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  1. #1
    FEP Super Member xctasy's Avatar
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    Default Any Ak Miller Propane Foxes around?

    In need some feedback on the Propane Ak Miller Foxes, as I'm doing a triple carb propane conversion.


    In Jay Storers 1986 book,

    "Propane Fuel Conversions" Economy or Performance"

    ISBN: 0931472121

    http://www.abebooks.com/servlet/Sear...12-1&y=13&x=20

    Bad photocopies and info used by way of example. Any objections, PM me.





    http://www.amazon.com/Economy-Perfor...ef=pd_sxp_f_pt

    there were some epic pictures of 1980 to 1984 Propane 2.3, 4.2, 5.0 and turbo 5.8 conversions on Fox platform Capris, Mustangs and Fairmonts were an inspiration to me.


    I've copied lots of his systems, but my car is full of road roughness gear, and the donut tank and another fuel hatch will have to do.



    http://www.jalopyjournal.com/forum/s...t=84007&page=3


    I've decided to get a donut (Toroidal) which is 15 US gal if 100% fulll, and its a 25.5 by 9.5 inch propane tank and Impco LP Gas set-up. It carrys only 80% of its full size, so its a 12.1 US gal tank.



    It gets mounted where the 220/55 390 goes, with that tire now placed above the wheel well.

    Basically, the concept is to do a common Offenhauser/Edelbrock style Tri-power triple carb conversion on the Mustang, and use an Ak Miller gasoline and Propane concept of doubling the range like they used to in the municipal dual fuel/Propane Fox Fairmont Turbos back in the mid 80's. Runit on Propane, then run it on gasoline, and alternate filling when the stations come up. Propane is common down here, less common than gasoline stations, but collectively, with the right combination of compact but long range fuel tanks, I can carry a lot of fuel.

    For the gasoline side, I'm looking at a Glenns Performance 22 US GAL (83 liter) drop tank

    That should allow me 12.1 US gals of LP Gas and 22 US gals of of gasoline. Since the triple carb system is practically an injection system in terms of brake specific power and fuel efficiency on propane and gasoline, I think this will be enough for 680 miles at 20 US mpg.

    As said, my bench mark has been my favorite Dane, Akton Moeller, or Ak Miller, famous as a leading light in propane conversions and a huge resource on triple carb log head engines.

    See his amazing, insightfull development work from 1967 to 1982 in these seven links. There is so much stuff in these two magazine write ups, its literary gold!!!!

    A stock 200 was something like 82 flywheel hp (65 rwhp), but you could take that up to 143 to 156 flywheel hp with ease, (115-125 rwhp) with twin SU's or quad Motocycle CV carbs...a growth of 61 to 74 hp!

    Or a big 200 cfm 1.08 or 360 cfm 1.21, or multiple 1-bbls could add 50 flywheel hp. Confirmation in these articles. So an 82 hp net engine can become an easy 132 hp with just these mods. A stunning 61% hp growth!

    Funniest thing? Well, old closed chamber 1960 to 1972 170 cubic inch log heads could be made to flow 30% more cfm than te best 200 cubic inch heads, so a 127 cfm 1981 EO head can have the same flow figures as a 1960 head. I've seen 103 cfm qouted for early 200 log heads, but Miller claimed 30% more, which would be 134 cfm! 30% flow is 30% more power with the right parts, right off the bat.

    I've confirmed this, and so Ak Millers info, though crazy sounding, is actually very conservative with respect to Hp gains.

    See Horseing around with the Mustang six

    http://www.classicinlines.com/HA1.asp

    Seocond bunch of links are from HRM's mustang magazine number 3.

    http://www.invectivus.com/hrm_mustang3/Cover.jpg
    http://www.invectivus.com/hrm_mustan...090%20copy.jpg
    http://www.invectivus.com/hrm_mustan...091%20copy.jpg
    http://www.invectivus.com/hrm_mustan...092%20copy.jpg
    http://www.invectivus.com/hrm_mustan...093%20copy.jpg
    http://www.invectivus.com/hrm_mustan...094%20copy.jpg

