300-350whp goal build
 

I am currently running low-mid 200s whp (haven't dyno'd with boost up'd) on a kraken manifold/gt2554r to a vibrant bar/plate intercooler, RX8 injectors, Skunk2 TB/EUDM intake manifold, and a MS3X with stock internals on a BP4W. I'm looking to build up an engine, get a bigger turbo, and aim for low-mid 300whp.

My plans as of now are 84mm wiseco 8.5:1 forged pistons and wiseco rings, with k1 rods, polishing the crank and ARP head studs, on a NA8 block I picked up. I have a NB 6 speed and a 3.9 Torsen,

Should a ATI balancer and BE gear to replace stock oil pump gear be in the books? Would a GT2871R be the preferred turbo for this goal? What fuel pump/injectors would be a good bet for this goal, to keep a good idle? Are ARP bottom end bolts worth it? ACL race vs King XP bearings? I'm getting a package deal on the pistons/rods, bearings, and all studs, so the ARP and bearings wouldn't be horribly expensive to pick up in conjunction at about 15% off retail....

Do I need to do any head work? I was planning on refreshing it, but have been looking at cams (will it still be streetable with 272's?) and debating on valve springs/oversized valves... I'd prefer to spend less money on the head if it won't benefit me much, and spend it on things to stiffen the car, and interior bits. If anyone has any other suggestions for things to me consider, I'm all ears - I've been reading a lot on here, and a lot of you know way more about this than I do! Thanks :)

Should a ATI balancer and BE gear to replace stock oil pump gear be in the books?
Yes
What fuel pump/injectors would be a good bet for this goal, to keep a good idle?
DW200 and Flow Force 640 or DW300 and FF960 if you want headroom the FF640 are good to 300hp
Are ARP main studs worth it?
Yes
Would a GT2871R be the preferred turbo for this goal?
No EFR 6258

Need to add rod and main bearings to that list

Do I need to do any head work?
No

Thank you, I'll add the balancer and oil pump gear to my list, a long with the ARP bottom end bolts, and plan on just a head refresh with my current BP4W once the time comes.

I updated the post right before you posted about ACL vs King bearings, I'm not sure if one would be a better choice than the other or it is more of a get what is available kind of thing, as that's what I've gleaned from discussions about them...

I was hoping to be able to keep my Kraken manifold, but I guess changing manifolds would let me switch to an EWG - it's just more money that could go elsewhere... Is there not a consensus on a good T2X turbo that would let me get up there without a large amount of lag?

Go with the ACL Bearings. As far as keeping your manifold the 2871 is a great turbo but doesnt spool nearly as fast as an EFR6258. It would probably be beneficial to sell the turbo bits you have now and get the trackspeed kit for a one and done shop. He has lots of kits on the market and hundreds of hours of proven track performance. You mentioned valve springs and it might be worth it to swap in the supertech heavy doubles but not necessary.

If it were me i would do what you have planned and leave the head as is. Then source and build a VVT head while you enjoy the built bottom and new trubo.

Hnghh... $3000 for the EFR trubo kit, that'd be more than fully building an entire block and head!

The VVT is worth it? I guess I could add functionality to control it to my MS3X... That is one of the things I have seen a lot of debate about, as it just changes duration of the intake cam and you could throw a higher lift cam in the intake on a BP4W and make more power, no?

Thanks for the input, it's appreciated!

Questions without usage goals are hard to answer. Are you planning on daily driving? drifting? track days? road racing? time attack/trials? auto-x? putting it into a ditch the first rainy day? any combination of these? That's really what determines what is acceptable along with how much your budget is and how quickly you'll get bored and part it out before completition.

While EFR's are the preferred turbo's around here, there are plenty of options for Garrett that fit your Kraken kit to get you there. Are they going to gain you cats here? Probably not, but people here are wired to only like the best product, even if others can't afford it. I suggest reading through build threads to see what others are using to reach your goals. Look at their dyno plots to see if power delivery is what you expect to wet your panties the most. If you have a BP4W head and don't plan on time attack or unlimited class road racing , then you'll be fine without a VVT head. Add it later if you watching your budget.

Its really not though. See my build sheet for and idea

You can make a lot more low end power out of the VVT head.

It is going to be a fun street car, with very occasional autocross... No plans on throwing it in a ditch lol.

Planning on building up my rotary Spitfire over the next year for track days.

I'll keep doing some more reading and figure out my turbo choice

Street car + 300whp goal = Rods only.

Take the money saved on the engine build and buy a 6258 and the kraken EFR kit.

I can get rods and pistons for $800 shipped, and I just have the bare block that is getting bored and honed - dont want to reuse pistons... I could spend another $800 on the Kraken efr and sell my current turbo/downpipe, but I think I am going to try to continue using my Garrett flange at this point to fund the rest of the build - Ill consider the EFR though, since youre the second to suggest

+1 on that.

