No FM Turbo for a 1.8-swapped '91 Miata--now what?

For years I've dreamed of installing a full Flyin' Miata FM2 turbo kit on a 1.8L, ideally stroked to 2.0L with a small turbo for better spool, in my 1991 Miata.  For a decade, I've been holding on to a 1.8L engine from a 1994 that I planned to build for the swap into my '91.  The dream has been downsized over the years as the stroker crank is no longer available, the FM2 was dropped for emissions reasons, and my fascination with raw power has dwindled after driving seriously fast cars.  I'd finally made peace with the idea of the FM voodoo kit for the 1.8l swapped in my '91.  I figure 180hp of turbo power is probably plenty, and I loved the idea of stock-ECU reliability and driveability without having to deal with tuning an ECU.

Now that I've finally got the financial resources to do it, and the FM turbo kits are back in stock today, I decided to place my order.  Not seeing any good way to specify that I wanted the kit for a 1.8l-swapped 1991, and knowing that I, at the least, needed a 1.6l voodoo box, I submitted a request from FM support only to find out that they just won't, for emissions reasons.

I've long been a vocal proponent of FM's stance on emissions issues--back from their early decision to stop selling cat delete pipes all the way though the understandable migration to only selling CARB legal turbo kits.  I totally understand the need to protect their business given the current situation with federal regulations on emissions defeat devices.  But now that this completely shoots down my own plans which I feel are completely reasonable, I'm frustrated.

It's fine that FM doesn't want to sell me exactly the kit necessary.  But the fact that I can't just order a 1.8L kit without the 1.8 voodoo box and separately order the 1.6L voodoo box feels like going way beyond what the law requires.  And this statement from FM really annoys me: "Unfortunately, there isn't a straightforward way to install a Flyin' Miata Stage 1 Turbo Kit onto a 1.8L swapped NA6 Miata due to the differences in the components required to suit the different year ranges. And due to emissions laws needing to be specific to the model years and standard (stock) equipment that they were delivered with from the factory, there isn't a way to legally utilize an FM Stage 1 Turbo Kit on an NA6 Miata with a 1.8L swap, anyway."

The first part is simply not true--folks have been trivially installing NA8 turbo kits on 1.8l-swapped cars for decades.

I'll admit I'm no expert, but I'm skeptical of the second part as well.  It feels like a 1.8-swap-turbo kit could be made legal.  If you can make an LS swap CARB legal, how is it that you can't make a 1.8 swap legal?  Forgive me if I'm wrong, but it seems like there's probably just no demand to do so, which is different than impossible.

I'm disappointed.  Now what?

I live at 9,200 feet.  Despite being happy driving a 1.6l Miata for the bast 28 years, my Miata is now so slow as to be unpleasant.  Part of this is a the result of a somewhat tired original engine with 215,000 miles.  Part of this is the fact that I swapped 4.1 torsen into it.  Most of this is because a 1.6l Miata just can't keep up with modern cars climbing a mountain pass at 9,000 feet no matter what.

(1) Hobble together a turbo kit from part vendors that aren't as concerned about federal regulations, install a standalone ECU and build what I want to build.  I've got the money to do this, I can probably acquire the missing skills, but I'm not sure I have the time or patience for a project this size.  I don't want to turn my very clean '91 BRG into a disaster of a project car.  I want it to be a Miata when I'm done, just one that's faster.

(2) Some non-Miata engine swap.  I'm not enamoured of this idea, either.  For one, I want it to still be a Miata.  I want power steering, air conditioning, and I want it all to fit properly.  I don't want a Miata that makes V8 or V6 noises.  If I wanted a Corvette, I'd buy one of those.  I don't.

(3) Buy an ND3.  Still a huge power loss at 9,000ft, but a lot more to start with.  Probably enough that I could at least not be a rolling roadblock at redline in 3rd climbing the hill to my house.  I like the ND3 a lot, but I'd really planned to keep a 1991 Miata as my primary vehicle forever.

