The Feather Duster/Dart Lite did not have a tuned exhaust. It had a 2¼" headpipe, a 1-7/8" tailpipe, and a 318-spec muffler.
This is a zero-sum waste of time at best. The alternator's torque requirement varies with electrical loading. The voltage regulator already "turns the alternator off" when the battery does not require charging. If you hack in some kind of a setup that doesn't allow the alternator to run until the battery's down to such-and-such a voltage, charging the battery back up from that point will require just as much work — and therefore just as much fuel — as if you simply left the system alone and let the voltage regulator do its job. And your battery will last longer with the factory system. And your electrical system will work better, including your ignition system.
I'm not sure I agree with you. What are you basing this on?
It's one factor. Diesel fuel also contains more energy per unit volume, and diesel engines have no throttling losses.
It wouldn't have to be a crossflow head, just one with a more advanced combustion chamber.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Light load and cruise you can not run to lean to the piont it burns pistons or valves. The only limit is the point it starts missfiring,bucking or surging.
I have run as lean as 17.5 without no problems in these conditions.


Now once that vacuum drops ( heavy load) or WOT you better be feeding it the fuel.



Jess

Awesome. now another new puzzle dropped in to the whole picture:

Now I can answer your question about vacuum drop for heavy load/accerelating stuff:

When I was climbing with steady throttle or accelerating, the gauge showed richer. Even I hold the throttle and when it get to the speed without moving the throttle, it gradually went leaner and stayed there.

To clarify: Picture this: holding throttle throughout: cruise/light loads read real lean, when it reaches hill that is steep enough, the gauge moves over to richer side on that carb's own, when it tops the hill or levels off, leaner again. go downhills stays lean. Even I step on gas just enough, it go richer for awhile during little accelerating then it levels off and automatically go leaner.

I'll plug in the vacuum gauge to confirm. Only way I can see that easily is looong drive at speed. City drives doesn't simply work.

Cheers, Wizard

Hate to disagree with SlantSixDan on a couple of things...but let me do it anyway:

Once when I was teaching electrical engineering I was involved in a research project working on 48 VDC automotive electrical systems. We found that for SHORT trips disabling the alternator (we used a clutch) improved your gas mileage--this was over the long haul, the alternator represents a sub horsepower load. We also found that by replacing the mechanical water pump with a thermostatically speed controlled variable speed electric water pump you picked up a few more MPG in the long run. There was a measurable difference in pumping efficiency with a elegantly designed water pump and the ten dollar MOPAR pump (go figure). Note that this WAS all based on a 48 VDC power supply with 12 VDC being used at various points of use, some (or all) of my assertions may be invalid for a 12 VDC system.

Finally, the heating values for diesel and gasoline are nearly the same, with a slight edge to gasoline for HHV, and to diesel for LHV (all in MJ/kg).

Gasoline: HHV: 46.7 LHV: 42.5
Diesel: HHV: 45.9 LHV: 43.0

In general we found in our heavily bankrolled project that there is quite a bit of efficiency to be gained in an internal combustion motor, up to its theoretical limit. The electro-mechanical valve train was by far the neatest thing. Worked great, but very expensive. The folks that paid for this work made it very clear that bean counting matter and that our work represented the upper end of cost control. Saving $10 on a 20 million build is real money! Interesting perspective from the money folks...

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Slanted D150

This was probably down to errors in measurement technique. Energy cannot be created, it can only be transformed. You can let the alternator exert a small torque load and therefore a small fuel cost on the engine to produce low current for two hours to keep the battery charged, or you can declutch it or turn it off for an hour and forty-five minutes, run down the battery, and then let the alternator exert a large torque load and therefore a large fuel cost on the engine to produce high current for fifteen minutes to charge the battery back up. The end result is the same: a given amount of fuel burned to produce a given amount of electricity. This is no different than the fact that you can lift yourself five feet up by stepping up atop a single five-foot wall in one go or by climbing ten steps of six inches each. The work to be done is the same, therefore the input energy required is the same, and therefore — modulo the efficiency curve of the particular alternator in use — there is no real fuel savings to be had by declutching or switching off the alternator.
The alternator's torque load upon the engine is a direct function of the electrical system's current load on the alternator. For some strange reason, it is commonly misunderstood that the alternator's torque requirement remains constant regardless of how much current is being produced. That's wrong. If it were true, the alternator would be a magical energy-creation device, a/k/a perpetual motion machine. We don't have those in this universe.
Gasoline contains 124 kBTU per gallon.
Diesel contains 139 kBTU per gallon.

