Centurion 128-mpg ... and smaller engines
 

128-mpg Diesel-Powered Sports Car

This text rings true to me:
"The technology used to produce Centurion's high fuel economy is very straightforward. An internal combustion engine runs most efficiently when it is operating at 60% to 90% of maximum output. In contrast, when an engine is throttled so it develops only a small portion of its power output capability, fuel economy plummets. Automobiles operate most of the time with the engine throttled to 5% or less of full power, such as when cruising at low speeds in urban traffic. Even on the highway, the average family sedan can cruise at 55 mph on a little as 8 to 10 hp, which is only a fraction of the power capability of the engine. An engine throttled into fractional power regions can use double or triple the fuel per unit of power output. It's as simple as that."

What do you think?

Do you think this had reasonable acceleration? :turtle:

And this text:
"Turbocharging the engine would increase maximum power and performance, and improve fuel economy as well."

I'm thinking turbocharging is key. Could you say turbocharging allows for two powerbands, and two "BSFCs"? How would a gas engine kept in the sweet spot compare to a diesel in efficiency? In other words, what percentage of a diesel's efficiency is due to no throttling?

So, it looks like one needs a non-car/motorcycle engine to achieve 100 mpg with an ICE and no driving tricks.

What might be good sources for used gas and diesel engines of ~20 hp with an appropriate powerband?

Or, if you could get the gear ratios numerically-high enough to have something like a Honda 175 motorcycle engine in its sweet spot (Wiki says "20 bhp @ 10,000 rpm"). That might be more fun- having something that'd rev versus a sewing machine engine.

What do I personally think? Save your $95 and do free research online. That's money that could go toward actually buying yourself a Kubota diesel, a donor car, the tools to do a swap, etc.

As for performance, I can't speak to that. But I would be leery about using a car with a top speed of 65 mph for highway use.

Its pretty significant. Look at a P-V diagram of the Diesel Cycle and the Otto Cycle side by side (especially at part throttle). The lower "loop" of the Otto cycle is pumping losses.

https://wiki.ucl.ac.uk/download/atta...=1240828681000

This is the reason for the Prius using an "Atkinson cycle" engine (not an Atkinson engine). It uses a delayed intake valve closing to allow air to be pushed back out before compression begins. This means it isn't pulling vacuum on the intake side of the engine, increasing efficiency. Toyota also programs the hybrid system to maintain engine load in a sweet spot while charging to maximize efficiency.

This is also the reasoning behind a Hot Air intake (among a few other factors). Hot air is lower in density, which means more is required for a given HP demand. Therefore at a given HP demand, the throttle opening is larger (less pumping loss) than without a hot air intake.

Edit, some more thoughts while I'm still @ lunch...

This is a great argument for a small ICE engine that could operate around 90% power at 80mph - lets say 35hp. Supplement it with a relatively large EV system that can regenbrake and provide acceleration force/hill-climb power and you have a pretty efficient system.

When looking for non-car/motorcycle engines in the small power output range, its common for the BSFC to be pretty crappy by automotive standards (also for them to be dirty). Diesel gensets, lawn equipment, etc. generally use quite low tech carbs and are designed for maximum reliability (neglect), not maximum fuel economy. The also rarely have emissions controls.

Energy density per gallon.

regards Mech

I never considered buying whatever they're selling.

What aboot it?

Pardon my confusion. You quoted and posted a link to a sales pitch, so I assumed you were asking about the product/offering.

how about a modestly powered diesel with propane injection for emergency power needs?

One of the basic reasons why diesels get better mileage. More BTU in the fuel.

You asked.

regards
Mech

1. more BTUs
2. no throttle losses
3. no need to maintain stoichiometry.
4. higher compression ratio

i think that pretty well covers the reasons. there may be more, but, i don't know what they are.

1200 pound car. 20 square feet with decent aero. diesel engine.

I'd bet a hypermiller could get 100mpg, but no way it will get that high in normal driving.

diesels are SURPRISINGLY efficient at lower rates and diesel fuel has quite a bit more energy per gallon then modern gasoline.

Trick is to keep the car light.

And small.

Is small, light, and aerodynamic gonna do it with a gas engine that's at 20% throttle, even if it's a smaller 4banger?

Only one way to find out!!!!!

If by "do it" you mean get 100 mpg, then no, probably not.

