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Unread 01-06-2014, 02:46 PM
Fair!'s Avatar
Fair! Fair! is offline
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Join Date: Jul 2004
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Default Re: Vorshlag Miata LS1 Alpha Project

Project Update for January 4, 2014: Wow, over a year without an update? Yikes. While it looks like I have been avoiding this build thread, we have been plenty busy working on this project and many others over the past 14 months. Most of the work we have been doing on this project over the early part of 2013 had to do with upgrades to the shop and building fixtures we needed to delve further down the rabbit hole on the Miata LSx swap. Later in 2013 we also tried a number of oil pans, designed and built a new tubular front crossmember, did all of the geometry calculations then mounted the new front suspension bits, and then we finalized the wheel and tire package. We also worked on a lot of other customer cars in that period, built a few race cars, developed our BMW E36 LS1 swap kit extensively, released our BMW E46 LS1 kit, and a number of suspension development projects in the same time period.

All pictures in my posts can be clicked for higher rez versions

We also had a very busy racing schedule in 2013, running 15 events with NASA (among many other groups' track and autocross events) in our TT3 prepped Mustang, shown below. We won 13 of those, got one 2nd and one 3rd, setting 8 track records along the way, while testing all sorts of aero and suspension work (we race to test, and test to race). Another project that kept us busy was developing a new set of NA/NB Miata shocks shown below. These are custom built with Bilstein Motorsports components, using massive 46mm monotube pistons, machined and assembled at Vorshlag, then custom valved by Maxcyspeed & Co. We just finished our final round of track testing last weekend, testing the latest valving package for a dual purpose street/track set-up. I had a blast hooning around in the tester's 2001 Miata below at Eagles Canyon Raceway. These dampers should be in production in Q1-2014 and we will have more information about these in the New Damper Offerings forum thread.

One thing to note about this post: starting in early 2013, I started making ALL of the pictures in all of my forum posts click-able for larger sizes. With a photographer like Brandon on staff it is a shame to only show the little "small" versions in our posts. So if you see an image you like, click it for a higher resolution version of the same image.

Before I get going on this update I wanted to shout out to - Just found this forum which looks to be a great resource for V8 Miata swaps, as the name suggests. Our build thread was added there today at this location. I already learned a few things reading build threads there, so if you have plans for any sort of V8 swap in any generation of the MX5 chassis, you should head over there and sign up.

Shop Upgrades Lead To LSx Swap Progress

So one of the things we needed to work on this Miata LS1 car was a 4 post lift, which we finally ordered and installed in early 2013. This made it easier to do drivetrain mockups. We quickly realized that we also needed a chassis dolly to make the Miata easier to move around once the subframes were out. So we built that in summer 2013, and soon modified it to fit two other chassis. Now that dolly thing gets used on a daily basis (should have built one of these sooner) to move a car around the shop that has no suspension, crossmembers, or wheels.

Believe it or not, the lack of the 4 post lift and chassis dolly were big impediments to this Miata LSx project. Since we are still in a somewhat small shop space we couldn't afford to have the Miata stuck on one of our lifts for more than a day or two, which kept us from pulling the front subframe out for more drivetrain mockup (ever try to move a car around without even subframes in it?).

The Real Engine Swap Work Begins

Once the lift and chassis dolly were built we rounded up the hardware needed to get the TKO-600 transmission mounted to another LS1 block we have, then put that mockup drivetrain in the car for some testing with the REAL transmission. Before we had eyeballed the TKO in the tunnel but not while attached to the block. This helped us see what the next piece was in the way...

After we did that round of LS1+TKO mockups we quickly realized that the OEM front crossmember was a HUGE hindrance to this swap, as even heavily modified and hacked up it would be in the way of the engine, oil pan and exhaust headers. We refuse to accept the huge compromises that come with "block header" exhaust headers on any of our swaps, so a new tubular front crossmember was going to be required.

You can see above some of the structure of the frame fixture that bolts to the body dolly, which Ryan built for the NB Miata. There's actually a lot of steel rectangular tubing you cannot see in this pic. The rolling cart attaches to this frame fixture from underneath the lift. This fixture was built to allow the car to sit at the desired ride height w/o suspension while sitting directly on the lift, with the rectangular tubing setting the chassis height. He then mocked up some 265/35/18 tires at both ends for a quick look. If you shove them in hard enough they almost fit under the fenders, heh.

Choosing Tires and Suspension To Build Around

We knew early on that we wanted to upgrade all of the factory (and very weak) 4 x 100mm NA/NB hubs hubs to 5 x 114.3mm RX8/NC hubs. The 4 x 100 hubs are a common failure point up front on Miatas that see any track time, and keeping the rear 4 x 100 hubs would limit the halfshaft strength greatly. Going to 5 x 114.3 bolt pattern opened up a lot more wheel and brake choices as well. Doing this "hub upgrade" is more work than you might think - this meant new uprights and control arms, so the NB suspension pick-up points on the crossmember were no longer sacred... so we might as well ditch it, right? Well we tried to keep the stock crossmember, probably far too long into the swap development. We tried cutting it to make room for this or that (like some of the kits are fond of doing), modifying the pick-up points, but it was getting weaker and more customized.

