Performance Head Build
 

I've had my new to me Miata for 5 weeks now. Thinking about building a head to run on my biottome end. I have NOT done compression or leakdown tests yet but will before this gets underway....let's pretend it's all good..mmmkay? It's a 2001 Special Edition with 106k miles ... stock bottom end ... performing daily duties as of this week... I have installed a 2.5" roadster sport midpipe and cobalt twin tip muffler. Car has 10:1 CR. My thoughts are:

MS3 Pro PNP ECU
Shave 20 thou, 3 angle valve job, port/polish
Supertech Dual Spring Kit
Supertech SUB Lifters
Skunk2 Throttle Body
Skunk2 Intake Manifold
Tomei Cams 252 deg intake 256 deg exhaust
Racing Beat Header
New Injectors
New Fuel Rail
Will be running 93 octane pump gas

My questions:
What ballpark HP can I expect to get out of all this?
What size injectors?
Why are VVT intake cams so expensive? ;)

Thanks...Loving this little car.
Dale

You can do all that and gain maybe 20-30hp. Or for about the same money put a turbo on your bone stock motor and double the hp.

Welcome to miatanaturallyaspirated

Sounds bad.

Skunk 2 throttle body and intake manifold wouldn’t be a bad idea. When he goes turbo those would carry over. MegaSquirt also wouldn’t be a terrible idea. Op, I wouldn’t change injectors unless you had a need for them. Stick with stock for now.

Bad as in good? Or bad as in no bueno? Please elaborate

I was under the impression that increasing flow would create the need for a little larger injectors....you're saying the stock injectors can keep up? What about adding MS / Throttle Body / Intake to a stock motor? Could the increased airflow give me some gains? It'd be nice to do this in stages over the summer and take the winter to make a bigg(er) change.

I might to F/I at some point but just want to tinker for a bit....plus I do like the idea of "massaging" power out of a motor.

I'm new to 4 cylinder cars but I've built plenty of muscle cars over the years....forgive me ;)

~Dale

doesnt psyberoptix have basically this same head for sale, with the addition of being CNC ported?


but yeah, 3k for 30 hp....that sounds terribad



8 cylinder engines.. you got 200% more out of any mod compared to a 4 cyl.

miata engines suck. If you want big na power and have it actually stay together, then put a K series honda engine in it.

Sounds like a bad time. Lots of work and money for very little gain.

The only money I would put into a naturally aspirated build is stuff that could be carried over to a turbo build, so the skunk2 intake manifold, their throttle body so you don't ingest a plate screw, and a megasquirt. You could fab up a cheap 949 racing style intake as well for under 100$, it would be decent power/dollar compared to other N/A gains according to emilio. Take some time to learn to tune it naturally aspirated, then go for a turbo. The benefit to this is if you blow the engine, you don't need to build one up again, just pull a junkyard one and put it in. I am only keeping my car N/A as I can't sacrifice reliability too much.

Link to the head for sale? I didn't immediately find it in the for sale section.

Dale

I'm interested in this option.....I may do that and think about it for a bit. Come winter, I may do a turbo. My wife likes the blow off valve sound ... lol

Dale

If your plan is to turbo in the relatively near future, I'd skip most of the stuff you have listed save for the intake manifold (a EUDM Squaretop manifold is another option), ECU, injectors, and the throttle body. The rest either doesn't help when turbocharged (RB Header), or can be compensated for with MOAR BOOST. ECU and injectors would be needed when turbocharged assuming you get the ones you need right off like FlowForce or Injector Dynamics.

Signed: A guy who arguably spent too much money on his head for the marginal benefit received.

I'll spend $500 8 times before I let go of $4k ... call me crazy ... lol

Sounds like making power with a Miata is not for you.

Meh...just trying to find my footing. I'll figure it out. :skid:

Step 1: Vomit all the money into an n/a BP.
Step 2: Realize it sucks and you wasted money
Step 3: Vomit more money into turbo setup
Step 4: Drive sometimes. Break often.
Step 5: part out car
Step 6: buy new car
Step 7: Turbo again, but do it right this time
Step 8: Drive on track
Step 9: Realize that care and feeding of a turbo miata on track sucks
Step 10: Part out car
Step 11: buy new car
Step 12: Do step 1, but less, because you don't want to waste money, then spend the rest of the money on safety equipment
Step 13: N/A track glory
Step 14: Sing "The Circle of Life" by Elton John.
Step 15: K swap


The question is: Will you spend the $20k up front to skip to Step 15? Or will you take the long, way more expensive, and way more annoying path.

There is so much truth to this it hurts.

Not interested in a K Swap. I'm thinking about turbo now though...That damn Quin and his all motor 185whp monster ... lol

True story: had I known how I would be using my car now a few years ago I would have gone K-swap. For a street car turbo makes a lot of sense.

And the story starts

Quinn does have a really nice NB, hes built that car over many years but its still a stock bottom end on his. However he has shaved the head to within an inch of its life to raise the CR and that helps too.

Personally I would turbo the car, "massage" or whatever, the miata engine takes very well to a turbo. A 200whp turbo miata is great fun and it can be done for the same amount or less than what you are planning on in your first post.

