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PostPosted: January 25, 2013, 11:23 am 
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Jack, if you don't already have plans for a coupe, that Alpine would be a great starting point... You can almost see a little Max in the tail lights!


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PostPosted: January 25, 2013, 12:14 pm 
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That Alpine is one sexy beeetch... If it IS French...

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PostPosted: January 25, 2013, 12:46 pm 
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Jack, besides just attaining your goal of 100 MPG with real world technology, are you competing for a prize or something? I ask that because I see the Mother Jones sticker in the photos of your car plus I'm remembering the escape from Bezerkely contest you were in before.

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PostPosted: January 26, 2013, 9:31 am 
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I agree that the lola body will have much better performance with low power than a traditional.

I've had the alpine photos for a long time, but didn't want to take away from Jack's Lola focus. Many of the aspects of the alpine can be incorporated into the lola by the end user if you don't mind a bit of glass work.

Aero makes it fast.
Low weight and an efficient drivetrain makes it quick.

CVT has higher parastic loss than some but is much more efficient for accel.

A top speed of 90 mph on the level with excellent aero (gearing limited) combined with a 10 second accel to 60 makes for a very practical car, rather than a just a weekend toy. I think about 75 mpg on gas at 65 mph is reasonable with the right parts, but Jack has more first hand experience in this area with Max.

My ford aspire weighs 2,000 lbs, has 63 hp (1.3l mazda sohc 4), and averages mid 40s in mpg with lots of hills and city driving, generally not getting over 65 mph. The best mpg I ever documented was 56 mpg steady state cruise at 65 mph with a few small aero mods. 0-60 is about 12 seconds and top speed is 90+, gearing limited. Aero mods make a big difference in 60-80 mph times. I've got about 260,000 miles on it now, and it is starting to smoke a bit, not that I could tell when driving it. It could just be the rear main seal leak, which I planned to replace with the first clutch replacement, which it hasn't needed yet.

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PostPosted: January 26, 2013, 9:57 am 
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Miatav8,MstrASE,A&P,F wrote:
A top speed of 90 mph on the level with excellent aero (gearing limited) combined with a 10 second accel to 60 makes for a very practical car, rather than a just a weekend toy.

I think about 75 mpg on gas at 65 mph is reasonable with the right parts, but Jack has more first hand experience in this area with Max.

My ford aspire weighs 2,000 lbs, has 63 hp (1.3l mazda sohc 4), and averages mid 40s in mpg with lots of hills and city driving, generally not getting over 65 mph. The best mpg I ever documented was 56 mpg steady state cruise at 65 mph with a few small aero mods. 0-60 is about 12 seconds and top speed is 90+, gearing limited. Aero mods make a big difference in 60-80 mph times. I've got about 260,000 miles on it now, and it is starting to smoke a bit, not that I could tell when driving it. It could just be the rear main seal leak, which I planned to replace with the first clutch replacement, which it hasn't needed yet.


Amazing that your Aspire has been so bulletproof! By comparison, my 78 Chevette -- which pretty much had the "performance" numbers you describe -- had a piston slap by 80k miles, and probably didn't live much past 100k miles. Certainly by then I'd rebuilt the engine in a failed attempt to get rid of what I thought was rod noise.

I'd like Jack (and the other brain trusts here) to talk about what is needed to get from 50 mpg to 75, then to 100. I suspect that, like horsepower needed per mph in top end, the curves are not exactly linear in what is needed in aero and engine efficiency?

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PostPosted: January 26, 2013, 12:04 pm 
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i would say that this could be divided into three sections,

engine and drive train,

weight,

aero,

but first we must consider at what speed and level of performance you need to acompany the economy, if you want a vehicle that will cruise at 70mph on the freeway and only drop to 60mph when you come to a hill without downshifting, i think 50 mpg could be easily obtained from a chevette.

starting with the engine, camshaft selection is the most critical, peak economy is technically acheaved at peak torque so that is the starting point, we must make peak torque at 60 - 70 mph, how we do that is the discussion to be had here.

if we can achieve the above then the next is weight, we could throw away the chevette body or lighten it up, at this point we need to decide how much comfort we need, we could throw away all the glass but it would be impractical so we must remove all the stuff we do not really need, heavy seats, air conditioning, sound insulation and any metal we could do without but not compromising the structure of the vehicle.

aero, i would subdivide into two, actual wind resistance and rolling resistance.

aero would be best aproached by making the frontal area as small as possible, yuo could chop the roof for example but there are other less drastic steps like paying special attention to panel fit, including bumpers and rain gutters or reduce the wheel well openings so they just clear the tires, speaking of tires, you could fit the skinniest tires available and the smallest diameter so that the footprint was as small as possible.under the car is an important area for some streamlining, not ground effects as you would find benifit in keeping the ride hight fairly high so the air could pass under the vehicle as easily as over or round it.

just thoughts, keep going guys.

