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Thread: Modern-day Miura

  1. #1
    Senior Member C5GTO's Avatar
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    Post Modern-day Miura

    This is a build diary for my home/scratch built Miura car project. Iíve been gathering information and planning the build for a few months now. I thought it was about time to share the project on a public forum as Iíve found comments and questions raised in this type forum are helpful to me and hopefully youíll find the project interesting as well.

    The overarching goal for this project is to complete a high performance oriented but comfortable street drivable car that has the beautiful looks of the Lamborghini Miura SV. I have made various car body pieces from scratch before, but not a complete car body. I plan to scratch build the Miura body myself in aluminum. This wonít be a replica or re-creation per se, but hopefully will look like a Miura to the average person on the street.

    For those not already familiar with the Miura, hereís what a well preserved Miura SV looks like.



    Miura with clips opened and as a cut-away.





    A brief history is that the Miura was the first mid-engine, street oriented V12 powered ďsupercarĒ sold to the general public. It was built by Lamborghini in Italy, first available in 1967 to 1969 in what is known as the P400 model and 275 of these were built. It was upgraded to P400S model from 1968 to 1971 with 338 cars built in this model. The Miura Sprint Veloce or SV model was produced from 1971 to 1973 with 150 of this model built. What is fairly unique to the Miura is the transverse orientation of its 4 liter V12 engine that is located just behind the cockpit. The Miura came equipped with a 200 mph speedo and independent testing showed it to be the fastest street car of its time with a top speed of 172 mph.

    My previous scratch built car project, a Ferrari 250 GTO, is almost complete (getting painted now) and has been 15+ years in the making. Iím hoping to complete the Miura much faster than that. A combination of not trying to do everything myself and now having more time for my car hobby should help. From the GTO project, Iíve found metal shaping to be the part I find most rewarding so I plan to do all the Miura body creation myself. The Miura is a very complicated car so my expectation is that this project will not be easy. I do think the resulting car will be very unique and Iím guessing the build journey will be as well.
    Joel Heinke
    Be original; don't be scared of being bold!

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  3. #3
    Senior Member RCR's Avatar
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    Hey Joel,
    I've followed your GTO since the inception in the Kitcar magazine. I'm very appreciative at you allowing us to follow in this journey.

    Thanx.

    Now to the meat...Powerplant? transverse?


    Bob
    Bob custom '84 Fiero SE --->>> custom F408
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  4. #4
    Senior Member Don's Avatar
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    Looking forward to the build progress Joel. You will make it outstanding I am sure.

    In case it hasn't been mentioned in previous conversations, V8Archie over on Pennock's took a Miura replica fiberglass body and built a Fiero frame under it. It was an amazing amount of work and ingenuity from him and his guys. Might be some interesting and useful pictures in his build diary for you. Link below.

    Good luck and keep us updated.
    Don

    http://www.fiero.nl/forum/Forum3/HTML/000003.html
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    Senior Member C5GTO's Avatar
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    Quote Originally Posted by Don View Post
    Looking forward to the build progress Joel. You will make it outstanding I am sure.

    In case it hasn't been mentioned in previous conversations, V8Archie over on Pennock's took a Miura replica fiberglass body and built a Fiero frame under it. It was an amazing amount of work and ingenuity from him and his guys. Might be some interesting and useful pictures in his build diary for you. Link below.

    Good luck and keep us updated.
    Don

    http://www.fiero.nl/forum/Forum3/HTML/000003.html
    Don,
    Thanks for the tip. I appreciate people chipping in with helpful information for my projects. As it turns out, someone had already mentioned the V8 Archie build diary a couple months back and I've read it through already. After reading it, that's where I became convinced that building a Miura will be a very complex project. In spite of that, I've decided to take this project on, at least I'm going in with eye wide open
    Joel Heinke
    Be original; don't be scared of being bold!

  6. #6
    Senior Member C5GTO's Avatar
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    Post Forming a high level project plan

    In a project of this size and complexity, itís important to define priorities and from there form a good plan.

