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View Full Version : NB1 head on NA. What should the machine shop do?



The Driver
02-26-2015, 11:41 AM
Alright folks, looks like I FINALLY bought my 96 Montego, a well deserved NB1 head.

This post is not regarding the actual install, but I'm planning to send the head to a machine shop for some light resurfacing. I want that head to fully mate with the engine block currently on the car.

Before I send it to the machine shop, what should I tell the machine shop operator? BTW, the NB1 head has less than 100K miles and remember, this is for a turbo build up!


FIRE AWAY! :)

kung fu jesus
02-26-2015, 01:33 PM
If the head is disassembled, 5 cut valves, port, polish, gasket match, new valve guides.

The Driver
02-26-2015, 02:10 PM
If the head is disassembled, 5 cut valves, port, polish, gasket match, new valve guides.

Not is not disassembled, and dude all this would cost mad cash! But gasket match and new valve guides sounds like a good start. Within a budget, anything else?

kung fu jesus
02-26-2015, 04:35 PM
With some careful organization, disassembling and reassembling a head is actually kinda easy. A valve spring compressor is really the only tool you need to rent.

I am a little ambivalent towards your goals with the turbo, but an NA BP motor is a relatively low compression engine. Shaving the head is something you could do to bump compression.

Among what I mentioned, I would add new valve seals, which are very easy to do with the head apart. I think ARP head studs are an absolute must-add. Unshrouding the valves in the CC would be beneficial for flow, maybe a plunge cut to the bowls would be relatively inexpensive without a lot of hand work P&P entails. Get a quality head gasket, too. If you haven't, it would be a good time to plan for a coolant reroute upon reassembly.

kung fu jesus
02-26-2015, 04:38 PM
Oh, and clean the piston crowns, inspect the cylinder bores while the head is off. Knock off any carbon ridges, if present.

kung fu jesus
02-26-2015, 04:40 PM
Have the intake manifold cleaned/tanked. :)
I am very happy how my e30 IM turned out having someone else have at it. The mating surfaces were well done, too. $27 wiped out 28 years of crud.

kung fu jesus
02-26-2015, 04:41 PM
Nice time to have the IM and VC powdercoated, too!

The Driver
02-26-2015, 09:30 PM
KFJ, I wish you would've post in one post...

But here it goes: head is still in FL, the machining will more than likely take place in Tampa. I neither have the time, nor the inclination to disassemble the head. I run, I rock climb, I snow ski and mountain bike; on top of dating. In any weekend I'll do 3-4 of those activities. In short, I'm busy enough, last thing I want is to eff up the head.

I don't want the compression increased, as that would mean fewer turbo lbs. The reason for the NB1 head/intake is to reach approx 240 or fewer hp @ 10-11 lbs of boost.

Intake cleaning, that I'll do!

No powder coating. Got to save for the MS3. I only have so much $ to spend.

BoBo
02-27-2015, 12:54 AM
Of course anything can happen within a 100k miles, but assuming the (NB head) was taken care of most likely you will just need a few things done on the head. A local machine shop usually charges $250-450 for the typical stuff such as: Checking for cracks, hot tank cleaning,resurfacing, and Valve guide & seat servicing. You might not even need the valve guides & seats done. I had one of my 1.6 heads rebuilt at 160k and the guides were still within spec but I had it done anyway since it was already off of the block.

If your gonna aim for 200-240hp or less then you better treat transmissions like consumables. Maybe I just had a bad luck with transmissions. My original tranny went out within the fist year of having around 240hp on my 92na. My 1st replacement went out after 30k of normal driving on 225hp plus 1 track day. My 2nd replacement lasted until I sold the car. At that time my 92 was tuned down to 180hp but was still fast in every way. I can't wait to boost my 96 I will probably just buy the FM Voodoo 2 and be happy with under 200hp. The mazdaspeed miata tranny should be able to handle 240+hp.

kung fu jesus
02-27-2015, 08:43 PM
Savvy advice ^.

Here's what I'm thinking after reading the last two posts, it is only conjecture, so take it as you will.

Bobo brings up a REALLY good point... Are you going to use the extra 20-40 hp for your intentions? I ran my turbo configurations between 160 to 240 hp. Honestly, the car felt best to drive between 180-200hp.

I am concerned that if you don't have time to mess with headwork, what are you going to do with the car running a borderline ragged 240hp? The more more power you run, the more support and attention you have to address to all the systems exponentially. Anyone can make 240 with the proposed parts you list, but can you make it reliable and still enjoy it? Making the turbo work harder to make the power when you have opportunities to help it with tertiary mods is leaving money on the table, or flushing money down the shitter.

So, what do want to do? Make the power, or make the power reliably? Planning goes a long way to hitting goals, but cutting corners leads to oversight. Leaving it to someone one else to deal with the car when things go pear-shaped get expensive, often.

