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Old 08-18-2007, 11:48 AM   #1
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100 mile per gallon engine!

I just read an article about a 100 mpg carburetor http://www.gofastnews.com/board/tech...lly-exist.html by David Vizard.
What he is saying is that the fuel system is already capable of better than a 100 mpg but the thermal efficiency of the engine is not.
So regardless of what we do with induction systems, fuel injection or carb, o2 sensor, aero mods, hot air intakes or anything else we will still be limited by the thermal efficiency of the machine burning the fuel,
So it’s back to the drawing board to look at the fuel burner not the fuel supplier so may be we need to push engine manufactures as much as oil and gas suppliers.
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Old 08-18-2007, 02:20 PM   #2
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I just read the referenced article. David Vizard is a well respected performance writer among automotive journalists. With that said I continue......

I think he may be severely disillusioned when he implies he may be the only person with the knowledge required to drastically improve fuel mileage.

There are large numbers of GasSavers members and other FE sites that have demonstrated what can be done with ingenuity and hard work.

When I first became a member of GasSavers, I was in awe of members who had posted 70-90 mpg tanks. I had just reached my first ever 50+ mpg tank.

Currently my car, Old Reliable, is listed with 104.7 average mpg for the last 90 days. My last tank amounted to 107.3 mpg. AND I do not have the highest recorded tank on GasSavers. Antoine in his Smartan2 posted his most recent tank at 107.9 mpg along with other previous 100+ mpg tanks. MetroMPG recently posted a 104 mpg tank in his Firefly 2 Blackfly. And others are within striking distance. I am sure not all these tanks were accomplished at moped speeds.

What really gets me is that, of the three cars mentioned above, none have drastic engine modifications, if any at all. This is in direct conflict with what Mr. Vizard considers possible. He no doubt has considerable education and experience but it may be time for him to expand his horizons.
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Old 08-18-2007, 02:39 PM   #3
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As things stand as of now I can detail how you can increase the output of a typical Detroit built street V8 engine by some 50% while improving mileage by some 40% That means if your vehicle is making 250 hp and doing 18 to the gallon now, I can show you how this can be bumped to 375 hp and 25.6 to the gallon.
Hmmm... Given a driver with the motivation, skill, and resources, I don't see why we can't have a 500hp/50mpg corvette or kit car. That being said, most people who can afford to drive a vette in the first place don't care much about mileage...
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Originally Posted by FormulaTwo
I think if i could get that type of FE i would have no problem driving a dildo shaped car.
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Old 08-18-2007, 04:57 PM   #4
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Originally Posted by CO ZX2 View Post
I just read the referenced article. David Vizard is a well respected performance writer among automotive journalists. With that said I continue......

I think he may be severely disillusioned when he implies he may be the only person with the knowledge required to drastically improve fuel mileage.

There are large numbers of GasSavers members and other FE sites that have demonstrated what can be done with ingenuity and hard work.

When I first became a member of GasSavers, I was in awe of members who had posted 70-90 mpg tanks. I had just reached my first ever 50+ mpg tank.

Currently my car, Old Reliable, is listed with 104.7 average mpg for the last 90 days. My last tank amounted to 107.3 mpg. AND I do not have the highest recorded tank on GasSavers. Antoine in his Smartan2 posted his most recent tank at 107.9 mpg along with other previous 100+ mpg tanks. MetroMPG recently posted a 104 mpg tank in his Firefly 2 Blackfly. And others are within striking distance. I am sure not all these tanks were accomplished at moped speeds.

