66 mpg 2009 Totoya Prius, Champrius 4.0 Under Construction now

[freebeard]

I have a gentleman's wager how much modifying the front of a car will gain in gas mileage.

Know your opponent

https://www.goodreads.com › quotes › 17976-if-you-know-the-enemy-and-know-yourself-you-need
Quote by Sun Tzu: "If you know the enemy and know yourself, you ne..."
2 days ago"If you know the enemy and know yourself, you need not fear the result of a hundred battles. If you know yourself but not the enemy, for every victory gained you will also suffer a defeat. If you know neither the enemy nor yourself, you will succumb in every battle."

California98Civic -- Bonneville 2012

I snapped these two when I bumped into Phil at Bonneville's "World of Speed" event. I was doing an aerodynamics science lesson with my 4th grade daughter, who we were homeschooling that year.

ecomodder.com/forum/showthread.php/phil-knox-fleet-34-years-aeromodding-1280.html#post628587

[Talos Woten]

Originally Posted by ps2fixer

Here's what I see at that link. Try a private browsing window, that will clear login cookies and such.

We have a mystery! I used a Private Window on Firefox, and I've attached what I see. There is a login bar overlay at the bottom, but it doesn't prevent any of the posts from being clicked, read, navigated, etc. How about if you try a new fresh browser?

Anyhoo, one of the reasons why I dual post to Instagram and Facebook is because FB definitely doesn't let people see things without having an account. But (in the past at least) Instagram does.

Originally Posted by ps2fixer

I'm not completely in the doubter camp, I do think there's gains to be had, but ~8-10% or so is quite a lot. I remember there was a challenge a while back where a team drove a prius for a whole tank and hit a crazy tank average like 100mpg. I don't recall if it was a stock car or not, it was driven at more ideal speeds (25-30mph average I think), no radio, windows up, hot day, etc.

Didn't realize you had a full boat tail and such. You could easily hit those goals with slower speeds =). I'm running a nearly stock prius 45mph and for any kind of longer trip I'm hitting 55mpg or so, just have a grill block and missing a couple bell pan panels lol.

It looks like you live more in the city, I suspect it's more shorter trips for the car and such. You could probably see some big gains from a block heater, trans heater, etc. My MPG is horrible when the car is cold. It starts off around 30-35mpg and climbs at 40mph. There's also a mod to spoof the temp sensor to help get it to turn the engine off a bit sooner and such, I haven't messed with it but read about it. It currently takes my car around 6-7 miles to come up to temp.

Actually, I'm claiming I can get +20% mpg from my baseline of 39 mpg = +8 mpg. So much more than +10%, which is what aerohead (and apparently you) thinks is the limit.

I'm uninterested in achieving high mpg for bragging rights. I use this car for extended camping trips, so I travel on the highway a lot. So what I really am trying to optimize is FE at 65mph cruise control.

I'm also not trying to win the bet just to win a bet. I honestly think there are real mpg gains to be had at the front of the vehicle. If that's the case, it's an area for substantial aero improvement that currently isn't being explored or exploited fully. If it's not the case, then I'm just deluded.

Champrius and I are both snowbirds, so we rarely see cold. In my case, it's because I'm solar powered and love the sun. In her case, it's because her ECU shuts off when it rains or gets too chilly.

[Talos Woten]

Originally Posted by freebeard

Know your opponent

California98Civic -- Bonneville 2012

ecomodder.com/forum/showthread.php/phil-knox-fleet-34-years-aeromodding-1280.html#post628587

So is Phil Knox = aerohead and that's his vehicle?

The 4.0 front of Champrius will be *way* better than that vehicle. You know, assuming it works.

I'm curious how much the sloped fairing in front of the windshield cuts down on drag. One of the things I wanted to experiment with after modding the front of the car was something similar, to replace the windshield deflector. It would be nice to know if it's worth doing.

The other is the side mirrors. I saw another fellow on here with a good idea for them, to place them farther out. I've been using VGs to try to reduce the shadow, but I think we can do that in other (hopefully better) ways.

[freebeard]

ecomodder.com/: Sticky: Index of Phil Knox Aerodynamics Seminars & Mod-data lists

Not secret, maybe not obvious.