Diesel, therefore, contains 12% more energy per unit volume than gasoline. This is independent of the efficiency with which any particular gasoline or diesel engine converts this chemical energy into kinetic energy.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

CrAlt,

My setup is pretty nice, see below. I would think your extra engine would be fine the way it is. It is very close to mine. Best jet in the 1920 is #58 on a overhauled motor like that. My favorite is a #57 for a little better mileage.
A #58 provides 22.5 mpg right on the money. A #57 gives me 24.5 mpg.

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Aggressive Ted

http://cid-32f1e50ddb40a03c.photos.live ... %20Swinger


74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG

I can't picture the advantage in a crossflow head, since the mixture needs to enter the piston, do its stuff, and exit the piston, presumably in a vortical flow. Engineering types?
Is vortical even a word? Spell check doesn't think so.

A read on alternator tweaks here:

http://www.metrompg.com/posts/alternator-optional.htm

In that R&D project we were well aware of the entropic nature of the universe and all that. Our tweaks to alternator use were based on frictional losses and incurring (perhaps) a slight decrease in battery life due to deeper cycling. Bottomline is that you do NOT need to create energy for short trips for the electrical system--it is already there. We are NOT talking about creating energy from nothing...what we were doing was avoiding the unneeded frictional losses from what is basically an oversized machine (i.e. the alternator). Alternators are sized for maximum load--they seldom operate at that level. We were saving fuel based on the incremental NONE use of the alternator.

The URL above does a fair job explaining why you DO get an increase in mpg by tweaks associated to the alternator (and ALL other belt driven stuff on an engine). Simply put there isn't a single part on a car or truck that is particularly efficient....belts, bearings, gears, etc all take there toll. Much of the energy in fuel is lost as heat (hence the term heat engine of course). Since the point of this thread is improving MPG I am simply pointing out possibilities that help--they work in some instances, in others they may not. We WEIGHED our fuel usage to avoid the fun with volume that you can have--but Slantsix is correct that diesel has more ommpph per volume unit so it does win out on gasoline in that regard.

Bottomline: Much of an automobile's engine is designed to be bulletproof and be cheap to build. Not really cheap to operate. This is why loosing a mechanical fan (replaced by an electrical fan), getting a clutched alternator, eletcrical water pump (loosing the thermostat at the same time) all make a difference. Note that these real efficiences come at a cost, they cost more $$ and complicate the engine. Consider the price for a mechanical fan (belt, pulley, fan blade) to a electrical fan--might be as high ten to one more expensive if you are buying in quantities (electrical fan vs mechanical fan).

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Slanted D150

A good cross flow head takes advantage of the "momentum" of the A/F mixture / exhaust gases. The path through a well designed cross flow head looks like an up-side-down "camel's hump" compared to the "horseshoe" or "Z" shaped path of a wedge head.
At low RPMs there is not much difference but a smooth / less turbulent air flow path make a big difference as engine speeds increase.
DD

I'm sure you found some valid conclusions for the academic exercise you described with the ultra-funded research car with the 48v electrical system. However, most of us on the board here live in the more mundane world of cars with 12v electrical systems.

Line voltage with the alternator, engine running: Around 14v.
Line voltage without the alternator, engine running: Around 12.3v.

Most of the ignition systems we use in our (real, actual) cars work better at 14v than they do at 12v, so even if you could theoretically figure out how to get a tiny theoretical improvement in overall mileage by declutching or switching off the alternator until the battery was run down so far as to need a charge, your combustion would suffer due to diminished spark quality, so your right hand would be eating up the fruit you were picking with your left.

We had a similar discussion some time back on this board with the question of whether there's a point to putting together an electrically-driven power steering pump setup in place of the belt-driven item (on an actual roadgoing car made in the 1960s).
It's tough to argue this point, because it's a little like a horoscope: sufficiently vague that pretty much any situation can be considered a good fit. If you were to define "particularly efficient", we could probably have a fun and interesting discussion about it, though.
Yup...and you might thus decide the cost-efficacy sweet spot is in a thermo-centrifugally clutched belt-driven fan (real-world pragmatic solution vs. theoretical ideal).

