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...