SR20DET in a Miata: Why not?

I too love the SR20DET having had one from a GTi-R in my old SE-R (250whp) and I now drive a homebrew turbo 96 Miata (maybe 200whp) so I've got some experience with these engines. Although I can appreciate the SR20DET, it does sound like a lot of work. If your ultimate goal is 250whp or less I'd stay with the BP, but if you are hoping to go higher, it might be worth it to go with the SR20DET. Especially if you consider the cool factor. Still, like the others, if you are going to the trouble to fabricate mounts, etc, I'd probably do a V8 swap instead (SBF on a budget, LSX if not).

BTW, I'm very happy with how cheaply I turbo'ed my BP (using an SR20DET T25 by chance). Here's a link to my cost spreadsheet. It would be hard to duplicate it much cheaper and still use name brand quality components for the clutch, manifold, downpipe).

I'd set a target of 250-275 rwhp for a stock-internal BP. I'm conservative - at that level, it'll last for years and years. I'm not going to claim 300+, but I know it's been done for varying time spans.

If the goal is to be different, go for it. But why stop with an SR20DET? Go for a Skyline motor!

The answer is Miata, somehow.

keith, i get the impression that getting a rb motor into a miata would be difficult lol, but hey, jag v12 has been done!

If you want to go big turbo power, why not an FE3? Should be easier than a SR20, being a Mazda engine and all.

Search over at www.miataturbo.net. Warning: search first, think, then post. Read the NOOB thread to avoid getting raked over the coals.

question is.. yes you can get 300+ hp out of an SR.. but how driveable is it?

jeffmx5 wrote: If you want to go big turbo power, why not an FE3? Should be easier than a SR20, being a Mazda engine and all. Search over at www.miataturbo.net. Warning: search first, think, then post. Read the NOOB thread to avoid getting raked over the coals.

No way will I post there. That board is the biggest bunch of immature "We have the information and you don't" shiny happy people I've ever seen on the internet. Plus, their search function sucks, and god help you if you ask a question that was answered peripherally in page 47 of a thread from six years ago.

No way will I post there. That board is the biggest bunch of immature "We have the information and you don't" shiny happy people I've ever seen on the internet. Plus, their search function sucks, and god help you if you ask a question that was answered peripherally in page 47 of a thread from six years ago.

Ive never been there, but well put. People like that suck.

Eh... if we're going to move into the FE3 discussion, then don't rule out the F2T, either.

It'll hit 300whp easy. It'll sound like utter crap doing it, and will have enough torque to stop the rotation of the earth if you drive the wrong way, but yes. It'll do it. I will not guarantee that you will EVER catch traction, though.

Bonus points in the F2T's favor is that it's already turbo'd so you don't have to worry about making custom exhaust manifolds. You'll have to do something about the dizzy, though, otherwise it'll probably poke the firewall. (Get a bigger hammer, clem!)

If you are planning on using a junkyard engine why not use junkyard turbo parts on your stock engine? That would be the most economical

I'm not really considering the FE or F2T. I don't particularly care if the car stays all Mazda. Plus, the FE3 is N/A, right? So I'd still have to turbocharge it. I think the SR20DET is the best low-buck four cylinder around in stockish form.

As for the junkyard turbo on the stock engine, I've considered it and actually had most of the parts to do it. I had to sell them a few months back when money was tight. It's still on the table, though, and would definitely be the cheapest. Without going EMS and wideband, though, I don't think I'm going to be able to get a 1.6 even to 200whp without risking serious blowuppage.

A big part of the appeal of the SR is that it's already turbocharged. No dealing with running new oil, water, and vacuum lines. No dealing with new manifolds. No rerouting things.

The flipside of that is making the auxiliary Nissan systems work with the Mazda car. I think I can work around that. It'll have manual steering, so no P/S pump. A/C may or may not stay, but I can get custom A/C lines made at my local O'Reilly's for cheap. Custom driveshaft is easy and cheapish. Custom trans mounts and engine mounts will take time, but I can do them.

After hearing some good counterpoints, I still think this plan is a good balance between power, low bucks, and the "dare-to-be-different" factor. Especially now that I know it will fit alright.

Been done.

Look up a guy named "Silviata" on Norcaldrift.org.

