Introducing my SuperPILOT - 50+% over EPA!

[hliew88]

Hey all,

I've been a lurker for about 3 months now, but after my first 3 tanks, I'm getting my 2004 Honda Pilot (rated 15/21/17) to about 27mpg combined, so I decided to chime in. I average about 35% city 65% highway.

I want to be able to hit 30mpg combined sometime, so I'd like some suggestions for CHEAP mods. I have some pics for y'all so you can see what I've done to get to where I am.

My personal tip: ELECTRICAL TAPE + ZIPTIES ARE WONDERFUL. Cheap, waterproof, and won't ruin paint/plastic/metal.

Aeromods I've done:

• Tires are at 46 psi front/ 42 psi rear

• Coroplast underbelly pan, attached with only electrical tape and zipties. Covers about 75% of the bottom between the axles, works really well.

• Coroplast sheet under the spare tire - otherwise rear bumper + hitch = parachute. Could I make a diffuser here?

• Rear side fairings made from transparent plastic sheets (see pics). Holding up alright, without looking too silly.

• Deleted roof rack, rear mudflaps, and about 200 lbs. worth of interior seats

• Front air dam made by curving 2 strips of some patio siding. Held on by zipties only, extends down to lowest point on car, around the front wheels. Better than lawn edging IMO. It doesn't seem to be helping my mpg though... explanations?

Fixing the nut behind the wheel:

• Using Torque App + cheap Chinese OBD-II adapter ($10 total LOL)

• EOC before most stoplights & down hills (car is able to be flat-towed, so I'm pretty sure this won't damage the transmission, but does shifting from Neutral to Drive at speed wear down the torque converter?)

• Accelerating at ~75% load, letting off the gas to force upshifts

• Not cruising much above 60mph, unless drafting a semi (kicks me close to 40mpg)

I haven't done anything to the engine, so I need some suggestions there! Here's what I found about speed vs. mpg though:

• Engine is happiest between 33-37 mph and 51-57 mph - I can get about 33mpg on a flat road

• Tranny shifts into 5th gear at 46 mph - it's not happy before or after this shift, gets no more than 31 mpg

• I really don't want to see what the winter cold & fuel blend will do to my mpg...

Sucks that this is an auto tranny though... the torque converter is really hard to get locked up.

I get a lot of wind noise around the A-pillars - does anyone have experience with turbulator tape or similar to modify airflow around there? How about at the back (around the trunk)?

Suggestions please!

[jeff88]

Welcome to the site! Looks like you are well on your way to a great vehicle.

Some suggestions:

*Maybe extend the front air dam down in front of the tires for a tire spat effect. This might make your air dam more worthwhile.
*I would seal up the outer edges of your belly pan, so that the coroplast attaches to the bottom edge of the side panel/door. I fear that air is coming in from the side, which might cause some turbulence and maybe a parachute effect, effectively making the pan useless. Seal it up and you might see a better result. (Only a thought, you'll have to confirm.)
*Kammback. You might be able to use the spoiler mounts to do it as well, so you won't have to make holes or even need tape.
*I would definitely try the rear diffuser. You can even design it so it deflects air away from your hitch, so that the hitch becomes almost non-exisent, aerodynamically speaking. You could also just extend the belly pan all the way out to the point of the hitch.

I have no advice for turbulator tape, but do a search here, I think there are a couple of threads that talk about it.

Don't be surprised if you have to replace your starter sooner rather than later. All that EOCing will kill your starter.

[2000mc]

hi hliew88, impressive mods for a new member

Originally Posted by hliew88

Front air dam made by curving 2 strips of some patio siding. Held on by zipties only, extends down to lowest point on car, around the front wheels. Better than lawn edging IMO. It doesn't seem to be helping my mpg though... explanations?

it looks extended out to the sides a little too much to me. if possible bend the ends back some to follow the curve of the bumper, if that cant be done trim a little off. i'm thinking the air is getting pushed out to the sides by the airdam, beyond the width of the tires.
also, if you added the panels under the body before you added the air dam, then youre going to see a smaller improvement than the same air dam on an unmodified vehicle

[hliew88]

Originally Posted by jeff88

*I would seal up the outer edges of your belly pan, so that the coroplast attaches to the bottom edge of the side panel/door. I fear that air is coming in from the side, which might cause some turbulence and maybe a parachute effect, effectively making the pan useless. Seal it up and you might see a better result. (Only a thought, you'll have to confirm.)

I've been thinking about that, but I'm not sure what difference it makes... will give it a try though. Also, I don't have the exhaust piping covered - should I seal off the sides on the left & right of the exhaust pipe too?

Originally Posted by jeff88

*Kammback. You might be able to use the spoiler mounts to do it as well, so you won't have to make holes or even need tape.

I really don't want to extend anything much behind the car... I've had trouble figuring out the benefits of partial kammback vs. sharp rear corners (like found on many new cars today)

Originally Posted by jeff88

*I would definitely try the rear diffuser. You can even design it so it deflects air away from your hitch, so that the hitch becomes almost non-exisent, aerodynamically speaking. You could also just extend the belly pan all the way out to the point of the hitch.

