1.6 turbo to k-swap???
 

I'm at a point where I would like more power and reliability. I currently have a 1.6 with an "upgraded" Greddy setup that I have running at 10 psi on the track. It certainly moves and I've been able to surprise lots of people on track with the little shitbox. I've been running into some problems recently with the ignition setup and I'm not convinced it isn't coming from some of the older tech the car was built on. The old Greddy setup also has a lot of lag compared to the more modern turbo setups and upgrading to a better turbo setup on the 1.6 seems futile.

I can obviously stick Mazda and go the 1.8 turbo route or I can do the k24 build route. The 1.8 (for the same price as the k24 build) will leave me with 300+ reliable whp with gobs of torque from what I've been reading. The k24 gives me 220 whp with a fantastic redline and more potential down the line and potentially better heat management. Goals for the build would include a good street car for spirited ralleys, a reliable track car that continues to help me learn, and ultimately to keep up / beat on the f80 m3 (2 track buddies have one and I don't want to be left behind).

My current dream build is a rotrex k24 with the getrag rear and bmw trans.

My question to you is will I miss the fun aspect of a turbo on the street if I decide to plog my money into a k24 swap? I'm looking for actual experience here not just bench racing.

No experience here but what made you decide k24 vs ecotec? I looked at both and it seems ecotec gives about the same potential for much less money.

I think a stock k24 is going to make the same torque as a greddy 1.6

Honestly, this is a thought I have been mulling over as well. 400whp k20 rotrex would be such a handful.

ecotech only makes like 170 doesnt it? And will feel like an unexciting turd compared to a K.

If I ever have to pull my 1.8 for any mechanical reason again, its going up for sale and I will K swap. I am of the opinion now, that for 225 hp track abuse, the k is a no brainer.

Can confirm. Except it will make ~200rwhp. Still feels gross.

When I was in your situation (I needed to build my motor) I would have done it in a second.

Concealer, were you saying the ecotech feels gross? Or the K24 feels gross?

The k doesn't look gross, but I have never driven one either. I can imagine a 6758 on one being quite the hoot.

https://cdn.shopify.com/s/files/1/11...fe0c908b83.jpg

From this thread:

https://forum.miata.net/vb/showthrea...light=k24+dyno

Ecotec feels gross. @vteckiller2000 can elaborate but i think he's got a long post in here somewhere about it.

I think we need a thread where everyone with a built BP gets to say whether they would go K or not, now that the swap is established with the BMW stuff too.

because I am in the situation where I can still choose, selfish I know.

i did, or at least very similar..https://www.miataturbo.net/general-m...p-turbo-91224/

Hate to throw more fire into the pit, but the swap to do these days is a K20 Head w/ K24 Block. There's tons of information on this swap online. With cams and FBO, they have been known to reach 260+ whp without touching the bottom end. This comes with stock-like reliability...

I want that, in an Exocet.

The shear thought of that makes me feel things in... places

ya, we know. its in the k swap write up by sav.

Sort of. I just want like, people's thoughts. We all know a K>BP in terms of performance and engineering and everything.

But for people like you that have gone down the road of built BP, would you do it again? That would be a good read.

10/10 would read. I'm in the same boat of determining if I go boosted BP or K...

Agreeed, built BP vs K. I keep going back to a turbo 1.8 but all the posts on here about cooling issues and turbo hardware make me cringe. Sure most of these issues have been thought out and potentially solved but OEM reliability seems hard to get.

With the supporting drivetrain now being being made available (rear end and trans swaps) the car now has tons of power potential. Id hate to build a BP to be limited by it. K's limit is much higher albeit with a cost.

track ready turbo bp- 10k
track ready turbo k- 20k

How wrong am I here? I bet not much...

Thats what i thought. I never understood the point of the ecotec swap.

k swap seems to be track ready out of the box at stock power levels.

fixed my earlier post to compare TURBO cost.

Comes down to power levels. You can legitimately do a K swap for $10k or less, before even accounting for recouping what is probably an existing modded BP in your engine bay.

Track ready turbo BP? Probably $5-10k if you stay in the limitations of a stock motor.