  2. #2
    FEP Super Member xctasy's Avatar
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    The 2.3 I4 Propane monster was a regular production option from 1981 to 1983



  3. #3
    FEP Member brianj's Avatar
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    Interesting option I did not know existed from the factory on a fox.
    1983 Mustang G.T. No-option stripper- I like strippers.
    5.0, GT40P heads, Comp Cams XE270HR-12 on 1.6 rockers, TFI spring kit, Weiand 174 blower, Holley 750 mechanical secondarys, Mishimoto radiator, Edelbrock street performer mechanical pump, BBK shortys, T-5 conversion, 8.8 rear, 3.73 gears, carbon fiber clutches, SS Machine lowers, Maximum Motorsport XL subframes, "B" springs.

  4. #4
    FEP Super Member 86fiveoh's Avatar
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    Thats pretty cool
    Boss block 302, vortech blower, 473whp@12 psi

  5. #5
    FEP Power Member gmatt's Avatar
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    Does propane offer higher octane rating than gasoline? I've wondered why there aren't more propane or natural gas powered vehicles in the US. There are a lot of fleet vehicles, not many privately owned. The fleets have their own refueling facilities, I think.

  6. #6

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    Ford made a few hundred LTDs and a few dozen Marquis with the 2.3L LPG engine in '83 and '84 at Chicago Assembly. Here are the numbers that I have (unconfirmed):

    '83 LTD = 349
    '83 Marquis = 43

    '84 LTD = 494

    Not sure about other Foxes.
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  7. #7
    FEP Super Member xctasy's Avatar
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    Quote Originally Posted by gmatt View Post
    Does propane offer higher octane rating than gasoline? I've wondered why there aren't more propane or natural gas powered vehicles in the US. There are a lot of fleet vehicles, not many privately owned. The fleets have their own refueling facilities, I think.
    The octane rating of most commerical propane blends by Anti Knock Index (AKI is RON+MON/2 as per std US pump label) is 95, or by Research Octane Number, its 99 RON.

    The advantage is that any time you strike crude oil via exploration, propane is a cheap by product of the cracking process, it is after all called Rock Gas by most petrochemical engineers, so it has to be gotten rid of some how, so why not sell for BBQ's and propane torches...

    The price varies. See http://www.arrowheadlpgas.com/docume...as%20facts.pdf

    Once pressurised, it becomes Liquified Petroleum/Propane Gas (LPG or LP Gas, or just propane), Chemical Formula. C3H8. LP gas requires an ignition source of over 900 degrees F to ignite, Boiling Point. -44 degrees Fahrenheit.


    Propane is actually huge in North America, you guys are in fact the world experts in it but on a percentage basis, less so than Australian, New Zealand and the Neatherlands.

    See http://www.jalopyjournal.com/forum/s...0688&showall=1, and for the best forum, hook on to the "Propane, Butane, LPG, GPL, C3H8, C4H10" forum. It rocks! http://fuelsforum.rasoenterprises.com/viewforum.php?f=5

    Now, about those Ak Miller items. There were four Fox kits, only one factory, the other three FX'S

    The first kits were 2.3 A code 1982 Granadas



    1. That engine above in Jays book is posted here in its splendor




    It was in an 82 Red Ak Miller RS Capri with 351W conversion, and then twin CA 425 Impcos for 920 cfm, and two E series converters able to flow 650 horsepower, and two nice big turbos. The kit was a 1982, I think, gave 15 mpg US highway.


    There were three other kits.

    2. The factory 2.3 non turbo A code, which is as above in the previous post

    http://i1215.photobucket.com/albums/...psf8b0ed3e.jpg

    See
    http://farm9.static.flickr.com/8176/...2fd3d5eeca.jpg
    http://farm9.static.flickr.com/8321/...297936c15e.jpg

    3. Very importantly, a 1980 Capri Turbo Carb and Propane Dual fuel item, which had the EFI Turbo/SVO exhast manifold and T03 blower with all the stock A code EGR gear and no internal mods. It gave 33 mpg highway on gasoline, and 22.5 mpg US higway on propane, but was fully California compliant. Range was 1000 miles with one tiny 1980 fuel tank and another 46 liter (12.1 US GAL) tank.