(4) Build a faster normally aspirated Miata engine.  High compression, ported heads, bigger valves, standalone ECU...  This would keep the character of a Miata, at least.  But I'm worried it'd be a crap-ton of work, and when I'm done, may still be a rolling roadbloack over the pass.

(5) Leave it mostly stock.  Refresh the engine.  Find a 4.3 Torsen diff.  (I need a functional LSD to reliably get out of 30 degree-inclined dirt driveway that's ice-covered much of the year, even when it's nice out.  The 1.6 vlsd doesn't cut it.  I have a MazdaComp clutch-type LSD that was great for about 200,000 miles, but I can't seem to get anyone to be able to set it up so that it'll stop whining, but that's another option.)

(6) Give up and rebuild the 1.6L for a 1.6 turbo kit.  This feels like giving up when I've got a 1.8L engine ready to rebuild, and 1.6L turbo internals aren't as easy to come by.  Obviously with the voodoo kit, stock internals are fine, but if I did decide alter to upgrade the injectors/ecu and crank up the boost, that wouldn't be as much of an option.  Not to mention that bigger displacement spools a turbo faster, and I think the 1.8 cams are probably better suited to boost. 

(7) The option I'm leaning toward: buy the 1.8L turbo kit as-is and go straight to an aftermarket ECU.  This would let me run the 1.8L throttle body and the rest of the FM kit as-is (except the Voodoo box).  I'd have to deal with tuning the ECU, and I'm worried about long-term reliability and driveability, but a zillion people are doing this (and FM used to), so how bad could it be?  I'll mention that while I'm a decent mechanic, I'm already spending most of my weekends in the garage wrenching on race cars and there's only so many non-working hours in the week.  On the plus side, I could go straight to something a lot closer to the old FM2 setup, but I'm less excited about doing that without FM support.

Any other good options I haven't thought about?  Anyone else in a similar boat recently?

Why not change the wiring harness and ecu to the 1.8 flavor and just say it's a 1994? Then add the fm turbokit with voodoo box?

I can't imagine a 1.8 computer and harness is that difficult or expensive to come by.

It's totally possible I am not understanding the situation.  I just know from years of champcar racing that it is VERY difficult to tell the difference between a fully swapped (to) a 1.8 vehicle and a stock 1.8 vehicle.

In reply to wvumtnbkr :

This is doable, but it's a *lot* of work.  I do have the entire donor car still, but a harness swap is enough extra work that I'd probably rather take my chances with an MSPnP than strip down 2 cars far enough to swap the harness.  But you're right, it's an option I hadn't even considered.

(8) - sell the NA, buy a nice NC2 and install FM's forthcoming turbo kit.

Our NA race car started out with a 1.8 VVT swap on MS3, so I've done the 1.8 in a 1.6 car on a standalone.  The 1.8 isn't a complete plug/play with the 1.6 harness, especially with boost added.  I made my own harness from the firewall forward.  The required mods will take things away from the "install this on a stock car and it's legal" path that FM has chosen for their forced induction products, and I don't blame them for that.  You can still DIY a turbo/standalone setup, and that path has been long established in the Miata community.  You're on your own at emissions time, however.

I elected to pass on forced induction on our race car, in favor of the N/A reliability of a K swap.  Once I worked through the usual teething problems, it's been fantastic.  I would definitely not choose it for a street car, however.... way too much NVH.

I had an NB street car that I had a lot of time and money into, that was going to get all the turbo parts I bought for the race car.  Until I learned FM was developing an NC turbo, and it would be 50 state legal.  Our NC PRHT was our favorite street Miata, so that was all the prompting I needed to push us back into an NC.

An aftermarket turbo/standalone setup is not difficult to put together for an NA/NB Miata if you're not concerned about being strictly legal.  FM's kits are the legal easy button, but only for the configurations that they've spent the time, money and development to bring to OEM levels of driveability and reliability.