I don't intend an attack with any of this, BTW. It's always interesting to debate the practical applications of theoretical principles.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

I have run the Mopar stock EI in both Demo Derby with no Alternator (318's/383/400 big block run hard- stop and crash for up to 15 minutes) and recently did a 1 hour trip in BV with no load on the alternator using battery power only and when the voltage gets down to about 11 the EI gets reallly salty and combustion misfires happen more often than not... if it dips lower you don't get much of anything (not enough juice to keep it all fed)... I also have noticed that if the alternator wiring isn't up to par, when the VR calls for 'max voltage' the first thing to 'fry' is the hot feed loop and wiring right at the alternator (and sometimes that terminals connection inside the alternator too...)


Just my experience...

-D.Idiot


"Yep I abuse cars just so I can say... Yes, it can do that... for a couple of minutes... then BOOM.."

This is a good and lively debate--as SlantSix points out if you want MPG increase for little money...well, that is tough. Detroit et al all ready gave it a go. That project we did was banked by Honda--ten years ago. We used Chevy 350's for testing though...go figure! Some of the suggestions finally found their way into production. That is nice to see.

Sadly none of us can build alternators, power steering pumps, etc in our garages so we are stuck with the miserable efficiencies they have. As I had pointed out earlier there are some things that can be done to get more milage, but if you go hog wild you end up with a Prius, not a Dart. Maybe I have spent too much time working in places were money can be spent to build a better mousetrap--got to think practical here!


I wonder if a toothed serpentine belt might be worth a mile or two increase. V-belts are pretty sloppy. That might be a tweak that is doable and cheap(er). Might fall under the PITA category though

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Slanted D150

Yep, cost-efficacy is the key. If I start out at 18 mpg and I spend $3,000 to improve my mileage by 2mpg to get to 20 mpg on average, and gasoline costs $4/gallon, then I must buy 7500 gallons of gasoline and drive 150,000 miles to make back my $3,000...after that, then I can start saving money.

If the price of a gallon goes up to $5, then I need "only" buy 6000 gallons and drive "only" 120,000 miles to make back my $3K.

If the price of a gallon goes up to $9, then I have to buy a little over 3333 gallons and drive 66,667 miles to make back my $3K.

H'mm...okay, let's wave our theoretical magic wand and give ourselves a much bigger fuel economy improvement for our $3,000. Let's get a large 25% improvement and go from 18 mpg to 22.5 mpg. Gas at $4/gallon = 3750 gallons and 84,375 miles to payback. Gas at $5/gallon = 3000 gallons and 67,500 miles to payback. Gas at $9/gallon = 1667 gallons and 37,508 miles to payback.

Whew...looks like it costs a lot of money to save gasoline!

You're right that none (or few) of us engineer and build alternators, water pumps, P/S pumps, A/C compressors, etc., but I don't agree with your portrayal of these as having been deliberately engineered sloppily. The pressure on suppliers to maximise component fuel-efficiency is enormous all over the developed world. Automakers demand it because above them the regulators demand it and below them the customers demand it (not so much in the US yet, but certainly in Europe, Asia, and Australia).

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Too many people who were born on third base actually believe they've hit a triple.

Dan,

Back to the practical, Juan from Argentian asked if you had any technical info on 1920 Holley air bleed sizes, jet sizes, and economiser body styles and settings from the various years. I am most interested in the air bleed sizes.
Do you have any technical data of that type for the various SL6 motors?
If so, could you please post that data so some of us can tune our Holley's up as economically as possible with spending allot of money?

Thanks!

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Aggressive Ted

http://cid-32f1e50ddb40a03c.photos.live ... %20Swinger


74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG

That's a good question. Air bleed sizes are probably going to be very hard to come by, because there wouldn't have been any reason for them to publish that data. They're not replaceable or adjustable, so what does it matter (except to freaks like us) what size they are? The info's probably on the blueprint for each and every model of Holley 1920, but I can't imagine those prints being at all accessible. I do have reference data and specs on many (not all) 1920s. Not sure if it includes air bleed sizes, think it probably does not. It's in storage in Colorado, some 3,000 miles away. I suppose it's time to start thinking about moving that collection up to me here.

I suspect the only way we're going to wind up with a database of air bleed sizes is to start measuring and build our own!

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一期一会
Too many people who were born on third base actually believe they've hit a triple.