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4shadesofblue
4shadesofblue New Reader
11/20/14 6:27 a.m.

The $4K number came from looking at the popular kits on the market and plus some cooling upgrade parts. I have thought about going with the 99 motor, and adding a turbo down the road do I need to worry about the increased compression of a 99 (9.5:1) over the 94-97 motor (9.0:1)?

Going the with VVT motor is an interesting idea. I believe it is a little more work to do the swap, which I am ok with but does anyone know what gains in power it would have over a 99? And is worth the extra work?

I want to say how great this forum is!! Everyone has helpful replies that may help people long after I am done with this project. I also have not seen one "Search NooB" by the guy that has 7000 posts all saying the same thing.

z31maniac
z31maniac UltimaDork
11/20/14 6:30 a.m.

Go spend a few days on Miataturbo.net, you will be able to find all these answers with a bit of digging around.

SVreX
SVreX MegaDork
11/20/14 6:58 a.m.

In reply to Swank Force One:

Yeah, I understand I am in the gross minority, and I would definitely not suggest attempting it on the kind of budget I have.

But $4K is HUGE for a turbo. It's over twice what I would have expected (though, I will confess, I have never looked at the price of an available kit), and I am completely unequipped to get my brain around that.

My car was built with a lot of creativity, some questionable low budget parts, and very little money.

Some people build by bolting on expensive parts, with very little creativity (not suggesting anyone here).

I guess I am asking, isn't there any middle ground ? Are there options that utilize some pre-packaged components, with some creative substitutions to find a middle road on budget ?

I have no criticism of spending a lot on your car. If you've got it and want to spend it, enjoy it!

I just bought a complete, clean title, rust free 1.8L car with a 2nd engine for $800. Maybe I am just a little weird.

LanEvo
LanEvo Reader
11/20/14 7:48 a.m.

I've had turbo track cars and went back to NA. It's just more fun for me not having to deal with issues all the time; plus, the throttle response (and sound!) is nicer with ITBs or Weber DCOEs.

In an HPDE setting, I do see the value of straight-line power since people are always checking you up in corners and you're not allowed to go around them. A momentum car is frustrating to no end. Now that I'm racing, I'm less interested in straight-line power because I'm allowed to enter corners properly.

Dashpot
Dashpot Reader
11/20/14 7:54 a.m.

In reply to SVreX:

Depends if you want a perpetual project or not. R&D is expensive if you're doing on a track. A fully engineered kit is a good way for those who'd rather be driving than wrenching to get going. However in turbo Miata terms - "fully engineered" is a constantly moving target.

Swank Force One
Swank Force One MegaDork
11/20/14 8:32 a.m.
4shadesofblue wrote: The $4K number came from looking at the popular kits on the market and plus some cooling upgrade parts. I have thought about going with the 99 motor, and adding a turbo down the road do I need to worry about the increased compression of a 99 (9.5:1) over the 94-97 motor (9.0:1)? Going the with VVT motor is an interesting idea. I believe it is a little more work to do the swap, which I am ok with but does anyone know what gains in power it would have over a 99? And is worth the extra work? I want to say how great this forum is!! Everyone has helpful replies that may help people long after I am done with this project. I also have not seen one "Search NooB" by the guy that has 7000 posts all saying the same thing.

The swaps are about the same difficulty, i'd suggest putting a Megasquirt on the car at the same time, so that makes things about the same.

That said, i like the BP4W a little better, and people tend to want far too much money for their VVTs.

Swank Force One
Swank Force One MegaDork
11/20/14 8:36 a.m.
SVreX wrote: In reply to Swank Force One: Yeah, I understand I am in the gross minority, and I would definitely not suggest attempting it on the kind of budget I have. But $4K is HUGE for a turbo. It's over twice what I would have expected (though, I will confess, I have never looked at the price of an available kit), and I am completely unequipped to get my brain around that. My car was built with a lot of creativity, some questionable low budget parts, and very little money. Some people build by bolting on expensive parts, with very little creativity (not suggesting anyone here). I guess I am asking, isn't there any middle ground ? Are there options that utilize some pre-packaged components, with some creative substitutions to find a middle road on budget ? I have no criticism of spending a lot on your car. If you've got it and want to spend it, enjoy it! I just bought a complete, clean title, rust free 1.8L car with a 2nd engine for $800. Maybe I am just a little weird.