I'm not concerned about being strictly legal, and there is no emissions testing where I live.  That said, I absolutely intend to run a catalytic converter and reasonable emissions devices.  I'm not even opposed to running an EGR system, if I can.

What are the gotchas with running a 1.6 MS3 on a 1.8L turbo car?  I found that something about throttle position sensor needs to be modified, is there anything else?  Maybe this is a lot less straight forward than I thought?

You probably don't need to swap the entire harness.  I believe you can buy both 1.8 and 1.6 ECU connectors, with those, you can solder together an adapter harness.  It's tedious work, but straightforward.  The 1.8 harness will have a few extra wires that aren't on the 1.6, those you'll have to supplement in an additional harness (can probably scavenge most of that out of the donor harness).  So if you want the emissions-legal FM kit, swap the motor and do the harness adaption so that it runs on the 1.8 ECU, then you can just buy the 1.8 kit and plug it in.

(FWIW, doing this would be full legal under California's emissions laws -- you can swap the engine, ECU, and other emissions-related components from a newer car into an older one, after which it is treated as if it *is* the newer vehicle for future emissions purposes).

As far as the options above

You can sort of combine 1 and 7 by buying the used FM parts that you need and a megasquirt or other aftermarket ECU.

2) I've never driven one, but a K-swapped Miata is supposed to be the ideal answer here.  4 cylinder, similar/less weight, same transmission, it's just a Honda engine with everything that implies.  A lot more work and money than a simple turbo kit though.  Also, a lot of the swaps I've seen online seem to have perpetual gremlins.

3) I haven't driven one of these either, but I expect it's a very different experience than a turbo NA/NB.

4) Agreed.  Tons of work for not a lot of actual power gained.

5) No comments on this.

6) I don't recommend building a 1.6.  Everything you can do to a 1.6 you can do to a 1.8 and it will be even better, and you can even swap most of the parts of a 1.6 turbo kit onto a 1.8 if you later decide to go for more power.  Once you go inside the motor though, that money is sunk on the 1.6 and can't be transferred.

From Rodan:  8) <insert nautical meme here>

I'd probably (9) buy an early ND and the BBR turbo for that before going for the NC, but this is totally a valid option that I should consider.  I have always liked the way yellow looks on an NC, and I'm way too big for an NA even though that hasn't stopped me for the last 28 years.  An NC is actually the only generation I've never driven--I've driven the rest extensively.  I don't fit in an NB, and the ND feels like a modern NA to me.  And as I get older and fatter, maybe I should get an older and fatter car:)

Berck said:

What are the gotchas with running a 1.6 MS3 on a 1.8L turbo car?  I found that something about throttle position sensor needs to be modified, is there anything else?  Maybe this is a lot less straight forward than I thought?

IIRC the 1.6 throttle body is a 3 position sensor ('idle', 'wot', 'something in the middle'), while the MS3 really wants one with a numerical range in the middle.  The 1.6 automatics got a full range sensor and that can be swapped to address this.

The difference between 1.6 and 1.8 megasquirts is basically just the connector/pinout that they put on the unit and the default starting tune that it comes with.

codrus (Forum Supporter) said:

You probably don't need to swap the entire harness.  I believe you can buy both 1.8 and 1.6 ECU connectors, with those, you can solder together an adapter harness.  It's tedious work, but straightforward.  The 1.8 harness will have a few extra wires that aren't on the 1.6, those you'll have to supplement in an additional harness (can probably scavenge most of that out of the donor harness).  So if you want the emissions-legal FM kit, swap the motor and do the harness adaption so that it runs on the 1.8 ECU, then you can just buy the 1.8 kit and plug it in.

I'm liking this idea, aside from wondering about long-term reliability on a splice job like that.  A few wires sounds a lot better than trying to transplant an entire harness, and it'd get me the stock ECU experience.  The stock ECU is the part about the current FM offering that appeals--the legality doesn't currently matter to me at all, but it's nice to know that as Colorado adopts more California regulations that I'd likely be okay.