Nor will a diesel of enough HP for what most people would consider adequate performance, installed in such a car do it. Jack McCornack is a member here, and has a 32 hp Kubota diesel-powered car of about this size. Prior to going for a better streamlined body, it was getting about 60 MPG at 60 mph. They are now getting almost 80 mpg, apparently, with the better streamlining.

The Riley figures are completely misleading, unless you read the fine print. Nobody else quotes mileage at 35 mph. (The auto manufacturers are not allowed to engage in such shenanigans.) 80 mpg at 60 might be reasonable. 70mpg in a real EPA highway test would be about right. By headlining 128 mpg, they are off to a bad start, so I am skeptical of everything they claim. The streamlining is awful, because the flow will separate as it turns the corner above the back window -- its "all show, no go."

In the VLC from Edison, you can see what is required to get 100mpg in a gasoline-engined car: a very small engine with specialized control to avoid pumping losses, 800 lbs, really excellent aerodynamics, including fully faired-in wheels. I doubt that there is a a diesel engine of around 20 hp that provides the same efficiency as the VLC engine. A 20 HP diesel will weigh twice as much as a 20 hp gas engine, and when new, cost more than twice as much.

Probably the surplus sites, Ebay, and farm equipment junkyards would be good places to look for used (or surplus) 20 hp diesel engines.

This "Centurion" is from the same company that developed the xr3 XR3 Hybrid Personal Transit Vehicle: A 125 mpg Plug-In Hybrid Three Wheeler You Build From Plans

I would not believe the high mileage on the Centurion because of it's aero. However, given that it is the same company, I believe they use the Kubota D902 engine: 900cc N/A diesel, 25hp @3600rpm (redline), 41 lb-ft of torque @2600rpm (see attached BFSC map.http://www.dieselenginemotor.com/kub...j1349-d902.jpg) They attatch this to a VW Type 1 transmission (up to ~'72 beetles/buses.) I believe that would be enough to get a 1000lb car (XR3 without hybrid system) to 125mpg with good aero given proper gearing and driving techniques. I am not so sure that I would believe their BS (nor buy their plans) but the logic is sound, the VW Polo Bluemotion has a curb weight of 2550 lbs and a coeficient of drag of .307 cd and gets around 70mpg with its 1.2?L engine.

The cool thing about using diesel tractor engines is that they are VERY durable/reliable, parts are relatively inexpensive even from the manufacturer due to how common the engines are, and they are very receptive to fuel conversions (veg oil, black diesel, propane, etc.)

As for the turbocharging comment, it is a double edged sword. A turbo will lessen the pumping losses and eliminate throttle plate losses because of boost pressure forcing air into the engine, especially in diesels which run much higher boost pressures than gasoline engines. However, like with anything if you USE the power that it gives, your mileage will suffer because the increase in air will cause in increase in fuel consumption to maintain stoichiometric ratio.

diesels don't have throttle plates, nor throttle plate pumping losses.

nor stoichiometry concerns.

i do believe the latest greatest TDs have a throttle plate. Has something to do with emissions. I believe the addition of the throttle plates causes better EGR flow.

i also believe that a properly sized turbo actually increases mileage, assuming of course you have the discipline to not tap into the surplus HP.

How is the VW 1L prototype getting 170 mpg when 100 mpg seems like a stretch?

Optimization.

I work at a dealership, although I am not trained as a diesel tech, I do work on the Mercedes OMP 3.0L in the Sprinters and the Cummins engines in Dodge pickups, both of which have throttle plates (electronically controlled, the old 5 cyl inline merc diesel did not.) Also, the lastest VW 16v 2.0 TDI engines have a motorised throttle body and lambda sensors to control egr and air fuel ratio.

Any combustion reaction has a perfect stoichiometric ratio (thermodynamics.) In a diesel there usually is never enough air in the engine to burn all of the fuel that is injected because of design and practical application, however, from my thermodynamics book- diesel will burn in the range of 3:1 all the way to 42:1. This is very different from gasoline which has a perfect ratio of 14.7:1 and will burn from only from about 10:1 to 16:1. The perfect ratio will minimize 5 gas emissions. For example- a gas engine with an afr of 16:1 will produce more NOx gases than one at 14.7:1, an engine with an afr of 10:1 will produce more HC and CO. (see picture) Diesels work the same way, but at different levels/rates but I cannot find a picture.

http://www.ft86club.com/forums/attac...1&d=1320785064

Gazuntite

I'll second Frank's answer: optimization. It's a $400,000 economy car.

