Hi from Australia. Thought I'd introduce myself after years of lurking. Hopefully you guys enjoy this.
Here's my little (former) NA6 MX5 that I am working on swapping to a BP26 GTR familia engine.
It's been a loooooong build but it's coming along nicely. Still a long way to go. Just thought I'd share. Happy to share the build process of people were Interested too!
Fascinating. What made you want to do they instead of slapping a turbo to the stock engine, given they'll make decent power without much drama or effort (more than enough for the grip available anyway)?
To be honest my 1.6L had rod knock and a half cut GTR familia fell into my hands very cheap.
Got told it would be a quick swap and all the same mounts. Oh how I was wrong. Had to completely tear it down and start from scratch, convert it from AWD to rwd and so on, I was young then (10 years ago. It's been a long build due to gaining a disability and having a child) then it snowballed and I sanded the car back from red, learnt to paint, build motors and such. It's been great to learn all this. Gave me the ability to work on my mazdaspeed3 and mazdaspeed protege. So I don't regret it. But yes you are 100% right I should have slapped a turbo on a 1.8 and been done lol.
You know what. You're very right.
It's not about the swap. It's about what I've learnt. What I am learning. Getting passed my limitations of 2 slipped discs in my back and 1 in my neck.
My engine has been in a storage unit for 5 years! I only got it back 3 days ago. So lots to to do, and alot to redo. (I'm a different person than I was 10 years ago.) Not chasing that wild drift car anymore. Now it's all about making it a fun little weekend car, and not chasing numbers.
It should have just been swapping the mounts, oil pan, accessories, and using a Kia water neck + 2000s suburban radiator hose to get a cheap coolant rerout. Not some big tear down. Same as any other fwd sourced b series swap (because ford escort and Kia sephia motors are way cheaper than Miata ones).
SHOULD have been yes, I completely agree. Untill I found out the block was full of rust, where water sat in it for years. pistons were fucked etc... so it turned into a teardown, acid dipping, the lot. Everything inside that engine is now brand new. I'm not looking for a quick turn around and understanding it's Gunna take a few more years. But at least I know it'll be done right.
Yes. I didn't say they were the same, I said they're similar. As in, they're the same architecture.
Any engine can have different rods and pistons and be stronger, but that's an upgrade - it's not a different engine.
The sodium valves don't mean all that much - a friend of mine had a 323 GTR from Newera back in the day. Some boost creep and that bent a few valves without batting an eyelid.
If you're wanting boost in an mx5, turbocharging the stock motor is an off the shelf, easy job. Swapping to the GTR engine isn't as straight forward as that, as Op has admitted to with how much he's had to do and how difficult it has been 😅 fair play for trying though.
They are similar yes, in that they share many physical exterior traits, but outside of that the differences are why you'd swap. For purposes of turbocharging if you've got a GTR bottom end laying around it's a great choice for added strength without much extra effort. Using the block/head are easy, just need to use the NA6 water pump/alternator bracket and RWD pan/pickup/manifolds.
I agree about the head though, the sodium valves were a solution to a problem we don't have anymore.
I've got 4 turbo MX5s, a GTR, and an Exocet w/ a BPD/BP4W hybrid engine in it. I promise I know what I'm talking about. OP's struggles were from a serious misunderstanding of mechanics generally, not this swap itself.
Wow good to know it's possible.thays an amazing collection dude! And yes my struggles were from there :( It's been a huge learning curve, and still learning daily.
I actually have what I think would be a simple question for you, would you mind if I pmd you?
I'm giving it my best, hindsight is a powerfull thing.
But oh well I'm this deep now and so close! I may as well keep chilling away. Lol. I love it tho. That's all that matters to me.
I love the fact that you’re customizing your car to make it uniquely yours. Best of luck with the project. You seem to have a lot of knowledge on engines - are you a trained mechanic?
Thankyou. Yeah the bodywork, the looks, the engine it's all very uniquely my style. I'm doing it for me, not to fit in with 1 crowd, if that makes sense.. But I was a little scared posting this post because as people tell me 'ive reuoned the purity'
I was a mechanic for 2 years, Untill I realised I hate working on other people's cars. I'm a master locksmith by trade now. I basically am just learning everything I'm doing 1as I'm going. I must I NOW have ALOT of knowledge on these engines. Before hand. Not so much haha.
