fbov

I have a set for the lourvred grills... baselining with the lourvres enabled first, in conjunction with the reductions higher on the front. Been gettin' frosty in the morning, but I'm hoping Winter will hold off until Thanksgiving!!! You may want to review this link if you're interested in intake improvements. Part 2 is his tuft testing. I'll give away one punch line (no emphasis added): "I have never seen a standard filter element cause any more than a tiny proportion of the total restriction in the intake of any standard car!" HAve fun, Frank

PM sent. Thanks for offering! Once tufted, it would have been quite easy to add aero test factors to the car like magnetic GasPods, save for my wife's impatience. Just keep in mind that you're limited to sheet metal... but you get to try different variants and see if there's an optimum for turbulence reduction. And here's the $64,000 question... (drum roll, please)... where would you put them for the greatest benefit? What are the group's thoughts? HAve fun, Frank

Gents, I assure you the step in the roofline isn't the issue it looks like it could be. I made a point of putting a row of tufts just downstream of the step. They're steady as a rock, just like the ones upstream. The whole roof looks laminar right to the rear edge, where you expect some turbulence. I come back to the relatively placid back window as a sign that there's nothing amiss above the beltline in this car. And the back window is easy to confirm; no cameras needed! I hit 60mph headed home, and the window stayed calm, with an orderly, fan-shape pattern around the centerline. Where do you get dirt on the back of the car? That's where you have a turbulence problem. HAve fun, Frank

Paul, take a closer look behind that grill (remove the 4 plugs) and you'll see that what looks like a nice ram-air intake is more of a water splash baffle. The engine air intake aims sideways. I tried to be patient and test one thing at a time, but I'm now jonesin' for more improvement after my PCM update 5%. I finally bumped the tire pressures from stock to sidewall, and that already shows a 5% reduction in parasitic losses in a coasting test. And the snow's coming and snow tires will not be an improvement... Take a look at the tuft test... HAve fun, Frank

One of the topics I find interesting on this forum is car mods, specifically those that improve fuel consumption through areodynamic improvements. In researching here and eslewhere, the general rule is that there's not much you can do up front besides block air infiltration, but you can get big drag reduction in the rear. I wanted to see what airflow looled like over the back end, and what sort of changes might be beneficial. I had also noticed that the hatch lid didn't meet well with the roofline. I laid out ~4" tufts of yarn and string in a 5" grid pattern over the back half of the car. The idea is to drive at speed and look at the patterns the tufts take on the car. I took video, but need the right SW to pull snippets. Here are a couple stills. General observations Laminar flow is everywhere - roof all the way back to the lip; that little step does nothing - windows sweeping up toward the roof, right to the hatch glass - door panels above rear wheel well, but ending under lights Turbulent flow dominates the tailgate (lots of blurry tufts) - lip under the glass down to the top of the bumper - flanks under rear lights sweeping forward to wheel wells The big surprise is the rear window - near calm - strings lay flat and don't move much - pattern is downward with slight outward flare - pattern extends to L/R edges of the glass, right next to high-speed laminar flow I see... ... evidence of clean separation from rear lights, up across upper hatch edge - a calm rear window. ... evidence of turbulent separation along the flanks, below the lights - a turbulent hatch panel below the window. Take a look and let me know what you think. I'll note that I'm looking at video as well for my descriptions. Have fun, Frank

I looked at the intake system, and have, in effect, blocked its cold air inlet. The plastic runner comes through the bulkhead, turns toward passenger side and ends in a perforated tube under the latch. Lots of open space into the engine compartment, far greater area than the intake plenum, so blocking off the slots in the grill should have little effect on intake air flow. Add in that lower drag always helps while we try to use the ICE as little as possible, and at low RPM at that, and it seems like a reasonable tradeoff. I'm most of the way to a set of lower grill blocks, but had some "other fun" on tap today... Have fun, Frank

Jus, stop trying to cheer me up...