    Then there was the fourth Fox kit, the neatest, which was one kit which took the stock 4.2 Windsor from 119 hp to about 210 hp with just a propane carb and a turbo. It was dual fuel, gasoline and propane, with RWHP up from 85 stock to 150 turboed. There's a Fox XR7 Cougar with the kit in the book.



    All the kits were opperative, and fairly simple Impco based kits. I've used these kits in my 1984 250 Falcon,

    http://kastang.tripod.com/fsp/xecute.html

    my 1982 Cologne V6 Cortina, and my mates 1974 350 Chevy powered Holden pickup, and they are the worlds easiest carb and converter set ups ever.


    I guess the reason it never got further is Ak swapped to the Over the Hill Gang OHG carbs after the Impco 2.3 normally aspirated kit. All that Fox V8 I4 stuff never went further, Ak and Marilyn and AME just did personal conversions for the California market, and they were always CARB expempt. I guess there was no option for 50 states dual fuel kits, and so the LPG dedicated factory Fox options sort of died out. Buick and Impco continured the work when the GM3800 got rolled out, but the Factory Impco/Ford kits were all over by 1984. Maybee it didn't pay off for a cash strapped Ford rolling out the Diesel LSC and Lincoln Mk VII compact, and especially the Toyo Kogo Diesel Tempo, they were the obvious econo and fleet vehicles, which Ford was pushing hard

    The reason for the comparitive lack of propane vehicles in the US isn't a suprise, even though Impco and OHG and Century are US companies who are leaders on equipement design. Its basically that you've got LNG and CNG and diesel and the two or three grades of petroluem, so it requires a preceived need in the market. The growth in port fuel injection and turbos and Diesel engines has limited its appeal in the US, and now hydrogen fuel cell and electric options, so there are other competitive options unless the price of proane drops some, it'll be a niche market. Its different in Australia, New Zealand and Holland where its sales are massive because of cheap Bass Strait and North Sea rock gas right to refineries. The US gaslone industry is just better structured for petroluem rather than LP Gas.

    Where its good is in forklifts and fleet vehicles, but Chrysler has done some really cool work with the 130 RON Compressed Natural Gas (methane), and it remains to be seen if LPG is as good as some of the new

  8. #8

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    The Red 1981 Capri actually belongs to my buddy. It was Ak Miller's personal vehicle back it the early eighties. I had a chance to buy it for $7000 but passed on it and bought a brand new 1983 Capri L 5.0L which I still own today. The 81' Capri is a twin turbo 351w with an AOD running 12 PSI of boost on propane. I ran a similiar setup but with a 302 and single turbo. I am currently building a 347 with a turbo but switched back to gasoline just recently.

  9. #9
    FEP Super Member xctasy's Avatar
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    Wow. Thanks!

    Due to the size and complicated issues with managing this great message board, your post was missed by me.


    I'm personally sorry for not responding to your note on the Red 81 Capri. I am fully aware of what it was from the 1986 book. I read everything about it I could. If it ever comes up for sale, please contact me via this message board or via my XEC website. I can keep aninimity if required, but the engineering in that car was a pivot point which the Australians and Kiwis copied.

    Ak Miller's work with propane was legandary, but those 255 and 351 Foxes in the Jay Storer book were very special. I fully understand where Ford were in 1981, with Henry Ford II and Edsel Ford II making some typically Ford flip flopps which resulted in very tough, anti Cleveland V8, anti plant development, anti motor racing edicts and rulings which pleased few people, but having a raft of project cars like that with FoMoCo's project level involvement was sensational.

    We are only touching the tip of the iceberg on Impco's fuel control valve stratergies and those vehicles which were Ak Miller influenced won't sell for less than 7 grand anymore.

  10. #10
    FEP Super Member xctasy's Avatar
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    It's back! I found this link to an Ak Miller video during Hanukkah, but then lost it again from Xmas untill now. I'd like to share it with you all.

    I've been doing some Ak Miller propane research, since I've been a US Impco propane kind guy since 1985 as a service assistant, and then with my old non Fox 84 Aussie Falcon and an 82 Colgne V6 Propane Turbo Cortina.