I'll add that part of the answer, however, lies in the website you referenced. Different test routines produce dramatically different mileage figures. The Riley is really a 70 mpg car (running through the EPA highway cycle) advertised as 128. The VW would not get 170 mph in an EPA test cycle. The X Prize results for the VLC are close to what the VLC would get in an EPA combined cycle (because the X Prize test was designed to be that way). They got something like 107 mpg, I think. The VW engine is probably more efficient as installed -- i.e. relative to the load. Total aero drag is lower, and if I recall, weight may be lower also. I would not be shocked at 135 - 150 mph EPA combined for the VW.

I may have mentioned this, but the Aptera with a 660cc kai engine (fuel injected gas) got 50 -55 mpg, almost all the time, according to Steve Fambro. Granted the Aptera is big, but it was very well-streamlined, and the small engine was at least pretty well-loaded. When you add a few sub-optimal choices here and a few more there, the overall efficiency can plummet.

In a plug in hybrid, like mine, there are lots of energy conversions. For the sake of simplicity, we'll say there are five processes. These can each be highly efficient: 95% .9^5 is 77%. They could each be OK: 80%: .8^5 is = 32% Big difference.

Comes out loose?

And this is the biggest problem with any type of "hybrid". Be it gas, diesel, A/C, or D/C. In a Chevy Volt setup, where the engine only charges the battery pack, the engine can be run at its most efficient rpm and therefore the generator can be optimized to produce X voltage at Y amps at this rpm. This at current technology levels is probably the best solution. The problem lies in the conversion of energy from mechanical to electrical (and any other losses on the way).

Gasoline (or diesel) is a condensed form of energy of which we are only able to extract 35-45% of its stored energy from the combustion engine depending on engine/fuel used. Then you convert that mechanical motion into electricity via a generator, which would at most be ~60-70% efficient (the most efficient that I have read about). This electrical energy would be somehow transferred to an electric motor which can be from 80-95% efficient. So like Ken said, but using high and low numbers, you have .45*.70*.95=.29925 and .35*.60*.80=.168

BEFORE losses in transfer (as opposed to conversion) you have a power plant that would be from 17-30% efficient. Losses in mechanical conversions/transfers are usually greater than electrical which is why hybrids do offer some improvement on mileage, but you can see where improvements can be made.

You have actually described the Zing setup (which is a strict series plugin hybrid) rather than the Volt setup which is a multi-mode hybrid that directly drives the wheels at times. The Volt architecture was changed (strangely to the chagrin of some EV enthusiasts) to improve the poor efficiency of the engine. Even with the 15% improvement gained by enabling direct-to-wheels drive at cruise speed, the gasoline-only fuel efficiency (37 mpg) is pretty poor if the benchmark is the Prius.

In the Zing, the engine either runs at full load or not at all, and driving force comes from the electric motor. Were it not for the hybridizing, the engine would vary in efficiency from 0% while idling to 5% at low load to 15% at moderate load, to 32% at full load, which would very rarely be used: there is no point in either the urban or highway drive sequence in which full power is required. The hybridizing allows for near doubling of fuel efficiency, despite the generator and motor losses (in my case each is 90% efficient). A bigger advantage, though, is that the fuel used most of the time is a small fraction of the price of gasoline -- and in most of the country is also cleaner from well to plug.

As you said the losses are large, but it is about the best we can do right now.










rid.

Thats what I meant by "today's technology". I didn't realize that the Volt had switched to parallel drive. The one I drove last April was brought up by the GM reps and was only driven by the electric motor and charged by the gasser.

Every production Volt has the power split capability. GM came out with some statement about how they had not lied when they earlier had stated that the was no mechanical connection whatsoever between engine and wheels. But in fact the connection is like the Prius, where the power is split. You can say for the Prius that there is no direct connection, no single transmission shaft between engine and wheels, but you'd be stretching the truth... a lot.

It would be like lifting one wheel of a car with an open differential of the ground and applying power. "See... no movement. Therefore, there is no direct mechanical connection." Seems to me this is beyond a stretch of the truth.