I think Emilio says that a Rotrex BP is the cheapest and most reliable 200whp in these cars. I'm not sure if his position has changed now that he's messed with a K swap. I doubt it.

To the OP, your first post explains much of the thought behind why we brought the K swap to market initially, and the same thought process as most of our customers.

It's such a suitable engine platform for these little cars. Sure, it comes at a price, but you end up with the best N/A 4 cylinder potential that's ever existed, with a solid 220whp starting point (not to mention boost potential).

If you're ever in the Chicago area, come by the shop and I'll take you for a ride :)

Track 200whp turbo BP - not incredibly difficult or expensive

Track 300whp turbo BP - incredibly difficult and expensive

Track 200whp k24 - not incredibly difficult but expensive

A k24 should be more reliable than a turbo BP just because it is less stressed and has fewer failure points.

True, and if we are talking turbo k24, for 300whp, i still think it may be better than the bp. You can run a larger turbo for less heat too. Maybe brotrex it? (I bet one would be hilariously fun) My research on that so far has indicated oe rods will die at 300whp. Put in some rods and pistons on a efr 6758 and decimate all?

OE k24a2 rods are typically good to 400-450whp depending on specific application, and OE k20 rods consistently handle 650+whp. If the end goal is boost, go with a stock k20a2 or k20z1 and call it a day. Much less stress on the bottom end thanks to the shorter stroke of the k20.

Thanks, i was hoping you would chime in. I have a hard time with those forums as it is hard to find the info you want. A problem with all forums I suppose. Seems to me like the k20a2 wins out if you want boost or a high revving n/a screamer. Why did yall choose the tsx motor then?

I'm another in the camp of putting in a kswap in place of my built turbo BP.

Anyone want to buy a full Absurdflow setup built BP?

Anyone want to buy a fireball making, EFR Artech setup?

Can confirm, ecotec is cheap, does things that an engine does, feels terribad. 0/10 would not bang again.




Yes.

TSX engine makes more power everywhere N/A once tuned, and 35 wtq more everywhere over a k20. It doesn't rev quite as high, but it also doesn't need to in order to make power. 8200 RPM out of a stock k24a2 is tons of fun and reliable. I've owned k20 and k24 cars, and I'll take the k24 any day in N/A form for a street or track car. Bonus is that the k24a2 is a good deal cheaper used than a k20a2 and k20z1 (RSX-S engines). But for a big turbo setup it's a different story.

It also depends where the OP lives, if this is at least partially a street car. AFAIK KMiata is still working on a PS and AC solution other than "roll your own." Living in Maine it's probably not a big deal; living in Texas it may be.

$10k is a solid, realistic, no-bullshit estimate for the cost of building either car (track-reliable K24 vs track-reliable stock motor BP, target of 225whp). You can creep up on that cost with the turbo setup (do your ECU, clutch, cooling, fuel mods first, then add turbo last), you're spending it all at once with the K-series. K-series is also ~2x the labor cost if you are paying for that (~40-50hrs vs 20-25hrs).

The K revs harder, some people like that. I personally think the K24 needs a whole bunch of gear to make it feel as exciting on track - I've driven one with a 6sp and 3.909s and the rear end felt way too tall for the ~7800rpm redline that car had. If I get around to building one it will have a 6sp+4.3s at minimum, maybe even 4.44s. The turbo car is going to make 20-30tq more, and it will make that torque ~1000rpm earlier, so it will dig off corners harder. I am a turbo fanboy, I prefer that.

Having driven both, it really comes down to personal preference. For a track car, I think a stock K24 with 6sp+4.44s would be a fucking riot. For a race car, I think there are more opportunities for a turbo car to play (Supermiata S1, NASA ST4). For a street car, IMO, the turbo car is much better.

Very interesting outlook right there ^^^^^

I ran a 6 speed with 4.30 for a bit with the K24 and I was always shifting into 5th everywhere, and was running out of 3rd gear out of corners more often then I liked. I eventually settled as 6 speed with 4.10 as the sweet spot for most tracks in the Midwest, with an 8200 RPM redline. I recommend 6 speed with 3.90 for the street guys.