No it's not, and it hasn't been for years.

What are you talking about? His car isnt nice and hasnt been built over many years and different iterations?

I skipped straight to Step 14 and am stuck. Step 15 is proving to be a challenging financial step from the previous.

I am amused that you picked the 3 out of the 4 things i was not referring to. :rofl:

It's not a stock bottom end. Hasn't been for years. :likecat:

I was pretty sure its a stock bottom end stock pipstons and rods with a boundary oil pump being the only not stock thing in there. The head has seen some work however.

lol, sorry I was like a newborn baby I had no idea what you meant initially.

What Quin built is not normal. For every one Quin I have seen hundreds of people try and fail. Doing headwork is not worth the money in the miata motor. They just suck compared to everything else. Adding a turbo and turning up boost 2psi more will get you more performance then thousands of dollars into the head.

It was a stock bottom end. 3-4 years ago. :party:


Disagree. What Quinn built is normal-bordering-on-disappointing in terms of results vs effort/parts list. Is it a normal build? No, because there's not many people dumb enough to spend a bunch of time/money/effort into building an n/a BP unless they're limited by a rules set.

The chances of a 106k NB2 having sufficient compression and low enough leakdown (<5%) to be ready for head work is nil. You are more likely to be surprised by lots of blowby when you put your trick new head on it.

As rebuilding the bottom end affects your budget significantly, do the tests now and post results. BP6D heads (or any VVT engine) need to have compression checked with oil up to temp.

Meanwhile, I'll read the rest of this thread..

I like my plan... duh, that is why it is my plan. Limited experience to date. Only one Miata (unlike Hornetball), so street tuned and run (in summer) at about 225WHP, and turn it down to a more empathetic 175WHP (waste gate) for the track.

Keeps track temps in check on a budget build. Power still a bit more than a massaged N/A.

Trick is to not turn it up over time.

From Quinn's build thread:

Stock injectors unless you run E85.
Assuming your 106k bottom end, ~145whp
Assuming rebuilt bottom end, ~160whp
Both assuming no catalytic perverter. Drop 10whp for cat.

Those cams will let it breathe well past 7000 but your old, stock bottom end will not be happy there. I'd budget for some name brand China forged rods (Manley, Eagle, K1, Scat etc.).
When you rebuild the bottom end, stay below 10.4:1 for 93 octane. If it will never see boost, go 85.5 because then you can round up and say "It's a two liter".

Well color me wrong AF, fam. :rofl: Apologies to those i misled. I'm not sure why i read that the 185whp variant had a built bottom end.

Looks like a stock bottom end to me.....

HOW DARE YOU QUESTION ME!

Quinn's build and result make sense. In 2013 we took a blueprinted 9.95:1, 83.5mm bottom end with stock weight rods, blueprinted BP4W head (no porting, stock size valves), big cams, ITB's, E85 and nothing else. Made 190whp. That bottom end was worth maybe 5-6whp over a stock rebuild.
So basically just cams and ITB's were worth about 35whp

Year before that made 182whp with smaller cams, BP6D CNC +2 head, 85.5/11.0:1, square top on 91 octane. That engine had a lot of fancy coatings.

You are not crazy, the bottom end is "stock" but the OEM pistons have had the valve reliefs machined to allow the .1" shave due to valve interference

MS3 Pro PNP ECU
Shave 20 thou, 3 angle valve job, port/polish
Supertech Dual Spring Kit
Supertech SUB Lifters
Skunk2 Throttle Body
Skunk2 Intake Manifold
Tomei Cams 252 deg intake 256 deg exhaust
Racing Beat Header
New Injectors
New Fuel Rail (this one is especially disgusting)
Will be running 93 octane pump gas

I will be ordering the MS3 next week. Curious why the fuel rail is "especially disgusting" I do admit that it's partially cosmetic but is there a real downside?

Dale

Now downside, but the stock fuel rail flows well enough.

Its ok. I was 2 years ago when he posted that list. I was just looking at the thread a few weeks ago for his dyno to see what effect the cams had on his torque. Given my recent dyno experience (148whp/133ft*lbs on a "heart breaker" Dyno Dynamics), I was curious where my motor compared.

Here is my motor build list. Roughly about $7k in parts. A friend and I assembled it, so the only outside labor was the machine work on the block.

BP6D short block
Supertech 11:1 (+1mm overbore) pistons
Manley H-beam rods
ARP head studs
Spec Miata head, VVT, short radius machined (pre-2014 rules)
Stock cams and valvetrain
Racing Beat header
2.25" exhaust
Square top manifold (ported to match throttle body and some casting clean up)
Skunk2 throttle body
2.5" Intake (24-26" length)
SuperMiata crank damper
Garage Star pulleys
Stock VVT injectors
DW200 pump
M-tuned fuel rail (single feed) - note, I bought this for cheap this instead of a BP4W fuel rail to swap into a NA8 chassis

Stock fuel rail and hardlines can flow fuel for more then 400whp. Savington has shown that. So spending money on those for a naturally aspirated build is mostly just buying bling and no bang.

Those garage star pulleys are sexy af .... wish I could find a set