Learn me NA Miata engine options

... that are not spelled LSx or SBF. In other words, stuff that says "Mazda" on it.

It looks to me like I have two and a half options:

• Rebuild the existing engine, which is something I've never done before, or replace it with a used or rebuilt NA 1.8L engine. That's probably the simplest option, if I rebuild it I can get a little headwork done (on the car, that is), bolt it together and hope it doesn't fall apart anytime soon.
• Drop in a VVT engine with the help of VVTuner. More power, depending on the source the engine isn't that much more expensive and it seems to be a relatively simple job.

Is it even worth considering dropping the higher compression 99/00 engine into an NA? Anybody done it? I know some of the sensors aren't the same, but is there anything that would prevent me from doing it (apart from finding a way to actuate the solenoid in the intake tract)?

My personal suggestion is rebuild + tarbo.

MSM swap? Evanb and Keith had parallel projecta going, and they are both still alive, last I heard.

I like the vvt option, myself.

z31maniac wrote: My personal suggestion is rebuild + tarbo.

Dumbass. Everyone knows it's torbo, not tarbo.

First thing is asking if you are going to run any class in any series with it or is it just for fun?

The later motor in the older chassis is "worth it" in that the older chassis is lighter. In fact, that motor swap is the hot ticket for CSP autocross IIRC.

That said, what is the price comparison between a direct drop in motor vs the later motor (more $, add prices of sensors and computer to drive it)?

If that price approaches forced induction $$, the turbo will be faster.

HOWEVER, IIRC you are interested in it being a bulletproof trackday car. From what I have been reading the turbo will not be anywhere near as reliable for a track car. (street and auto-x no problem really from what I have seen)

How badly do you want the extra power of the later motor? Is it worth the price difference to you?

I have a 96 motor with a bad crank nose, I grabbed another motor from a junkyard and have been happy (there were only 30k miles on the JY motor, screaming deal at $675, saw others like that on car-part for $1200).

Remember to budget new timing belt, water pump, and oil seals for while the motor is out! (also check and see how your motor mounts are doing. I put the Mazdaspeed ones in mine when I found one mount with a crack halfway through the rubber)

On the other hand, I got to try a home-brew turbo'd NB at and auto-x and it was everything I wish my NA was power-wise. I would say even more fun then my ESP mustang cobra (but it was on a small lot) (funny, all the NB's I have driven were turbo'd and I havent driven a turbo NA)

In your shoes.. easy button in a JY motor, maybe hold onto the core and rebuild on the side as time/money allow. (because downtime makes us all tempted to sell a car)

Most JY's give a few months warranty on their motors, if there is an existing problem you should come across it by then.

If you want to turbo, you are making it a whole different beast. Your taking a fun little momentum car and making a little rocketship.

rebuild. do a lil head and intake work. bump the compression to 11.5 and do a 40 over bore when rebuild. have fun.

F2t something something

z31maniac wrote: My personal suggestion is rebuild + tarbo.

No turbo - I'm trying to keep it reasonably simple and with the temperatures at the local track I don't think I want to deal with the potential cooling issues when it comes to running a turbo.

Apexcarver wrote: First thing is asking if you are going to run any class in any series with it or is it just for fun?

This is for a car that is mainly used as a D-ishD with the odd PDX/HPDE and hopefully at some point SCCA Club Trials. But we're talking a few days a year here.

Eventually I'm hoping to be able to do a little vintage racing but at the point I'll buy a real racecar.

Apexcarver wrote: That said, what is the price comparison between a direct drop in motor vs the later motor (more $, add prices of sensors and computer to drive it)?

The used engine supplier that was recommended to me wants about $250 more for the VVT engine. On top of that, my understanding is that at the very minimum I'd need the diyautotune VVTuner to basically make the newer engine speak older ECU. I'm still at the research phase on that so I might be missing something obvious (which is why I'm putting this up here). The VVTuner is $200 + the cost of the harness. Call the price difference about $500 compared to just dropping in the same type of engine I already have.

Apexcarver wrote: HOWEVER, IIRC you are interested in it being a bulletproof trackday car. From what I have been reading the turbo will not be anywhere near as reliable for a track car. (street and auto-x no problem really from what I have seen)

I know that FM tracks the cars they build, but I don't really want to pour that sort of cash into the Miata right now.

Apexcarver wrote: How badly do you want the extra power of the later motor? Is it worth the price difference to you?

For the above price difference and maybe anything up to a grand, I think it's worth it. Anything more, no.

The way I'm looking at it is that the conversion work is mostly work that I am comfortable with (bolting E36 M3 on and dealing with electronics) whereas, say, rebuilding an engine would be an interesting and very new experience..

