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Thread: LFX (GM V6) in a Miata @ Goodwin Racing

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    I wanna go fast! thepass's Avatar
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    Default LFX (GM V6) in a Miata @ Goodwin Racing

    I'd like to share something we're working on here so everyone can follow along. In the never-ending search for more power (and the silly desire to have it from a reliable package) a full drivetrain swap has begun for my #13 time attack car.

    The car:



    This is a 1990 chassis that has been running a turbocharged 1.6 for many seasons. Current power is around 215 whp, it's been enough to beat up on some much "faster" cars at the track thanks to good suspension, aerodynamics, and lightweight. Won a season of Miata Challenge, even took home a 1st place last year in one of the rounds of Redline Time Attack. However, with sights set on higher levels of competition that pit us against cars of all makes/models, many of which have big V8s and the like, it's time for some more firepower.

    The donors for the new recipe are the Chevy Camaro and Cadillac CTS, with conversion parts from V8Roadsters and some good ol' fashion fabrication mixed in.

    Engine comes from a 2012-2014 Camaro. Transmission can come from either the Camaro or CTS of those years. Differential comes from a 2006-2008 CTS:





    Why the change? Why not go for more power with the Miata motor and turbo?

    One, turbos put off a LOT of heat. I've melted just about every plastic or rubber part on the driver's side of the engine bay at one point or another. Second, there's a laundry list of changes that need doing to just about every turbo kit out there to have a hope of running reliably under racing use. This car got there, but it took half a decade of custom revisions and improvements to do so. Finally, at the end of the day you can't get away from the fact that when you're asking a motor to put out 100-200% MORE power than it was originally intended to, longevity is not its strong suit any more. Then we get to the rest of the drivetrain.. a Miata transmission's lifespan begins plummeting above 200 ft-lbs of torque. And that brings us here: the search for a great motor pairing for the car that was designed from the beginning to make all the power we want, which should make for not only a faster car but also a more reliable one.

    We've done a lot of paper-napkin estimates about this swap, and on paper it looks very good for power and drivability without sacrificing light weight. There are more than a few reasons that it looks more appealing than a V8 swap - less chassis modifications needed, smoother and higher-revving than the V8s, better weight distribution, etc.

    To top things off, V8Roadsters is working on CARB approval for this swap. No promises yet, but that could mean big things here in California. If the kits get CARB approval then we'll likely be doing a lot more of these swaps in the future, so this is a great opportunity to work through the process first-hand.

    I'm already a good portion of the way through this project, will be posting in future days to get things caught up!
    Last edited by thepass; 10-06-2016 at 10:54 PM.
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    Ryan Passey
    Singulär Motorsports | Goodwin Racing

    #13 1990 Miata
    "The sport dedicating to the spirits of time attacking motoring" -Emilio

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    I wanna go fast! thepass's Avatar
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    The LFX Motor

    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 is packed with tech; direct injection, variable valve timing, a composite intake manifold to reduce weight, timing chain (not a belt), 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).



    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.

    The fuel system's hardware is all designed to be E85-capable, with injectors sized at 109 lbs/hr (1,100cc). So switching to E85 is just a tune away - no hardware changes needed.

    Last edited by thepass; 10-06-2016 at 11:07 PM.
    Ryan Passey
    Singulär Motorsports | Goodwin Racing

    #13 1990 Miata
    "The sport dedicating to the spirits of time attacking motoring" -Emilio

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    I wanna go fast! thepass's Avatar
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    Transmission

    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

    Because this is a road race car, the evenly spaced ratios look a bit more appealing. Here's our MV7, fresh out of a donor CTS:

    Ryan Passey
    Singulär Motorsports | Goodwin Racing

    #13 1990 Miata
    "The sport dedicating to the spirits of time attacking motoring" -Emilio

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    Differential

    We'll be using the tried and true Getrag limited slip differential for this - the same differential used in many V8 Miata conversions. It's a clutch type limited slip with smooth engagement that can handle all the power we can throw at it. Sourced from the 2006-2008 CTS and several other GM cars, it's available with a 3.23, 3.42 or 3.73 ratio. Those all sound long in Miata terms, but with the short ratios of the transmission we're using it's actually a great set of options. This particular unit is a 3.42:



    The Getrags all have their ratio labeled on the back side, so it's very easy to know which ratio you've got:

    Ryan Passey
    Singulär Motorsports | Goodwin Racing

    #13 1990 Miata
    "The sport dedicating to the spirits of time attacking motoring" -Emilio

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    RaceTape Ninja Force McCocken's Avatar
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    There are a couple of these running around ATL. I like the specs on this far better than the V8s. I think it's impressive. 300bhp, nice tech, lively curve. I would consider this swap for myself.
    Yer pal,
    Force

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    Kam
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    I appreciate the desire to do something slightly off the beaten path!