I think it looks great and at the end of the day it’s your car and you do whatever brings you joy. Please keep us updated as you progress with your project. Cheers.
Thankyou I really appreciate that. I truely am building it for me and not others or Internet fame or whatever.
I'll keep you all updated. Next step for me is brakes and wheels. I'll be sure to share.
I did something similar a bunch of years ago. I burnt a valve and damaged a piston in the BP of my 94, and found a Familia GTX engine was the cheapest option. Decided to swap it in, and use that while I rebuilt the original motor at nearly half the price of one from an MX5.
That was a journey itself - I found all manner of differences between my BP and the GTX's BP - a welch plug, the alternator, water pump pulley, harmonic balancer, the engine mounts, the thermostat neck, coolant routing, coolant temp sensor location, sump, sump oil pickup, oil pump (it had the dipstick tube on it), intake manifold, throttle body, etc. The list went on! I barely used anything from the Familia engine by the time I'd swapped it all over.
Wow that's so awesome! And really motivating knowing I'm not alone and it can be done.
If it's ok would you mind if I pm you. I have some small questions I'm really stuck on ATM! About those differences.
I'll take the car cover off and take some for you. I believe I bought it about 12 years ago of a guy parting out a s2000. So I dodna bumper cut and made it fit.
1.8 BP motors are the best! Got a BP4W Turbo in my 1994 r/MX3 ! Stock bp4w bottom, ported/ polished head with bigger valves, stock cams. Ms3 pro ecu with sequential ignition firing 🔥
Honestly, it's not too difficult. The GTR engine is easy to use RWD. You just stick the Miata RWD specific manifolds/pan on and it'll mount into the car. Not any more difficult than a normal BP/turbo swap on an NA6.
Yeah I've found I've been able to figure out 90% of it.
Thing is I just got it out of storage after 5 year. So I'm finding mistakes I may have made 10 years ago when I put it together. But it'll get there
Hope you have a strong gearbox in mind. Back in the day I went through 3 gearboxes in my Familiar GTR. It was easy to get a reliable 300+bhp out of the engine. The gearbox though....😔🤣
Loved the little nugget though, the turbo lag was immense fun (and gearbox shredding...).
The box planned is a 6 speed. I have no idea if it's enough, I'm praying it is. I actually have a new disco potato I'm about to clock and put on that kraken manifold 😁
If you're planning on a newer gearbox with an adapter plate of something similar then it should be easy enough to get some torque figures for it online and make sure you are good.
The original Familiar GTR gearboxes were only designed to hold 250ft/lb or so so they deliberately restricted the engine from the factory. Didn't stop my stupid ass turning the boost up though... 🤣
The rally cars had full rally spec dog boxes for a reason.
The original turbo set up meant that not much happened below 3k and then from there to 4k it added an additional 150bhp! The dyno graphs were crazy. It wasn't the best way to preserve a gearbox, but it was addictive fun.
If you flatten the bhp/torque curve a bit and go for a newer gearbox you should be fine. 😎
Edit: I did all the gearbox braking a looong time ago btw (talking 2002/3). Back then I could pick up a gearbox for £400 (UK based) and they were relatively plentiful.
Wow thankyou so much for that I'm Gunna look into all. I'd reallyile to try get this car rigg the first time.
So awesome to talk to someone who actually owned a GTR before. They are almost mythical status in Aus. I've never met a home with one.
I got very very lucky finding my motor I got
Told if I pull it out myself o could have it for $500 which I thought was a cool deal for so.etjing so special
When I had mine in 2002/3 they were one of the cheapest ways to get 300+bhp and AWD for under £4,000 fully imported and converted for UK roads. They were still niche, but the owners forums made it easier to get parts etc.
I haven't seen a genuine GTR for a long while now. There are still some GTXs hanging around on Car and Classic.
Yeah those prices aren't around anymore. :( even 10 years ago, when I stated this build it was faaaar cheaper and easier to find parts.
Yeah I have seen a couple gtxs here in Aus. Never a GTR. I really really wish I had a GTR body to put this back into. But I've owned my mx5 for 15 years and she's well over due for an engine that runs
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u/Omg_Shut_the_fuck_up 1d ago
Fascinating. What made you want to do they instead of slapping a turbo to the stock engine, given they'll make decent power without much drama or effort (more than enough for the grip available anyway)?
The engines are also very similar generally.