Apexcarver wrote: o budget new timing belt, water pump, and oil seals for while the motor is out! (also check and see how your motor mounts are doing. I put the Mazdaspeed ones in mine when I found one mount with a crack halfway through the rubber)

Yeah, I'm budgeting for that and a new clutch - I have a suspicion that the rear main seal on the current engine is leaking somewhat, plus it would be silly not to change a clutch that's got 130k on it when you already have the engine out.

If the engine comes in at a reasonable price (ie, the one I was quoted at), I might even be able to upgrade the cooling system.

Apexcarver wrote: On the other hand, I got to try a home-brew turbo'd NB at and auto-x and it was everything I wish my NA was power-wise. I would say even more fun then my ESP mustang cobra (but it was on a small lot) (funny, all the NB's I have driven were turbo'd and I havent driven a turbo NA)

I have owned a homebrew turbo NA for a while, built by a forum egg-spurt over in the UK. If I turbo one these days I'm buying the kit off FM .

When it was running, it was fast though - roughly as fast as my stock Lotus Elise S1. The problem was, the Lotus was a lot less trouble.

My autox-centric brain says later motor. A well prepped CSP car looks like a lot of fun. But more practically, it seems a car built with a little bit of focus in this regard will be easier to sell should you decide to.

KATYB wrote: rebuild. do a lil head and intake work. bump the compression to 11.5 and do a 40 over bore when rebuild. have fun.

The only issue I can see with that is that I will have to get proper engine management to run a motor with that sort of compression, which will make the whole endeavour a little more expensive. I'm also not sure that my first attempt at rebuilding an engine should also include mapping it before it blows up .

Ian F wrote: My autox-centric brain says later motor. A well prepped CSP car looks like a lot of fun. But more practically, it seems a car built with a little bit of focus in this regard will be easier to sell should you decide to.

I don't think I'd have a problem selling a car like that, especially not when built carefully. It might not be CARB legal though, which would pretty much rule out the biggest market over here but I think I could find someone who'd need to buy it on this side of the border.

The other option is always to keep it as an MEV Exocet donor should I accidentally stuff it into the scenery.

Yeah dang CARB we don't get to go as crazy as we would like here

We don't have any smog checking where I live and that makes life a lot easier, but modifications that are fine down here often won't even fly up in Reno, let alone over in CA.

It's probably way too wide, but has anyone ever tried a KL-series V6 in a Miata? Will the trans mate up?

That has been tried - there are a few cars around with KLZEs(?) but IIRC they're not that easy to fit, plus you run into the usual ECU-related issues. A lot of people think it's a lot of effort for not a lot of gain as the engine is a bit of a squeeze and not that powerful either. It's one of these "it's cheaper to turbo or supercharge the car for more power" conversions.

They sound cool, though .

Magic spinning triangles....

I was wondering how long it would take for someone to come up with that suggestion .

What's the going rate for a Renesis + gearbox these days?

Switch to the bellhousing from a RX7 and drop in a ported 13B? The gearbox guts are identical (in fact I think you can play musical gear ratios if you have a few different years of RX7 gearboxes to crack open) and from there its just a matter of getting an RX7 clutch+flywheel and fabbing up motor mounts and one hell of an exhaust to keep it quiet

Turbo. That and a 160 buck ebay sourced aluminum radiator and a set of Spal fans or somesuch. Build the engine with hbeams and 8.5:1 and you'll be able to push it to 2 bar on pump gas, all day long, shocking the E36M3 out of yourself and everyone else out there. If that setup can handle being rallied on for a weekend, which I already know it does, or being abused in a poor ol' street car which it does, then you can track day it to your heart's content.

The rotary swap has been done a bit hasn't it? I still can't get over the gas mileage on those engines =/

Ouch just reading some threads that looks like way too much work. I think you would be best off just going to a 1.8 and maybe building it a little

Jay_W wrote: Turbo. That and a 160 buck ebay sourced aluminum radiator and a set of Spal fans or somesuch. Build the engine with hbeams and 8.5:1 and you'll be able to push it to 2 bar on pump gas, all day long, shocking the E36M3 out of yourself and everyone else out there. If that setup can handle being rallied on for a weekend, which I already know it does, or being abused in a poor ol' street car which it does, then you can track day it to your heart's content.

Sorry, no turbo as mentioned above. I also don't really want to find out how well a 160 buck ebay special radiator holds up to the temperatures out here in the high desert when tracking a car.

Jaynen wrote: The rotary swap has been done a bit hasn't it? I still can't get over the gas mileage on those engines =/ Ouch just reading some threads that looks like way too much work. I think you would be best off just going to a 1.8 and maybe building it a little

The mileage is one thing - I've had rotaries in the past - but it's the amount of (fab) work that you need to put into the swap that scares me. Walk before you run and all that...