    I figured, if Ak Miller could win his class at Pikes Peak in a propane powered 250 Mustang II in 1977, anthing is possible

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    The Fox Propane cars were specialty items mostly, I just copied everything from the Impco manual and Jay Storers Ak Miller inspired Propane Performance book..

    See http://www.ahrf.com/legends/ak-miller/

    In my opinion, Aks true secret was being a dirt under the nails technician who could swing working with engineers, (even the dumber ones from Ford...he used to be Ford Engineer appolo-gists when on retainer to Ford from the Total Performance Area till the early 80's SVO era, and an engineer mocker when he had to sort out the details. He's and Enguneeer he'd say in mock Danish. The stories about him fill the internet, and large chunks of the Earths Hot Rod So-Cal history books are made up from this mans expliots.

    He said this (with emphasis mine, I hope its right)

    "When you start out with nothing
    And you come up with something
    That's a little bit better....
    Carburation
    Or a little better system of camshaft or whatever...
    in fuel engineering, lotta things good here with an automobile
    And I saw all that and thought
    "G_d, a guy can have, you know,....amplify
    one area here, and he's got a lifetime running"
    -Not that your gonna have Hot Rodding for a life...
    but when you think of something like that
    You don't think about how long its gonna last
    Cause you know damn good and well
    ITS NEAT!!!!!!"


    and watch his video as a ripe old 80 year old.

    and listen to this voice tape, from Tales Form the Track with Tom Maddigan

    about how some thought Ak was nuts and a crazy sob....

    http://talesfromthetrack.com/audio/ak-miller

    I was profoundly influenced by this great man.


    If anyone sees some of these Fox propane machines, I'd sure like to know!

  11. #11
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    Most propane vehicles here are used for fleet vehicles, taxis and police cars.
    Very rare option otherwise.

  12. #12

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    that awsome, but also can be danger at same time ?
    Always Stay Humble. -Sinister-

  13. #13
    FEP Super Member xctasy's Avatar
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    Quote Originally Posted by Monty78
    Most propane vehicles here are used for fleet vehicles, taxis and police cars.
    Very rare option otherwise.
    Nods head

    As the 886 logged by Fox Chasis above proved....

    Quote Originally Posted by Sinister View Post
    that awsome, but also can be danger at same time ?
    In an accident, very safe, safer than any thing, due to the safet systems everything from a propane floor polisher to a Forklift or automobile have to use. The only issue, and its rare, is the outage valves can crack off in cold conditions if fulled up to the 80% maximum, and in that instance, the propane sinks to ground level, and can, in very concentrated air fuel ratios, then it could possibly ignite. But it is hard to ignite normally. Its only when concentrated outside a vehcile in confined spaces.

    Off road trucks, like AK Millers old F100 had Forklift proane containers while it jaunted up Pikes peak in 16 minutes or so. Offroaders love it becasue its so safe, and its the safest gas around except for maybee methane/Compressed Natural Gas.

  14. #14

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    Quote Originally Posted by xctasy View Post
    Nods head

    As the 886 logged by Fox Chasis above proved....



    In an accident, very safe, safer than any thing, due to the safet systems everything from a propane floor polisher to a Forklift or automobile have to use. The only issue, and its rare, is the outage valves can crack off in cold conditions if fulled up to the 80% maximum, and in that instance, the propane sinks to ground level, and can, in very concentrated air fuel ratios, then it could possibly ignite. But it is hard to ignite normally. Its only when concentrated outside a vehcile in confined spaces.

    Off road trucks, like AK Millers old F100 had Forklift proane containers while it jaunted up Pikes peak in 16 minutes or so. Offroaders love it becasue its so safe, and its the safest gas around except for maybee methane/Compressed Natural Gas.
    thanks for explaint
    Always Stay Humble. -Sinister-

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    I loved reading this. Thanks for putting it on here. I'm thinking it could be a good thing for California and Colorado residents as they may face being regulated out of driving older cars. It's no secret that some in the government are trying to do this. But an alternative fuel exemption may be a viable way to outsmart the forces out there. I love the cars you can get in New Zealand and Australia that we can't get in the States or in Canada. I wanted to cry when I heard Ford and GM were pulling their production facilities out of Australia.