Meanwhile we had been mocking up this RX8 front control arms and uprights and even tried an 18x10" wheel and later a wheel and tire. Ryan put in several days of work, and with Jason's help, they did a lot of measurements and calculations and got the front suspension sorted out fairly well. At this point we knew we would be able to re-use the RX8 front spindles, brakes, and control arms. I was worried we would need to fabricate control arms, but it all fit very well with the forged aluminum RX8 arms. Small victory.

Video we made for the customer, showing the RX8 suspension and 18x10" wheel in action

In the video linked above we were showing the customer the current location of the wheel and suspension with the big 18x10" wheel, to which we later mounted a 285/30/18 tire. This video shows the front 18x10" wheel turning at ride height, and we later made some adjustments to clear that wheel at full lock, inboard (obviously the fenders will need to be cut and flares added to cover the tire). Our customer has had regular e-mail updates every 2-4 weeks, showing all of what you see here and more. We send these email updates with pictures and videos to all of our long term project customers - basically anyone that has their car in our shop for anything more than just "day work".

Later a set of 18x8" Mustang wheels (from my 2013 Mustang GT) were installed, shown above left. We noted that these barely fit under the stock fenders, but they didn't have enough positive offset. We might pick up some higher offset RX8 18x8" wheels (above right) and tires, which would sit farther inboard. This could possibly avoid the need for cutting and flares for some folks. Luckily, our Alpha customer is going with the 285mm tire option. Why so much tire? Well the LS1-based 5.7L motor that was built for this car will make 425-450 whp, and in a 2600 pound car with a short wheelbase, that is downright hair raising... we felt that a 285mm tire (Hoosier!) was going to be barely enough to keep it on track when the loud pedal is cranked up to 11.

One thing that had me a little worried during our wheel and tire mock-up was tire height. Most NA/NB Miatas are using a 23" tall tire, which is SUPER SHORT and only come in sizes out to about 215mm or the occasional 225mm. We went away from the typical 14-15" wheels to clear larger RX8 front "sport" rotors, which at over 324mm diameter are too big to fit inside a 15" or 16" wheel. Then tire width choices started to come into the picture... there just wasn't anything wide enough in 14, 15, 16" or even 17" diameters (the last two diameters tend to top out at a 255mm tire width for most brands), so we jumped straight to 18" - which currently has the most options for wider tires in both street and race compounds, covering widths including 275, 285, 295, 315 and beyond. We're building our TT3 Mustang around a 345/45/18 in the 2014 season, for instance. You can almost never have too much tire width on a race car...

Turns out there wasn't any tire anywhere near 23" tall once you left the skinny options in the 14-15" wheels, so we chose the shortest tire that is also wide that we knew of - the 285/30/18. This tire is normally the magic solution to "going wide" on track or autocross cars, and we've used this 24.9" tall monster tire on lots of BMWs (see above right, which has a bit more tire height room), EVOs, Subarus, and more. They even are used on RX8s and NC MX5s, but those cars have a lot more "wheelhouse" room than the NA/NB chassis. So we will likely cut the front upper frame horns for more clearance at full bump travel (then add back more structure with welded steel tubing). The above left picture shows the suspension at about 1.5" of bump, which isn't enough. Oh well, using a 2" taller than stock tire causes some problems we will have to overcome, but they aren't anything we haven't tackled before on other chassis.

New Crossmember Development

Once the tire was chosen and the front hubs and suspension components were tested and mocked up, we were ready to start burning in the pick-up points onto some sort of crossmember - either the stock piece or a custom design. At this point it was obvious that the OEM front crossmember was the next big stumbling block and it had to come out, once and for all. We just couldn't save it (it was already cut-up so much to clear the engine that it would need major reconstructive surgery), we didn't need it (we were changing all of the suspension pick-up points), and it was just in the way. So first the Vorshlag crew fabricated a crossbar that held the front of the engine from the top, which rested on a part of the upper chassis that wasn't going anywhere. Then they made a similar and also temporary rear transmission crossmember that was bolted in place, so the driveline position and angles were set. In the step above you can see the OEM crossmember out of the car for a bit, but now it was time to be fully replaced.

Now that the drivetrain was where it needed to be we connected the dots to build our new front crossmember. Using lengths of 1.75" diameter x .120" wall DOM steel tubing, Ryan measured then mandrel bent the new fore-aft frame members. These tubes were spaced inboard enough to maximize exhaust header space as well as set the final lateral and vertical locations for the RX8 lower control arms, which had geometry already determined above. These main fore-aft tubes bolt at both ends of the engine bay, onto factory chassis mounting locations that have substantial strength. Unlike the stock front crossmember, which mounts at the rear of the engine bay and at the midpoint (where the suspension parts mount), the new tubular design would mount at those points plus forward at the front tow hook tie down mounting plates. Our crossmember should make for a more rigid chassis when it is completed, with less cowl shake and more stable suspension mounting.

continued below

Last edited by Fair!; 01-06-2014 at 04:01 PM.
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