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TomSimon
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Joined: January 13, 2004
Posts: 751
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 Posted: Fri Jun 15, 2012 4:27 pm Post subject: |
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| [email protected] wrote: |
| I was simply pointing out that it is easier to get good MPG #s at elevation as opposed to sea level. |
I understand the theory, lower drag due to fewer molecules of air interacting on the body... but I have never heard of anyone performing a meaningful test with an automobile, at the altitudes we drive at (versus air or spacecraft). Have you ever seen anything written on the topic? |
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[email protected]
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Joined: August 03, 2002
Posts: 12785
Location: Salt Lake City, Utah
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| Posted: Fri Jun 15, 2012 4:41 pm Post subject: |
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No, but think about how much slower you are at Denver compared to Sac. 15% less power? 15% less wind resistance? That is significant.
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aryue
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Joined: January 16, 2006
Posts: 1027
Location: Austin, TX
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| Posted: Fri Jun 15, 2012 5:30 pm Post subject: |
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John - if each cylinder is being filled with 15% fewer air molecules - would a "properly tuned" 2 liter engine in Denver operated at a steady speed on a flat stretch of road - only need the amount of fuel used an 1.7 engine of the same design operated, if it is operated at the same speed on a flat stretch of road at sea level?
- Andrew in Austin, TX
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TomSimon
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Joined: January 13, 2004
Posts: 751
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| Posted: Fri Jun 15, 2012 5:43 pm Post subject: |
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| [email protected] wrote: |
| No, but think about how much slower you are at Denver compared to Sac. 15% less power? 15% less wind resistance? That is significant. |
Maybe 15% less power, but less fuel consumption along with it.
I see (and feel) the power difference at altitude, but that's when we want max power for low ET's. I say that engine efficiency remains the same. Power is down, but that is because there is less O2 in the same volume of air. As long as our air/fuel ratio has been adjusted to compensate for high altitude, and we are making less power... We must also be consuming less fuel per 1/4 mile pass.
If the above is true, then cruising down a flat freeway at 60mph at 5,000ft versus 50ft (adjusted A/F ratio for differing air density), requires the same power, and therefore would consume the same amount of fuel. Right?
I can only think of a couple things that might help fuel economy at higher altitudes.
1) At high altitude, the engine makes less power, so the throttle blade must be open wider to maintain our 60mph. With the blade open wider, the intake tract experiences less restriction. If that is true, then pumping losses must go down. If it's true that pumping losses go down, engine efficiency goes up, and fuel consumption is reduced. Right?
2) If you have fewer air molecules to push out of the way, vehicle drag goes down, so does fuel consumption.
I don't know weather either of the two above potential fuel economy helpers are large enough to even be measured, any difference might be lost within the error bar of the collected data. But I think the theory is right... What do you think, John?
oh crap, there I go sounding like a science geek again   |
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krusher
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Joined: September 24, 2002
Posts: 7652
Location: europe
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| Posted: Sat Jun 16, 2012 4:52 am Post subject: |
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| Eaallred wrote: |
I agree with Krusher. You should improve your MPG's if you keep your foot out of it.
When I ever get around to my MPG motor my goal will be 60mpg, @ 60mph, and able to make over 60hp. I think I can do it, or come real close to it. I just honestly need to sell my drag car to make it happen. I don't seem to have enough resources to make it all happen.  |
Whats CC are you considering, those number are what I am seeing on the latest 1000cc/1200cc engine here in Europe.
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Eaallred
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Joined: May 18, 2003
Posts: 5756
Location: West Valley City, Utah
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| Posted: Sat Jun 16, 2012 6:11 am Post subject: |
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| krusher wrote: |
| Eaallred wrote: |
I agree with Krusher. You should improve your MPG's if you keep your foot out of it.
When I ever get around to my MPG motor my goal will be 60mpg, @ 60mph, and able to make over 60hp. I think I can do it, or come real close to it. I just honestly need to sell my drag car to make it happen. I don't seem to have enough resources to make it all happen. |
Whats CC are you considering, those number are what I am seeing on the latest 1000cc/1200cc engine here in Europe. |
Whatever I do, it will end up being a 94mm bore. Either stock 69, or 82 stroker.
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You have to remember something: Everybody pities the weak; Jealousy you have to earn. |
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mark tucker
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Joined: April 08, 2009
Posts: 23937
Location: SHALIMAR ,FLORIDA
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| Posted: Sat Jun 16, 2012 6:45 am Post subject: |
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| spence I have been thinking on this for a while now,(see the smoke rings?) And I think the right answer is"A GOOD ONE"so you dont waste any $$fixing it. |
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[email protected]
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Joined: August 03, 2002
Posts: 12785
Location: Salt Lake City, Utah
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| Posted: Sat Jun 16, 2012 7:34 am Post subject: |
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but you are running at WOT, you don't have a choice if the air pressure decreases. But at 8k', if you want more power you open the throttle a little more.
