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Thread: Modern-day Miura

  1. #21
    Have you thought about going off the less beaten path in terms of V12 engines, like the LS based V12, or the 2JZ based V12? Both of those are probably out of your budget since they are more of a one off design, but definitely have the power capability you were looking for.

    Another option could be bike engines. I don't see that too much anymore, but a triple Hayabusa setup with the cranks tied together at 60 degrees apart would have the same firing sequence of a V12 and spins to over 10k RPM, so I imagine it would sound closer to an F1 style engine if the exhaust primaries are tied together properly. Stock they are around 190hp a piece, so you could be sitting pretty reliably at 570hp, plus they come with their own transmissions already. You would just have to tie the chain drives into a rear differential. Probably not the most tidy engine bay, but it would certainly be unique looking, have the go, the sound, and the reliability at a "reasonable" cost.

  2. #22
    Senior Member C5GTO's Avatar
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    Post Transaxle mockup

    I’m going to step back in time a few weeks here to talk about transaxle mockup and show pictures. I’m guessing this process just might be interesting to you and give context to the work that went into sorting out the Miura sizing question.

    A lot of good things start as a pencil drawing on the back of a “bar napkin”. Here’s our bar napkin drawing for the engine/transaxle package:



    It became apparent right away that the best way to figure out just how compact we could make the engine/transaxle package was to mock it up. I’d already identified the engine but not the transmission. After a bit of searching we narrowed it down to the Tremec TKO 600 5 speed transmission. The main case and gear set on this 5 speed transmission can certainly handle the HP and torque (the 600 in name gives the torque rating) of the Coyote, it is fairly compact, and the shifter can be mid-mounted out the top of the transmission. Having a 6 speed would be nice but the 6th gear adds more main case length and I didn’t think a second OD gear was really needed for the Miura.

    Given this is a custom transaxle build, I knew I needed to have an experienced and willing transmission expert to help out. I poked around and found Bob Hanlon of Hanlon Motorsports in Elverson, PA. (www.hanlonmotorsports.com). Bob quickly understood the project, was willing to help us out by providing measurements, explaining various gearing/ratio options, and with cores, etc. for purposes of mockup.

    Pete located an engine block and head. We got the transmission main case from Bob. The mockup process started.







    The first stage mockup objective was to situate the engine and trans main case as close together as possible to minimize the diameter of the gear set that would connect them. The bar napkin design called for use of a chain in addition to gears and but it looked like we could go with a 2 gears and no chain from the initial mockup. The distance from crankshaft center to transmission input center is about 11 inches in this initial mockup. So a transfer case could be made using two 11 inch gears. In addition, that distance could be shortened a bit by shaving off a protruding ear near where the factory starter mounts from the engine block. More work to go but this gave us something to start with.
    Joel Heinke
    Be original; don't be scared of being bold!

  3. #23
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    First, before you (or any one else) misinterpret(s) my comments, please bear in mind that I'm humbly offering constructive commentary. Tone is not always evident in the written word.

    Anyway, as I recall, one of the reasons you discounted the F40 in your earlier thread was because it didn't have enough longitudinal distance between the engine crank centerline and the transmission output shaft centerline to induce the weight transfer you were looking for. On the F40, that distance is 7.28" (185 mm). Your proposed set up with an 11" distance between centrelines adds only 3.72" (94.5 mm) to that of the F40's measurement. On a 104" wheelbase, that's a 3.6% shift forward of about 20% of your chassis weight (a 450 lb engine in a 2500 lb chassis). That doesn't seem like a lot of weight transfer considering the extra complexity, cost, rotating mass, fixed weight, and unique parts involved in your proposed set-up. That pair of 11" diameter steel gears alone are going to be like adding two more flywheels to the crank! No?


    You've probably also discounted the F40 because it's rated for 300 lbft of torque. But bear in mind that's a very conservative rating. Many others here and on Pennock's have been beating the Muncie 282 with twice (or more) the torque that that gearbox was rated for, for years. Sure, there have been failures, but these are now 30 year old used boxes. You can easily buy an F40 brand new for $500. In fact, you could probably buy ten F40's for the money you'll invest in your transaxle set up.

    If it's uniqueness you're looking for, then as a guy who spent 600 hours developing a multilink pushrod rear suspension for a Fiero, I definitely understand that. Uniqueness is worthy cause without further explanation. Otherwise, did I miss something?

  4. #24
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    Quote Originally Posted by Bloozberry View Post
    First, before you (or any one else) misinterpret(s) my comments, please bear in mind that I'm humbly offering constructive commentary. Tone is not always evident in the written word.