But all the Volts, when at high speed and as required, power the wheels partially with the engine, via gearing.
Exclusive: Chevrolet Volt Chief Engineer Explains Volt Drivetrain, Says "Volt is an Electric Vehicle" | PluginCars.com
Motor Trend Explains the Volt’s Powertrain

From motor trend:
"Markus liked driving the car and he noted he was surprised about the direct mechanical connection."
GM flavors it this way so people have a harder time saying they lied: "GM says the engine never drives the wheels all by itself, but will participate in this particular situation in the name of efficiency,"

As you experienced, most people selling them had no idea there was this connection.

Another oddity I learned (?)** from a driver/promoter: the Volt does not charge up the battery when the engine is on. It simply keeps the battery at a low charge level***. This person was surprise when I told him that my Zing had gained charge on the way into Atlanta one day*. I guess that is what the "mountain" mode is about with the Volt. This if turned on before reaching mountains will increase the battery charge level, so you can climb the mountain without the performance falling off too much.

*This seems to me to be the way it should be, and actually, I'd have to make things more complicated if I wanted to avoid charging up the battery. Why on earth would I want to do that??

** I am not absolutely certain it is really this way -- but he's an electrical engineer and pretty convincing.

*** As I think about it, maybe this is one reason for the poor fuel efficiency. This would lead to a lot of short cycles, or a lot of time spent at less than full load -- neither on optimal.

Well at least you didn’t suggest getting a free pirate copy. ☺

Robert Q. Riley is a designer, not a manufacturer, and he makes his living selling plans. If your objective is to make one of his designs, the plans are a bargain. If you want to make a similar design, his plans are money well spent—I don’t have his Centurian plans, but I have other works of his, and they’ve been an inspiration.

If you want to make a car completely from scratch, his book Alternative Cars in the 21st Century: A New Personal Transportation Paradigm will save you days of dead ends. I paid $49 for my copy, off his web site page…
Alternative Cars in the 21st Century (2nd Edition)
…but you can get it cheaper from the SAE bookstore, particularly if you’re a member. I bought mine from him direct ‘cause that way he gets to keep more of the money. My copy is about worn out, I’m guessing it’s cost me a dollar an hour for time not wasted going down rabbit trails.

When doing your free research on line, I hope you’ll consider…

Automobile Ride, Handling, and Suspension
Three-Wheel Vehicle Handling Characteristics

PS-- RQ is very smart and he knows it. I hope we don’t get into trashing him on this forum, just because he Actually Does Things and/or he thinks his knowledge and effort are worth money and/or his writing style lacks warmth.

I have the Centurion plans... got 'em back in the day, when they were brand new. I had a Spitfire then too, but for whatever reasons "my" Centurion didn't get built (IIRC I couldn't locate a reasonably priced diesel engine at that time- pre-internet shopping was sooo much harder!).

Another thing that really seems disingenuous today is the mileage claim at 35 mph... yes, it's ridiculous, but back then most fe claims were ridiculous. We had been gradually moving away from nonsense and towards usable fe estimates until, IMHO, they were quite good with the last generation of EPA tests, which have now gone downhill to reflect the stupidity of the average driver today. :(

You've hit the nail on the head, Frank, it does seem disingenuous today.For a bit of historical perspective, the prototype was built and those plans were offered 30 years ago, when the National Speed Limit was 55 mph. Riley's mileage figures are clear ("At 35 mph, Centurion delivers at 128 mpg. At 45-mph, fuel economy is 103 mpg, and at 55 mph it drops to 85 mpg.") and are in the body of the information of that page, they're sure not hidden away, and by the standards of the era they're pretty impressive.

The styling is a bit too yesterday's-car-of-the-future for my tastes, and Riley's more recent vehicles are much improved in the streamlining department. Auto styling is a compromise of many factors; one factor is streamlining, one is cost, and one is what the public will accept. Circa 1980 the acceptance bar was not where it is today. I'd call the Centurion streamlining dated rather than awful, and again, streamlining was less important at 55mph than today's speeds.

Or perhaps I'm defending my own work by proxy. I too quote my mpg at 20mph slower that the highest legal speed I've seen of late (75 in Wyoming, yet I've bragged about getting 100mpg at 55) and while I didn't personally write it, my own 127mpg result in the 2011 Mid-Ohio Vetter Fuel Mileage Challenge (100 miles of mixed environment, including a short 70mph blast on the freeway) made at least one headline, and you had to read the article to find we were mostly just gently cruising on rural roads and had perfect weather for a mileage competition.