Wheels with an oversize centerbore usually come with centering rings, spacers that fill the gap between the hub and the wheel. Use them, as you really don't want the lug nuts centering your wheel. HAve fun, Frank

Others have mentioned the gap at the front hood edge on either side of the upper grill, suggesting one lower the stops to close the gap. I looked at it from an aerodynamic perspective, especially when Ford announced mods for 2014 that include front hood seal modifications. The existing seal didn't seal; there was a air gap to the hood. There was also a gap a the edge of the hood all the way around, not just at the front edge.What to do? For the hood seal, I added high density rubber foam weatherstripping to the underside of the hood where the existing seal is supposed to make contact. Afer sitting overnight, you can see a crease in the rubber where the seal is making contact... and perhaps see how you can aim better than I did! That's the base of the latch at lower right. I also used this material to build up a multilayer seal on the hood tall enough to seal outboard of the existing bulkhead-mounted seal, but left the center latch access open. This doesn't look reliable, so no pictures to prove I ever did it. For headlights, I used a "bulb-style" silicone weatherstripping in clear. I mounted it on the headlight itself, tucked in at the front and cut flush at the rear, and cross the upper grill facia where it meets the hood edge. The hood lead edge gap was larger than the weatherstripping could bridge, so I added a piece to the hood edge. At the other end, you could also continue past the headlight up to the windshield, but I didn't see a gap parallel to flow as being that important. If you like the look, it also fits the door jams; any where you get an 1.8" gap, but I suspect it's gong to be decorative The hood now likes to be dropped to close, but it's tight and looks fairly clean with the clear being the only addition visible. (Using flash at dusk because I did this last night, the grill block this morning...) HAve fun, Frank, who couldn't wait until Spring to start doing the aero stuff. PS remember, weatherstripping is designed to be used outdoors; it's designed to get wet and frozen and still stay put when you open gaps. the only risk I see is longevity, maybe some adhesive residue after removal...

Paul, your work was one of the first I looked at, as it well documents an improvement. I'm looking for new "low-hanging fruit." I notice that you only block the lower grills, the ones with louvres, and with the change in lourvre operation contained in the PCM update, I'm again going to leave that area alone. The upper grill looks like little more than a cold air intake for the ICE, and there's lots of open area behind the grill face to feed the plenum; it's hardly a pressurize feed. While I was at it, I also did hood seals. Starting point I pulled the plastic retaining plugs (pry up and remove cap, pry out plug) so I could access the area behind the upper grill. A little newsprint and a marker gave me a rough template, which I cut out in scrap plexiglass. Here's it in place,with the grill pulled back. You can see the plexi best near the latch, where it's notched; reflections make the rest hard to pick out. It's bent slightly, so no rattle conerns. And all closed up... Next, hood seals... Frank

Not sure where this best goes, but since it's a report on the PCM update, I pick here. I show results in two flavors, mileage and fuel consumption. In each case, I plotted data for a 15.5 mile commute, taken both ways every day, on sparsely-traveled 35-45MPH-posted roads at about a 30MPH average speed. 5 "stop" signs and 12 lights. I make a point of driving 0-10MPH over the limit, with most time spent in the upper half of that range. I have removed any rainly days, and limited the temperature range as the recent dips below freezing have resulted in a non-linear pattern that I believe includes more than variation due to the PCM update. Based on 40F-60F data (linear range?), I am seeing a +5.4% change in mileage and a -5.1% change in fuel consumption at 50F. Now, for some expressway driving! HAve fun, Frank

I like the way you're thinking, but read the rest of the sentence; your snippet obfuscates my statement. You can't do a proper tuft test with one car. I'll use a chase car, and hope the camera mount is steady enough that the images are useful. We'll see... HAve fun, Frank

Under the cargo area cover is the HV battery. Stay away. On the right side of the cargo area is an always-on 12V connection, if you're looking for unswitched power, as for a powered cooler. HAve fun, Frank