The Driver
03-01-2015, 08:54 PM
So far, I've only tracked my car twice, both times @ FM's summer camp; since buying it in May 2010. Once I go Turbo, Bob Bondurant/Skip Barber type of drivng school is a strong and real possibility.

What racers refer to as "consumables" I refer to as: dating, traveling, road running, climbing gear budget.

As for the projected power levels, I have driven a almost two dozens turbo cars (all but two were FM's, the others were Begi), and the bell curve would show Skip Cannon's 300 hp yellow Miata (not fair, that car has a 1.9 built engine, with forged internals; and two maybe three maid less than 210 hp.

In other words, 20-21 cars with dynoed 220-250 hp. Of course, the more power, the more heat created and the more things will go wrong. But based on all the info I have gatherer thus far, I feel perfectly comfortable that once my Miata goes turbo, that the car will not impode/explode just because the car is dynoed @ 240 hp @ 6K ft @ 5,700 rpms.


Heck, Skip Cannon himself told me that if the head is in good shape, I could just slap it in. But I don't honestly know the heads condition, and I'll have it checked prior to install. I'm big on maintenance prevention, and GOD knows I'm not trying to cut corners, but I'm also a big believer in not let project creep take a life of it's own either.

Also about the trannies, most of the turbo Miata folks around here (including two techs @ Flyin Miata), go with the 5 speed as opposed to the 6 speeds, for it's superior driving characteristics. That includes individuals who have had their working 6 speeds replaced on their Mazdaspeed Miatas.

I know ya both mean well, but I'm far from doing this while blind. I've been researching turboing the Miata, more or less since 2010. The whole NB1 head conversion, is what's rather recent, as I was actually leaning on dropping an NB2 engine instead.

kung fu jesus
03-02-2015, 07:50 AM
Good luck!

The Driver
03-02-2015, 06:39 PM
KFJ, it seems Keith Tanner agrees with you, when I asked him the same question, with all the info I gave you, this is what he had to say: "Service wise? Just ask the machine shop to give it a valve job. They'll probably do new guides and seals as part of it. But if they're a good machine shop, they'll know what to do".

So I was wrong, you were right, and now we have an informative thread for future NB1 head swaps! :)

wannafbody
03-02-2015, 07:06 PM
I'd leave the compression ratio as is. I'd invest in a square top manifold to match the BP4W head.

The Driver
03-02-2015, 07:18 PM
^ Nah, I don't want to move the power curve any higher. That, and I don't see the bennie of the square top.

Ultimately, I want a torque curve, as flat as Tampa.

kung fu jesus
03-03-2015, 11:07 AM
There is no right or wrong. It is just opportunistic. If you had to remove your transmission, a rear main seal, maybe a clutch/flywheel combo would be under consideration because the opportunity presents itself to do so. Preventative maintenance is one thing, but additional performance is something these situations add value to because it would be hard to go back later and do it AFTER it was already installed. You may not have been planning on doing any headwork, but given your goals and opportunity, having it done is like a capital investment AND peace of mind. That's a rare win-win in car performance. I do understand the budget creep concern, though. :)

Willywongka
08-19-2015, 07:34 PM
Sorry to bring this thread back to life, but I have a 99 head that I have had sitting around for around 2 years and decided it was time to start researching the parts I need and what steps I need to take to do a proper 99 head swap on a 96 engine. I am planning on keeping the build naturally aspirated.

I have a few questions:

1) Is it worth doing a port and polish?

2) There are so many coolant reroute variants, which do you guys recommend?

3) Are there any NB1 gaskets I should get to properly install the head?

4) Are all NA headers compatible on the head?

That should be it for now, sorry to thread jack. But I figured it would be good to keep all the info in one thread.

etikoner
08-19-2015, 11:31 PM
Might be if they know what they're doing. You wanna keep the ports small to keep good velocity. Cleaning up the castings help out a bit.

M-tuned coolant reroute is standard and comes complete, but you can do it the DIY way following what threads have done it for much less.

You can go for a cosmetic MLS gasket and ARP studs for security.

NA8 Headers will be compatible. na6 - no.

Should also install a MS to see the real benefit.

Others can chime in here as well.

Hyper
01-20-2016, 07:43 PM
Sorry to bring this thread back to life, but I have a 99 head that I have had sitting around for around 2 years and decided it was time to start researching the parts I need and what steps I need to take to do a proper 99 head swap on a 96 engine. I am planning on keeping the build naturally aspirated.

I have a few questions:

1) Is it worth doing a port and polish?

2) There are so many coolant reroute variants, which do you guys recommend?

3) Are there any NB1 gaskets I should get to properly install the head?

4) Are all NA headers compatible on the head?

That should be it for now, sorry to thread jack. But I figured it would be good to keep all the info in one thread.


Buy my coolant reroute, are you doing to build for IRTB or turbo?