On the new market, $4k gets you the most bulletproof off-the-shelf kit available, a clutch, and possibly a radiator and a coolant re-route.

You'd still have to address fuel and exhaust.

But yes, there's most definitely a middle ground. FM will sell you a manifold and downpipe, and you roll your own from there. The hotside and cooling are the biggest issues on a Miata.

Or buy used.

If i shopped HARD i bet i could get a reasonably track-worthy turbo setup going on a car that has already had all the other things addressed (Suspension, transmission, rear end, brakes, etc) for about... $2500-3000.

calteg
calteg HalfDork
11/20/14 8:45 a.m.
SVreX wrote: In reply to Swank Force One: Yeah, I understand I am in the gross minority, and I would definitely not suggest attempting it on the kind of budget I have. But $4K is HUGE for a turbo. It's over twice what I would have expected (though, I will confess, I have never looked at the price of an available kit), and I am completely unequipped to get my brain around that. My car was built with a lot of creativity, some questionable low budget parts, and very little money. Some people build by bolting on expensive parts, with very little creativity (not suggesting anyone here). I guess I am asking, isn't there any middle ground ? Are there options that utilize some pre-packaged components, with some creative substitutions to find a middle road on budget ? I have no criticism of spending a lot on your car. If you've got it and want to spend it, enjoy it! I just bought a complete, clean title, rust free 1.8L car with a 2nd engine for $800. Maybe I am just a little weird.

The happy middle ground seems to be: Spend the money for a name brand turbo, manifold, and engine management ($500-$5,000, depending on your level of frugality). Cut costs on everything else.

Ebay intercooler, piping, exhaust all seem to work okay. Scavenged injectors are fine.

Keith Tanner
Keith Tanner GRM+ Memberand MegaDork
11/20/14 9:08 a.m.

We sell kits with no electronics (popular amongst the Megasquirt crowd) for $2995. If you want to source your own turbocharger, they're $1995. That gets you well proven and waranteed parts for under $2k, and you can add your own junkyard/DIY/whatever turbo/ECU/injectors. Just FYI. $750 gets you the manifold/downpipe/turbine combo instead.

You'd be amazed at how little time I spend wrenching on our turbo cars at the track. Some of that is due to proven "brand name" hardware, some of it is because our drivers all drive as if they don't want to break the car. Some are more aggressive than others, but nobody wants to break the car. On Miataturbo, that attitude is looked down upon. I break a lot more stuff with the V8 car than I do with all the turbo cars put together.

9.5:1 is fine for a turbo engine. You'll get more power per pound of boost, but you won't be able to run as much boost. Makes for better response though. I'd go with the VVT option if you can find a good price on the engine and you think you might stay naturally aspirated. If you're going to go turbo, then the 1999-00 head will do well.

In our testing with a naturally aspirated car, the flat top was worth power but only at the expense of the midrange. Good dyno queen and track car, not something I'd want on a street car.

kb58
kb58 Dork
11/20/14 11:34 a.m.

Moderate boost and sensible turbo selection can give a very reasonable torque curve. This is a Honda 2.4L and about 11 psi. As was said above, making the powerplant very robust is extremely important. In general, the reason why turbos "aren't reliable" is because people cut corners instead of doing it right. Heat is A Big Deal and must be kept at bay.

4shadesofblue
4shadesofblue New Reader
11/20/14 11:46 a.m.

So for a Miata what are the best options for managing heat? This is what I was thinking about.

Good radiator

Fans?

Oil cooler the size of Texas

Coolant reroute Louvered hood

Good tune

Swank Force One
Swank Force One MegaDork
11/20/14 11:57 a.m.
4shadesofblue wrote: So for a Miata what are the best options for managing heat? This is what I was thinking about. Good radiator Fans? Oil cooler the size of Texas Coolant reroute Louvered hood Good tune

That's a good start. FM has a really nice "Airflow kit" with shroud and some ballsy fans.

Ducting is good, too.