We usually see stock k24a2s hit peak torque around 2700 RPM, so the low end is there, but its not going to be the same as a turbo car obviously.

I like the 6sp/3.909s in Rover (215whp, 7krpm limit) so I'm basing my selection on that. I spend most of the time in 4th and 5th at CA tracks, with enough speed in 5th to avoid 5-6 shifts at most tracks and sparing use of 3rd gear to squirt off tight corners. A 7800rpm limit and 4.30s would be the same shift points. If I had 8200rpm to play with, I would definitely pick 4.44s for CA tracks.

Typo? IIRC we were seeing peak torque around 5k in Andrew's car.

Contingent on being a JR based kit, I still maintain the Rotrex is cheapest/most reliable. Also the easiest to install, set up and tune by far. That threshold holds up to about 220whp where a turbo starts to be more cost effective and faster. K swap, while fascinating and very high max power potential, isn't the cheapest or easiest as long as good turbo and Rotrex kits are on the market. For the $10k a good 210whp K swap (healthy junkyard motor) costs, you can make 280whp with a Rotrex or Turbo.

p.s. My comments assume an NB 1.8. Unless you are in a country that heavily taxes engines over 1600cc, don't waste your money on the B6.

Thanks for this. The K swap intrigues me as it has loads of potential but it's not going to be a whole lot better power wise than my boosted 1.6 (comparing dynos). It will however help with heat issues and be more reliable. Not sure how relevant that is anymore to me since I did some ducting work and have had zero heat issues plus I just bought a tow vehicle.

Maybe it's time to build a 1.8? Still so torn......

It'll be released any day now?

We stopped waiting about two years ago. Could be tomorrow, could be never. JR is quiet on the subject so who knows. Someone else told me the brackets & pulleys might be available, just not the rest of the system. Dunno if that's true or not. I have wto production TSE kits.

I talked to JR a few months ago about their rotrex setups for something else silly I was thinking about. It seemed like then at the time the hold up was get CARB. They were not going to release the setup until they had that, and they had several other larger projects to get done for OEM's before they would get back to working on the miata stuff. I am not sure how accurate or not this is, but I spoke to an engineer there for about 20 minutes and it did not seem like he was talking out of his ass.

Soooo rotrex K24/20? A "reliable" +400whp option lol

Do you mean the TDR rotrex kit?

No

:rofl:

Sorry guys, slow to the party, I was out of town.

Andrew, yeah you're right, true peak torque is higher, but we see 95% of the final peak torque number typically quite low though, which was what stuck in my mind. This the setup currently in my car and you can see what I'm talking about (sorry for the terrible pic):

https://cimg7.ibsrv.net/gimg/www.mia...5631de7140.jpg

Per earlier discussion on K vs. Rotrex, vs. turbo: yeah, N/A power will almost always cost more. The obvious benefits are less weight, less heat, less complexity, and fewer failure points. Emilio, you've certainly proven the value of this on your N/A BP builds. Our core market is all the guys that want that N/A life. The TSE and Rotrex stuff is definitely top-notch. I consistently recommend the TSE kit any time someone says they want a turbo BP setup.

Also worth noting - most NB guys these days are spending about $8500 for a basic K24A2 swap and making north of 220whp if they use our reflashed ECU (even when re-using their existing 2.25" exhausts). We've worked very hard to increase affordability, quality, and simplicity over the last year. But yes, an NA owner wanting a full custom stainless 3" exhaust setup can quickly spend $10k, and usually will see 225whp, 180wtq with a full tune.

It's 2017, there's no excuse for a turbo miata to be overheating/unreliable on track. I ran a 3 hr. enduro last month. Stock 1.6, FM manifold, 12 PSI, 225 whp/190 lb/tq, every single shift at 7K for 3 hours. Mosport, 3/4 mile, 25 sec./uphill back straight. As long as you have a cast manifold from FM or Trackspeed as the foundation, the rest of the recipe for OEM reliability is right here and it's fairly simple.
I'm glad there's all these swap options out there, something for everybody. There's a local NA with an S2K powertrain that sounds glorious, I do wish my car had that scream.