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PostPosted: January 26, 2013, 12:21 pm 
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Diesels are a good choice too because they don't have throttles. In gas engines they suffer loss of efficiency when run at partial throttle. So that why the emphasis on small and turbo gas engines for economy. You work them harder at low rpms in normal use, so they are more economical.

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PostPosted: January 26, 2013, 5:32 pm 
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This is not a Locost but I took the easy way out and bought this one owner 2005 Honda first generation Insight Hybrid last month. I am amazed at the fuel mileage it gives with careful driving. As one owner said, "It's like driving a video game with the goal of high mileage."

Attachment:
File comment: 2005 Insight, Cd .25, 3 cyl 1 Liter
Insight side.jpg
Insight side.jpg [ 26.41 KiB | Viewed 2215 times ]


I typically cruise at 80 to 92 mpg at 55 mph on level road with no cars nearby. What helps the most to get good mileage is an instantaneous fuel mileage gauge and that the engine can run at 25:1 fuel air ratio in "lean burn" mode. And I thought my CRX-HF was lean. at 17:1 :roll:

I think my CRX is mad at me because when I left after the test drive of the Insight the CRX exhaust pipe came loose within a mile of starting home. :cry:

Here is an accurate fuel mileage vs speed chart that the car can get.

Attachment:
MPG vs MPH fuel economy.jpg
MPG vs MPH fuel economy.jpg [ 41.12 KiB | Viewed 2215 times ]


The car is very sensitive to slight changes (up grades, down grades, drafting, & small throttle changes that you don't even realize you made etc).

[edit] After reading some of the planing to get mpg with a good home built car I'd suggest looking at the CRX-HF design because it already gets 50+mpg at 65 mph. The Insight does not use the electric assist once you are cruising and it's high mileage is done with the 3 cylinder, 1 liter engine alone. And there are engines for sale on eBay.

The two cars are different animals. The Insight has a Vtec engine that kicks in at about 2800 rpm and then it loves to rev out. But it doesn't get great mileage if you take advantage of the extra power. Without the electric assist the engine does feel gutless because its low rpm torque is not all that pronounced because the car was designed to use the electric motor to assist the gas engine at low rpms.

The CRX is more of a low speed torque engine that likes to cruise below 2000 rpm (64mph in 5th) with reasonable torque down there. Above 2000 rpm you can feel a definite boost in torque and the mileage does fall off if you persist in driving above 2400 rpm. The Insight weighs ~1800# and the CRX is ~1880. Both cars have similar hp the Insight @ 67 hp (with 1 L) and the CRX @ 62 hp (with 1.5 L).

The ideas I see posted so far are spot on for getting good mileage.

If you're interested in more info here's where a lot of the Insight owners hang out. Don't be surprised to hear of people averaging over 100 mpg on long trips. And of course there's the non conformist who put a turbo on one and another with a VW Diesel engine in his.

insightcentral.com

And now back to our [non] normal programming. :)

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PostPosted: January 27, 2013, 2:20 pm 
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This is a perfect thread for me, I ant to build a Lalo like Jack's - maybe this question belongs in another section, but is it reasonable to use an old rusty MGB, midget, spitfire or similar British vintage as a donor vehicle? Specifically I like the idea of wire wheels and they come cheap when attached to rusted out midgets.

Plenty of rusty examples here in the PNW with smaller engines.

Jim


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PostPosted: January 27, 2013, 8:17 pm 
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Miatav8,MstrASE,A&P,F wrote:
Rear aero has a bigger piece of the drag pie than anything else.
Right you are, Miatav8--presuming you don't make such a mess of the front end that the air doesn't get to the rear of the car in a coherent form.

