[BP4W Head Swap] Definitive list of parts
 

Hey! :likecat:
I'm sorry for my bad english

So, I have a 96' NA8 miata and I'm going to do a head swap with a friend.
I have the 98' head with intake manifold and fuel rail from 98' NB8 and I normally found the right FPR (n° of the part: BP5B-13-280), the one who fit right in place of the old fpr without modification.

I would like to make a complete list of what I'd need before starting the swap:
-> BP4W Head
-> 98-00 Intake Manifold
-> 98-00 Fuel rail
-> 98-00 Euro/JDM FPR (BP5B-13-280)
-> Head gasket
-> Intake manifold gasket

Parts reused from my 94-97 Engine:
-> Injectors
-> Header/Exhaust Manifold
-> CAS

Have I forgotten something?
Thanks!

Ps: Yes, I'm sorry for this reccuring topic done several times before ;)

New water pump, new timing belt and components, new cam and crank seals. CAS seal. Valve cover gasket. EGR delete. Coolant reroute. Some method to control VICS. If you get a VVT block you can swap the BP4W head to get 10.5 compression, then build your short block with the VVT head for boost.

Use your throttle body unless you have an ECU. Then you can wire up the newer tps and iacv and simplify the intake.

Yes, the water pump will be changed. Timing belt has only 1 year old so I will keep it ;)
New came and crank seals, yes and CAS seal!
Valve cover will also be changed. I think I will buy EGR block to delete the EGR.

If I do not want to control the VICS, the only thing I lose is mid-torque, right? No risk to run this without a RPM switch?
Concerning the compression, before I put the BP4W head into my NA, the head will be shaved by 40thou (Maybe I need adjustable cam gear?)

I run OEM ECU, so with that, you think that it will run fine? No risk to run lean?
Thanks!

These are tired old engines. Getting rid of what little mid range they have hurts, a lot. I'd keep the stock heimholtz inlet tube and VICS as long as possible. 40 Thousandths is a LOT. About a full point of compression and quite a bit of cam retarding, like three degrees, further hurting your midrange. I'd budget for adjustable gears. Your bottom end should be fine with the extra compression, most NAs are in the mid to high 8.x:1s. Run premium.

Stock NA ECU
NB head
.040" head shave

Playing with fire

Yes surely, but no risk to hurt the engine without rpm switch?
Yes, I'm going to run adjustable cam gear ;)
I have the possibilities to run a good quality essence (RON 98)

@Savington Why do you tell this?I learned a lot on forum/guy who shaved the head (40thou/50thou and also 60thou), this engine run stock compression by 8.8:1, I read everywhere that 40thou is not to much on this engine.Stock ECU with higher compression (something around 10:1) should not be a problem, the air/fuel ratio will be substantially the same (maybe higher with the NB manifold but to much).I didn't understand why?

You make assumptions about what "should not be a problem" that are quite poor

You're adding a full point of compression, 20% intake port flow, and a completely different cam profile to an ECU which ignores its oxygen sensors at wide open throttle, relying entirely on its pre-set calibration, which is preset for a motor completely different from yours

An ECU would not only make your car completely safe, but it will also allow you to extract at least another 6-10whp from the setup once it's properly tuned, and probably 20ft.lb of torque on average under 4000rpm.

Doing all of this work and leaving the ECU stock is lazy, dangerous, and foolish.

^What he said.

Changing the volumetric efficiency of your engine will cause it to ingest a different amount of air and therefore require different amount of fuel to not be rich or lean. In this case it will be ingesting more air leaning out your mixture significantly. Increasing the compression will cause an even greater likelihood of detonation.

@Savington @sixshooter Yes you're right. The MS it's a great thing to run perfectly well.
The oem NA8 ecu running rich, even with slightly more air and a stock BP4W cam, the car should run great. I read on forums from guys who did the same swap running nicely with oem ecu (maybe a little lean at idle).
Only increasing compression ratio doesn't affect the AFR, the fills of the cylinders do not change so doesn't create air/fuel problem because we stay in what the calculator knows and what the devices can do.

You are wrong. Buy an ECU or risk motor damage, your choice.

Please stop tagging me in your posts.

You really have no idea what you are doing. The head ports flow significantly more at higher rpms than the head on the NA8, not just at idle. The compression difference doesn't effect AFR. It effects the propensity for detonation.

Shavington oh sorry!
Yes but it's difficult in my country to run a MS2/3, coast around 800€ and need to find a good tuner to make a good tune, another 300-400€...

SixShooter, I know the head ports flow better but I don't know at this point...?
So, concerning the compression, if I have the possibility in my country to run 98RON, I should not have any problem to shaved the BP-ZE head ?

Neg cat for ignoring/questioning advice given.

Running an AFR of 16 to 1 when the ECU thinks you are running at 13 to 1 would still cause problems with operation.

I understand you have limitations. My ECU costs about $1200 new. If you can't afford it, you can't afford it.

Yes you're right!
I'm going to make this with an AFR and a wide band to control the AFR :)

If I realize that I run to lean, i'm going to put a 10 ohm potentiometer (on the temp line for lie to the air temperature)