What really gets me is that, of the three cars mentioned above, none have drastic engine modifications, if any at all. This is in direct conflict with what Mr. Vizard considers possible. He no doubt has considerable education and experience but it may be time for him to expand his horizons.
I don't think he was refering to hypermiling or coasting down hill with the engine off like a soapbox derby car, but actualy driving.
I believe his article was refering to carbs not injection and electricity.
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Old 08-18-2007, 05:17 PM   #5
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Originally Posted by rookie View Post
I don't think he was refering to hypermiling or coasting down hill with the engine off like a soapbox derby car, but actualy driving.
I believe his article was refering to carbs not inljection and electricity.
Easy there newbie. Leave the personal baggage at home. I agree with CO's take on the article, especially with statements like this.
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But there is a third alternative that really will benefit you and that is you can hop up your engine using the proven tech that I can supply you with. However it cost me a lot of time and a seven figure money number to do the research and testing needed to verify what I am proposing. If I am going to give this info to you for free I need you to do something in return. I simply want you to tell all your auto enthusiast friends about this web site. When I have a big enough audience I will spill all in great detail with extensive text, color drawings and a lot of top notch photo?s ? and that?s a promise!
Where're the four easy installments of $19.95?

What I'm saying is that there's nothing new under the sun. You design a car based on aesthetics, performance, emissions, ergonomics, cost, and efficiency. And it's all a trade off to some extent. Anyone, including yourself, can improve various aspects of your car, but these improvements will all come at some cost. Stating you need seven figures to research something has got to be one of the silliest pitches imo. Most people who know or can learn at least a little bit about physics and mechanics can figure out how to optimize their car according to their own wants and needs. It ain't rocket surgery man!
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I think if i could get that type of FE i would have no problem driving a dildo shaped car.
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Old 08-18-2007, 06:54 PM   #6
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Originally Posted by theclencher View Post
Vizard is a pretty smart cookie but he isn't always right. And, the book selling figures prominently into everything he says. That was a good rebuff of the elusive 100 mpg carb though.
And you are?
I find it interesting the number of people in the industry that cannot hold a candle to him in writing or engine building and they usually make smart-!@# comments with nothing to back them up with.
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Old 08-18-2007, 08:20 PM   #7
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Please move thread - is in wrong forum

I'm surprised nobody has pointed this out yet.
This thread does not belong in the FE Challenge forum, probably belongs in the General Fuel Economy Discussion forum.

As to the usefulness of what Vizard wrote - assuming it's all an honest portrayal of what was done and what was learned, then fine, it might be useful to someone somewhere.

The question of thermal efficiency is valid. I think something like 20% of the energy released by combustion is actually converted into motive mechanical energy. The rest is given off as heat, mostly through the exhaust and the cooling system. If we could capture even part of that energy and make use of it we could get much higher FE numbers, all other things assumed equal. Maybe run a turbine off the exhaust and use it to charge a battery bank or compress a gas to bank the energy.

IMHO, the whole business of a 100 mpg carburetor is moot. That is, pointless. No carb will give you 100 mpg if it's driving a Hummer or a "performance" car that weighs 3500 lb.

And, um, I've owned cars with carbs. I'm very glad we've worked out electronic fuel injection so we don't have to deal with those d**n carbs any more. Ever have to pay to get one rebuilt? My estimate, every couple years in normal driving, if you want to pass your local emissions test.

For performance people, there are fuel injection based aftermarket engine management programs such as Megasquirt that let you program anything you want for fuel/air mixture, spark advance, etc. Much more flexible and detailed than any carb ever was, and more reliable also.

Sorry for the rant. Hope there's something useful in here.
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Currently getting +/- 50 mpg in fall weather. EPA is 31/39 so not too shabby. WAI, fuel cutoff switch, full belly pan, smooth wheel covers.

Now driving '97 Civic HX; tires ~ 50 psi. '89 Volvo 240 = semi-retired.
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Old 08-18-2007, 09:33 PM   #8
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Originally Posted by brucepick View Post

The question of thermal efficiency is valid. I think something like 20% of the energy released by combustion is actually converted into motive mechanical energy. The rest is given off as heat, mostly through the exhaust and the cooling system. If we could capture even part of that energy and make use of it we could get much higher FE numbers, all other things assumed equal. Maybe run a turbine off the exhaust and use it to charge a battery bank or compress a gas to bank the energy.