  16. #16
    FEP Super Member xctasy's Avatar
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    I used to think that way too.





    ( but even though my wife and I loved the transformation from a 123 hp 18 second Falcon ambler to a standaout sub 16 second proane AK Miller style "hot rod", I think that a better way is to have alterations covered off as a regular gasoline vehcile. I'm big on the SLP type thing, but for Fords.

    I differ in that Propane for Performance because the gains in propane are very easy to get. I used just one Mazda MX6 IHI turbo on my 114 hp 2.3 Cortina, the Impco CA 300, and with just 5 psi, there you had 170 hp. .Thatt makes turboing really easy, but then it pushes people away from hardout back to back tested gasoline V8 engine modification which has made a modern Mustang from 1982 to date a 26 mile per gallon grocery getter, or a SSP Spy plan catcher. Next, it'll be electrics. I do love the 80 to 110 mpg ethonal Aero Mustang Doug Pelmear, as it is really a Hybrid electric engine, so its not the same as a classic gasoline engine.



    How many people have called this guy a scam artist shows that people don't even get the concept at all.


    The law is anti Hot Rod. Having to go Propane aids and abbets bad law makers marginalizing our sport, turning us in to back against the wall zealots.

    We should be able to trial a modification, and have it pass the 50000 mile durabilty test if its simple. SEMA and tthe aftermarket should be allowed to updgrade catalytic converters and have new EO numbers for basic emissions gear parts should be easy. The US aftermarket should be a world leader in this, but the inherant simplicty is lost. I should be able to put three carbs on my 81 I6, or three on your 84 GT350, and have the whole system covered off as a certified EO modification. The gasoline modification industry needs to get its crap together. Propane was and still is, the easy way out. Simple compliance with the gasoline emissions rules by a more extensive IM four gas analyser test should be all thats required. The illegality of Hot Rod engine swaps, and periferals with regards to turbos, carb modifications especially really upsets me. I should be able to put a 1969 429 in my 1981 Mustang if I can prove I pass the regulations applicable to that model.


    A great propane car is a lot of fun, I've had smiles from ear to ear, but a well worked gasoline car done within the normal past Hot Rod methods is cool too. If you make it easy for Federal law to push you into alternative fuels, it'll happen more and more.

    In Australia, its kind of sad the 9 second Street Mustangs are in line six and turboed. Im sure AK would've approved, but he did some nice propane 255, 351 Windsors and 351C and 390's too, and propane cars don't have the same sound and feel as a heavy heavy fuel Ford. I like the 175 hp 15 second Pinto based Pangra, the dual fuel turbo 1980 Mustang's the best. Gasoline is there, why not use it?)

  17. #17

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    i worry more about reliability, first, here on the east coast, we get very dirty propane, i work on forklifts everyday and the tar that builds up inside the stop valve, regulator and filters is insane, from what i understand, on the west coast they dont have these issues, but i find that hard to believe.

    now lets talk about safety with tuning, a stop valve is a shut off valve that is opened by either engine vacuum or electronically, they fail OFTEN, so lets say your pushing the limits of the engine, and the stop valve fails and shuts off propane flow, your going to run into a lean condition with no warning.

    then the impco regulators are by far the best, but they fail, often, usually rip a diaphragm and flooding the engine by allowing full pressure from the tank to the engine, the engine will not start or run if this happens.


    you can point out all the possible problems with just running fuel, but how often do you see a fuel pump go bad, i carry 3 impco regulators and stop valves on my work van

  18. #18
    FEP Super Member xctasy's Avatar
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    My fuel pump in my 1981 Mustang went. My 1984 Falcon XE, my Mini, and my 1958 Vauxhall. I've had a propane 1984 Falcon and 1982 Cortina, and as long as the system is clean, I've never had a VFF30 fail in 8 years of propnae motoring. Neither have I had a Duraspark induced lean intake backfire with any of my CA 300A carb conversions, but I've been told I would.