Let me just address a couple of things. 

Berck said:

It's fine that FM doesn't want to sell me exactly the kit necessary.  But the fact that I can't just order a 1.8L kit without the 1.8 voodoo box and separately order the 1.6L voodoo box feels like going way beyond what the law requires. 

We have to protect our livelihood. It's easy for someone to post to the internet that "why not just mix and match these parts, it seems like it's probably legal". It's not. If you want to sit down and talk about the strict definition of the Clean Air Act, we can do that. For this discussion, take it as a given that we cannot sell devices that could affect emissions without proving that they do not. Yes, we're more conservative than some and we are always talking about where the line should be drawn. But we have also not been heavily fined by the EPA or the ARB, so that's a plus. 

And this statement from FM really annoys me: "Unfortunately, there isn't a straightforward way to install a Flyin' Miata Stage 1 Turbo Kit onto a 1.8L swapped NA6 Miata due to the differences in the components required to suit the different year ranges. And due to emissions laws needing to be specific to the model years and standard (stock) equipment that they were delivered with from the factory, there isn't a way to legally utilize an FM Stage 1 Turbo Kit on an NA6 Miata with a 1.8L swap, anyway."

The first part is simply not true--folks have been trivially installing NA8 turbo kits on 1.8l-swapped cars for decades.

I'll admit I'm no expert, but I'm skeptical of the second part as well.  It feels like a 1.8-swap-turbo kit could be made legal.  If you can make an LS swap CARB legal, how is it that you can't make a 1.8 swap legal?  Forgive me if I'm wrong, but it seems like there's probably just no demand to do so, which is different than impossible.

The first part is true. You cannot take an off-the-shelf FM turbo kit - as available from FM - and install it on a 1.8 swapped NA6. There are parts that can be swapped around or modified, but that does not make the statement false.

The reason we could build a legal LS Miata is because GM invested a bunch of money into obtaining a remarkable EO for an LS swap that covers ALL vehicles up to 1995. It's the existence of that EO that makes it plausible. The other option is to insert all of the emissions equipment from a donor vehicle - ALL of it - into a Miata. In order for us to make a 1.8 swap legal, we'd have to take the swap through the full emissions test regimen which is remarkably expensive. So while that does make it possible, it makes it a non-viable option as it would involve tens of thousands of dollars worth of testing. Until that is done, it is not legal. So again, that's a true statement at this time and will remain so until someone takes a swapped 1.8 with an FM turbo kit through the full EO process.

I suspect a fairly large number of our turbo kits get the Voodoo Box removed and replaced with an aftermarket ECU. So you could buy a 1.8 turbo kit and find a Voodoo on the secondary market. Or go with an aftermarket ECU and suck up the hassle of dealing with cold start and the like. Since you were talking about bigger injectors and higher boost, you're looking to go that way anyhow.

As for the 1.6 TPS, we do sell a kit to install a BMW TPS on the 1.6 throttle body. That plays nicely with an aftermarket ECU. Or you just use a 1.8 throttle body which actually makes the engine swap a bit easier.

I own a 1.8 swapped turbo Miata. I repinned the wiring harness to allow me to make it a "native" 1.8 - I think it's a 2004 MSM, technically. It runs an FM turbo kit for a 1.8.

Berck said:

codrus (Forum Supporter) said:

You probably don't need to swap the entire harness.  I believe you can buy both 1.8 and 1.6 ECU connectors, with those, you can solder together an adapter harness.  It's tedious work, but straightforward.  The 1.8 harness will have a few extra wires that aren't on the 1.6, those you'll have to supplement in an additional harness (can probably scavenge most of that out of the donor harness).  So if you want the emissions-legal FM kit, swap the motor and do the harness adaption so that it runs on the 1.8 ECU, then you can just buy the 1.8 kit and plug it in.

