#11
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Regular or plus sized Miura?
Ok, so first off, I’m not your average sized guy. I’m taller than most at 6’ 5” and 225 pounds. But if I were an average sized guy, I’d 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 you’re 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, I’ve 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. I’d like to pass along my gratitude here to Geoff Provo of GP Enterprises (www.gpenterprises99.com) for getting me access to this Miura. He’s 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 safely drive it or call it a comfortable fit. The input from those in the know is that a 5’ 8” person fits a Miura very comfortably and people up to 6’ fit alright. Above 6’ and the angles in your ankles and knees becomes too great to be long trip comfortable. So it’s 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.
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Joel Heinke Be original; don't be afraid of being bold! |
#12
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What engine/transaxle to use?
Absent other constraints, I’d 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 they’re just not available. That’s 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, I’d like to choose a power plant that has a large, active community of people using and modifying it as well. Hmmm…so after a few weeks of research, the V12 route wasn’t 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 that’s not the chassis I’ll 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, “What engine do you want to use?” 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 don’t appear to be separable from their OEM ECM/PCMs. I’d 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, there’s 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, we’re 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 I’m sure your heads are spinning from that last sentence. I’ll be posting pictures for the transaxle mockup after answering the chassis question in a subsequent post.
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Joel Heinke Be original; don't be afraid of being bold! |
#13
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Very, very cool to hear Pete Aardema will be tangent or more to your build. I've only read about his engineering creativity, but really like what he does and can do.
I had the opportunity to look over a real Miura rebuild/reconstruction at Rick's shop last year. Pretty amazing work and equally amazing machine. the lines between complexity and simplicity are not as obvious as one might think. I'm looking forward to your build. Edit- especially now that it will have a Ford engine and more.
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AC Button II http://CarolinaSculptureStudio.com https://www.youtube.com/channel/UCzSYaYdis55gE-vqifzjA6A Carolina Sculpture Studio Channel Last edited by cliffrod; 06-09-2018 at 07:58 PM. Reason: See edit |
#14
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Quote:
Have you investigated Megasquirt? http://megasquirt.info/ programmable fuel-injection and ignition maps, plus a host of other useful functions, at a fraction of the price of most of the competition. It can be made to work on most engines and for those who want carburettors, Megajolt fits the bill and is the ignition part of Megasquirt, Cheers Charlie
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Why does dust stick to everything, but nothing sticks to dust? |
#15
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Great project Joel. I know it doesn't have a heap of horsepower, but what about a Lancia Thema 8.32 engine and transmission? Basically a 3.0l Ferrari V8 in a transverse front drive configuration. Sexy looking engine I gather based on the Mondial/308engine. They messed around with it according to Wikpedia and gave it a cross plane crank and smaller valve (4 valve heads). One presumes that a proper flat plane crank could be installed and the heads opened up or swapped out. Plenty of people around with experience of extracting more power from the small Ferrari V8's. Solves the transmission problem with no engineering.
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Richard "I know nothing. I from Barcelona" (Manuel - Fawlty Towers) Link to our racecar project https://www.facebook.com/pages/Elan-...ab=public&view |
#16
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Quote:
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Neil |
#17
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Heinke,
Considering what can be done with "additive" (3D Printing) machining, consider a "custom" transaxle. Use the 3D to create a pattern and have it cast up!
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Marc |
#18
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Here is a quick example via digital restyling of lengthening the wheelbase on a Miura. A few inches in the engine bay (offsetting the internal firewall/bulkhead rearward for more cockpit space is an option), longer cockpit and 17in and 18in Campy style wheels (versus 15in original). FYI: One negative of the Coyote engine is width and especially in a traverse configuration. You will need to determine the transaxle setup with engine before you know where the firewall (rear bulkhead) will go. A narrower engine (or head configuration) might allow you some additional cockpit interior space. On a current de Tomaso Mangusta project for a customer, the Coyote option was skipped and the engine selected was an old school 289 with Gurney-Weslake heads because it was dramatically narrower. (It will get injectors with an ECM to modernize along with ignition system) Red lines show offsets based upon centerline of rear wheel forward. (top image is "stock")
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• me: Mark • home: Dry Heat, Arizona USA • quote: What did you design or build today? • projects: Curve Grande and the 11Plus Le Mans Coupe Last edited by Superleggera; 09-19-2021 at 10:59 AM. |
#19
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Speaking of Supercars:
Sold at Auctiion: 1963 Ferrari GTO for $70 Million ! Wow !!!!! https://www.hemmings.com/blog/2018/0...ar/?refer=news Methinks I've been priced out of the market !
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Tom |
#20
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Quote:
In addition Rick Mullin has also helped me out with some Miura cockpit measurements that I needed but couldn't find anywhere. His help was key in moving the chassis selection process forward. Thanks for watching and thanks again to those who've already contributed with a helping hand with the project.
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Joel Heinke Be original; don't be afraid of being bold! |
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