Your current manifold and downpipe combo are plenty sufficient for your goals. I'm probably approaching 100k miles in a 300+whp miata over the last 10 years, all in a setup based around a plain old boring cast t25 manifold. A gt2871 will absolutely get you to your goal without changing out other parts. If the funds are there, no doubt the borg setup is all around better, but with a fully assembled turbo setup already in place that's certainly the easy button at this point.

Go big on the injectors, you want 1000cc's, no sense in messing with smaller stuff and needing to upgrade again. E85 is great if it's available.

I've gone through several motor setups and the most reliable setup I've done has been a rods only motor, reusing stock pistons and with the stock oil pump/damper. That setup has dyno'd 330hp on a mustang dyno and run 11.6@124 in the 1/4.

A 2871R will be just fine. Mine has a fair amount left in the tank and I think it's running in the 330 range right now. I'd get ID1K's or the FF960's for injectors because why not. DW200 with larger injectors will be fine. I'm running ID1k's with a dw200.

I'm a bit risk averse so I decided to overbuild. My original goal was 300ish or so, but that's been creeping up as I want to see what this setup is capable of although 300 is likely where I'll setup for day in day out driveability. I'm hoping to tune things and make everything happy and go dyno things and call it a day.

I went with eagle rods, 8.6 supertechs, ARP everythang, ACL bearings, BE VVT Pump, and 949 damper. I took my time and pieced together parts from deals that I saw. If I had gone rods only, I would probably have been happy to stay at 300 because that feels pretty fucking fast in these cars.

You just really have to decide if you're going to be happy staying under 300. There's no line in the sand, but if you keep pushing the limit, you're more likely to get burned. I need to do more ducting and run an oil cooler if I want to be able to run my AC in the summer because it tries to overheat the second the damn thing goes on. It just really depends on what you want out of things.

I just want a reliable 300whp, and then go up from there as I feel comfortable... I'd love to hit 350whp, but I feel like as I start bounding across the 300's I start running into compounding issues with differential and transmission reliability, and everything else will start wearing much more quickly too, which is why I was aiming for under that mark as a pump gas tune for street use

That's good to know that just rods was reliable (taken with a grain of salt :D) at above 300whp, though.

I guess I should also add that I have a set of Toyota COP and pigtail harnesses that I was going to use for spark on the car, so I don't blow it out under higher boost...

Thanks for the input everyone, by the way!

I am 99% sure kraken t25 manifold is the same for garrett and EFR turbos. With the difference just being the downpipe.

just message kraken on Facebook, he responds quickly. Maybe you can order only the efr downpipe from him.

300hp is easy on a 6258 setup. Takes about 17psi.
Once you approach 350ish hp on pump gas, that's when tuning becomes critical and you really run into knock and such.

a rods only build will bring you to 300hp no problem.

my engine is rods only with stock NA pistons and a vvt head, I dyno at 309hp. Did 2 track days and 4 autos on it and a year of weekend street driving.

although I run wastegate only 10-11 psi on the track for mechanical emphaty to my 5speed. Which yields 250hp 220tq.

I'm swapping in a 6 speed and 3.63 torsen shortly, so I might leave the boost at 17psi next track day.
and I'm adding an ATI damper, because it landed in my hands for free.

so in summary, you can fully build the block if money allows. Or just do rods, bearings, seals and call it good enough.

no need to touch the head at all for 300hp.
forget about cams.

Gtx series 2860 and 2871 are nice, but are more expensive than efr 6258 and dont spool as fast. An efr 6258 can be had for $1264. And gtx I believe are around $2k. And for this price difference you can have kraken send you a new EFR downpipe and you'll still be ahead

But since this is a spare motor if he is doing the rods, bearings and seals he might as well throw in arp stud and pistons. its only what $450 to do both. Then his block would be bulletproof

Nope. It's more like $700. Then you really should get a BE pump if you go that far. Rabbit holes man.

Redemption! My vote goes for this over a 2871/2860. For a relatively similar price the efr is definitely a more advanced design.

FYI, the Kraken T25 manifold is the same as the one in their EFR kit, confirmed by Kraken themselves on FB. Part of why i bought their kit for my NB.

Still a different kit. As borka said the downpipe is different. I would wager it would be cheaper to sell his current kit with down pipe to buy a efr kit than it would be to buy a down pipe alone.

A quick search shows about $1500 for a GTX2860R Gen II from ATP with T25 housings. $1700 for a comparible EFR 6258 from Trackspeed.

shhhh dont say that. 10k in a motor i dont know what you are talking about:ugh:

I don't have pistons that are good for this extra block, and I'd really rather not reuse my 130k mile pistons that are currently on the car... I figured $800 for both is a good call, and then with the lower compression ratio I can get more pshh noises coming from under the hood without throwing a rod through the firewall into my forehead. I had no clue so many people just did rods on the block, I mean you're already in there, why not refresh the pistons and gain power/reliability at the same time?

I just messaged Kraken about the downpipe, so I'll see what he says back... Whatever turbocharger I do get, though, I'm probably going to try to source used, I like bang bang noises too much to buy new :firedevil

Pistons don't generally wear significantly which is why so many reuse them. You'd want to get used NA8 pistons though.

IMO there are only 2 sensible ways to build a BP short block. Either you do nothing but rods, or you do rods/pistons/ARP main studs/BE oil pump. The mains also have to be line honed if running main studs.

Rods only has proven to be reliable at 300whp+ on the street. Around 350 you start seeing main stud and more frequent oil pump failures which is why I feel those need to be upgraded if you're going through the trouble/expense of forged pistons.

Just didn't know so many people did that, but looking for rods only specifically as a search I'm seeing a lot more... Thanks, I'll get the bottom end line honed when the crank is being polished. The big reason I'm not pushing for more power than 350whp is 6spd/3.909 Torsen start becoming points of failure at over 350whp, and then that becomes compounding in terms of costs... At least, that's my impression?

Yes. All the more reason to do nothing but rods and stay around 300 IMO.

I sold my 2560 setup for $1400.
new efr setup from kraken + turbo was $2k.
my net cost $600ish to upgrade.

so if OP sells t25 setup as a package, it should not cost too much to get a new kraken efr kit and new turbo.

efr 6258 is $1264 from industrial injection in salt lake city. It's a miata turbo special I setup when I bought mine from them. If calling ask for Gavin.

I was quoted $320 for the new downpipe setup for EFR from Kraken, which seems like it would be better than selling and repurchasing again?

just do the math.

whats your turbo worth? $400?

so $320 + $1264 = $1584 - $400 = $1184

if you sell your setup as a package for say $1000. its $750 (kraken kit) + $1264 turbo = $2014 - $1000 = $1014 net cost.

so i mean its pretty close, and up to you. if you buy new downpipe, your old downpipe is pretty worthless to sell, as it works only with kraken manifolds.... but if you can sell it for say $150, its a wash.

if you want cheapest/easiest setup, sell your turbo, and get a used 2871 from the 240sx guys, and the upgrade will only cost you a few hundred bucks. yes it will spool later than a efr, but it will still be fun and will hit your 300ish hp goal.

for what its worth, my vote is for a gt2860. I am currently installing one. It has been proven many times to be more than capable of 300hp, and will allow you to reuse your manifold, seems like a no brainer!

lmfao that turbo is trash. And I'm not just talking shit I am currently running a gt2860r and talk about slow spool. It's like watching the loading screen for a movie on dial up. You want to talk about proven fast spool big power look at one of the thousands of efr builds out there. My efr6258 on a 800cc snowmobile spools faster than a 2860 on a miata.