I'm liking this idea, aside from wondering about long-term reliability on a splice job like that.  A few wires sounds a lot better than trying to transplant an entire harness, and it'd get me the stock ECU experience.  The stock ECU is the part about the current FM offering that appeals--the legality doesn't currently matter to me at all, but it's nice to know that as Colorado adopts more California regulations that I'd likely be okay.

It's possible for a home mechanic to make splices that are the equal of factory ones. It's also possible to repin connectors so that splicing isn't actually necessary, although you'd have to add the extra wires for the sequential injectors and (I think) one more for the TPS as well as EGR. Go for a 1994-95 harness/ECU as it's the simplest one and the connectors at the ECU are the same as the 1.6 with most of the same pin locations IIRC. I probably have one of the ECUs. Thinking about it, I'll bet that's a fairly easy conversion to make. Most of the harness is the same.

In reply to Keith Tanner :

This is fair, but I think you can also appreciate my disappointment.  Especially since it's something that you guys used to fully support, as well as even build for customers.  I get that the world is a different place now, and I applaud you for complying with the law.  I also appreciate that it's not my livelihood, but it does feel aggressively conservative even if I'm wrong.  I'm genuinely angry that it's still trivial to purchase the coal-rolling devices that started this enforcement wave, but my plans to build a clean-burning Miata are the ones foiled.  Not your fault, I know, but it doesn't make me less annoyed.

My 1994 engine is still sitting in my crashed donor car in my driveway, with a '94 ECU and a '94 harness.  Pin-swapping sounds even better than splicing.  I was mostly deterred by the warning in the FM engine swap instructions.

In reply to Keith Tanner :

To add to this post a little...

It's one thing to be probably correct that the 1.8l swap with the turbo is likely to be the same as the 1.6 in terms of emissions.  It's very much another thing to prove it.  

So Berck, I totally get the disappointment that you have posted, that's very natural.  But I also know the testing requirements that companies have to go through, and it's a lot harder than most people think (in terms of process and expense).  If you wanted a 1.8L turbo, you needed to start with a 1.8l Miata.  It may seem conservative, but given the expense to go through for FM, how many 1.8l swapped NA6s are they going to sell?  

Trust me, I get it. "Are we being too risk adverse" is actually a conversation we're having, and as always the easiest option is to avoid the grey areas. It's partly my fault because I'm one of the decision makers at FM, although I tend to be a little more on the cowboy side. And as for those coal rolling devices, just ask the vendors how that's working out...

I'd be happy to help figure out the repinning involved to get that '94 ECU into your '91. It's been a while, but I'm pretty sure I've done it in the past and it's fairly straightforward. We have to put the warning in the instructions because otherwise people can get in WAY over their heads without enough knowledge.

Here's a fun thing: there are 1994-97 BRG Miatas in Canada that are legal to import into the US. So there's a way to get a 1.8 BRG without an engine swap :) It can even already come with a 4.1 Torsen.

In reply to Keith Tanner :

I did not know that!  I suspect finding one for sale in as good a condition as mine (albeit high-mileage) and then dealing with importing it is no easy feat.  Also, I like the NA6 interior better.

Okay.  1994 FM Turbo kit ordered.  I'll do the '94 ECU swap.  Here's hoping the ECU is still good after a decade in my driveway...

Now for the more fun questions: the 1.8 is absolutely getting rebuilt.  I'm leaning toward the FM Wiseco pistons and Carrillo rods since I'm rebuilding anyway, even though it's likely overkill for stock injector power levels.  What else should I consider?  I'd like to refresh the head, not sure if it's worth going crazy with the valves?  It was shaved after a head gasket failure, which increased the compression enough that it demanded higher octane fuel (87 at altitude, where 85 used to be fine), but I have no idea how much that was... is it a bad idea to reuse it in a turbo application?

