Nothing huge, but my rods showed up today, this weekend I should be going to get my 6spd msm trans along with the bp4w head. Hopefully within 3 weeks I will have everything to the machine shop.
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So, I have started compiling a spread sheet of parts that I have/ need or want for this build and its starting to add up quickly. My primary point of contention right now is with the valvetrain and whether or not ST in/ex valves and double springs are necessary for my goals, or if I can achieve 300hp- 400hp without going crazy with the head.

As I have stated, I'm going with the BP4w head that I have found for a solid price, my question is, realistically, would just going with OEM in/ex valves and ST valve springs be sufficient for ~400whp?

I do not plan to track the car regularly, I may go out for a track day or two, the only real purpose for this car is to have a fun street car, its not a purpose built racecar or anything of that sort.

What route would you guys suggest in regards to how to approach the head while being budget minded.

Subtract 200hp from your goal :)

Springs and valves are insurance in my mind. A perfect tune won't burn exhaust valves, but any small screw ups in the tune and they're toast.

Oh and a 6758 will help your 400hp goal.

I agree with them being insurance, but ultimately almost everything could be added to the build in the name of "insurance" and I am trying to avoid justifying purchases with them being for insurance purposes lol
Im not referring to being budget minded throughout the entire build, that comment was in reference to the in/ex valves in particular. Also I have %100 faith in my tuners ability to calibrate this setup properly, that is the least of my worries.

The 6258 flows enough to make well over 400whp, although you are correct with your statement, I don't think that's a required change in things.

I don't think anyone in the miata world has made 400whp with the 6258. At least no one I have seen.

Fair enough, but ultimately how many have tried? Legitimate question. I don't doubt people are running them, but I personally see no reason it wouldnt make that power. Realistically if I get to a point where the turbo is my limiting factor and I have not achieved said goal, I will assess the situation and go on from there, either leave it as is and be content with whatever power its made, or replace the turbo and go for more. If its determined that going with aftermarket valves is a necessity then I will go ahead and go with them, if they arent mandatory and we can agree that I should be safe without them, then its a win win ya know?

Soviet made 450 at 29psi with a 6758.

No it doesn't flow enough for well over 400. It might just make 400 but I'm still skeptical. I wish you luck though!

It'd be such an easy swap, you won't have to do anything but buy a supercore and leave the exhaust bit bolted up, unplug the intlet and outlet couplers and swap. Sell the supercore or keep handy for just in case measures.

I'm just curious because the compression ratio and e85. I don't recall if anyone else was using 10.5:1 because I think most of the EFR users seem to use them mostly on pump.

He's using 9:1 and an ultra aggressive timing map which they backed down after the glory run iirc.




As a side note....I used the same machine shop as soviet for my build.

I will also be using said machine shop lol

Ultimately my current concern is not the turbo, and after looking at pricing for OEM valves, its relatively comparable to what I will be paying for these ST valves, so I guess its not really even a question at this point. The price difference is so marginal that I would be stupid not to spend the extra few dollars for the ST oversize valves.

I have no doubt that I will be more than happy with what this turbo is capable of producing.

Remember, all the other things you'll probably want. It's not just achieving the power, but holding it down lol

My build is damn close tho this.

same pistons
same rods
bp4w (+1 intake/exh valves)
EFR 6758
300whp+ goals
Pump+Meth.. No e85 close and HOA doesn't like barrels of flammable things sitting around either. There is a VP 100 pump across the street from my house, however $9/gal :hatecat:

OP: I approve of your choices. :party:

He has 6258. Your 6758 will make 300 without trying lol.

If you're doing headwork, I would consider flow testing and cams budget permitting. The Maruha cams I put in idles vary from lumpy to almost OEM sounding depending on timing. I only regret not polishing my combustion chamber before he re-assembled things. This guy's got a lot of good videos on how to DIY, IMO it's only worth paying someone else to do if you're positive you can't DIY.

Small update. Decided to go ahead and pull the car in the garage and pull the engine and everything out so i could prep the bay. I decided to pull the engine out of the bottom since i will be doing all the work in the bay and potentially replacing the front subframe with a tubular unit. Ive decided that while its out im going to do a small wire tuck and shave the bay/ repaint the bay. I'm also debating whether to replace the dash with either an NA6 dash or an NB dash while i have it out. This car doesnt really have much of a purpose or a timeline for completion, so I am sort of just doing whatever id like with it as I get there.

Also in regards to the cyl head, I have decided to just go with a set of 63lb double valve spring kit with a 5angle valve job on the BP4w head while retaining the stock valves. I dont see this being an issue given the type of use this engine will see. I have a set date finally as to when im dropping the engine off at the machine shop, 5 March it gets dropped off with approx 2 week turn around time for everything. I also sourced a MSM 6spd trans with 56k miles for just $650, so i think thats a win.

Now I need to source an intake manifold. Ideally i would like to have a flat top manifold, however i havent seen many for sale lately and when the time comes idk if i can justify $650 for a stock intake manifold, so i very well may have one fabricated locally for a little bit extra.

Things i have left,
intake manifold
fuel system- injectors, fuel pump, fuel line, fuel pressure regulator, fittings, fuel rail.
Rear end- still undecided between OS giken with 3.63 or a Getrag rear end conversion.
Clutch
LS COP conversion
Radiator/ coolant re route

This weekend the welder will be here so i can fill the holes in the bay, grind everything smooth and begin the bondo work and get it ready for paint.

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Update-

Dropped everything off at the machine shop this weekend, should have the block and head done in about 3 weeks. I have made some good progress with the shaving of the engine bay, finally got almost all of the holes welded shut and grinded down, the bay should be ready for bondo by this coming weekend.

Oh, and I very well may be exchanging the 6258 for a 7163. When I initially purchased this turbo I had no desire to build the motor at the time. But I think it would be the most financially beneficial for me to go with the turbo i plan to use now vs buying 2 turbos.

To do list-
-intake manifold- Psyber got me a flat top that I will likely get from him soon, still considering the honda manifold is Begi would ever get back to me with a price for the head flange.
-fuel system- injectors, fuel pump, fuel line, fuel pressure regulator, fittings, fuel rail.
-Rear end- still undecided between OS giken with 3.63 or a Getrag rear end conversion.
-Clutch, ACT 6puk
-LS COP conversion
-Radiator/ coolant re route

//Chris
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I would go getrag. You get better gear choices, and its cheaper than an OS Giken+3.63

That's my thoughts as well, I have read a few threads where people mention the V8R Getrag kit needs some additional brackets and everything even after its all installed. Not a deal breaker, just sort of a turn off ya know? I am surprised you didn't comment about my turbo exchange comment ;)

Missed that. Excited to see a 7163 pushed. I think you will need a transmission solution before you find out how far it will go. IMO the best solution on the market right now that isn't completely custom is http://www.maverick-motorsports.com/...-adapter-plate + FC trans + rear trans mount + getrag diff.