And that, in a nutshell, is why it's difficult to streamline front engine coupes. "Rear aero" starts at the thickest point of the car, which in a car optimized for low drag is the cockpit--specifically, and please refrain from thick-witted jokes, where the driver's head is located. Thus to get enough "rear aero" behind a car like a Locost, which has the driver's head only inches forward of the rear axle, the car gets loooong. No problem at Bonneville, but a nuisance in downtown traffic and parking lots.

As an example, through the Miracle of Photoshop, here's an Alpine A210 body adapted to a Locost--the cockpit and rear are unchanged, but the wheels are moved forward (and the nose stretched) to accommodate relocating the rear axle relative to the driver. It's not too bad with a roadster (though not ideal) but it it weren't for Kamm effect it would be virtually impossible to make streamlined front engined closed cars.

This is my primary motivation for developing a middy* ecocar--middies are easier to streamline than fronties.

*Not that I intend to bail on Locosts--different vehicles have different raisons d'etre.


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AlpineFE.jpg
AlpineFE.jpg [ 23.95 KiB | Viewed 2164 times ]

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PostPosted: January 27, 2013, 11:31 pm 
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JustDreamin wrote:
A CVT (continously variable transmission) as John mentioned, is certainly a viable player.
Please pardon me for harping on the Insight & CRX-HF but both of these cars are the best in their class (gas only or hybrid) for high fuel mileage. Luckily I own one of each so I'd like to share some of what I've learned in 22 years of owning the CRX and what I've learned about the Insight in months of researching the car and finally buying one.

The 2000 to 2006 Insights came with either a 5v speed manual or a CVT (metal belt) transmission. The CVT typically gets 10% less fuel mileage as compared to the 5 speed. The USA Insight with the CVT did not have lean burn which would likely account for much of the difference. Only the Japanese CVT Insights seem to of had lean burn.

Rather than try to use a normal engine and modify it to give better mileage it seems logical to me to use an engine that already gets great mileage (and a Diesel might be a good choice if it's light enough) and concentrate on lightness, streamlining, reducing frontal area, etc. That's why I mentioned the CRX-HF and the first generation Insight to start with.

Tires are also very important once you are making small changes to increase the mileage. To get maximum mileage out of an Insight the original equipment tires were Bridgestone POTENZA RE92, P165/65R14 and when people try other tires the RE92s always give the best mileage (typically 10 mpg more). Some of the hypermilers are running 80 psi in the tires!! My car has Tempest tires of a wrong size and I run them at 45 psi and still get very good mileage while I wait for them to wear out.

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PostPosted: January 28, 2013, 12:36 am 
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This may be a dumb question but what exactly is "lean burn"? Do they just lean out the mixture in areas of low load where it won't destroy the engine?

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PostPosted: January 28, 2013, 1:05 am 
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geek49203 wrote:
[snip]
I'd like Jack (and the other brain trusts here) to talk about what is needed to get from 50 mpg to 75, then to 100.

Pretty much what Honda did, more and more attention to all the details discussed so far. Like most hybrids now days the Insight has "auto stop" (the engine stops running) as you drift up to a stoplight in neutral. As soon as you put the car in gear (with the clutch pushed to the floor) the engine is instantly started by the 13 hp electric motor.

Some of the minor things Honda did only account for 1% or 2% increase in efficiency or Cd (partial belly pan, strakes in front of the tires, spats for the rear tires, narrower track on the rear wheels so the body could be narrowed down behind the driver etc). But when you add them all up --- bingo!


I suspect that, like horsepower needed per mph in top end, the curves are not exactly linear in what is needed in aero and engine efficiency?
From my experience with the CRX and a solar powered race car you don't need a lot of hp if you have light weight and exceptional streamlining. But you will be limited in acceleration. Jack with Max 1 could give us some details on low hp driving. Unfortunately if you expect to drive in town you have to have more hp available than what is needed to give good fuel mileage.

The solar race car is shaped like an airfoil and only has a 5 hp rated motor. But the car has gone 80 mph on special 14" diameter bicycle looking tires (slicks) inflated to 100 psi! :shock: It has a calculated Cd of .18 The acceleration is quite good but it is fully battery powered with solar cells to charge the battery. It cruises at over 50 mph. It's a balancing act to not run so fast that the battery pack is discharged before the time allowed on the track is done (distance is counted over several days of "racing"). And you have to allow enough time to solar [only] recharge the battery when not running the car.