    No issues at all. When I was 15, I did the serivic on our Central Otago Power Board pickups. No propane problems from 1984 to 1988 in a million miles of conversions from 1976 Lnad Rovers to 1987 Fuel Injected 4.1 liter Fairmonts. The New Zealand propane might not be as waxy.

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  20. #20
    FEP Power Member 4-barrel Mike's Avatar
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    Yep, Ak Miller showed that, and Hot Rod documented it, in the early '70s with Ford stuff, cheaply.

    zzzz

    Mike

  21. #21
    FEP Super Member xctasy's Avatar
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    Although its a Chebby, here is the propane system gr79 and acedautoworx have linked

    Quote Originally Posted by acedautoworx View Post
    900 HP On Propane - 1970 Chevrolet Chevelle
    Mothers' LPG-Powered '70 Chevelle Gets a Bigger, Stronger Powerplant


    writer Brandan Gillogly
    photographer Les Bidrawn
    Oct 15, 2012

    Any Power Tour(tm) or HOT ROD TV aficionado will recognize this '70 Chevelle. It was built at the request of Mothers' Jim Halloway to show off the capabilities of propane and prove that a hot rod can be green. And this was before E-rod crate engines! Jim was active in HOT ROD TV and built the Chevelle to debut at the '07 HOT ROD Power Tour(tm). As with any build with a firm deadline, it came down to the wire, and there was a bit of drama. Jim didn't seem to have any gray hairs after the stress of the first build, so when new propane technology debuted, he chose to update the Chevelle.

    When Jim was first planning the car, Mothers' marketing partner, based in New Zealand, suggested going with propane. In Europe, Australia, and New Zealand, propane-powered cars are much more common. After hearing about the benefits of propane, especially its 110 octane rating, Jim was sold. His marketing partner even found him an engine--a 16:1, 430-plus ci small-block Chevy. The catch? It was in New Zealand, between the frame-rails of a sprint car that was in the hunt for the championship, and it was gasoline powered. The sprint-car team won the championship on a Friday, pulled the engine, bolted the propane intake manifold on, put it in a crate, and shipped it to the States. Johnny Omundsun, the chassis and power-train engineer behind the Chevelle, un-crated the engine on Saturday. Despite the challenge of running that big of an engine on propane, four days later the small-block was revving happily in the Chevelle, making somewhere north of 800 hp. That engine, while still propane powered, was far different from the engine in the car now. It was naturally aspirated with a massive cross-ram intake and a vaporous injection system that ran propane gas to the injector at around 15psi. Jim says that compared with a gasoline engine of the same output, that application emitted about 30 percent less hydrocarbons, 87 percent less carbon monoxide, and 10 percent less CO2. That explains why the oil on the Chevelle was always so clean. Nowhere near as much carbon gets past the rings. The engine went through a second iteration with a new intake manifold and a liquid-propane injection system before Jim decided to go really big with the current power-plant.



    01] Wheels are one-off six-lug designs from MHT, with 335/30ZR20 Pirelli rubber used in the rear and 235/40ZR18 in the front.


    02] Johnny started with a Viper bearing and designed a billet-aluminum spindle around it. Six-piston Baer brakes are used all around. Coil-overs are parallel to the frame and run on a bell-crank. Ride height can be adjusted without pre-loading the springs, and the spring rate can be changed by running a different bell-crank ratio


    03] The frame is 21 inches wide to allow for long control arms. The main rails twist and turn and tie themselves together to create a frame that resists twisting. Flat-oval exhaust tubing helps maintain ground clearance.


    04] The PPI tank is an aluminum extrusion with robotically welded end caps. It's a modular design that can be made to fit nearly any application. Also seen in this photo is the Speedway quick-change IRS center-section.

    05] The IRS also uses custom-machined billet control arms and spindles.

    06] Jim Grifn fabricated the aluminum panels that back the upholstery and the custom center console. Katzkin leather was used on the Cobra seats. The Long shifter connects to a T-56 with a dual-disc Centerforce clutch.


    07] Despite the swoopy headers and array of injectors, the engine is still recognizable as an LS. Johnny says the engine is stock internally, and he just runs a cooler plug.