If you're looking for a cheap, already turbocharged motor to dump in there...

Why not grab a BPT? I imagine that dropping that in would be a simple matter of factory legos kit.

what 93celicagt2 said

Because the BPT was only ever used in transverse applications, and the turbo location doesn't sit well with the metal in the Miata's engine bay. Like, the frame rail and the turbo want to be in the same place. So it's not the simple legos option in the Miata. If you have a Kia Sephia GS, yes.

A better choice would be the factory Miata engine, but that turbo is on the small size and there aren't any easy bolt-up options. So it's actually easier to install an aftermarket setup for this sort of power level.

With an SR swap, you'll have a manifold and oil and water lines handled. Not that this is difficult. But you're going to have to build a custom downpipe, new intercooler piping and built an intake. Plus you'll need to find a way to support the nose of the diff, whether it's remaking the PPF to fit the Nissan trans or designing a support for the diff itself. This is remarkably difficult for people to do well for some reason.

Not to say it can't be done, but don't look at the Nissan swap as being the easy road out. And the Skyline engine has been done...

So I will again suggest an adapter plate and a VW 1.8T!

I stand corrected by Keith.

I still feel like there's easier/cheaper ways through this.

Altezza 3sge + 3sgte bits?

I mean... if you're going to do a Nissan swap, may as well totally blow some minds while you're at it and dump in a VG30DETT.

I fail to understand why you think you cant get the 1.6 to 200whp with a junkyard turbo and junkyard engineering..

The more I think about it, it just sounds like the SR20DET engine would be more trouble than it's worth. Keith brings up a good point about the diff support. And oil and water lines couldn't be easier on a Miata to get/make compared to a custom downpipe, driveshaft, AC lines...

Intercooler piping, etc would have to be done either way. I would still love to see it though.

And I agree about Miataturbo.net. It's very useful info in general, but pretty hostile. BUT, saying their search function sucks while posting here is... ironic.

200 hp? Different? KL-ZE? And it'll sound like sex on wheels...

ScottRA21 wrote: 200 hp? Different? KL-ZE? And it'll sound like sex on wheels...

Now THAT is a swap that's a lot of trouble. But i would still consider it worth it. Simply for those sounds.

Nissan VQ? I'd love that.....

KL-ZE has been done (I lost the link) in a dedicated autocross car. It DOES sound like sex on wheels. It DOES bolt up to the Miata trans, IIRC. It DOES require some pretty serious engineering to make it work, though...I think it's major oil pan/minor subframe surgery, etc., etc..

I'm not shooting for 200 hp. I'm shooting for 300. Not that 200 wouldn't be a great improvement over the 92 I've currently got. I'm just greedy like that.

Now that we know 300 is the real number then we can dispense with all the minor formalities.

• Ford 5.0L
• Chevrolet LSx
• Chevrolet small block
• Lexus V8
• Nissan V8
• Northstar
• RB26DETT
• 2JZGTE

For starters.

We did some preliminary research on a RWD KL-ZE conversion in a Miata when we were considering various powertrains for our $2010 car.

The punchline was that it wouldn't be possible to swap in the motor and boost it on a Challenge budget, and we wanted to go faster than 200hp. It's doable, but there are a few things. (Disclaimer: this is all from memory, from last November)

-Coolant flow would have to be reversed. Considering it's conventional FWD layout, the T-stat and radiator inlet/outlet would be at the "back" of the block. Not impossible, but will require some fab.

-Oil pan would have to be almost entirely reengineered.

-It doesn't bolt up to a Miata trans at first. You need to swap to a Turbo-II bellhousing, and even then a bolt hole doesn't line up.

It can be done, yes. That engine would be LOVELY with a small T3. It's fairly high compression, IIRC, so you'd have to be careful with tuning, but I would LOVE to do that. If it was the $3000 Challenge, we might have gone forward with that swap instead, I liked the lower displacement over the VG30E we settled on, but the simplicity of the VG's EMS and propensity for boost were major selling points.

On that note, after the Challenge, I'd LOVE to work with someone to replicate our swap in a more "normal" environment without the ultra-tight budget constrictions. There are some things I would have done differently if we'd had a little bit more breathing room. Keith, y'all interested in hiring a new engineer with a business minor in a couple of years?