    But, why not F22C? Hell, F22C w/ SC making 350whp would be reliable and fast.
    4.6lbs / whp -- 4lbs / bhp

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    http://www.trackhq.com/Banners/yellowsitesponsor.gif emilio700's Avatar
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    Net weight gain?
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    But obviously I just dont get it. -fatbillybob

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    Old timer craZee's Avatar
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    Why not just put a Miata body on a Cow-maro chassis? Same net result :-)

    Looks interesting
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    I wanna go fast! thepass's Avatar
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    Quote Originally Posted by emilio700 View Post
    Net weight gain?
    Car should be 2150-ish lbs when it's back on the ground. Will scale it of course

    Quote Originally Posted by Kam View Post
    I appreciate the desire to do something slightly off the beaten path!

    But, why not F22C? Hell, F22C w/ SC making 350whp would be reliable and fast.
    You're joking right? Ok, assuming you're not...

    Torque.

    The LFX makes a nearly table-top flat torque curve at ~250 ft-lbs through the whole track-useable range. That's bone stock. For any F22C vs LFX option with equal peak horsepower numbers, the LFX will be faster. And you never know, might add boost to this engine in a few years...

    Here's V8R's dyno of their street LFX demo car. Stock motor on pump gas:



    The engine is a wear item. The more you have to invest in it to make the power goals you need, the bigger the sting if you lose the motor. In some cases that can put guys out of racing for months while they save up to replace it. At the end of the day, this is still my personal car and if I lose a motor I'm the one replacing it.

    Most around here are familiar with the SuperMiata build recipe: stock/junkyard motor and trans with a just a couple easy bolt-ons. Can run all day long for many seasons, and when the motor pops you can have another junkyard replacement in the car the next weekend. No fancy parts needed. There's a LOT to be said for that kind of simple recipe. The idea here is to build a similar recipe in terms of the drivetrain, except with just about double the horsepower/tq Obviously, there's a lot of one-time work that goes in to making the switch, but once it's done it's making 300whp on E85 right out of the junkyard.
    Last edited by thepass; 10-07-2016 at 08:56 AM.
    Ryan Passey
    Singulär Motorsports | Goodwin Racing

    #13 1990 Miata
    "The sport dedicating to the spirits of time attacking motoring" -Emilio

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    Señor Member b3d3g1's Avatar
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    What do you have for engine management? Are there problems with running an aftermarket ecu and tuning a DI engine?
    -Anthony
    1991 Miata - Trogdor SuperMiata
    2011 Ram 2500 - all the torque
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    Factory GM ECU, fully tuneable without any surprises.
    Ryan Passey
    Singulär Motorsports | Goodwin Racing

    #13 1990 Miata
    "The sport dedicating to the spirits of time attacking motoring" -Emilio

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    http://www.trackhq.com/Banners/yellowsitesponsor.gif emilio700's Avatar
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    Quote Originally Posted by thepass View Post
    Car should be 2150-ish lbs when it's back on the ground. Will scale it of course
    What does a dressed LFX weigh? Trans weight, diff weight?

    Dressed BP is around 285#. AZ-6 is 80#. Dunno what the diff weighs but I'd guess 55#
    WWW.949RACING.COM
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    But obviously I just dont get it. -fatbillybob

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    Straight comparison that way is misleading. Aside from there being a lot of secondary parts that get changed which also affect net weight change, unless you know of a way to make 300whp on a naturally aspirated BP then it's apples to oranges.

    Having weighed just about every component coming off/going on it is looking conservatively like the car will gain 50 lbs on the nose, 75 lbs in the center, and 25ish lbs on the tail compared to the turbo 1.6 config the car was in previously. With a 1.8L that net gain on the nose would be a bit less. I have corner weights for the car just before the tear-down began, and will do the same once it's back on the ground.
    Red_5 and bawareca like this.
    Ryan Passey
    Singulär Motorsports | Goodwin Racing

    #13 1990 Miata
    "The sport dedicating to the spirits of time attacking motoring" -Emilio

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    A quick look at the engine..