The pic dates to 2012. The cowl deflector didn't make the cut.

Mirrors need to move away from the A-pillar; peep mirrors, fender top mirrors or stalks forward from the windshield header. [IMHO of course]

[ps2fixer]

I did it in a private window, same thing. I'm on Linux but that shouldn't effect things. I jumped in my Windows 7 VM and it does the same thing as well as well as a server I have setup that runs windows 7. I've had other people link insta posts before but can never view them as a guest.

Kind of funny, for me facebook works as a guest, this is my facebook group, but it's a public group. Twitter also works as a guest, but you have to click posts the right way to view comments or it wants you to login (very annoying). Weird that you can load insta with out logging in though, I suspect you're on windows 10/11? I refuse to install that spyware that Microsoft made. I'm probably pretty biased since I'm fairly deep into computers and I know how info can be used.

https://www.facebook.com/groups/derbyws

Anyway, not sure what you mean exactly by fresh browser, like reinstalled type of fresh? Chrome isn't an option for me due to their terrible privacy issues, and there's no IE on Linux lol. Facebook is terrible too, but I only use it for business.

I see, I didn't have all of the details on what the claims were. I think the grill block is good for around 10% vs stock. My corolla with grill block and half belly pan under the engine and passenger mirror delete would get 38-44mpg, drive home unmodified the car got 33mpg with a bunch of issues I fixed right away.

Anyway, you're looking at a base mpg of 40mpg (mine is 46 with panels missing driving "normal" lol) and the target is 65mpg+ with all mods, not just the front end?

Of my understanding there are larger gains at the rear of the car vs the front. The high pressure zones at the front kind of work out to make an effective areo shape that most of the air flows over. The air dam and such up front helps, but it's it's to redirect the air to less turbulent areas of the car. It's been a long time since I read about the areo civic, but if I remember right, the custom shaped nose cone vs the mostly (or fully) blocked off stock nose was good for like 5% difference.

I do long trips somewhat often, 55-60mph on the express way, the energy to over come the wind drops quickly at those speeds. I just drove my prius to a couple cities away going 75mph (pressed for time) and with the highway driving and city I pulled 50mpg going to the place. On the trip home I went 55mph expressway and around 45mph on back roads and pulled 64mpg according to the scan gauge. Expressway speeds at 60mph with no slower sections I hit around 50mpg as well (based on a ~1.5hr trip with 4 people in the car and such). For my car anything over 45mph the mpg drops lock a rock. With a boat tail and such it should make quite a difference I would think.

I haven't personally experienced having a boat tail yet but I'd expect it to be by far the largest single mod you can do. There's a lot of other little mods that add up pretty fast though.

Here's a section about the areo civic. It's basically modded to the max, manual trans, lean burn Honda engine. Based on these numbers, that car should see roughly 80-85mpg on a long trip at 65mph (with today's' 10% ethanol gas). The prius doesn't seem to do well for high speeds vs low speeds, I suspect it's because of the CVT setup with the electric motors and battery requirement (more drive line losses than a manual trans at high speeds), it really shines at low speed and 40mph and under auto engine off coasting and such. Can your car hit 65mpg at 65mph, I think you'll get close. At such high speeds, it might be better to remove the solar pane or rework the boat tail so it's flush, the leading edge and tunnel effect I think creates a lot of drag, even dropping it down flat and reworking the front and rear edges I think could see some reasonable gains.

The approximate mileage on a level road burning non-ethanol gasoline at 85 degrees F ambient (29.4 degrees C) is:

95 mpg (US) at 65 mph
(2.5 L/100 km at 105 km/h ... 40.4 km/L ... 114 mpg (Imp.))
85 mpg (US) at 70 mph
(2.8 L/100 km at 113 km/h ... 36.1 km/L ... 102.1 mpg (Imp.))
65 mpg (US) at 80 mph
(3.6 L/100 km at 129 km/h ... 27.6 km/L ... 78.1 mpg (Imp.))
50 mpg (US) at 90 mph
(4.7 L/100 km at 145 km/h ... 21.3 km/L ... 60.1 mpg (Imp.))