MPG tuning is so different because we are trying to use less fuel (not more of it). SOMETIMES using less fuel means more throttle (as in the case of lean tuning on the progression).
Think of it this way. If it takes 16hp to drive 60mph at sea level, that's probably ~12hp at elevation. Which uses less fuel?
There is NFW that you use the same fuel at elevation as sea level in a 1/4 mile pass. How can we, we are going slower. Less power, less fuel (assuming optimal tuning).
Lets drive our car in space, which is infinite elevation, and we get infinite MPG once we get up to speed, because wind resistance is 0. So is power, but that's not the point.
We could also build a pressure tunnel and increase air pressure to the point where the air is a liquid, MPG goes way down (Despite power going way up).
As elevation increases, air pressure decreases, and MPG increases (assuming optimal tuning).
| Tom Simon wrote: |
| [email protected] wrote: |
| No, but think about how much slower you are at Denver compared to Sac. 15% less power? 15% less wind resistance? That is significant. |
Maybe 15% less power, but less fuel consumption along with it.
I see (and feel) the power difference at altitude, but that's when we want max power for low ET's. I say that engine efficiency remains the same. Power is down, but that is because there is less O2 in the same volume of air. As long as our air/fuel ratio has been adjusted to compensate for high altitude, and we are making less power... We must also be consuming less fuel per 1/4 mile pass.
If the above is true, then cruising down a flat freeway at 60mph at 5,000ft versus 50ft (adjusted A/F ratio for differing air density), requires the same power, and therefore would consume the same amount of fuel. Right?
I can only think of a couple things that might help fuel economy at higher altitudes.
1) At high altitude, the engine makes less power, so the throttle blade must be open wider to maintain our 60mph. With the blade open wider, the intake tract experiences less restriction. If that is true, then pumping losses must go down. If it's true that pumping losses go down, engine efficiency goes up, and fuel consumption is reduced. Right?
2) If you have fewer air molecules to push out of the way, vehicle drag goes down, so does fuel consumption.
I don't know weather either of the two above potential fuel economy helpers are large enough to even be measured, any difference might be lost within the error bar of the collected data. But I think the theory is right... What do you think, John?
oh crap, there I go sounding like a science geek again |
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Please do NOT send me Private Messages through the Samba PM System (I will not see them). Send me an e-mail to john at aircooled dot net
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spencerfvee
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Joined: August 19, 2004
Posts: 3071
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| Posted: Sat Jun 16, 2012 11:13 am Post subject: |
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hi every one i just filled up my tank and got 32 MPG with the fuel reg. installed its been a heat wave here in ohio and when it gets hot the black top on the roads gets soft and slows the cars down . lol i just put i new empi 34 pict carb on my bug i installed a 27mm venturi . with a 132 main jet 60 idle jet the bug run much better above 45 mph after that it pulls to 5,000 rpms real fast . i allso went from a 26 1/2 inch tall tire to a 25 inch tall stock tire on the rear. my 4 1.25 ring gear loves the shorter tire . it runs much better. i did this because i am going to drag race my bug at the north coast vw drag racing association this sat.at drag way 42 in ohio . i think my bug can run low 17s maybe high 16s i hope lol then i will put the bocar 34 pict carb with the stock 26mm venturi back on after raceing . and will test the stock 25 inch tall tires for MPG ..i also am trying 35lbs of air in all the tires to see if that helps MPG every one have a great fathers day spencerfvee.......