I don't post much on ecomodder nowadays. Maybe I'm thin skinned, but it seems like the meanies have taken over the asylum and I don't want to paint a target on myself. It's getting kinda cliquish, and folks that don't fit the mold get trashed for doing their own thing. This Centurion forum started well, with a technical discussion of the Centurion, then it drifted to accusations of "shenanigans" that seemed more about writing style than content, and now it's about the Volt.

Ken, if you dispute Riley's claims for the car, I'd like to hear about it, and I'm sure so would others. Are his figures "completely misleading" because they're wrong? Ragnarok thinks they're wrong ("I would not believe the high mileage on the Centurion because of it's aero"), I think they're likely pretty accurate; it might make for an interesting discussion--we could all give reasons for our opinions. There's plenty to talk about re the Centurion (the OP made a good start) but for folks that don't like its presentation and would rather talk about plug-in hybrids, couldn't you start a fresh PIH or Volt thread instead of hijacking this one?

How does efficiency change with load and rpm for the generator?

How does efficiency change with load and rpm for the motor?

How about the controller?

What is the overall efficiency in terms of vehicle speed and load?

And is energy moving "through" the batteries? What conditions affect the charging/discharging efficiency? (not counting regen)


Like we don't consider ICE engines to be really 35% efficient because of operating conditions, we should not make the same mistake with electrical drivetrains, no?

Just to be perfectly clear, have you actually purchased these 90 percent motors and generators yet?

Have you fitted them to a vehicle yet?

lets say we are cruising down the road, and the batteries get low.

So we fire up your 32 percent efficient IC. Lets say your cruise speed doesn't need all the generator can produce, so we try to recharge the batteries.

What efficiency do your batteries recharge at?

There will be a range where your 32 percent efficient IC will have excess power over cruising, and yet your batteries won't accept the excess amps the generator will accept.
In this case, the generator will not operate at peak efficiency, or the generator will start cycling on and off.

A lot.

By the way, where do we purchase one of these 32 percent efficient IC engines? Sounds pretty neat.

Not only 32%, but, 32% air cooled gas engine.

I was under the impression that liquid cooled gave a slight efficiency gain due to maintaining optimal head temps.

I guess in the end, there is one number that matters. How far did I get and how much gas/electricity did I have to pump into it.

That is three numbers :)

The OP asked in the OP (re the Centurion)...Not by today's standards of reasonable. My car is similar layout (but with the 21st Century version of that engine--lighter and a good 50% more powerful) and it's routinely mocked for its low acceleration. I doubt the Centurion could outdrag a loaded UPS van and I think passing slower traffic would take some serious planning ahead. That is, if one could find slower traffic. :)
I think that's true in practice, though not in theory (huh?). In my experience, what turbocharging gives me is access to more power when I need it, which is rarely, but it sucks plenty of fuel at turbo-power. Most of the time, it acts like its 25 hp NA version (I cruise at low power and zero boost) but when I want it I can get 33 hp, thanks to the turbo, but it's not a particularly efficient 33 hp. Point is, 33 hp is available on demand, though I probably only demand it an average of 20 seconds per hour of driving. To get the same power NA, I'd need the next size up, one cylinder and 400cc bigger, which would hurt efficiency at cruise and I'd still only want full power for 20 seconds an hour.

So in theory, turbocharging doesn't help efficiency, but in practice, it lets you run a smaller motor so the overall effect is positive. At least, that's my experience with the Kubotas.
Basjoos's Aerocivic site says he gets 100 mpg at a steady 60 mph and 120 mpg at 40 mph, with a standard Honda Civic lean burn engine and extreme aerodynamic mods, so it looks like it's possible. It doesn't look easy, though.The Kubota D1105T (like mine) is used in some commercial greenskeeper's lawnmowers, and some folks upgrade to the V1505T (the four cylinder version) and others just crash their mowers. Now and then I see these engines used on Craigslist for fifteen hundred bucks or so. Also there's a guy on eBay that's bringing in used Kubotas etc from Japan, only the NA models but if 25 horse will do you, they're there.

My idea about turbocharging is very similar to what you said, so I guess I should've left [fuel] efficiency out of the sentence. Set up the engine more or less for cruise speed, and the turbo kicks in for acceleration needs- passing, climbing, etc.