    My top priorities are:
    1. Build a high performance car that Iíll want to keep and use for a long time. In other words, make a car that will be thrilling to drive but also comfortable to drive both around town and on extended trips. Iíve never owned a ďgarage queenĒ and donít intend to start now.

    2. Stay true to the ďspiritĒ of the original Miura but donít restrict project choices to the ones Lamborghini engineers made over 50 years ago. To me, the Miura spirit includes a powerful transverse engine (i.e. capable of propelling the car up to 172 mph) placed in the middle of the car and with a body shape that could easily be mistaken for an original from 15 feet away.

    3. Take advantage of automotive technology advances by including them where it will make for a better driving experience but wonít take away from the Miura spirit in priority 2. Some modern technologies that quickly come to mind are things like EFI, ECM, and performance tires. The Miura was a very technologically advanced car for its day and there are still some areas where todayís factory cars (USA made anyway) and OEM parts are still catching up. Iíll want to strike the right balance between sticking to technologies used in original Miura and modern ones.

    From these priorities, a few top level questions came to mind:

    ∑ Can I comfortably fit in a regular sized Miura or do I need to go for a plus sized car?

    ∑ What engine and transmission package should be used?

    ∑ Will I need to build a chassis myself or is there a source where I can buy one at a reasonable price?

    As it turns out, the answers to these questions are very inter-related. Iíll provide my thoughts and conclusions in subsequent posts.
    Joel Heinke
    Be original; don't be scared of being bold!

  7. #7
    Senior Member Don's Avatar
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    Hey Joel;

    It was probably me or RCR that mentioned it as we watched it come to life through his whole build and I was amazed at when they did.

    Good luck and looking forward to the updates.

    V8 with an f40 trans like so many Fiero guys do with the transverse driveline or are you going to do a BMW V12 up against an f40 trans? Fellow on here can probably help with the engine to trans adaptor as he does them for a lot of applications. Always Kennedy Engineering as well....

    Should be fun to watch and help where we can.

    Cheers
    Don
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    I too am looking forward to following along. I have every confidence that you'll be able to pull it off. One thing that I'm anxious to see the answer to, is this:

    Quote Originally Posted by C5GTO View Post
    ...What engine and transmission package should be used?
    Are you thinking auto or manual transmission?

  9. #9
    Senior Member C5GTO's Avatar
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    Post Regular or plus sized Miura?

    Ok, so first off, Iím not your average sized guy. Iím taller than most at 6í 5Ē and 225 pounds. But if I were an average sized guy, Iíd build a regular sized Miura. The real question is if a regular sized Miura will be comfortable for me (at taller than average) to drive.

    The most obvious way to answer this question is to find a Miura and take a seat. In reality, this is much easier said than done when youíre talking about a car whose value is around 2 million dollars. Well after working hard at this for a few months, I finally this week was able to track down a Miura and check out the fit.

    Before answering the fit question, Iíve got to say that the Miura is even more beautiful in real life than in pictures. The car I found just happened to be a finely restored Miura being prepped for show at Pebble Beach Concorso Italiano this year, but still what a beautiful car. It even further strengthened my resolve for this project. Iíd like to pass along my gratitude here to Geoff Provo of GP Enterprises (www.gpenterprises99.com) for getting me access to this Miura. Heís a real nice guy and quite knowledgeable about Italian sports cars.

    Well the answer to the fit question is that I fit well enough that I could drive it but not well enough to to safely drive it or call it a comfortable fit. The input from those in the know is that a 5í 8Ē person fits a Miura very comfortably and people up to 6í fit alright. Above 6í and the angles in your ankles and knees becomes too great to be long trip comfortable.

    So itís a plus sized Miura for me. Now the question becomes 103%, 104% or 105%? Since the answer to this question is inter-related with the other top level questions, those questions need to be moved along in order to completely answer this question.
    Joel Heinke
    Be original; don't be scared of being bold!

  10. #10
    Senior Member C5GTO's Avatar
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    Post What engine/transaxle to use?