Two comments... We mortals can't afford the hourly run-time cost of something like NASA Ames, much less set-up costs... Lockheed, however, has a low speed wind tunnel in Smryna, GA, with a contact. I, too, and thinking of ways to tuft Porter this weekend and dashcam the results. I'm thinking I can mount the dashcam on a tripod out the window of the wife's car, to get a roof angle. FWIW, I was only planning to tuft from the start of the rear wheel well, back, across the tailgate and bumper, as the research I've seen indicates that's where you get the most payback. If anyone had removable mods, like grill covers, wheel covers or magnetic GasPods, show us with and without (tufting the appropriate area of the car of course)! I will also ask you to look at something on your cars for me. I left the camera home, so pics to follow. I put a straight edge on my roofline next to the sat antenna, and there's a nice vertical gap to the lead edge of the hatch. Even with the trail edge flip, the hatch line never gets close to the roofline. I would have expected a continuous roofline transition to the hatch might be beneficial. Take a look at your cars... HAve fun, Frank

For those interested in a little aero testing, I can upon a very nice set of articles, one of which shows how vortex generators can reduce drag. The idea is to set up the back of your car for a "tuft test" wherein you tape tufts of yarn to the car surfaces and then photograph them at speed to see what the airflow is doing. - Laminar flow regions, the tufts lie flat and straight. - Turbulent regions they bend and twist in many directions. The link explains this all very well, including a practical analysis of rear window turbulence and the effect of vortex generators at the rear edge of the roof, 2 ft. ahead of the turbulent region. My first thought was if anyone had done this with a C-Max, because I like to understand a problem before trying to fix it. My next thought was how busy I am this weekend... Any chance someone's aready tufted their C-Max? HAve fun, Frank

I could not disagree more, salman. As my first new car in 30 years (left a '94 Volvo that was also going bald), I'm quite impressed with the inital build quality, road performance and how well the car's meeting our needs. It's not perfect, but I like the cap-less fueling enough to ignore the occassional steady check engine light. I didn't choose a C-Max, it chose me, and I couldn't be happier. Best of luck in whatever you buy next. Have fun, Frank

I spent the money on sensors for my snows. I asked the dealer to initialize them before I put them on, and they were unsuccessful because you can only program 4 tires, those on the car. In the ensuing discussion, my SA asked why I spent the money? He also has snows on dedicated wheels and the only downside he sees is the MIL stays on. Nothing about traction control issues... Have fun, Frank

No.

Actually, you were pressing your luck on the way out! Prevailing winds in the continental US are from the west, so you were traveling into the wind, on average. Quite to my surprise, you had no net elevation change; Newnan's already at 1000ft. and you start out uphill, get 45 ft. from sea level crossing the Mississippi, then climb back up to 1000ft. Pressing your luck in my book is driving for 25 hours. I'm only good for 8, maybe 12 in my youth. HAve fun, Frank

Matt, there's a reason... It's a very human thing to distrust what we don't understand. Folks can understand aero wheel covers - they look like they smooth the side of the car and smooth is good - at least they think they can. In fact, aero wheel covers and GasPods work for the same reason - they modifying parting edges. The wheel well is a hole on the side of the car. Air exiting that hole is skewed relative to the laminar flow along the side of the car. Injecting air into that laminar flow causes far more drag than simply passing it over an uneven surface. It's the flip side of blocking air entry across the front grill; that air's aero damage comes when it exits, not when it enters the grill. Aero anaysis is odd in that the front of the car's not what's important, it's the effect in the air just behind that shows you evidence fo damage done farther up the stream. In addition, if you have vented disk brakes, the wheel well contains a fan in the form of that vented rotor. I found a nice paper on rotor cooling that includes wheel effects, motion and wind tunnel testing. There's not much on wheels besides this: Clearly, preventing air flow through wheels has negative impact on brake cooling. I point this out not as a problem, but rather as proof that there is airflow out of the wheel and into the air stream along the vehicle's flanks. The blocked wheels are substantially similar to aero wheel covers in blocking air flow. A comparison of flush disks to simple blockinig might be interesting... and no, a hybrid is not in danger of brake overheating unless you're on a race track! I'll also point out that GasPods don't change a C-Max frontal area if placed on the trunk lid spoiler, as the high point is at your head. The spoiler edge is farther along the template and so low enough that the little bumps only intrude into the air stream, but don't add frontal area. Not unlike the winglets, they modify parting edges for a beneficial reduction in drag. Have fun, Frank

