Collins' Custom GT40 MK1 Build

Hello, everyone! I thought I would start this build thread in order to be able to ask questions with context and keep track of our progress. We will be building two cars. My friend Chuck and I got together a team of really knowledgable guys that are just excited to get a couple of GTs together. John is a great fabricator, Greg is a master welder, and Chuck owned a business making Cobra kit cars for a number of years. It's as good a team as any.

As mentioned in my intro thread, I'm a Mechanical Engineer that graduated from KU back in 2012. I helped build the 2012 KU FSAE car that took 1st place in Lincoln, NE. I've never built a full-size car before, but figured I would give it the old "college try." :)

This is the JMS12c. I was the wing/aero guy but helped in all matters composite. We designed and fabricated our own parts including the molds to make them. We have a full carbon monocoque. Fun stuff. The car is currently on display at the Museum of Speed in Nebraska if anyone local cares to go take a look.


The thought behind our GT40 build is to use easy-to-replace (off the shelf) parts where possible and to make the car suitable for road use, not purely a track car. It won't be a purists car by any means; just fun to drive. I am designing the entire car from the ground up in SolidWorks.

We will be utilizing the C5/C6 Corvette suspension in the correct Corvette geometry, albeit with a shortened wheelbase and track width to match that of the original GT40. Our car will use the Ford Coyote 5.0 mated to an RBT 5 speed ZF Transaxle.

Here's the Coyote mated to the ZF. Quick Time just came out with a bellhousing for the Coyote-ZF coupling, we got the first two sold from Jegs.



We have our own set of molds pulled from a Superformance car, and have gotten a couple sets of body parts out of it already:


And our progress so far with the frame:

Laying it out:


Suspension mounts. I 3D printed my own jigs to use when welding them up. (used a spacer to make sure they stay the correct width, as well.)






Lower suspension arms bolted to the frame, still have to weld eccentric hoops to the front and rear mounts for alignment purposes at this point (they are on there now)


And the upper part of the chassis is now coming together:




And my current SolidWorks progress. I was able to find models of both the Coyote and a surface-only model of the GT body for reference.

As you can see the extension for the front and the rear upper part of the frame are still in progress; Motor/Transaxle fitment is still a question mark for us until we can verify that everything looks good with the rear suspension mounts.





The next step for us is to get the body from storage, trim it where needed, and fit it to the chassis both checking for possible interference (it all looks good in the computer, but one thing we learned in school all too well was that computer and real life often don't coincide perfectly) and to check wheel/tire measurements (tire sizes, backspacing, etc.) with relation to the body before we order wheels and tires.

I will try and keep this updated, and will surely be asking quite a few questions along the way! We'd like to add an 8 stack to the coyote, and I would really enjoy designing/fabricating my own. Part of my hesitation to use the Coyote in the first place was how I thought the air intake would have to be routed but then I saw Jason's Coyote RCR40 build thread (a FANTASTIC looking build, by the way!) and it convinced me to use the Coyote and throw an 8 stack on there. Now all I have to do is start. :)

Looking forward to sharing my build; all comments, questions, and advice are appreciated!

Collins
 
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Props for at least admitting you splashed someone else's car..........
I'll take credit where I'm owed it, and give it where it's due. This seems like a great site with a wealth of information, I don't want to disrespect anyone by lying about stuff!

Chuck already had the molds, He's not actually positive what car it came off of, he has had the molds for quite a few years. They popped off a couple nice sets of body panels, though! The two sets we have are in glass, I would like to do a couple sets in carbon as well.
 
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A little progress since the last post. I have done a little more to the frame in the computer, and have mated Boris's new GT body to my chassis. The newest model looks great! As I mentioned in my previous post I originally found a model of the GT40 body on the internet (grabcad.com) and, as it turns out, that model was one that Boris did a few years ago and put on there. The newest version that he sent me seems a lot more accurate, and I'm excited to use it. Thanks, Boris!



In addition to the computer stuff, we also have gotten the body trimmed up and ready to fit together. We're just going to rig it together and test how the body fits with the wheel/tire/backspacing size that we have determined that we want to use with the Vette suspension before we order wheels/tires.

Body is trimmed and ready for fitment:


I have tagged the rear upper suspension points in place with a "quick and dirty" jig, now to do the same with the front so that we can build the upper part of the frame up to it and test fit the motor/transaxle. Halfshaft locations are still a question mark, I'm not sure how those will fit in the rear in conjunction with the rear shocks. The Vette system uses a leaf spring, we are going to switch to coilovers. I may end up designing a bellcrank system for the rear shocks before all is said and done.

We just got the oil pan in; I went with a Moroso oil pan, part number 20570. It is designed for Coyote swaps (Cobras, specifically) and is the lowest profile oil pan that I can find off the shelf. The 4.375" depth will allow us to place the motor much lower in the car than if we used the stock oil pan.

I have done a little more research on the 8 stack scenario. I definitely want to develop one for these cars, as it will look GREAT when finished and look how a GT is supposed to look. I know that InnoV8 has one (and Borla too, I think) but they are (understandably) expensive, and I don't have the extra cash at the moment to purchase one. Plus, designing my own will be exciting! Does anyone happen to have points for where the intake manifold bolts to on a coyote that I can use to put in the computer and start designing? :)
 
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A little progress since the last post. I have done a little more to the frame in the computer, and have mated Boris's new GT body to my chassis. The newest model looks great! As I mentioned in my previous post I originally found a model of the GT40 body on the internet (grabcad.com) and, as it turns out, that model was one that Boris did a few years ago and put on there. The newest version that he sent me seems a lot more accurate, and I'm excited to use it. Thanks, Boris!