Keith Tanner
Keith Tanner GRM+ Memberand MegaDork
11/20/14 12:10 p.m.

You have to get the heat out of the engine and into the radiator, then you have to get the heat out of the radiator.

The stock pump seems to cavitate at about 6500 rpm or so, the electric pump deals with that. I don't know if anyone's seriously investigated underdrive water pump pulleys. The billet crank pulleys trash the oil pump, so that avenue has been neglected. The electric pump is really impressive, though.

To get heat out, you need an efficient radiator with good airflow. If you're on track, concentrating on lowered underhood pressures helps a bunch (louvers louvers louvers) as well as managing the intake. Most people concentrate on the former only and I think that's a mistake. The goal is as big of a pressure differential across the rad as possible. On a mixed use car, kickass fans do quite a bit. The actual air speed across the radiator is surprisingly low, even on the highway.

E85 is a good tool as well. The car runs cooler, has greater knock resistance and makes lots of power.

kb58
kb58 Dork
11/20/14 12:10 p.m.

There's no free lunch. If you make a 160 hp engine produce 300 hp - via a turbo, supercharger, or swap - there's now 300 hp worth of heat to get rid of.

codrus
codrus GRM+ Memberand Dork
11/20/14 1:13 p.m.

So far, there have been five "Miatas at Mazda Raceway Laguna Seca" events. I've brought my turbo Miata to to all of them and run in the "A" group, with a 40% success rate on bringing my car home in one piece. So here's a few anecdotal failures to consider:

The first event was 2009, just before lunch on Saturday I split the little tiny coolant hose that goes between the factory oil cooler and the back of the head. This proceeded to boil all of the coolant out of the car, generating some oversteer, a meatball flag, and an empty radiator in the paddock. After it cooled down I borrowed some parts from Keith to bypass the hose and filled it back up with water, but it was making steam out the tailpipe. Worried about the head gasket, AAA towed it home. The head gasket turned out to have a tiny leak, which seemed to fix itself over the next 6 months, but then I decided to tear it down and rebuild before 2010.

2010 I arrived with a freshly built motor. The car ran fine, although the weekend had quite a bit of rain, which limited how hard I could push.

There was no 2011 event. 2012 featured a lot of rain on Saturday so I turned the boost down, but clear and dry on Sunday. The second session I turned the boost back up and proceeded to strip all the teeth off third gear coming out of turn 11. Fortunately I now had a trailer complete with a winch, so I didn't need AAA to get it home

2013 was sunny and clear, my car ran fine all weekend, although I chewed up the brakes badly. The guy parked next to me in the paddock owned a nearby Spec Miata shop -- he sold three transmissions that day to other turbo Miata owners.

2014 was also sunny and clear (and now in September instead of March/April). The car seemed to be running fine at the end of the weekend (albeit with a minor coolant leak resulting form a hose clamp that needed tightening, and chewed-up brakes again), but when I got it home it was howling whenever it went into boost. This turned out to be a throttle body screw that had broken and been ingested through the motor, trashing a couple of pistons and the turbine along the way.

So, 5 events, 1 unqualified success, 1 partial success (rain meant I was taking it easy most of the weekend) and 3 failures. What do I take away from it? Running a car at the track is hard on it, and running a turbo car is at least twice as hard as a naturally aspirated one. None of the failures I saw were exceptional -- the cooling system is working hard, turbo cars kill transmissions, and throttle body screw failures are not uncommonly on heavily-tracked cars. This is all with an FM2 kit, running a 2560 turbo and making in the low to mid 200s in rwhp. These aren't the only known weak spots in a turbo track Miata either, I have put a fair bit of effort into addressing other known-weak spots on the car through inconel studs, a coolant reroute, an oil cooler, ATI super damper, big brake kits, proactive maintenance on fluids, bearings, known-weak electronics, etc.

The one problem I haven't really had at the Miatas @ MRLS event is overheating, but I put this down to the fact that it's in Monterey and usually in the spring. It's usually foggy and cool in the morning, warm in the afternoon but not hot.
OTOH, Laguna is tough on brakes, and I've pretty much never had a weekend there where the rotors didn't need replacing at the end. I now have an 11.75" Trackspeed kit waiting to go on the car once I get the rebuilt motor installed.