    11] Hardtop 900 horsepower on propane 1970 Chevy Chevelle

    09] The Chevelle had been sitting for 20 years and had begun to rust, so a donor car in Texas gave it a lot of sheetmetal bits and pieces to complete the basic bodywork before the custom work began shaved door handles, rocker skirts, and narrowed bumpers make the heavy Chevelle look downright trim.
    To show that an enthusiast could build his own propane-powered muscle car and still be green, Jim and Johnny ditched the high-strung small-block and opted for a Chevrolet Performance LSX 454 topped with a Magnuson 2300 supercharger. They reasoned if their propane-fuel delivery system can feed a blown 7.4L engine, it should be able to handle most resto-mods and performance builds. Starting with a 20-gallon tank marketed by Propane Performance Industries (PPI) that stores propane at about 200 psi, the fuel is moved to the injector as a liquid. This required special, high-impedance Siemens Deka injectors you'd typically find in an industrial refrigeration application. The benefit to liquid injection is that the liquid fuel expands to more than 200 times its volume when injected into the port. Not only is that excellent for atomization, but when a liquid under pressure turns into a gas, it cools--lowering the intake air temperature and preventing pre-ignition. Also, as was discovered in the engine's second version, the rapid expansion can also add a couple of pounds of "free" boost on a naturally aspirated application.

    All this talk about the benefits of propane probably has you wondering just what it all means for performance. On an engine dyno, the 454 put down 924 hp and 980 lb-ft. using a 102mm throttle-body. Jim has since moved to a 90mm throttle body that's not so prone to frying the tires, but they're not yet done tuning, either. The mileage is also comparable to gasoline, because while gasoline has a slight edge in energy density (it has more BTUs per gallon), propane runs at much leaner 16:1 air/fuel ratio.


    OK, so it's efficient, clean, and it has oodles of octane, what's keeping us all from switching to propane? The infrastructure's not there yet. It is relatively cheap to build a pump that's compatible with the PPI fuel tank, and the guys carry an adapter in the car that lets them fill up almost anywhere that sells propane, but it's just not convenient to run propane until some major fleets make the switch. But that's already happening.


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    Overall:6.5

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    Exterior:6.5

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  22. #22

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    I think I still have an old 1980s book on propane conversions. So interesting to read about.
    performance has been proven but probably got a bad rep from people filling to 100%
    you can’t fill propane to 100% like you can with gasoline
    79 Zephyr, 4.6L 4v/4r70w swap, with team z front and rear suspension, 8.8 and upgraded brakes and coil overs. Running Holley Terminator X Max.

  23. #23
    FEP Senior Member BMW Rider's Avatar
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    At the shop I worked in we did quite a few propane conversions, mostly for farmers and commercial pickups. That was back in the mid to late 80s when propane was bout 1/10th the price of gasoline. The cost of the conversion could be paid back pretty quickly. As the cost of propane rose and with the introduction of fuel injection, which both made the gasoline engine more efficient and more expensive to convert, the popularity of propane dropped.

    One thing about propane is that it contains less energy than an equivilant of gasoline so there was always a power trade off, though it has a very high octane rating. It did run exceptionally clean though, the engine when opened up was pristine with little carbon buildup and the oil would stay clear throughout the service interval. We were mainly an engine shop, so we did build engines specifically for propane too, higher compression ratios and hardened valve seats with bronze guides to withstand the lack of lubricating qualities as compared to gasoline.

  24. #24

  25. #25

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    My Uncle worked for the City of Wichita (KS). He was notorious for buying cars from the city auction when they phased out fleet cars. Later in life it was Chevy Corsicas, but earliest memories were 4-door Fairmonts. White with blue interior and they ran on propane. City logo at the time was somewhat like Seattle Seahawk Blue and Green. Two thick stripes down the side of them. They had at least 2 of them.

    I'd love to build a tribute car some day to that. But want to somehow merge that 80s graphic stuck in my head with that blue and green color and blend it into the EcoBoost logo...because rather than a propane motor, that's how my tribute resto mod would save the environment

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