I'm not quite sure what you mean by deflect the air away from the hitch... besides, that rear angle is hovering around 20 degrees, does that matter?

Originally Posted by jeff88

Don't be surprised if you have to replace your starter sooner rather than later. All that EOCing will kill your starter.

I'm worried about this too... I only drive my car about 2-3 times a week, so I figure if I do EOC about 15 times a trip, that's not much more than starting a car like 6 times every day. Is there any way I can find out how many start cycles my starter motor is rated for?

Originally Posted by 2000mc

i'm thinking the air is getting pushed out to the sides by the airdam, beyond the width of the tires.

Yeah, I've seen that most OEM wheel spats only cover about the inner half of the tire width (the stock one on this Pilot covers like 20% of it). Is there any sweet spot, where I'm not pushing too much air to the sides?

[2000mc]

I think there's a thread on tire spats and that topic on here in the last few months. Thinking of your factory dam only covering the inner edge of the tires, I had thought the shape of the airdam on the new silverado was designed for keeping air out of the wheel wells (I don't know if anyone else agrees with that though)

[UltArc]

Welcome aboard! I always get excited with Ohioans joining!

Look forward to reading more and chiming in

[euromodder]

Welcome to ecomodder.

Looks like you've made a good start already

Originally Posted by hliew88

I want to be able to hit 30mpg combined sometime, so I'd like some suggestions for CHEAP mods.

You've already gone a good way regarding mods, and mpg.

Coroplast sheet under the spare tire - otherwise rear bumper + hitch = parachute. Could I make a diffuser here?

Looks like you already have a diffuser there, as the aft belly pan section is angled up quite a bit.

It's a vehicle with a (nearly) horizontal roofline, so a diffuser won't help there - and by itself may make the drag even worse.
Though it's helping the belly pan to work, and eliminating the aft parachute effect which both help your mpg, the diffuser is possibly reducing some of what you gained.

Old aerodynamics research showed diffusor angles should generally be rather small for drag reduction, like 2-5°, and 0° on horizontal roof lines (old station wagon style).

Rear side fairings made from transparent plastic sheets (see pics). Holding up alright, without looking too silly.

Do you see much effect of these ?

At best, I'd expect some cleaner separation of the air, which you might see as changes to dust and rain accumulation on the rear end, though it may not be apparent in your day-to-day fuel consumption.

Front air dam made by curving 2 strips of some patio siding.
It doesn't seem to be helping my mpg though... explanations?

It's a bit too wide.
Air dams (and bumpers) push out the air a bit further than where they end.
This increases the apparent frontal area - even though they are within the original vehicle frontal area.

It's OK if the airdam ends a few inches inboard.

Same with your rear-wheel deflectors.
They seem to be positioned too far outboard.
Unless you add side skirts between the wheels, the air will flow out to the sides @ about a 15° angle - though a diffuser would suck the air more to the rear .

The position and angle of the deflectors in front of the rear wheels needs to be chosen in relation to the air that hits them.
They can be extended aft as vertical strakes on the inside of the rear wheels, separating dirty (wheel side) and clean (belly pan) air, the strakes can then be carried further aft as a diffuser side plate and/or inboard side of a rear wheel fairing.

I haven't done anything to the engine, so I need some suggestions there!

You've already done some mods there : the grille block and belly pan keep in the heat better, so it'd warm up quicker.

Warm air intake.
Keeping the air filter clean also helps - with OEM often being more efficient than K&N style filters.
Pre-warming coolant or oil.
Engine blanket - or some simple cardboard as some ecomodders are using.

Engine is happiest between 33-37 mph and 51-57 mph - I can get about 33mpg on a flat road

So that's where you want to be.
Around 55mph is a nice speed for many cars as far as mpg goes.

Sucks that this is an auto tranny though...

You can always correct that in your next car

Buying a fuel efficient car is the best mod to start with.
I'm surprised it's still not high up on the ecomodder Mods & Tips pages

The latest automatics - like the ZF 8-speed box (BMW / Jaguar / LR) - are good for FE though.

I get a lot of wind noise around the A-pillars - does anyone have experience with turbulator tape or similar to modify airflow around there?

I do

It actually works, even when using dimple tape - which is only a series of heat-formed holes made into a sturdy tape, making what looks like very small volcanoes, the holes being the crater

Doing it again I'd use zig-zag tape rather than dimpled tape.

I put dimple tape along the A-pillar, quite close to the windshield (before the air is making it around the corner to the sides) and on the mirrors.

The tape, though ridiculously thin, audibly reduced the A-pillar noise - very common on this car series .

It altered the air flow over the side windows enough to affect the flow pattern of raindrops that'd get onto it, then stay on the upper front half of the side window and block vision.
With the dimple tape, the raindrops became near-horizontal streaks and got carried aft with the airflow, restoring vision.

Pics are restored in this message :
http://ecomodder.com/forum/showthrea...tml#post323190

How about at the back (around the trunk)?