IMHO, the whole business of a 100 mpg carburetor is moot. That is, pointless. No carb will give you 100 mpg if it's driving a Hummer or a "performance" car that weighs 3500 lb.
Thank you,
the whole point of the post was to point out that what ever you do to save fuel, the thermal efficiancy needs to be taken in to account.
Regardless of what your fuel delivery system is.
Also that there is no such thing as a 100 mpg carb. because the engine is not capable of it under NORMAL DRIVING conditions.

Also you can rebuild a carb. for less than the price of one fuel injector and an avrage 300 dollar, 750cfm carb. will out perform most 2500 dollar fuel injection systems they both have ther place.
As John Meany, one of the most advanced fuely guys said to fully understand fuel injection you first need to understand the simple workings of a carb.
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Old 08-18-2007, 10:02 PM   #9
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Originally Posted by theclencher View Post
I'm not always right either. Newsflash: neither are you rookie boy.

Here's one bit of back-up: I have a Vizard book and in it he obsesses quite a bit about rod/stroke ratios, trying to make some astronomically minute ratio differences out to be something of substance. The whole rod/stroke ratio thing has been disproven.

I also enjoyed the smart-*** comment from Vizard on that referenced site re: gassavers not doing anything but copying. There's a hella lot more going on here than at his site for sure.
I'll be the first to admit i'm wrong in a lot of areas, like responding to this post but I just could not resist.
The whole rod/stroke ratio thing has been disproven.
Disproven for what, piston speed, rpm, torqe,side load on the block,there has been a lot of use for tailoring rod/stroke to a given application.
Lets suppose for a second that David was wrong on half of everything he ever did in the automotive industry,the amount that he has contributed world wide would still be twice what anyone else will ever contribute.
As for the engines he has built.
Track records (half) would be about 84.5
National Championships (half) 2.5
As a full time writer half his articles about 1550.
Books (half)13.5
Half of the results from MSN search for David Vizard 8938
but who is counting?
As for the website it's only been online two weeks and hasen't been advertised yet, already has 61 members.only time will tell.
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Old 08-18-2007, 10:08 PM   #10
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Originally Posted by rookie View Post
Thank you the whole point of the post was to point out that what ever you do to save fuel, the thermal efficiancy needs to be taken in to account.
Regardless of what your fuel delivery system is.
Also that there is no such thing as a 100 mpg carb. because the engine is not capable of it under NORMAL DRIVING conditions.
That's true. However, since everything depends on everything else we can't look at thermal efficiency alone as the way to better mileage. For instance, most cars today have a minimum fuel consumption of ~200-250g/kWh at ~2-3000rpm and near full load. Sure, we can just take a stock car under normal driving conditions, which around here seem to be WOT until we slam on the brakes for every light with bursts of 70-85mph highway, and look at a BSFC map compared to our gearing in order to figure out what the best ratios are so that our engine is operating as efficiently as possible w/o compromising "performance". Even though it's absurd to think 2000-3000lb manufactured cars are actually fast... In any event, once we do this, we would probably come to the conclusion that for normal driving, the way most people drive, the cars we have are relatively efficient and making changes wouldn't be very productive. In order to see better mileage, something has to give.

Be it our driving habits, the physical characteristics of our cars, or both. We may get LRR tires and add plastic panels to smooth our airflow, only to find that we haven't seen gains as large as we would've liked because now the engine is operating less efficiently. So we change our driving style a bit, and get even better mileage, but we still aren't where we would like to be. So when we've changed our driving style, and the Crr/CdA characterstics of the car as much as we find acceptable, we know the only thing left is to address engine operating efficiency. Going after that first is silly because it's a relatively large amount of work, and likely already optimized for normal driving from the factory. We have to be willing to change many different synergistic things if we expect any significant change in mileage.
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I think if i could get that type of FE i would have no problem driving a dildo shaped car.
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