    Anyway, as I recall, one of the reasons you discounted the F40 in your earlier thread was because it didn't have enough longitudinal distance between the engine crank centerline and the transmission output shaft centerline to induce the weight transfer you were looking for. On the F40, that distance is 7.28" (185 mm). Your proposed set up with an 11" distance between centrelines adds only 3.72" (94.5 mm) to that of the F40's measurement. On a 104" wheelbase, that's a 3.6% shift forward of about 20% of your chassis weight (a 450 lb engine in a 2500 lb chassis). That doesn't seem like a lot of weight transfer considering the extra complexity, cost, rotating mass, fixed weight, and unique parts involved in your proposed set-up. That pair of 11" diameter steel gears alone are going to be like adding two more flywheels to the crank! No?
    Never mind... I forgot to take into account that the differential adds another 8" to the difference in the distance between axle and engine centerlines. The observation about rotating mass still applies though.

  5. #25
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    If its not too late you could consider the Toyota 1GZ-FE v12. This is a 5l DOHC engine. There are a number of them running on the web with EFI stacks!

    https://youtu.be/eT0TgL9-2Pw

  6. #26
    Senior Member C5GTO's Avatar
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    Post Transaxle mockup transitions to build

    It was now time to figure out how wide the engine/transaxle package would be so that meant figuring out the bellhousing and transfer case between engine and transmission. Pete dug up a Ford bellhousing, it’s depth measured 7 inches and it had lots of unused “air space” inside. We could slice off the area making up the air space and go from there but that felt like a hack. Pete had some large billets of aluminum and decided to machine up a bellhousing from that.



    For the transfer case, more aluminum billet was used.





    You might guess that by now we’re transitioning from rough mockup into making parts for real. The outside half of transfer case shows this with some of Kevin’s nice CNC machine work.





    You might also notice the mockup engine now has 2 heads on it. Pete found another core engine so there would be no worries about shaving off some metal and snuggling the transmission up even tighter.

    As it turned out, the bellhousing and transfer case is about 7 inches deep, about the depth of a standard bellhousing. The transfer case still needs some doughnut shaped extensions on outside to hold bearings but these should be fairly thin. The length of the engine from front of damper pulley to outside of transfer case is about 33 inches. Even at 33” it’s going to be a tight fit into the chassis engine bay but we’ve made it as narrow as possible without going down to V6 or something. There’s no way we could have made a V12 this narrow.

    I’ve got to give Pete Aardema and Kevin Braun credit and recognition for what’s been accomplished on the transaxle so far. Their talents are amazing and they’ve given the Miura project a huge shot of adrenaline. At this point, I felt we had enough engineering completed and information to know that the Strickland chassis would work. I’ve caught you up on project progress to-date and will give project updates more real-time as more progress is made.
    Joel Heinke
    Be original; don't be scared of being bold!

  7. #27
    Senior Member C5GTO's Avatar
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    Post Miura chassis construction underway

    As a reminder, I decided to use an all aluminum monocoque chassis from Strickland Racing for the Miura. I’m very excited about this chassis for the Miura as to me it represents a big technological advancement. The original Miura chassis was known to exhibit some flex and was prone to metal worm attacks over time. The Strickland chassis should be much lighter weight, more rigid, and shouldn’t deteriorate over time given the use of “marine grade” aluminum. In addition, Charley’s highly automated approach to chassis construction keeps the cost in the reasonable range.

    A small part of the car sizing answer was in consideration for chassis table fixture mounting. By adding .5% on 105% giving the 105.5% this resulted in good alignment to the chassis table such that mounting holes aligned to fixture holes. The chassis was fully modeled with a CAD application and then the CNC cutting instructions are generated from the model. Chassis parts are made from 5052 aluminum and are cut from ¼” sheet on a 3 axis CNC router. I’m told the accuracy of the CNC cut chassis parts is incredible and they fit to one another easily by hand.

    Some chassis parts after cutting and removal from sheet.





    Sheet on CNC cutting table after the cut pieces have been removed. With careful placement on the sheet, there’s very little waste after cutting.



    The chassis is assembled on a precision chassis table. The chassis members are secured to the table during assembly to ensure alignment for a straight and true chassis. Tabs and slots are used to accurately index the chassis members to one another.





    After trial fitting to ensure fitment, the chassis members are fastened together with special metal bonding epoxy glue. As you can see in these pictures, the chassis is quickly taking shape.

    I’d like to thank Charley Strickland for providing these progress photos. I know it provides much better insight for you as to how something is made when you can see it in the various stages of construction.
    Joel Heinke
    Be original; don't be scared of being bold!

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