Using E10 (10% ethanol/gasoline blend) drops these numbers by about 5 mpg

Anyway I played around with some numbers, with the areo civic level of CD, you should be seeing around 65-70mpg at 65mph. If you change it to 60mph and it looks like 75-80mpg is possible.

My guess is your car is sitting around .21 (factory is .24) and you're targeting around .18. Of course all of those figures are guesses based on some areo calcs and such, I'm far from any kind of expert. I think if you did the full blown Areo Civic setup, you could hit the goal.


https://www.aerocivic.com

[Talos Woten]

Originally Posted by ps2fixer

Kind of funny, for me facebook works as a guest, this is my facebook group, but it's a public group. Twitter also works as a guest, but you have to click posts the right way to view comments or it wants you to login (very annoying). Weird that you can load insta with out logging in though, I suspect you're on windows 10/11? I refuse to install that spyware that Microsoft made. I'm probably pretty biased since I'm fairly deep into computers and I know how info can be used.

Hmm. I wouldn't think the OS would be a factor, but perhaps it could be. I am on Windows 10. By the way, if you are interested, I wrote a script to turn off the telemetry and unnecessary services. Every time Windows did an update, it would reactivate it's crap, so I made something that automatically turned it all off again. Anyhoo, if you use a debloater and my script, it actually changes Windows 10 into something more reasonable.

Originally Posted by ps2fixer

Anyway, not sure what you mean exactly by fresh browser, like reinstalled type of fresh? Chrome isn't an option for me due to their terrible privacy issues, and there's no IE on Linux lol. Facebook is terrible too, but I only use it for business.

Yes, fresh install kind of fresh. If you are on Linux, Safari or Opera are good choices.

Originally Posted by ps2fixer

I see, I didn't have all of the details on what the claims were. I think the grill block is good for around 10% vs stock. My corolla with grill block and half belly pan under the engine and passenger mirror delete would get 38-44mpg, drive home unmodified the car got 33mpg with a bunch of issues I fixed right away.

Wow. The best I ever got from my grille block was 5%, and that was with something that I felt was unsafe to actually use. The grille block I settled on was around +3.5% mpg.

Originally Posted by ps2fixer

Anyway, you're looking at a base mpg of 40mpg (mine is 46 with panels missing driving "normal" lol) and the target is 65mpg+ with all mods, not just the front end?

For the wager, yes. My actual goal is 70 mpg unladen with Champrius 4.0. I'm hoping to get high 60s by redoing the front, and then to refresh some other mods I already have to push me over the 70 mark. That would mean that once I dump in all my camping gear I should get mid 60s at 65 mph.

Originally Posted by ps2fixer

Of my understanding there are larger gains at the rear of the car vs the front. The high pressure zones at the front kind of work out to make an effective areo shape that most of the air flows over. The air dam and such up front helps, but it's it's to redirect the air to less turbulent areas of the car. It's been a long time since I read about the areo civic, but if I remember right, the custom shaped nose cone vs the mostly (or fully) blocked off stock nose was good for like 5% difference.

That's everybody's understanding... because they haven't seriously considered modding the front as a whole unit. I'm not going to be doing what basjoos and everyone else has done. I'm trying something brand spanking new which I believe will be much better.

Originally Posted by ps2fixer

I haven't personally experienced having a boat tail yet but I'd expect it to be by far the largest single mod you can do. There's a lot of other little mods that add up pretty fast though.

On v3.0, the boat tail got me +20% mpg. On this last version, it netted me +15%. It's pretty substantial.

Originally Posted by ps2fixer

Here's a section about the areo civic. It's basically modded to the max, manual trans, lean burn Honda engine. Based on these numbers, that car should see roughly 80-85mpg on a long trip at 65mph (with today's' 10% ethanol gas). The prius doesn't seem to do well for high speeds vs low speeds, I suspect it's because of the CVT setup with the electric motors and battery requirement (more drive line losses than a manual trans at high speeds), it really shines at low speed and 40mph and under auto engine off coasting and such. Can your car hit 65mpg at 65mph, I think you'll get close. At such high speeds, it might be better to remove the solar pane or rework the boat tail so it's flush, the leading edge and tunnel effect I think creates a lot of drag, even dropping it down flat and reworking the front and rear edges I think could see some reasonable gains.