Keith Tanner said:

It's possible for a home mechanic to make splices that are the equal of factory ones. It's also possible to repin connectors so that splicing isn't actually necessary, although you'd have to add the extra wires for the sequential injectors and (I think) one more for the TPS as well as EGR. 

I suggested soldering because the only ecu-side connector I was able to source when I was making an extension harness was one intended to be soldered onto a circuit board, so repinning/crimping wasn't an option for me.  It worked out fine, but in this situation I agree that repinning makes way more sense -- I'd forgotten that the connectors are the same between the 1.6 and 1.8.

Berck said:

It was shaved after a head gasket failure, which increased the compression enough that it demanded higher octane fuel (87 at altitude, where 85 used to be fine), but I have no idea how much that was... is it a bad idea to reuse it in a turbo application?

It depends on how big a turbo you're going to use, how much boost you want to run, and how easy it is to source higher octane fuel.  My head has been shaved 3 (I think) times, and that was enough that I needed 95 octane to reach MBT at 24 pounds of boost.  That was fine at the time because I had fairly easy access to 100 unleaded, and it was a lot cheaper than it is now.

If you're happy with low-200s of rear wheel horsepower then I don't think there's any real need for "performance" head work, the turbo will do that just fine.  You'll get small improvements in spool, but that's about it.

In reply to codrus (Forum Supporter) :

It's going to need to be able to run on 91 octane, which is all I can get at gas stations out here.  I'm thinking I'm likely going to be content with it in on the stock ('94) ECU.  If I do decide I want more, I can't see wanting to higher than something like 14psi.

You said you wanted response. High compression on a turbo engine will get you that. It'll help make up for the slower spool at altitude. You won't be able to make as much power on a given octane but it'll be perkier. 

The one other thing I'd do if you're rebuilding with a look towards durability would be an upgraded damper. It'll make the engine smoother, give you a more precise timing signal for an aftermarket ECU and will help protect your oil pump. Not really necessary at the power levels you're talking (initially) but you'll probably notice it more day-to-day than the rods!

The thing about Canadian Miatas is that they tend to be summer-only cars, which both protects them from rust and keeps them lower mileage. You're right about the NA6 interior but I've done that swap before :)

In reply to Keith Tanner :

I definitely care about about response.  The thing I miss most about my Focus RS was how it made power instantly, and even did so at low RPM and at altitude.  I'm pretty sure it hit full boost well before 3,000rpm thanks to the super clever twin-scroll turbo.  I've never driven another turbo car that felt that responsive.  I think it had a lot to do with spooling at low RPM rather than turbo lag. The GR Corolla we replaced it with doesn't have much in the way of turbo lag, but it has more than the Focus, and it definitely doesn't spool all the way until more like 4,000rpm.

I've never driven a turbo Miata of any sort, but I know that I'm not going to get anything like the Focus RS out of it.  I mostly want to be able to enjoy the car and drive home up the hill while maintaining the speed limit:)  I'm definitely willing to sacrifice outright power for responsiveness.  I'd like it to still feel like a 1.6 Miata if that's even remotely possible.  I also can't just build it for the altitude--I want to be able to drive it on a road trip without worrying about blowing it up.

Are the rods overkill? I need to buy pistons for an overbore, anyway.  I figured the rods would be worth it for the peace of mind and assumed the fact that they were lighter wouldn't hurt spool times, either?

What I really don't want is the turbo experience from my WRX: no power forever, oh-my-god-all-the-power-shift-already, followed by another eternity of no power.

A good turbo Miata definitely doesn't feel like a WRX.

Rods are probably unnecessary. IIRC aftermarket rods aren't usually any lighter, it's the pistons where you save weight. A lightweight flywheel helps as well. To help spool, you'll want high compression, a good flowing head and not a lot of exhaust backpressure. High compression doesn't mean you can't drive it at sea level, it just means you can't run as much boost.

You'll have to adjust the boost for lower altitude unless you use an electronic boost controller that uses an absolute manifold pressure target, but that's easy enough.