Thunderhill is an entirely different story on cooling. You want the biggest radiator you can find, lots of ducting, no AC condenser to block airflow, etc.

As Keith says, I could likely have avoided many of those failures by not running the car quite as hard. OTOH, I take the car to the track to have fun, and to see how fast I can go. Turning the boost down because the car is overheating, or lifting because the brakes pads are fading isn't fun.

Hey, Keith, any word on the 2015 event yet? :)

kb58
kb58 Dork
11/20/14 1:32 p.m.

In reply to codrus:

But would the failures be any fewer if you'd have swapped in a bigger engine producing the same power and torque? In my mind, the transmission would still break. The cooling line would still fail, and the brakes would still overheat. I guess I don't see the fact that it's turbo to be root cause of the problems, it's that the engine's making more power than its support system can handle.

Swank Force One
Swank Force One MegaDork
11/20/14 1:35 p.m.

The turbo presents its own set of problems due to some of the issues with the BP.

But yes... any motor making the same power/torque would have the same issues in a Miata. Maybe less so on cooling, because turbos do present their own cooling challenges (and so do BPs, for that matter), but the trans/rear end would have the same limits.

codrus
codrus GRM+ Memberand Dork
11/20/14 3:39 p.m.

Well, it's the torque that breaks the transmissions, not so much the power. But yes, swapping in a V6 that makes 300 lb-ft and bolting it to the Miata transmission is going to result in similar life expectancy. The original question was comparing naturally aspirated BPs to turbo ones, and you'll never break a 5-speed with an NA BP.

Cooling, brakes, etc are going to be common problems with any form of making power but I think throttle body screw failure is a fairly uniquely BP thing, at least I've never heard of it happening on other cars.

Keith Tanner
Keith Tanner GRM+ Memberand MegaDork
11/20/14 4:02 p.m.
codrus wrote: As Keith says, I could likely have avoided many of those failures by not running the car quite as hard. OTOH, I take the car to the track to have fun, and to see how fast I can go. Turning the boost down because the car is overheating, or lifting because the brakes pads are fading isn't fun.

So, how much fun did you have and how fast did you go with a broken car?

Shifting at 6000 instead of 7000 means the car stays much cooler, that's the sort of behavior I was suggesting. It might be a half second slower per lap (and feel even slower), but if it means more laps then you win.

The split coolant hose isn't the turbo. Neither is the lost throttle screw. So, of that antectode, it sounds like you had one transmission failure that was due to the turbo. The others would have happened without it. The brake problems are due to a car that had more engine than brakes, that's easy to fix. It's good practice for endurance racing

2015 will be in the fall again. It will be one of two specific weekends, I'm waiting for the decision on which one before I make the announcement.

codrus
codrus GRM+ Memberand Dork
11/20/14 4:32 p.m.
Keith Tanner wrote: So, how much fun did you have and how fast did you go with a broken car? Shifting at 6000 instead of 7000 means the car stays much cooler, that's the sort of behavior I was suggesting. It might be a half second slower per lap (and feel even slower), but if it means more laps then you win. The split coolant hose isn't the turbo. Neither is the lost throttle screw. So, of that antectode, it sounds like you had one transmission failure that was due to the turbo. The others would have happened without it. The brake problems are due to a car that had more engine than brakes, that's easy to fix. It's good practice for endurance racing 2015 will be in the fall again. It will be one of two specific weekends, I'm waiting for the decision on which one before I make the announcement.

I actually mostly shift around 6500 on the track, with the torque curve on the 2560 there wasn't much point in going to 7200.

I don't know what the ultimate cause of the split coolant hose was, but I'd assume it was heat, and there's a lot more heat with the turbo than with an NA car, even if you're shifting at 6000. Perhaps that's a fluke, it doesn't seem to be a common failure. The throttle body screws do fail on NA cars, yes, but as I understand it that's mostly in high-revving ones, not cars with stock redlines. My rev limit has always been stock, and I don't bounce it off the limiter.

So how much lifting is required to get a turbo Miata to last reliably? There's no way to know except to say that it wasn't enough after a failure. I've always tried to practice mechanical empathy -- that 5 speed went over 50K miles with the turbo on the car before giving up at Laguna.