Or if you want to save even more, you can still buy a 2871 and hit 300whp+

Then rebuild anyways when you convert to banana rods

I already have another block separate from the one I'm currently running, want to try and do my best to "bulletproof" it so I dont get stranded on the side of a mountain road without reception when I'm hammering on it

Since you have a spare just build it up right the first time like you planned. Rods, pistons, bearing, ARP studs, bp pump and ati damper then just stock head with springs and injectors.

Perhaps I'm mistaken but wouldn't the 0.64 turbine housing'd-6258 bolt right up to the T25-flanged Kraken manifold he's already using for the 2554? In which case I don't think you'll really gain much by buying the trackspeed manifold especially if it's for a street build.

My vote would be for eBay rods, forged pistons, and new bearings+fasteners in the spare motor, a 6258, and getting a local shop to fab up a turbine outlet v-band to kraken downpipe v-band right-ish angle adapter to replace the garrett-specific cast elbow it comes with. If he opted for a 3" downpipe from kraken and already have a 3" exhaust I imagine some new injectors and a tune would get you to 300 on 93 pretty easily given the dyno results I've seen of other 6258 builds.

I havent followed the kraken stuff much. Someone mentioned that it wouldn't so i recommended an alternative.

What's the price difference between a GT2871 and a GTX series turbo? GTX2860 should see you well over 300whp and spool significantly quicker. There's a couple of people who have done plots in the dyno section with the GTX series turbos - eg:

https://www.miataturbo.net/dynos-tim...si-dyno-96545/

There's more to it than the flange. The turbos are very different dimensionally. That's why people make EFR specific kits.

Gotcha, had just thought the Kraken design was forward and high enough to fit both. Had seen the results Borka had with a Kraken manifold + 6258, didn't realize he'd done a different casting for the EFR turbos.

I was looking at the GTX28's, too, just harder to find those used. One of those would probably be my top pick it I could though, from what Ive seen reading around

eBay rods? I was thinking K1, Manley or Eagle just because they are a weak point...

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.

What level of boost are you getting at a given rpm? How about downpipe diameter, i'm only asking this because if it is really such a slow spool, than i might return mine!

A 6258 spools as fast as a 2560...no problem. Will also pull till probably 350tq easy.Personal experience.

forged pistons give a good bit of insurance, while learning to tune. Assuming this is going to be tuned by yourself, a button clicking toonernoob, I would want that headroom. I sure used up my engines 9 lives...a few times and everything is aok.

I second that a 2860 sucks balls.

I had one, on a 2002 miata, with a begi cast manifold > 2.5" downpipe and exhaust. 10psi wastegate only boost control.
That turd hit the power at like 4500-4800rpm, where my 6258 takes off at 3200-3300rpm. same as my ex 2560r but makes 309hp instead of 265hp at same 17 psi.

ridetheclitche has a gt2871r setup, and he is spooling really well on a kraken T25 setup
https://cimg7.ibsrv.net/gimg/www.mia...8c558daf5b.jpg

Well, the opportunity just arose to pick up a cleaned up and rebuilt BP4W head with supertech double valvesprings, and supertech hi flow intake and exhaust valves, for $500... Will I see enough benefit out of these to warrant the investment with my goals?

That is 200tq at 3100rpm - pretty good and a big argument for going the "cheap" route

You'll make your goal on any BP head with the turbos mentioned. That head would just get you there at less boost with more area under the curve.


I'm definitely sounding like a broken record at this point but if it were me I'd probably take the forged piston money and trade it for that head.

Very cool, but that's not something the average person is going to find with a quick internet search.

the efr is not hard to find for a good price.

Plz halp meh t00n mah vvt.

Seriously... my setup isn't optimized at all. VVT is going nuts and oscillating like mad down low so there are likely some gains left down low. Those VD logs are with a Squaretop as well which didn't really act as expected. Maybe I have a boost leak from things. I'm honestly not really sure.

In any event... Is fast man. Point being, yeah... It does spool better than expected. I see 12-14 psi at 3200 like I did with my '2560' FM Ewg setup and it takes off from there. It's kind of a wonderfully weird feeling to realize that the turbo is just now starting to get into it where the old one was tapping out.

look at borka's EFR 6258 plot, same Kraken setup, BP6D, blah blah https://www.miataturbo.net/dynos-tim...9/#post1486956

He is hitting 200tq at ~3200-3300rpm. I didn't know that a 2871 can deliver as much torque down low as a 6258, but it does. Can't wait to get my GT2560 running on the Kraken stuff!

The Kraken stuff has some kind of voodoo magic built in. I am hitting 10psi and 175ftlbs at 3200-3300 rpm on a 1.6 with a 2" exhaust, a TD04 and a crappy street tune made by me (who has no idea what I am doing).