Crazily enough, on the previous boat tail, the solar panel had negligible impact. If it reduced mpg I couldn't tell. I think it was because it was so well oriented with the airflow. On this version, I don't know. The v3.0 was flat and straight from above. The v4.0 version is more rounded and tapers in all directions. So the back edges of the panel are probably interfering with airflow.

Before all my car troubles, v3.0 got 66 mpg at 65 mph unladen. That's why I'm pretty optimistic I can achieve my claimed numbers; I've already done it before.

Originally Posted by ps2fixer

My guess is your car is sitting around .21 (factory is .24) and you're targeting around .18. Of course all of those figures are guesses based on some areo calcs and such, I'm far from any kind of expert. I think if you did the full blown Areo Civic setup, you could hit the goal.

The Gen II Toyota Prius has a 0.26 drag coefficient stock, not 0.24. My previous version was around 0.21, and my goal is 0.185 Cd (good guesses!).

We'll see how things stack up against the Aerocivic once I'm done. Onward!

[ps2fixer]

I see, lot of effort to see posts on a site that I very rarely visit (like 2 times in my life I've wanted to view a page there lol).

I'm sure windows 10 can be changed so it's not so bad, but I don't support the company and how they view privacy and such, so I don't give them any of my money. I build my own computers and have been wanting to run linux for a long time. My windows 7 I paid for (win 7 ultimate), I really should have just went with pro since it's way more popular and seems to have less problems but overall it did ok. I miss the days of xp when things didn't have animations and such as much, everything felt so instant and quick unless there was some real processing needed lol.

On my corolla, it was a massive effect. I didn't drive my prius much with out a grill block to really get a feel what the effect is like, I just knew it was a real easy low hanging fruit. Once I have a solid way to monitor inverter temps, I plan to do a full grill block, right now it's only the bottom blocked off which isn't ideal since the inverter section is at the bottom. It's more than enough for the engine though, With the corolla I left around a 6in wide opening on the bottom for winter time and completely blocked the upper grill, sealed around headlights and hood (tiny help but isn't massive, it helped retain heat much longer though).

I recall someone reshaping the front of their car, I keep thinking it was the areo civic where they had clear plastic from the front bumper arched up to the roof line. There was increases, but it added a lot of problems and the idea was scrapped. One is cleaning the outside, windshield wipers work on glass pretty well, but it doesn't play so nice on plastic and such. The other issue is the inside of the plastic gets dust and such on it and is hard to clean. If you reshape the whole front end, I know there's gains, but that's not exactly as easy to do, I think even a boat tail is easier which I suspect why most people focus at the rear side than the front.

If you was driving a van or truck, I could see larger gains reshaping the front end. I think the Prius shape is reasonable. It can be improved on for sure though. I suspect if you rework the front end to be more of the ideal shape, it's going to mess up the areo in the back, about the best solution I can think of is make the nose the ideal shape, then have a straight section back to the roof line. The clear material used will likely make things appear a bit funky though. Not sure how the laws are around a mod like this. Starting with a van might actually be more ideal for the desired shape but small vans prius sized with hybrid systems I don't think exists, at least not common in the usa lol.

The first google result said .24 for stock prius, but can't ever trust a single source lol. When I was playing with the mpg areo calc I actually bumped the cd to .26 and increased frontal area a little to get numbers that looked more correct to me for the experience I've had with my 2006 prius.

I'm not sure how accurate the coast down cd calculation is, but it would be really interesting to see those numbers along side things. It's smaller number changes, but going from 26% of drag vs a wall down to 21% is still a lot. I'd think the prius is more of an ideal shape for lower cd so if you do a full car overhaul similar to the areo civic but with the more ideal front end, you should be able to beat his cd numbers (in theory at least). Wheel skirts and mirrors I think are a couple areas that could be reworked pretty easily to see good sized gains too.

Have you looked into the mirror laws for your state? Here in Michigan driver side and rear view is required, and it defines it as being able to see objects behind the car like 1000 ft. Most laws don't account for modern tech (I see the backup camera), ideally no mirrors would really be needed if cameras and screens were used.