I think really what I'm saying is that stock Miatas do well at the track because they're light, nimble, and grossly underpowered. You can fix the latter part fairly cheaply with a turbo, but in so doing you expose a big pile of other stuff that needs addressing and now it's not cheap any more. You can make it last longer by lifting (and thus effectively making less power), but if you're not going to use the power then why bother to put it in the car in the first place?

4shadesofblue
4shadesofblue New Reader
11/20/14 5:04 p.m.

Codrus, Thank you for the great insight in your experience with a turbo Miata on track. How much boost were you runnung? If you had to do it all over again, what would you do?

I would love to make it to that Miata event, but it might be a little far. Maybe FM could sponsor a Miatas at Road America event

codrus
codrus GRM+ Memberand Dork
11/20/14 5:18 p.m.
4shadesofblue wrote: Codrus, Thank you for the great insight in your experience with a turbo Miata on track. Do you know much HP you were running? How much boost? If you had to do it all over again, what would you do? I would love to make it to that Miata event, but it might be a little far. Maybe FM could sponsor a Miatas at Road America event

At the first event, with the stock bottom end, the car was making around 220-230 at the wheels, running a MAP of around 180 kpa (roughly 12 psi of boost at sea level). After building the engine I turned the boost up, and it was making 250-270, a MAP of about 200 kpa.

Stuff I'd do differently, hm. Given the constraints I had at the time I made the various decisions, I don't have a big list of stuff. I wish I'd ditched the Wilwood-brand pads sooner, I kept trying stuff to make them work when I really should have just gone with something else. I'll be running Hawk pads at the next event. I also wish I'd read more about the throttle body screw failures and either bought the Skunk2 throttle body sooner, or at least epoxied the stock one. Epoxy doesn't stop the screw or shaft from breaking, but it does at least contain the pieces and stop them from being ingested.

Dashpot
Dashpot Reader
11/20/14 8:59 p.m.

In reply to 4shadesofblue:

I've had similar but slightly better experiences than Codrus running an older FMII. I'd do 6-8 events a season and average 2 DNF's a year; one each mechanical & electrical.

I run the car at 200 WHP and had a fair bit of frustration keeping the turbo stuff alive early on. With experience, the mechanical stuff became straightforward once the right bits hit the market. Inconel turbo studs, braided SS oil & water lines, lots of heat shielding & ducting later - it works pretty well and it's a fun and balanced car.

I got a fair amount of comments over the years for being "the only reliable turbo Miata" to run time trials. The only way to get there is a lot of upgraded parts, a good conservative tune, keeping the hours down, and keeping a close eye on the mechanicals.

If you're not in for that kind of commitment, I suggest keeping the motor fairly stock and thrashing it with abandon. There are trade-offs but you'll have fun either way you go.

4shadesofblue
4shadesofblue New Reader
11/21/14 7:52 a.m.

After reading comments on here and on TurboMiata, the amount of time and money put into a making a Turbo Miata a reliable track car might not be for me. My concerns are that the cost could end up skyrocketing trying to get all of the pieces to make it reliable. I enjoy the working on the car, but I do not want to spend time at the track working on it other than little things. The worst case for me would be to drive 6 hours to RA and lose a half of a weekend because of a broken car.

I think the 99-00, or the vvt would be a good choice for this year. About 40% more power than what I am running now with the 1.6 and should be pretty reliable. I believe Keith said that would end up at around 140whp? Is there a way to get a little more power without building a motor or FI? This would still leave the option down the road for a turbo if I change my mind.

How about a wing to help pick up more speed in the corners, how much HP would be needed to overcome the drag to make it worth wild?

Leafy
Leafy HalfDork
11/21/14 8:04 a.m.

Realistically its going to take 6 grand just under the hood to make a reliable turbo miata track car. You're into the $600 radiators, quality oil coolers, inconel fasteners, skunk 2 throttle body, ducting, hood vents. And thats only if you're looking for ~220hp. Bump that up over 250 and you're quickly adding even more beyond the cost of building the motor.

There's always the K series swap to get you to 200hp, without having to worry about a lot of the turbo issues.

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