circuitmstr74

iTrader: (1)

SuperMiata CNC Miata Head

6speed

Pretty healthy price increase. That probably puts it out of my reach.

Leafy

iTrader: (1)

If I understand the price at the top correctly, that includes the $500 core charge you'd get back if you sent them your head.

Scrappy Jack

iTrader: (2)

If it is $3,250 minus $500 when core is received, that puts it right at the target of $2,750.

6speed

Hopefully that's the case.

EO2K

iTrader: (37)

Emilio, I have 2 relevant questions:

1. With the deshrouding, decking, OS valves plus whatever other voodoo you guys do, how much does the volume of the head change over stock? Selecting pistons to reach a reasonable CR becomes somewhat more complicated. I'd hate to use 9.5:1 pistons and end up around 7.4:1 or worse, 10.5:1 (I haz no E85)

2. My '00 4W head has a 5A cam in it that I purchased from you a couple years ago. I'd prefer not to buy another 5A as mine has all of about 12k on it. I could in theory reinstall the stock 4W cam (if I can find it) and mail you the 5A ahead of time for the head build, but I don't know your what your policy would be about customer supplied parts. I trust you guys to shim it right the first time rather than me deal with swapping cams and then trusting myself to reshim it correctly later.

Thanks!

miata2fast

iTrader: (2)

I am assuming you mean flow numbers? Typically when heads are tested, it is at various lift amounts. The increments are usually in .050" or .100" increments. By knowing what your camshaft lift is, you can get a pretty good idea of what the maximum flow rate would be. Not including induction and exhaust further upstream or downstream from the head.

There is data floating out there that shows what a stock head flows. I have that info in my build thread. I could not determine if the info I obtained was from a 1.8 NA or NB head.

sv650_ck

iTrader: (10)

or mail the core ahead of time

The option for shim under bucket lifters would be required for?

emilio700

iTrader: (3)

1. Virtually no change. Heads are shaved a tiny bit to compensate and keep chamber volume around 52cc of OEM

2. Ship us your 5A cam

High revs. For stock cams or shift points below 7500, SUBs are nice but not absolutely necessary. We suggest them with bigger cams or shift points closer to 8000rpm if you want the motor to last.

scenturion

iTrader: (9)

Strange question: I want a BP4W head for the simplicity on my NB1, but I have a BP6D head right now. Could I return the BP6D head as the core on a BP4W?
Thanks!

EO2K

iTrader: (37)

Awesome, thanks Mr C. I'm just waiting for someone to pay me for some side work at this point, I'll shoot you a call/email when things are ready to roll.

emilio700

iTrader: (3)

Nope. You must return the same component list we ship to you.

circuitmstr74

iTrader: (1)

I ordered mine today! Yay
I wanted to shout it from the top of a mountain but this will have to do

6speed

I'm jealous!!

Quick question for emilio. Is a head shave for a compression bump an option or even recommended? I have no intention of ever going forced induction, I just want a nice revvy street motor.

emilio700

iTrader: (3)

Chamber volume is adjusted to remain the same. Compression depends on fuel. 10.5:1 on 91. Add .25 pt for each point in octane. Subtract 2pts for big turbo or PD blower. Subtract 1 pt for small turbo (~2554) or Rotrex. Add 3pts for E85.

Those are my informal guidelines based on my experience. Most of the N/A motors in our shop run our weak 91 (California) gas so 10.5:1 is about the max and still be able to reach MBT everywhere. I have learned that the gains from being able to reach MBT are usually greater than that extra half point compression.

EErockMiata

Very relevant info. Thanks. Ever since the info on this head got released I've been interested in it. I've been turned off by the idea of building an engine lately as it seems people building for track use are the ones blowing motors up consistently.

To me this head costs about the same (a bit less) than having an entire motor rebuilt to OEM plus the safe track stuff (rods+valve springs + light headwork). That being said... Is it a stupid idea to put this head on an oem 01+ long block? (reving to 7200 and properly tuned). I assume the mid range and top end gains would be noticeable and I certainly like that idea over a 3-5k turbo setup for track use.

I just wouldn't mind more power and a trick head... I just don't know if I want to go down the rabbit hole of bottem end builds. This is prob a ymmv or depends on situation question... so Idk why I'm even asking but w/e. What else are forums for?

emilio700

iTrader: (3)

Port velocity and flow are improved everywhere so gains are everywhere. People blowing up N/A track motors are making mistakes in either the build, tune or driving. It isnt rocket science. Forged rods/pistons, double valve springs - tune it <13.0:1 at full load and don't money shift it. Running coolant and oil a bit too hot still won't kill it, it just makes less power and wears out faster.

Decide on what your power goals are. Circuitmster74's build is for a torque monster power capped N/A race engine. Uncorked on E85 might make 30whp over his cap.

z31maniac

Emilio, do you guys use custom pistons to get the comp ratio that high for E85? Is if safe to assume to you can't (or wouldn't want to) deck the head enough to get there?

emilio700

iTrader: (3)

Custom pistons. 85.5 JE slippers for 13.5:1 in our 200whp project build. It'll take some work as the CNC head has 2mm O/S exhaust valves and we're using .450 lift cams. So getting everything to place nice in there and reach 13.5 will be a challenge.

6speed

[QUOTE=EErockMiata;1088432]
That being said... Is it a stupid idea to put this head on an oem 01+ long block? (reving to 7200 and properly tuned).
[QUOTE]

This is basically my question also. From the responses I guess a head shave for another half point or so of compression is a no no and the compression should come from high comp. pistons instead.