    Intake manifold is removed in these pics:




    On the back you can see the high pressure fuel pump and hard lines for the direct injection:



    Front cover removed to get a look at the timing chain layout. Don't worry, no reason to do this except to satisfy curiosity. Three timing chains which should be good for the life of the motor, no belts here. Variable valve timing on all four cams:



    Some sockets that usually lie in the toolbox untouched in a Miata shop are getting some action on this new motor... 1/2", 15mm , 18mm, 22mm, etc.

    Flipping the motor over with the pan removed we get a good look at the forged crank, very beefy 6-bolt main bearing caps (4 from the bottom plus two going in through the sides of the block) as well as the internal crank trigger wheel:

    Last edited by thepass; 10-07-2016 at 09:48 AM.
    Ryan Passey
    Singulär Motorsports | Goodwin Racing

    #13 1990 Miata
    "The sport dedicating to the spirits of time attacking motoring" -Emilio

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    The Real Captain Slow Red_5's Avatar
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    Great project Ryan, thanks for sharing here too.

    One reason why I like this swap so much is that V8 Roadsters is said to be working on having the swap CARB certified.

    Personally I think this swap would also be great in an RX-8. I know it has been done but haven't seen much info on it.
    99 Mazda Miata SuperMiata #515 - AKA Sparky SOLD
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    Looking forward to seeing this car on track, and leaving some nice black marks coming out of the corners with that flat power band.
    1:46.3X @ BRP CW13 - 11/12/15 (400 whp, TD )
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    2:00.01 @ CVR CW - 9/28/13 (350whp, RS3)
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    Quote Originally Posted by Red_5 View Post
    Great project Ryan, thanks for sharing here too.

    One reason why I like this swap so much is that V8 Roadsters is said to be working on having the swap CARB certified.

    Personally I think this swap would also be great in an RX-8. I know it has been done but haven't seen much info on it.
    Thanks for reminding me I hadn't posted this here yet! I have been meaning to.

    An LFX RX8 would be a very fun car as well I think. How could you not like this option over the anemic rotary that car came with? However, for road racing with an RX8 I'd do an LS (V8). Sounds contradictory since I don't like V8s in a Miata, I know.. but let me explain.
    IMO, the big problem with a V8 in a Miata is too much torque with too short of a wheel base. V8 Miatas on the track are something you have to tip-toe around with, rarely at full throttle. You don't drive a V8 Miata like a Miata (aka momentum car) and that kind of ruins the Miata. But, anyone who's driven a Corvette knows it feels like a big Miata with way more motor, and Corvettes make magic out of that same motor. The wheelbase is the key I think.
    An RX8 is almost literally a stretched 3rd gen Miata. All the great suspension/chassis elements of the MX5 but 14+ inches longer. Same wheelbase as a C7, within 1 inch. I think an RX8 would be wonderful with a V8 for the same reason the Miata/MX5 isn't.

    If/when I go for more power with the LFX down the road, very likely will do a rotrex for a smooth and linear powerband while avoiding making 400 ft-lbs at 2,000 rpms in order to keep the car in, what I think, is a sweet-spot for torque for this chassis.
    Last edited by thepass; 10-07-2016 at 11:37 AM.
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    Ryan Passey
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    #13 1990 Miata
    "The sport dedicating to the spirits of time attacking motoring" -Emilio

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    Master of Disaster SteveLevin's Avatar
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    I'm quite chuffed to see folks working with these engines. Ever since they came out (and had the power that a "V8 GT" had just a handful of years ago) I have been thinking that this class of engine is really cool.

    Hopefully CARB doesn't shove a hot poker into the hind end of these plans -- that would be tragically sad.

    Steve

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    http://www.trackhq.com/Banners/yellowsitesponsor.gif Blackbird's Avatar
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    Quote Originally Posted by emilio700 View Post
    Dunno what the diff weighs but I'd guess 55#
    I seem to recall factory 7" weighing around 67 Lbs. but haven't had one weighed in a while.

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    I wanna go fast! thepass's Avatar
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    Quote Originally Posted by Blackbird View Post
    I seem to recall factory 7" weighing around 67 Lbs. but haven't had one weighed in a while.
    Spot on. From my notes:

    Torsen differential 4.10 ratio 67 lbs no hardware
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    Ryan Passey
    Singulär Motorsports | Goodwin Racing

    #13 1990 Miata
    "The sport dedicating to the spirits of time attacking motoring" -Emilio

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