Borka and I have spoken quite a bit about our setups, so I've seen that a few times. You have to remember that I'm pushing more boost than he is and I believe my timing map is more aggressive so there are certainly differences in the setups, but yeah, lower down in the region you're describing that's not a factor.

If you look at the latest logs I've posted on my thread, the VVT angle, duty, and target are all going a bit haywire in the active zone, so I'm just saying that there's a chance that my spool could be slightly better if that was dialed in. I'm just really not sure how to do it, so I've been reading up on how to confirm angles and then just tuning it like I did EBC.

But yeah; TLDR; these outdated turbos still have a few things going for them with a good manifold and exhaust setup. I'm pretty pleased with the torque curve. EBC is fantastic.

300whp is dope. That was my favorite power level ever. 350whp just blows tires and transmissions and axles.

at 300 my 245s wouldn't hook in 3rd on the street, also would spin in 4th if it was cold.

EFR6758.

Do you have a dyno or log/virtual dyno of your setup as it was at that time (and/or later)? If so, please post it!

Dunno. Take my 380whp dyno and flatten the torque lower

Went and found Aidan's ish...

15 and 20 psi runs .
https://cimg8.ibsrv.net/gimg/www.mia...ed61f9d950.png

Allofit.
https://cimg9.ibsrv.net/gimg/www.mia...1a1ee64214.png

On my phone, so this is a pain in the ass, but it looks like he hits 200 rwtq and also full boost about 500revs after I do. More valid comparison will be after I get to the dyno. I think his timing map is much more conservative than mine as well and from his thread, it seems the he was still on setup mode for ebc so there's likely some ish there.

Why does Aidan's car make 7psi at 3000rpm and 14psi at 3600? Acamas made 10psi at 3000rpm and 18psi at 3400rpm. https://www.miataturbo.net/diy-turbo...6/#post1441885

Aidan does 150tq at 3300, 200tq at 3600. Acamas made 150tq at 2700rpm, 200tq at 3200rpm. https://www.miataturbo.net/dynos-tim...-scared-95108/

I am also incredulous of your VD plot. My old 2871R was about as bitchin as it gets, even compared to what you can build today. Real Garrett CHRA, Absurdflow manifold, E85, VVT head, open 3" exhaust. Didn't make 200tq until 3500rpm. Your VD plot soundly beats those numbers, which makes me doubt the validity of that plot. http://img.photobucket.com/albums/v3...E85-351whp.jpg

Look at my last dyno plot. Torque is on the right side.

150ft/lbs at 2700 rpm, 200ft/lbs at 3300ish?

https://cimg3.ibsrv.net/gimg/www.mia...8d832c5666.png


Not sure about boost levels. I had multiple issues with my dual port wastegate leaking, could have been the cause there

A couple of thoughts:

First, Virtual Dyno is tricky to get right. You have to be extremely careful to get the car data entered correctly, because it's very sensitive to weight, drag, and gearing info. You also need to make sure that the road you're running on is perfectly flat, and that the tires aren't spinning. It is possible to get a VD graph that matches (say) a dynojet one from the same car, but it's not easy. Your charts do not look like normal Miata dynojet charts -- the torque builds more quickly than anyone has seem from that kind of setup before and the torque curve from 3900 to 5500 is much too flat. Miatas with stock cams almost always have a noticable peak in torque around 4800 RPM, that's just what the cams are tuned for. (turbos with boost spikes or centrifugal blowers may differ due to boost levels).

Second, if you want to measure spool, the way to do that is with a regular datalog and to look at MAP vs RPM, not at wheel torque. This removes a lot of the variability in the virtual dyno approach, because spool is being directly *measured*, rather than inferred based on a calculated value with a lot of mystery coefficients in it. We actually have a whole thread for comparing spool numbers. :) Note that spool is heavily gear-dependent, because in lower gears the RPMs rise too quickly.

FWIW, my GTX2863R hits 150 rwtq at 2700 RPM, 200 rwtq at 3500 (on a dynojet in 5th gear), 7 psi at 3150, 10 psi at 3500, 14 psi at 3700, and 18 psi at 3900.

--Ian

...no? :)

Look closer at the chart. The lines you are referencing are demarcation lines for horsepower, not torque. There are no torque demarcation lines, so you have to extrapolate. I see 150tq at ~3000, 200tq at ~3500. I also won't fault you because the pull started at 2500, not 2000rpm as God intended. Also, your dyno operator deserves to be slapped for not scaling horsepower and torque the same.

Could be. You definitely have an issue somewhere. Next time you're on a dyno, set overboost to 220kpa, wire the wastegate shut, and let it rip. With a 4-port setup, you should be right on that line to within 200-300rpm of peak boost.

You definitely have boost control issues, IMO, based on those dyno plots and spool datum.