| spencerfvee wrote: |
hi first off HAY JOHN WHERES YOUR MPG MOTOR BUILD LOL i know john your busy this time of the year. and i understand . i am still working on my MPG motor but i am driveing my 78x 92 cheater cam mofoco 40x 35 valve heads motor i did some changes to the motor i took off the 44mm kadrons .and installed a 34 pict 3 stock carb jetting 132 main the intake is a CB alum one fully ported the stock end castings are ported . my first MPG run only got me 27 MPG city highway i then put a 1 3/8 header on.( witch realy helps low end power and boy does it pull hills now ) with a fat boy muffler and installed a 60 idle. jet and installed a auto stick dizy with 009 guts . i just got a reading on city and highway 33 MPG. i shift at 3,500 rpms i just put a fuel reg. on. set at 2 1/2 lbs i allso went to the drag strip with the kadrons my bug ran 16. 24 1/4 mile at 91 mph best time with the stock carb it ran a 17.74 at 82 mph 1/4 mile thats 1 second slower than with kadrons . but with the stock carb it runs so much better i got 32 MPG with the fuel reg. installed at 2 1/2 lbs its been real hot here in ohio and the black top roads get hot it slows down a car on the street. i can go as low 20mph in forth gear and the bug can run on the free way at 65 mph to 90 mph if i want to . it has all the passing power i need. and is more of a fun car to drive now . with the fuel reg. on now. it runs even better i am hopeing for 38 mpg when i take a trip and will be on the high way only ( on the high way i run about 60 to 65 MPH . i allso am going to install a 5 lbs stock pulley .to see if that helps. mpg .the thing that surprizes me the most is that a big motor with big valves dose so well on MPG . and how well a small 1/38 header does spencerfvee.................
| spencerfvee wrote: |
lol i like dave . dont get me wrong . daves dave. i just like messing with him . you make a point .on vws being hard to find here in the north the rust and salt end there lives fast . and lets not for get the dune buggy guys and trike guys cutting up nice vws one buggy guy cut a rust free rag top vw bug up for a rear torshion and title . and how many buses gave up there gear boxes for pipe buggy guys . i would say that where i buy my vw parts here in ohio that 85 % of the people that buy vw parts are buggy guys so in a way they are keeping the air cooled vw alive . with out the buggy guys and trike guys there would be no vw store. where i buy my parts here in ohio .around here there are still a lot of vw parts to be had for vw bugs . we are like the flat head ford guys. saying flat heads for ever . now we are saying air cooled vws for ever lol lol spencerfvee
| yamaducci wrote: |
I think what Dave's concern, as many would think, is that with the Aircooled VW becoming so rare that there is no real need to Create a Frankenstein out of it. Sure you did whatever it took to achieve your objective back when there were plenty to hack up.
Not being a purist or anything but why be pro-choice about hacking on good cars (and threads about them) and parts when there are so few left. If the more mature guys can write on here about hacking the remaining cars then it is basically giving posterity a permission slip to do so. Building a higher milage engine than what VW built will not only be outweighed by the cost of it but may not even get out of it's own smoke among modern cars. You know what I am saying Spencer with your 2 cylinder story (which was great and a real knee slapper). |
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manxcraig
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Joined: November 12, 2006
Posts: 617
Location: pendelton (indianapolis) indiana
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| Posted: Sun Jun 17, 2012 8:47 am Post subject: |
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I haven't gone back and reread the whole thread so this may have came up already. I asked the old German VW mechanic here in town this question and he told me to buy an old 36 horse car and keep it stock. Any thoughts?
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WANTED, Meyers Manx license plate frames, repo OK, don't like the new smiles per miles ones. |
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EverettB 
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Joined: April 11, 2000
Posts: 69807
Location: Phoenix Metro
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manxcraig
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Joined: November 12, 2006
Posts: 617
Location: pendelton (indianapolis) indiana
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| Posted: Sun Jun 17, 2012 9:54 am Post subject: |
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A LOT cooler than a Prius !!
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69 Meyers Manx II on 65 pan, 1 owner !
WANTED, Meyers Manx license plate frames, repo OK, don't like the new smiles per miles ones. |
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veedubcrazy
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Joined: February 14, 2005
Posts: 2130
Location: La Porte, Tx.
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| Posted: Sun Jun 17, 2012 12:39 pm Post subject: |
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Just a quick note here on MPG's. I drove my '67 to Austin and back and netted 32.2 mpg's. This from a stock geared, low compression 1641 using an E100 cam, all else stock. I am sure I could get a few more mpg's using a 1 3/8" header and single muffler. Didn't think 32.2 was too bad. And that was going 65mph. 
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louis-123
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Joined: March 21, 2004
Posts: 438
Location: Montréal, Québec!
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| Posted: Sun Jun 17, 2012 2:17 pm Post subject: |
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| Eaallred wrote: |
Whatever I do, it will end up being a 94mm bore. Either stock 69, or 82 stroker. |
For what its worth, i thought i should share this quote...
According to Corky's Bell book, Maximum Boost (p190) :
| Quote: |
| With lower engine speeds comes the ability to take advantage of longer-stroke, smaller bore engines. For reasons buried in the foggy depths of thermodynamics, longer stroke engines can enjoy greater fuel efficiency. |
85.5 * 86= 1976
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nsracing
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Joined: November 16, 2003
Posts: 9462
Location: NOVA
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| Posted: Sun Jun 17, 2012 2:54 pm Post subject: |
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So true ^^^^^! There is nothing like stroker motors.