My commute is only 15 miles. 45-55 MPG is nice, but nothing beats 999.9MPG My hybrid mileage is worse the shorter the trip, especially as the seasons change for the colder. Engine warm-up is an MPG-killer, and it takes distance to warm up. My electricity is only partly fossil fuel (hydro, nuclear) so there are social and environmental benefits. 20 miles is "enough" when you have a capable ICE as backup. I could go on... HAve fun, Frank

Perhaps it needs to be pointed out that turning on headlights with wipers is not the car's responsibility, it's the driver's. It is perfectly legal for the wipers to come on without turning on headlilghts. It's your responsibility to turn on the headlights when using wipers if that's what your state requires. Mine does, and I remember the flurry of kits that became available to do this automatically, because no car had this feature at that time. Which is what this Ford does. You turn on the wipers, you get headlights. Note that autosense is an intermittent setting, and intermittent isn't "on" it's "intermittent." You want the headlights flashing? Buy a different car, if you can find one... You want the headlights on, turn the wipers on. Have fun, Frank

Paul had the right answer - the only advantage to nitrogen in tires is the absence of moisture. If you use a small compressor on a cold, dry day (low moisture content air) you can avoid most of that. The only reason to avoid water vapor is pressure consistency. It's well known that gas expands when heated, but it's a linear relationship (PV=nRT, ideal gas law). However, the pressure resulting from water vapor is exponential with temperature. You get a far greater pressure increase when the tire warms up than if you used a pure gas. It also doesn't hurt that N2 is more stable than O2 molecules... our oxygen-nitrogen atmosphere is unique in the known universe because O2 doesn't like to stay O2. It's far happier as H2O or CO2. Think of it this way; plants ingest nitrogen (fertilizer, respiration) and give off oxygen. We mammals ingest oxygen and give off nitrogen (albeit in solid and liquid form rather than gas). Without plants, we'd likely have a CO2 atmosphere like Mars and Venus do now, and we once did. But I digress... Regarding altitude, keep in mind that tire pressure is expressed as "pressure above ambient atmospheric pressure." If you go up in altitude, atmospheric pressure drops, and tire pressure increases by a comparable amount. Regarding temperature changes, PV=nRT works as long as you express T in Kelvins (absolute temperature). Kelvin scale is simply Celcius + 273, as absolute 0 is -273C. Going from 273K to 300K is about like Winter to Summer in temperate zones. You should see a ~1/12 loss in pressure, or ~3psi at 36psi. Not huge, but real. Have fun, Frank

Traction control without an "OFF" button will leave you stranded. Doc, you were correct for some cars, but thankfully not ours. A buddy's son has a VW that can't be parked in his father's driveway in winter. It simply won't move up a snow-covered driveway... and we get snow daily. In fairness, "traction control" of any sort is in its infancy. We're early adopters of a technology that has glaring inadequacies in certain situations.The need for an OFF button extends to all aspects of the technology, not just systems like TCS. Remember: - optimized ABS does not always result in the shortest stopping distances (deep snow, gravel) - modern traction control will immobilize the car on slippery surfaces - the "roll/skid" controls like our RSC can only throw the car into oncoming traffic (brake hard and you go straight every time) The day will come when snow plow operators will no longer have to choose among disabling their vehicles, watching them self-destruct, or unemployment. We're still in the "gee whiz, cool" stage. Next will be the litigation phase, as soon as the technology kills someone, followed by advances that correct the defficiencies if the technnology survives. The technology will evolve. Until then, the options are to disable ABS or stay home! HAve fun, Frank

I just ordered an ice storm kit like I think Chuck did from paintscratch; spray cans vs. pens. I have an area above the drivers' side wheel well where there are a bunch of scratches on the door frame. I inherited the car from my Father-in-law, who used a rolling walker to get around. The scratches are from him putting the walker in the back seat... 5600 miles of scratches. I'm glad he stayed active, but I want to address the issue before the snow flies up here (and with it, salt). Now, for one more somewhat warm day... HAve fun, Frank