Hi Jack,
I'm a little taken back by your reaction, because I had you in mind when I wrote that the 128 mpg figure is misleading. Riley's headline claims that his car gets 50% better mileage than yours. I think that is unfair, because I doubt that there is that much difference. Nor do I think the Centurion is as efficient as the VLC.

For me, reporting a number that is not representative (or in the ball park) of performance on the combined EPA cycles is not OK for a commercial endeavor. The combined cycle is more strenuous than a 60 mph cruise for almost all cars.

You find Frank's comment to be just fine. It hits the nail on the head, you wrote. ("Another thing that really seems disingenuous today is the mileage claim at 35 mph... yes, it's ridiculous, but back then most fe claims were ridiculous.")

My comment, however, does not go so far as to say "ridiculous" or "disingenuous" (which carries a connotation of deception). I simply wrote that it is "misleading". But you seem to be characterizing my comment as coming from the "meanies."

But the fact is this: we are not living in 1982. Riley is advertising the car as 128 mpg, today. That is misleading because the standard today is the EPA figures, and per the fine print, this is not a number obtained in anything remotely close to the EPA cycles.

I don't agree with your contention (or Frank's) that the industry routinely dramatically exaggerated fuel mileage claims in 1982. There were many sources for fuel economy ratings (Road and Track, Car and Driver, Consumer Reports, Motor Trend, etc.) and not one of those reported fuel efficiency at a 35 mph cruise. I have followed this stuff quite closely for the last 5 decades, and can not remember any manufacturer advertising as a headline, a mileage figure produced at 35 mpg. The CAFE law had come out in 1978, and manufacturers were not getting away with dramatically overstating fuel efficiency. I've owned perhaps 30 cars in the last 45 years, and I don't recall any in which the mileage was dramatically overstated by the manufacturer.

It was not my intention to hijack the thread, incidentally. I used the case of a hybrid only to illustrate the effect of optimising: by picking components that are more or less OK, the cumulative effect produces rotten efficiency, By picking stuff that is excellent, the overall efficiency ends up fairly good. I was not intending the illustration to apply directly to the Zing: I don't have 95% efficient motors, for example, although they are available.

Then someone brought up the Volt, and had a misconception about it. So I responded to him, etc. If this site has an Off topic button, I would have clicked on it to minimize such posts. It seems rude to simply fail to respond. And it seems like a time waster to start a thread about random issues in plug-in hybrids, etc. -- there must be tons of that stuff here.

But I agree that the thread seems to have drifted away from the Centurion. I'll answer the other questions, from other posters (that seem to related to the Zing or Volt, in the Zing thread.)

The "awful" aerodynamics comment is the same one I would apply to the 1960's Jag XKE. I love the XKE's but their streamlining was all show no go. "Modern aero is not inherently better than old aero. The 1940's era MG streamliner had a Cd of what? .16 My point was just that The Riley is not stunningly efficient by virtue of aero. 65 mph on 17 hp is not impressive.

Regards,

Ken

DCB, Doug, Pete:

I'll provide answers over at the Zing thread.

http://i146.photobucket.com/albums/r...er/4141394.jpg

http://i146.photobucket.com/albums/r...icleInline.jpg

You must remember that first set of EPA ratings back then... the little cars were rated at 40-50+ mpg and there was no way in hell anyone out in the real world was going to get that. Then the EPA revised their ratings and things got real. Basically I'm saying I think the last gen EPA ratings were about as accurate as we could hope for.

I remember in 1984 when I bought a CRX 1.5 new, I averaged 44 MPG for close to 50k miles. I was considering the 1.3, especially when I read about a car rag driving it at 55MPH until it ran out of gas. They got 73 MPG. I chose the 1.5 because it would do 0-60 in just under 10 seconds while the 1.3 took close to 14 seconds to get to 60 MPH.

If you want really slow 0-60 acceleration the 58 VW was really slow at something over 20 seconds to 60 and would really suffer trying to get to 70 MPH if it would make it at all.

Not many modern cars (if any) are slower than 0-60 in 10 seconds today. I also remember my 63 Valiant with the 170 fighting to stay at 40 MPG up an 8% grade on Afton mountain between Charlottesville and Waynesboro Va. 2-3-2-3-2-3 shifts for close to 7 miles climbing that grade, but I did manage 28 MPG on that trip. Supposedly 101 HP, but I had the carb set lean so probably not near that power. Used to like buying the Valiants when the PCV got plugged up and the owners thought the engine was gone at 40K miles.

regards
Mech