    Absent other constraints, Iíd use a V12 for this project. Given the original Miura had a V12, the smooth exhaust note of a 60 degree V12, and the distinctive scream at revs, I was really hoping I could make a V12 work. So what realistic choices of V12 engines are out there?

    Using an original Miura engine is out of the question as theyíre just not available. Thatís too bad because they are very unique in that the engine and transmission are cast together in a single alloy block.



    So while finding a workable V12 is already hard, finding one that can be hooked up to a transverse transaxle makes the level of difficulty go up considerably.

    Of the modern OEM made V12s, the BMW M70 engine is still readily available and makes decent power. The downside is that the engine is fairly long at just over 29 inches, rebuilding costs can be high, and adding horsepower over the 325HP it came out of the factory with is quite expensive. The chassis I was evaluating (more to come on this later) has an opening 33 inches wide where the engine will go. 4 inches of space for a bellhousing, etc. was just not enough space to work with. The Jaguar and Mercedes V12s were even less amenable for various reasons. In addition, Iíd like to choose a power plant that has a large, active community of people using and modifying it as well.

    HmmmÖso after a few weeks of research, the V12 route wasnít looking very promising. In addition, I needed to take into account the mating up of the engine with a transaxle. I really like the notion of transverse engine transaxle package because all the rotating parts, from engine out to wheels, are operating in a parallel plane. There is no power loss from needing to turn the rotation 90 degrees like in a standard hypoid differential. Also a transverse engine is needed to fit the spirit of the Miura.

    So I started to seek out options for factory built cars that have transverse engines (both front and rear wheel drive). Transverse engine packages in front wheel drive cars and Fieros are common but almost all are either v6 or inline 4 and fall short on the power criteria (i.e. must push a 2,800 lb car at least 172 mph). I looked at Fiero V8 conversions using the F40 manual transmission but these make for a wide engine transaxle package given the transmission is basically inline with the crankshaft. Yes, people make this work in a Fiero chassis but thatís not the chassis Iíll be using for this project. I looked at racing oriented, sequential transaxles and the $16-20K price tag quickly scared me off.

    The next path of investigation was to use a V8 along with a custom built transaxle. I have a friend, Pete Aardema that is a diehard DIY car guy with a soft spot for mid-engine transverse platforms. Pete had already built a couple street rods with transverse V8s in the back seat so he has both the interest and experience. Pete teamed with master machinist Kevin Braun to build the Chevy LS3 SOHC conversion on the engine in my GTO so I know they have the knowledge, experience and machinery that surpasses most prototype machine shops. Pete cranked out a pencil drawing with the concept and offered to scout up an engine for mockup purposes. His question back to me was, ďWhat engine do you want to use?Ē

    So what V8 both fits to the spirit of a Miura and is short in length? Well it needs to have alloy block/heads and overhead cams just to equal the 50 year old Miura technology. The Ford 5L Coyote has this plus 4 valve heads so some advanced technology to boot. The BMW and Mercedes V8s are also technically advanced (more even than the Coyote) but donít appear to be separable from their OEM ECM/PCMs. Iíd really like to emulate the Weber carbs visible through Miura back window with an 8 stack EFI system so this brings an aftermarket ECM into the picture. I checked and yes, thereís an 8 stack EFI for the Coyote that uses very realistic looking Weber like throttle bodies.

    So there you have it, the plan is to use a Ford 5L Coyote engine, most likely a new Ford Motorsports crate motor as they look reasonably priced. The factory output of 435 HP with 400 ft lb torque should propel a Miura up to 172 mph and beyond. For the transaxle, weíre mocking up a custom bell housing/transfer case mated up to a Tremec TKO600 with a shortened output mated up to a Super 8.8 limited-slip differential carrier from a 2015+ Mustang IRS all these components meshed up with custom made helical gears. Ok, so Iím sure your heads are spinning from that last sentence. Iíll be posting pictures for the transaxle mockup after answering the chassis question in a subsequent post.
    Joel Heinke
    Be original; don't be scared of being bold!

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