[/QUOTE]

Good evening, Collins! Thanks for the nice words! I also want to thank you for the valuable assistance and knowledge! I look forward to our long cooperation! Good luck in your business! I am always ready to help. Boris.
 
Good evening, Collins! Thanks for the nice words! I also want to thank you for the valuable assistance and knowledge! I look forward to our long cooperation! Good luck in your business! I am always ready to help. Boris.
Thanks, Boris! Did you get those files that I sent you, and did you get them to work ok since we last talked? I am using SolidWorks 2014, what version are you using? I think that may have something to do with your issue. Let me know!
 
Good afternoon, Collins!
I am also using version 2014 and Catia V5. Unfortunately, the files that I mentioned have not opened.
 
I have made some progress in the past few weeks that I'd like to share with you all! We ended up back-tracking a little bit with regard to the intake, but for good reason; after diving deeper into the 8 stacks available on the market for the Coyote (Ingeles, InnoV8, Borla, etc.) their design, and the costs associated with them, I decided to go ahead and design my own. We were debating whether or not to design or purchase one (or just go with the factory manifiold) up until now, but the GT really needs a set of velocity stacks on there to look right. The designs out there are great (InnoV8 especially. Wow!) but we just don't have the extra cash to purchase two kits and I'm excited to make my own.

We looked into it and decided to explore a "crossram" style stack with an air cleaner on each bank. It isn't like anything out there on the market for the Coyote and seeing as how I'd like to be able to drive my car more often than once a month, I'd like a nice, stout filter on there. K&N makes one for the Datsun 240 that will fit nicely with how I have my ports mapped and will give us more than enough intake area, with a couple different filter heights to choose from.

The plan is to 3D print the intake here for prototyping (we have a Dimension SST1200es, it will print P430 ABS Plastic) and get it printed at a local vendor with a more advanced machine in PPSF plastic for the final product. With a heat deflection of 370deg, it will work just fine for this application. The top and bottom plates of the air cleaners will most likely be milled from 6061 on one of our CNCs.

This is just the "proof of concept" model if you will. Don't even have throttle plates modeled yet. The final plan is for a five-piece bolt-together set of runners for every set of parallel (albeit offset 1") ports. Two lower runners, a center "x" piece (for added strength horizontally), and two upper runners going to their respective air cleaners.

Attached are a few renderings of what I've come up with so far. As always, comments are appreciated!







 
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Made a few changes: I designed the previous filter assembly without thinking about the velocity stacks that would have to be housed within. I made some dimensional changes (a little wider, a little longer, and a little taller) so that there is an appropriate area around the edges and above the actual bellmouth itself.

In order to get the runners to cross without interference I had to make the path elliptical for a short portion. In my previous design I had that ellipse carring all the way to the filter plate, but I made some changes and loft the shape back to a perfect circle a couple inches before the bolt plate.

The intake will now be a three piece affair, with a lower runner on each side and a single "x" piece up top to strengthen the two sides and move the fulcrum point that the weight of the filter will hinge on further up the runner length.

New render is below with a see-through cover showing the bellmouths.

 
ummmm - - how do you plan to get the rear body work open to work on the engine with the cross ram manifold overhanging like it shows in your solidworks drawing????
 
Collins,

Those long runners will have a resonance tuning at a relatively low rpm and an anti-resonance at another. What rpms were you planning for the multiple resonances and anti-resonances and how does that complement the exhaust tuning?

-Bob Woods
 
ummmm - - how do you plan to get the rear body work open to work on the engine with the cross ram manifold overhanging like it shows in your solidworks drawing????
The body is unmodified from Boris's design, like I said the manifold is just proof of concept at this point. The cutout on over the motor will need to be modified in order to get the rear body open.

Collins,

Those long runners will have a resonance tuning at a relatively low rpm and an anti-resonance at another. What rpms were you planning for the multiple resonances and anti-resonances and how does that complement the exhaust tuning?

-Bob Woods
Bob, I'm going to have to do some research to be able to answer your questions. (I'm glad that you're asking them, though! Lets me know what to look for!) The factory Coyote manifold has an approximately 12" long runner from the head to the mouth within the stock manifold. These prototype runners are approximately 15.5" to the filter, not counting the bellmouth.

I'm not an intake or exhaust guy, I was one of the Carbon guys while in JMS. I was just trying to match the factory runner length as closely as possible while still being able to place the filters where I want them; This is what I came up with on the "first shot out of the cannon," so to speak.

I found a couple articles Intake Resonance tuning. From what I understand, you want the runner length to be such that the intake pulse "bounces back" at the port at the exact time that the throttle plate opens back up in order to force a little more air into the motor and make it more efficient, correct? And this tuning is done typically at WOT, made ideal by adjusting runner length? Any insight you could provide would be helpful! The math seems simple enough and I can adjust the runner length using the bellmouth, but I'm guessing that there are other factors to consider.

Thanks for the feedback!
 
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