Debated over this for a while. The Camaro comes with an Aisin LY6 6-speed with the “MV5” designation. That box has some interesting ratios. From 1st to 6th gear: 4.48 / 2.58 / 1.63 / 1.19 / 1 / 0.75
1st and 2nd are super short, 3rd has a big drop and is very long, then 4th is very short again. I can think of arguments for and against this, depending on the specific scenario/track.
The base model Cadillac CTS uses the same engine, and has a manual gearbox option – that transmission is the MV7, and it has much more evenly-spaced ratios: 4.16 / 2.51 / 1.69 / 1.27 / 1 / 0.75
To visualize the differences between the two transmission, I graphed them:
I decided to go for the MV7. Turns out this trans is rather rare – likely because the base model CTS is rarely chosen with a manual – but I finally found one with low miles in Texas and had it shipped over. $1200 including freight:
Pondering the total weight and weight distribution change vs a stock Miata… Depends on the car. V8R’s MSM was nearly a wash between the factory drivetrain and the full LFX swap from what I recall. I’m sure a stock naturally aspirated Miata would have it beat, but nobody is making 250+whp on a naturally aspirated car, so that’s apples to oranges. Compared to a turbo car, I expect this to have a better weight distribution – some of the rear components add weight over what is coming out (but are stronger), and in the front you’ve got a tubular subframe and all aluminum motor.
My weight distribution is worse than most would probably expect. That’s partly due to aero additions up front, and a lot of easy weight saving in the rear, but the turbo makes matters worse. For those who have seen my V-mount setup – that’s a big intercooler and other bits far ahead of the front axles, plus the turbo and cast iron manifold.
Currently I’m at 59% F / 41% R. I’ll double check that on the scales right before the tear-down begins and then scale it again with the new drivetrain, so we will have some solid answers by the end of things.
For the differential/limited slip, I’m going with V8R’s Getrag Stage 2 kit which consists of everything to make a Getrag diff from a Cadillac CTS work in the Miata. That includes the diff mount, axles rated for 550 ft-lbs, full billet replacement hubs with ARP studs, and driveshaft. This is their same kit as designed for the V8 cars, but with driveshaft specific to the transmission. Opted for the aluminum driveshaft because race car.
Most of the swap parts are en-route right now, but the Getrag diff mount is already here. The two bare steel tabs get welded to the Miata rear subframe:
I’ve heard good things about the Getrag diffs. The V8R “spec” cars all run them in their L33 V8 swapped cars with good results according to Shandelle, and others have reported that they are an upgrade in behavior from the Torsen. Also good ground clearance (for flat bottom). If I turn out to not like it, I’ll explore other options.
V8Roadsters LFX Subframe Same design as used for the V8 cars, but with LFX-specific mounts:
V8Roadsters LFX Oil Pan This is a factory unit modified for clearance (compared to unmodified stock pan on the right):
Power Steering kit
This adapts the GM power steering pump to an NB rack. All of the hard lines are replaced and it includes fittings for both the pump and the rack.
Not 100% sure at this point what I’ll end up doing for the steering. I was initially planning to run without power assist for the weight benefit. But, haven’t had power steering for years, and I picture it being really nice to have again – easier to be fast and consistent if you’re comfortable after all. BUT, will very likely need a cooler for the P/S fluid for track use. At any rate, I made sure to get the P/S pump with the motor, so I can play with it.
The LFX is Chevy’s “High Feature” 3.6L 60° V6 DOHC all-aluminum engine found in several different specs across the 2012-2014 Chevy and Cadillac line-up. It has a composite intake manifold to reduce weight, and an integrated exhaust manifold head design that collects exhaust gas into one single exhaust port on each side of the engine (in other words, a dream to fabricate exhaust for this). It has direct injection (awesome).
The LFX acronym was supposed to denote Flex Fuel capability, but that feature is not integrated into the Camaro from what I’ve found. Unknown as of now whether the ECU has the capability to run a flex fuel sensor. However, I’ve done some digging and turns out that the fuel system’s hardware is all designed to be E85-capable, with injectors sized at 109 lbs/hr (1,100cc). So even if flex fuel is out, it looks like switching to E85 is just a tune away – no hardware changes needed.
Although found in the Cadillac CTS, ATS, Chevy Impala and others, the one to get is from the Camaro. Rated at 323hp and 278 ft-lbs at the flywheel.
Picked up the motor last week, 5 miles from the Mexico border. I specifically looked for one that had just come in and wasn’t pulled from the car yet so that I could point at all the components I wanted to keep attached to the motor and get a package deal for it all. That way I also didn’t spend hours figuring out where stuff goes later.
For $2100 – Engine – Alternator – Power steering – A/C – Engine wiring harness – Starter – Gas pedal (for the drive-by-wire)
I likely won’t need all the accessories, but this way I have a template for the factory belt layout from the beginning. I just MIGHT play with keeping the power steering – low-effort steering with 15x10s would be mighty nice…
This is the only time I needed to be picky about the motor and pay extra for all the accessories, wiring, etc. Next time I need a replacement motor everything will be in place and can swap over, so expect ~$1700 for a replacement long block with low miles.
Time to document the conversion of my 1990 time attack car from the current 1.6L turbo to the new-hotness LFX 3.6L V6 and drivetrain.
The donors; A bit of this, a bit of that:
Now is a very exciting time for Miatas, lots of options and knowledge for making horsepower in various flavors. The 1.6L motor has served me well, but to be competitive in the “run what ya brung” time attack structure open to any chassis/motor, more power is needed.
I’ve been carefully weighing the options for a long time. I’m looking for ~40% more power than current turbo setup while hitting these marks: *reliable *smooth power delivery (consistent lap times) *low weight/good weight distribution *low heat *low replacement cost *robust drivetrain
I’m not the type to gamble on things, and this is certainly the path less traveled, but after a lot of research and discussion with V8R, everything looks really really good on paper. I’m going for balance over sheer gobs of horsepower. Expecting that my weight balance will actually improve over the car’s current config.
One of the biggest reasons for taking this direction is to preserve the recipe I’ve ran for years where I utilize a motor straight from the junkyard. Think of this as the same recipe as a SuperMiata, but with double the horsepower and torque; Engine and transmission drop in straight from the junkyard. Trans and diff are overrated for the power output of the motor. Run till it won’t go no more, then get another one. Going rates on the longblock and transmission are only about 25% more than an NB1/2 motor and 6 speed.
Here’s the kicker, relevant to some: V8R is working on CARB certifications for their kit. This could mean big things for those in certain states, especially all of us here in CA.
This is my personal car, but development transfers directly to new products and knowledge for Good-Win Racing and Singular Motorsports. If the kits get CARB cert then we’ll be working with V8R to sell these to our West Coast customers, so this car will give us the opportunity to work through the swap process first-hand. There are a couple things I’m already working on and working with other companies to create solutions where current options either don’t tick the boxes we need or don’t exist at all.
This will serve as an information dump where everyone can follow along with the progress. I’ll try to thoroughly document weights of everything coming off and going on as well as scale the car before/after the swap.
Feel free to ask any questions, contribute information, discuss anything related to this swap, etc. We have a solid plan in place for the overall process, but there will undoubtedly be lots of things that we will just work through and find solutions for as we progress, so if you have a question right now for “how will X and Y work together” the answer may be an honest “Not sure yet!” but we will figure it out.