It's pretty useless at the back as I found out.
See the link above for what I did @ the back end.

Tape is simply too low to effectively alter the airflow here.
The boundary layer will be too thick.
I never saw any change in flow (rain, dust accumulation) pattern there - let alone in mpg

[elhigh]

The Pilot's a nice enough vehicle, especially if you're at all outdoorsy or go in for adventure sports. But aerodynamically, you have already determined it's a dog's breakfast.

Your wheels don't permit much in the way of smoothie discs. I wonder if you could add bulgy skirts on the rear to close up some of those big buckets they're riding in?

You have way more confidence in electrical tape than I. But if it works, hey. Go with what works.

+1 on closing up the edges of your belly pan.

Side skirts.

Warm air intake on your car. Some guys do better with it, some without. Testing req'd, usually a nearly no-cost mod and easily reversible so you aren't committed.

Not much else to do regarding weight reduction. You could take out carpet and stuff, but it's already a big boomy box - do you want echoes too? I don't think you have enough gains left to merit making it a noisier ride.

I've read more than one project where the owner was able to install a clutch lockup switch that forced lockup at any speed. Usually they're able to do it without throwing a check engine light, which is key. You could do as well and come close to eliminating your torque converter losses; generally the TC is crucial only at stops and during initial acceleration, the tranny can shift without unlocking the TC, though in some instances the shift feels a bit harsher. Again, more research and testing required. Also reversible, especially if you install the switch in an existing knockout.

You have a tough row to hoe. Taking a 17mpg combined EPA ride to 27mpg in the real world is really, really good. Getting another 10% to hit 30mpg...well, I'm glad it isn't me that's trying to do it. I'm rooting for you, but I'm glad it isn't me.

[spacemanspif]

Do you use the vehicle to tow stuff? If not, take that hitch out and save the weight and headache that is causes with the belly pan.

x1000 on finishing the belly pan and closing up the openings.

With a full belly pan, you shouldn't need the air dam; if air is flowing smoothly under the car and not developing turbulence, you don't need to block it. Side skits could help keep air away from the leading edge of the back tire but a slopped spat could do the same. Looks up member "arcosine" and his build thread on aeromodding his Saturn SC...pay close attention to the treatments he makes to the front and back of the wheel wells.

Great job so far! If you want to get "hard core" you could always change the gears in the rear. But that would cost double if you have a 4 wheel drive model...

[hliew88]

Originally Posted by euromodder

It's a vehicle with a (nearly) horizontal roofline, so a diffuser won't help there - and by itself may make the drag even worse.
Though it's helping the belly pan to work, and eliminating the aft parachute effect which both help your mpg, the diffuser is possibly reducing some of what you gained.

Old aerodynamics research showed diffusor angles should generally be rather small for drag reduction, like 2-5°, and 0° on horizontal roof lines (old station wagon style).

Thanks for this info - what could I do then? In my pic of the side view of the back, the bottom of the suspension is about at the bottom of the rim, whereas the bottom of the hitch bar is probably a full 6-8 inches higher. You can make out the slope of the pan I have there already...

The other thing I notice is that most of the turbulence does come from underneath. In the rain I just see water coming up, whereas it seems to go straight off the top and sides.

I pulled in the ends of my air dam! (see pics)
What I did has the added benefit of going all the way back to the edge of the wheel well too. Win.

Also pushed my rear wheel spats in about 2 inches or so.

Originally Posted by euromodder

The position and angle of the deflectors in front of the rear wheels needs to be chosen in relation to the air that hits them.
They can be extended aft as vertical strakes on the inside of the rear wheels, separating dirty (wheel side) and clean (belly pan) air, the strakes can then be carried further aft as a diffuser side plate and/or inboard side of a rear wheel fairing.

Could you explain what you mean by this?

Originally Posted by euromodder

Warm air intake.

If you see the last pic, it turns out my air intake comes from in front of my left front wheel well - so much plumbing! There are holes I see in front of the wheel where the air gets sucked up. I wonder why it's designed this way... and if this thing gets anywhere near water when off-roading, it'll just choke itself!

I would get a warm air intake just by lifting that box up that contains the filter, right?

Originally Posted by euromodder

Buying a fuel efficient car is the best mod to start with.
I'm surprised it's still not high up on the ecomodder Mods & Tips pages

This is my parents' car, so no changing that!

Originally Posted by euromodder

Doing it again I'd use zig-zag tape rather than dimpled tape.

I put dimple tape along the A-pillar, quite close to the windshield (before the air is making it around the corner to the sides) and on the mirrors.

I had some extra time, and decided to cut my own out of electrical tape. Put it on the top half of the A-pillar, as many have said too. You think this will work?

Nno way is the hitch coming off. My family does do some heavy towing at times (notice the big trailer connector hanging off). Plus it's so rusted that the bolts will never come loose!

Tomorrow I'll try to close off the sides of the running board/belly pan transition with something black. Then maybe I'll take a run at 55mph and see what mpg I can get.

Anyone have experience with how long starter motors last?