Built NA 1.8 Block - Getting 03 VVT Head - Valve Train Upgrade
 

Hey guys so I'll be making a build thread soon. I'm a noob I've never had a built car before and with the Miata in it's current state it's the closest I've ever been. I bought built a Engine(block)/Trans/Megasquirt from a forum member.

'97 Miata - running Megasquirt DIYPNP built by Braineack
- MS from 94/95 did pin out all emissions deleted basically ODB1 now

JE Pistons
Carillo Rods
Exhaust cam Mod
OBX adjustable Cam Gears
Protege Valve Cover
All seals and Bearings
Cometic Head Gasket
Gates Racing Timing Belt
Toyota Coils
M-tuned dual feed fuel rail
2.5" ebay Headers
Custom 2.0" center exit hacked up from old miata exhausts. (being replaced with full 2.5" all the way soon, still debating 3")
Dual Row Radiator from Amazon
MAF and all emissions stuff deleted
Begi Coolant Reroute modified deleted front neck
Nb lower Rad hose
Flyin Miata FM2 Clutch KIt
AASCO Racing Flywheel

Getting a '03 VVT Head. I want to upgrade the valve train for slightly higher red line and better reliability (is that even a thing). With the VVT Head I will be adding the 10AE Intake Manifold which I already have.

Supertech Valve Springs 1.8 Mazda

If i go with these at a heavy double spring what else do I need to upgrade? The head has less than 40k, I daily the car, will be doing track days and maybe some autox.

Is it worth it even to open up the head? I rather do it before I put the head on. What other upgrades would be worth it?

I was doing some research and cams play a role from what I see. Intake cam will be stock from my understanding the exhaust cam is the same and as such will re-use the exhaust cam mod. Will the new valvetrain present a problem?

I was thinking the double heavy springs to red line around 8200-8400ish and have extra breathing room so i can beat it everyday and have peace of mind??

I'm so confused any insight on this would be appreciated.

I will be going with a small turbo sometime this year possibly or early next year (really when I see a good deal on the forums). I want to drive the car NA for a while and see if I'm happy that way.

THANKS for any input!

If you want N/A power then you should replicate whatever emilio700 runs in his N/A cars
https://www.miataturbo.net/general-m...project-63125/

If you want turbo power then its a different story altogether.

Why do you need to rev to 8400?

I don't need to or have to. I've put so much money into the Miata so far at this point it's why not. The head is incoming so now would be the time for upgrades. I'm a noob I just want to have fun driving my Miata. I'll be going small turbo soon, just NA for now. Thanks for the input everyone.

Sweet link, Soviet.

If you wanted to rev to 8400, you probably should have started with a 4W head.

8400 + small turbo = full retard.

8400rpm in a Miata is not intelligent if you expect it to last.

Start by never calling it a 10ae intake manifold again. Don't be a m.net sackrider, it's just a VICs manifold.

Secondly, stop thinking about anything over 7500rpm until you have a $3k CNC head. Won't breath past that, so there's no point. Your hp and tq curve will look like this:


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That being said, I'd say a balanced rotating assembly, 949 or ATI damper, BE oil pump, forged rods, and upgraded valve springs are the minimum for anything over 7500 to be reliable. Even then, you'll want the CNC head to actually make power.

I'll be the opposing thought here. Doesnt matter what the power and torque does up high, if it gets you and extra couple mph without having to shift its 100% worth it. 8500rpm is fine in a built head for auto-x only. However, 8000 is more reasonable unless you're running the big sticky tires and will actually need the extra speed. Either way you'd want valve springs. Stock the vvt head can be reved to 8k in an auto-x setting but you're just asking to eventually drop a valve, this is what the top csp cars are doing with vvt heads right now.

If I was going to build another VVT head for auto-x here is what I'd do.
Manley valves, the extra $10/set is worth it for the better metal
supertech heavy doubles and ti retainers
zetec lifters, the valve tips will have to be ground shorter than normal for these to work by ~.05" but they're cheaper than the supertech subs and lighter but slightly more of a pita because you have to buy complete new lifters to adjust your valve lash.
3 angle valve job, I think the 5 angle or radius and the hammering the poor sucker is going to take would be too much.
viton valve seals
bronze valve guides
etc

That head would cost marginally more to build than my trackspeed head that I redline at 8500rpms and would be longer lasting. I seem to be pounding either my intake valves or intake valve seats into submission. Re-shimmed and installing the inner springs from the doubles this winter. But if the intake valve lash tightens more than a couple thou this season the heads going to get pulled.

If willing to spend a little more, some custom double valve springs made from pacaloy with ~80lb seat pressure would go further for reliability/life. You can get pacaloy springs off the shelf for these motors but they're only 66lb seat pressure.

Building an engine to handle 8400 rpm for a car that will "maybe some autox." seems like a strange use of the budget.

OP: Stop buying parts until you have a clear picture of what you want the car to do. People here can help you figure out a cost effective way to reach your goals. Also, exactly what pistons do you have and what is your actual compression ratio?

Hey guys like I said I'm a :noob:. I've been doing more research. I realize I won't be making power at such high RPM. My main concern is something that can handle abuse. I did autox and am more interested in HPDEs. I will also never call the intake manifold a 10ae intake ever again :) I'm just trying make an awesome Miata.


8400 was just a number I threw out there, didn't consider what would need to happen. 7500 - 8000rpm range would be more than enough. Compression Ratio is 9.5:1 with JE forged Pistons around what a stock NB engine would be at for CR.

As mentioned in OP bottom end is completely built, so just looking to spruce up the VVT head before putting it in. I think a valve train upgrade would be more than enough but that's why i came here is for input. I appreciate everyone who has posted.

I'm going to try some things that Leafy mentioned. Please don't stop the comments. Thanks!

Is it too late to consider doing a bottom end with a compression ratio that makes sense?

Or spending way less money and gearing the car to use a 7200-7400rpm rev limit effectively?

Honestly, if its not a serious auto-x car dont bother. Set the rev limit to 7200, slap the turbo on and have fun. The extra 10 or so mph difference between 7200 and 8500 isnt going to matter in a non-serious car at auto-x, if you're not on the 275 hoosiers, if you're on street tires forget it. And even if it did need to get going that fast you'd be able to feel like mario andretti going from 2nd to 3rd and back all the time.

Is the CR too high or low?

@Leafy
Valve train not worth it?

Pump gas = 8.6 Supertechs. If corn juice, i'd think about going higher.

High for a turbo build, low for an N/A build.

Damn isn't that really low compression? This engine was running 18 psi on a super charger without issue it was actually the super charger that kept having issues! I would only go up to around 10-12 psi.

I really appreciate everyone's input. I think I'll do a basic port polish, and not go crazy on the valve train upgrade.

I'll probably get flamed for it but I think the compression and some boost will not be cause for disaster. :beer:

It's not a disaster thing. It's about making power.