Attachment:
Solar car.jpg
Solar car.jpg [ 6.25 KiB | Viewed 2127 times ]


Here is a spreadsheet I did to compare the CRX & Insight gearing etc. The Insight can do 112 to 115 mph (in 4th gear) with 67 [gas only] hp the CRX has 62 hp but I never ran mine wide open. I had it up to 100 mph and it had more to go. Both cars have respectable acceleration. More than enough to keep up with local traffic.
Attachment:
CRX-Insight-Gears.jpg
CRX-Insight-Gears.jpg [ 72.82 KiB | Viewed 2127 times ]

There is a good Cd list of various cars here,
http://ecomodder.com/wiki/index.php/Veh ... _Drag_List

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PostPosted: January 28, 2013, 12:37 pm 
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a.moore wrote:
This may be a dumb question but what exactly is "lean burn"? Do they just lean out the mixture in areas of low load where it won't destroy the engine?
There's no dumb questions. Only dumb answers. :)

The Insight has a specially designed 3 cylinder, 1 Liter engine with Vtec. The combustion chamber etc was designed so the engine can still run and produce acceptable power on very lean mixtures. My CRX was a stepping stone in that direction and I've measured 17:1 F/A ratio when cruising along keeping up with city traffic.

The Insight has the capability when running along at low power demands to go into a distinctive mode ("lean burn") where the mixture is leaned out up to 24+:1 ratio.

Running that lean does produce more NOx than is acceptable for emissions but the Insight has a 2nd cat converter that absorbs the NOx. When the O2 sensors detect that it is time, the computer commands a "purge" to be done for 5 to 15 seconds by making the F/A ratio richer. After the purge the car re enters lean burn and the cycle repeats every once in awhile. For the short time you are out of lean burn you will still be getting 60 or more mpg. You can definitely feel a slight lurch as the car enters and leaves lean burn. But your butt dyno has to be tuned to notice it. :wink:

To force the lean burn condition you go a few mph over the speed you want to maintain and hold the throttle steady. At that point you will probably be seeing 55 to 65 mpg on the instantaneous mileage gauge. Then you let off the gas pedal very slightly and the fuel gauge will go up over 100 mpg (and even up to 150 mpg, the top of the gauge). At that point you feed in just a little throttle to maintain your speed and the mileage will go down to "only" 80 to 100 mpg and stay at that mileage. With the correct tires, high tire pressure, level road, no wind etc 120+ mpg numbers are obtainable without drafting.

People that don't know the trick of forcing the car into lean burn still get the advantages because they go through the steps of entering lean burn in the course of driving along without realizing it. By just driving carefully they could stay in lean burn for an extended time and even double their mileage. It's really weird to be driving at 20-30 mph and seeing over 85 mpg.

This is the technology that is out there that could be used as a donor car. But only 17,000 first generation Insights were sold worldwide in the 2000-2006 time period they were made. Luckily the largest percentage were sold in the USA. And wrecked or damaged ones can be found on eBay etc. Parts for the cars are quite expensive if bought from Honda though. I bought mine through craigslist.

Typically the cars will have weak high voltage batteries but they can many times be brought back to working condition by trickle charging (the term used is "grid charging") the batteries and going through several charge/discharge cycles. Just like the RC guys do with their Ni-MH batteries.

By the way I do NOT work for Honda (I'm just an over enthusiastic owner). :lol:

Lot's of info and maybe ideas can be found at the Insight forums.
http://www.insightcentral.net/forums/

This is a review page of the car,
http://www.insightcentral.net/KB/index.html

Jack: I'm sorry if I'm hijacking your thread but this might be a good source for the engine etc for a fuel sipper. But topping a stock Insight is going to be a challenge for sure. I'll go to the back of the room now. :)

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PostPosted: January 28, 2013, 7:12 pm 
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JackMcCornack wrote:
Miatav8,MstrASE,A&P,F wrote:
Rear aero has a bigger piece of the drag pie than anything else.
Right you are, Miatav8--presuming you don't make such a mess of the front end that the air doesn't get to the rear of the car in a coherent form.

This is my primary motivation for developing a middy* ecocar--middies are easier to streamline than fronties.


Speaking of really bad front aero, the recumbent bicycle crowd have used only a rear fairing and found significant improvement at low speeds. If you take a cube and can only stream line one end, it should be the rear. Like you said, no way without a kamm back or gross amounts of overhang and/or wheelbase past the driver. A middy would be easier, and a rwd reverse trike even more so.

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