If say... a carbureted engine is set up to stoich at sea level and runs at altitude on that setting, it will run rich (same amount of fuel at sea level but thinner air at altitude) and prolly will run like crap. Not sure how much fuel one can save driving at altitude if it is all UPHILL!
A smaller single carbureted engine will be the way to do it if we are going to pinch pennies for fuel. The 1500cc - 1600cc is good w/ the 32PIct or 34pict. And only have 2 people in the car max'd. By all means, get rid of the spare tire. I don't like stranded so I will keep the spare in the trunk.
One can tighten up the CR a little more on the 1500cc/ 1600cc to get more HP. Not sure how much more you can choke that thing and still push a 1500 lb car. |
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spencerfvee
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Joined: August 19, 2004
Posts: 3071
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| Posted: Sun Jun 17, 2012 3:30 pm Post subject: |
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hay evertt. just how much now adays. would that 1952 or 1953 bug cost me to buy ?lol lol a 25 hp motor in a 1971 super . mmmm lol hope every one had a nice fathers day spencerfvee
| EverettB wrote: |
30-40 MPG
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manxcraig
Samba Member
Joined: November 12, 2006
Posts: 617
Location: pendelton (indianapolis) indiana
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| Posted: Sun Jun 17, 2012 4:58 pm Post subject: |
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| spencerfvee wrote: |
hay evertt. just how much now adays. would that 1952 or 1953 bug cost me to buy ?lol lol a 25 hp motor in a 1971 super . mmmm lol hope every one had a nice fathers day spencerfvee
| EverettB wrote: |
30-40 MPG
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OK, a stock 36 HP in a late model sedan, (pre freeway flier), a 6 volt starter with an adapter bushing and 12 volt solenoid, and a rewound generator ti 12 volts.
Any thoughts?
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69 Meyers Manx II on 65 pan, 1 owner !
WANTED, Meyers Manx license plate frames, repo OK, don't like the new smiles per miles ones. |
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DarthWeber
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Joined: November 24, 2007
Posts: 7543
Location: Whittier,CA
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| Posted: Sun Jun 17, 2012 6:38 pm Post subject: |
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| manxcraig wrote: |
OK, a stock 36 HP in a late model sedan, (pre freeway flier), a 6 volt starter with an adapter bushing and 12 volt solenoid, and a rewound generator ti 12 volts.
Any thoughts? |
Why? What would you rather have, an honest injun 36 horses OR (behind door #2!) a 90 hp 120 ft lb torque 1745cc dual port engine. Your choice, both get almost 40 mpg.
Hint: Hot VW's Mileage Motor!
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| Mitey62 wrote: |
| Swapped the Compufire for a Bosch blue and some points I had sitting around, started 1st crank. Took her out for a drive, pulls harder, more RPM, and runs smoother. I think I'll be sticking with points from now on. |
| RockCrusher wrote: |
| JB weld the case halves....that'll keep the fretting to a minimum. |
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spencerfvee
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Joined: August 19, 2004
Posts: 3071
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| Posted: Sun Jun 17, 2012 7:05 pm Post subject: |
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hay darth evertt started it . blame him . lol and darth its a 25 hp motor not 36 hp lol were just bench raceing lol spencerfvee
| DarthWeber wrote: |
| manxcraig wrote: |
OK, a stock 36 HP in a late model sedan, (pre freeway flier), a 6 volt starter with an adapter bushing and 12 volt solenoid, and a rewound generator ti 12 volts.
Any thoughts? |
Why? What would you rather have, an honest injun 36 horses OR (behind door #2!) a 90 hp 120 ft lb torque 1745cc dual port engine. Your choice, both get almost 40 mpg.
Hint: Hot VW's Mileage Motor! |
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DarthWeber
Samba Member
Joined: November 24, 2007
Posts: 7543
Location: Whittier,CA
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| Posted: Sun Jun 17, 2012 7:12 pm Post subject: |
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25HP till you hit the nitrous! You cheater!!!
Hey, I remember Competition Motors in Hollywood. I also remember when all the phone numbers had alphabetic prefixes like the HO for Hollywood. Boy am I getting old! 
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| Mitey62 wrote: |
| Swapped the Compufire for a Bosch blue and some points I had sitting around, started 1st crank. Took her out for a drive, pulls harder, more RPM, and runs smoother. I think I'll be sticking with points from now on. |
| RockCrusher wrote: |
| JB weld the case halves....that'll keep the fretting to a minimum. |
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