Too bad your prius wasn't a 2010 (maybe engine/trans swap some day?!), they can be in electric mode at a much higher speed than our cars. Clearly it's not ideal to run off electric, but it gives the option of shutting down the engine after the battery gets charged up and such. I think that's likely a large part in why they seem to run around 10mpg (20% or so) higher mpg averages.

I'm still kind of amazed at my old corolla, I could go 60mph on the highway and hit 40mpg on long trips. My prius in it's current form hits around 50mpg under the same conditions. The prius has stock belly pans and such, where the corolla I had to add them and I didn't fully cover the belly. The corolla is about 400lbs lighter and is a little less frontal area, so what the prius does is still pretty amazing, but it would be even more amazing if it was corolla sized.

Using the same figures, 40mpg to 65mpg for you, I should see roughly 50-55mpg turn into 81-89mpg. I don't think it's a 1:1 comparison for me, but it would be interesting to hit 100mpg+ with a prius at somewhat "normal" speeds. I'm not super worried about the look of this car. I got it for cheap. I just haven't had much time to do mods to it. First thing I want to do is fix up the under body panels or recreate them to get it back to somewhat stock. Hub caps, fender skirts, probably something todo with the passenger mirror (need to keep it encase I'm hauling a trailer so I can see better). I've been thinking a boat tail would be interesting, would like to design something that folds up and can be stored inside the car and likely attaches to the hitch so when I need to haul a trailer I can swap it out somewhat easily. I think my concept would look somewhat similar to how yours appears. I don't expect gas prices to get better for quite a few years so it's not going to hurt anything saving extra money on fuel (main reason of owning the car) =).

[freebeard]

Originally Posted by ps2fixer

I build my own computers and have been wanting to run linux for a long time.

When you decide to run Linux, it should take about an hour. Populate a USB drive and boot from there.

Else, do what I did and throw down for a Raspberry Pi 4B and do an immediate and regular update/full upgrade in the Terminal.

I left the Apple ecosystem instead of Windows, at least for the world-facing machine.

I've been thinking a boat tail would be interesting, would like to design something that folds up and can be stored inside the car and likely attaches to the hitch so when I need to haul a trailer I can swap it out somewhat easily.

It's been a while since I posted this:




Mocked up since I had the parts lying around. I'm more inclined to a receiver hitch box.

[ps2fixer]

I've been on linux full time for about 6 months. I have some programming tools (IDE and such) I need to find alts for, but so far it's working well. There's a couple things with the file manager I don't like, but can uninstall it and install a different one, just haven't messed with it.

I've installed linux before in VM's and such, but never full time for my daily computer till the 6 months ago. Either case, a website shouldn't change based on what OS you're running unless it's for like pc vs cellphone type of logic which can be done in a lot better way.

Apple is the distant cousin of Linux/Unix, somewhat like how Android is related to Linux as well but google has their fingers in that one.

I saw those pics, or something real similar not long ago, not sure what I was looking up but I remember the fold up wheel. Guessing the concept is the boat tail folds up behind the car? The prius is a hatch back, so there's a reasonable amount of storage inside, just need to make it fold up small enough to fit inside, or pull pins, etc.

Would be funny to make an inflatable boat tail from something clear. Not sure if the cops would like that too much since the license plate might be harder to read, but if there's an on board air pump, it would be pretty quick to deploy or take down and ideally should take up almost no room. I'd guess it would have to be pressurized a fair bit though to be stable in the wind.

[freebeard]

You can see how I misinterpreted the quote?

What flavor of what Richard Stallman would want us to call Gnu-Linux do you run? Raspian is somewhat limited. The Pi 4B doesn't even have a real time clock.

I was with Mac OS from 7.1 IIRC. But when they pivoted to OS X, my favorite tool Norton Disk Editor was never brought forward. Symantec paid me to sit in a $900 chair at their knowledgebase terminal and bring back peoples' data files from the Void. It was the most satisfying work I had.

Boat tails!

Other than the mockup on the Superbeetle, I also did a scale model you may have seen.



This is hinged like a single wheel trailer. The rigid floor would help the difusser and stiffen the structure, shown as fiberglass rods ribs like a mountaineering tent. It should have a wheelie bar for ground strikes.

This is from the 1960s.



edit:

If you was driving a van or truck, I could see larger gains reshaping the front end.

Here's a front for the VW Type II: