one is considering this approach, that they have other reasons than FE for doing it as the return on investment may not be there. Another category is boattails and other larger devices that attach to the bodywork. What G.S.ers think is cool might scream "dorkmobile" to potential buyers if not really well executed. You do want to re-sell it at some point right?
I dunno, it looks good to me and it's GREEN, so I’d leave it.