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Old 12-21-2011, 12:01 PM   #1
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Default Head Work Necessary??

I am putting a begi s3 turbo kit on my 97, and i was wondering if i needed any work to be done on my head? I am having the bottom end built with forged internals (I just prefer forged ones), along with a lot of other little things like pulleys, water pump, fuel system, exc. I am hoping to get between 200 and 250whp with a conservative tune, Should i get head work done? Or will the stock head be ok?
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Old 12-21-2011, 12:11 PM   #2
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In all honesty at the power levels you are shooting for headwork is over kill.
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Old 12-21-2011, 03:45 PM   #3
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This might be a dumb question but i haven't ever had anything machined, If i get my head rebuilt will i have to buy all new valves, retainers, and valve springs? And the stock cams should be fine to reuse right?
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Old 12-21-2011, 03:53 PM   #4
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This might be a dumb question but i haven't ever had anything machined, If i get my head rebuilt will i have to buy all new valves, retainers, and valve springs? And the stock cams should be fine to reuse right?
The machinist will look at the parts and change what looks old or tired. Seals and guides aren't cheap. If you have the cash, Supertech single springs and SS valves aren't a bad idea. I recently put 100-hours at 250whp on my car and found I had bent intake valves most likely from an over-rev. I did the Supertech single springs for insurance and did SS valves because I saw very slight erosion on one valve that was not detonation. There's no reason to not run a stock valvetrain unless your car hobby is driving instead of wrenching on cars like me.
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Old 12-21-2011, 04:16 PM   #5
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I have been looking around and will probably be getting the valve spring kit from flyin' miata, but I am still unsure about the stock cams? Should they be fine with the power I am trying to make? This car is my Daily driver so it wont be driven to hard.
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Old 12-21-2011, 04:22 PM   #6
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For your power goals stated above, no work would have been required on a stock engine in good running condition. You don't need headwork. If you're going to refresh the whole motor anyways, then yes, you might as well get a little extra done while it's all apart. Stock cams are adequate.
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Old 12-21-2011, 05:24 PM   #7
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I wasn't going to get the head rebuilt, but I might as well do it when i get the bottom end rebuilt, I just feel more comfortable getting it rebuilt because it has 142,000 miles
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Old 12-21-2011, 05:27 PM   #8
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What year head are you working with?
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Old 12-21-2011, 05:31 PM   #9
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It is a 1997 head
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Old 12-21-2011, 06:18 PM   #10
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Here is a little advice on how to make a cheap and reliable head with a tad more power.

The 95 to 97 head has the stiffest springs of any BP head. So I would keep your springs, and perhaps invest in a set of new Supertech valves. They will have an undercut stem, so they will flow more despite the fact they are the same diameter.

I would suggest using the 99 or later valve keepers and retainers. They are less prone to coming out at high rpm.

Next, go to either the 99 and up shim over lifter, or step up to the more baller shim under lifters. With the shim under lifters, you will be able to swing the motor to pretty close to 8000 rpm with no problems. They are very light, and will allow the springs to snap back faster than with the heavy HLAs (hydraulic lifters).

With the above simple and inexpensive modifications, you will make a tad more power and you will now be able to run a more agressive camshaft if you desire.

One final note: The Supertech valves are a bit longer than stock, so depending on what camshaft you plan to run, you may need to shim the spring to get the desired seat pressure for what ever cam you will run. If you do use more cam, make sure you test the spring coil bind. The more spring shimming you do, the less lift the spring will take before coil bind.

Last edited by miata2fast; 12-23-2011 at 12:36 PM.
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Old 12-21-2011, 06:21 PM   #11
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Honestly I would not touch the head unless you are planning on dropping a 99/00 or a VVT head on it. The later year heads are worth more then any machine work you will put into yours.
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Old 12-22-2011, 09:13 AM   #12
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Quote:
Originally Posted by miata2fast View Post
Here is a little advice on how to make a cheap and reliable head with a tad more power.

The 95 to 97 head has the stiffest springs of any BP head. So I would keep your springs, and perhaps invest in a set of new Supertech valves. They will have an undercut stem, so they will flow more despite the fact they are the same diameter.

I would suggest using the 99 or later valve keepers. They are less prone to coming out at high rpm.

Next, go to either the 99 and up shim over lifter, or step up to the more baller shim under lifters. With the shim under lifters, you will be able to swing the motor to pretty close to 8000 rpm with no problems. They are very light, and will allow the springs to snap back faster than with the heavy HLAs (hydraulic lifters).

With the above simple and inexpensive modifications, you will make a tad more power and you will now be able to run a more agressive camshaft if you desire.

One final note: The Supertech valves are a bit longer than stock, so depending on what camshaft you plan to run, you may need to shim the spring to get the desired seat pressure for what ever cam you will run. If you do use more cam, make sure you test the spring coil bind. The more spring shimming you do, the less lift the spring will take before coil bind.
Thanks, this is going to help me alot.

shuiend- I see what you are saying. Its not that i want to make more power from my head, but i want to make sure that it will be reliable with the power I will hopefully be making
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Old 12-22-2011, 07:02 PM   #13
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Honestly I would not touch the head unless you are planning on dropping a 99/00 or a VVT head on it. The later year heads are worth more then any machine work you will put into yours.
Agreed. Money spent on machining OEM parts that aren't the best available is money wasted if you later decide to upgrade to the better parts. This is speaking as someone who has a worked-over 99 head who now wishes he had a VVT head. (although in my defense the VVT heads were considered undesirable at the time I got my 99 head done because there weren't any off-the-shelf control solutions for them yet).

--Ian
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Old 12-22-2011, 08:34 PM   #14
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Ok, so if I was to get the head machined I might as well get a stronger valvetrain. Can a stock head handle around 250whp? I might just get it rebuilt, because I am on a budget
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Old 12-23-2011, 07:09 AM   #15
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I to would agree, porting may not be needed at this point, how ever it would help make the inefficiency of the miata head flow better, thus resulting in not only throttle response out side of "boost" but also increase "spool time" it self. I will say that if the head is off, look into minor up grades. Don't look at it as being needed for power but try looking at it to become a for reliable runner. This though process of only needing to upgrade only if more power is decided is a common mistake. I say protect your investment and and build a reliable fun car. most of us know from experience that if one thing brakes you replace 10 other things that broke as well.

If you are interested we can offer you some smoking deals on what you need to finish your build. Keep that engine running long and strong.
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Old 12-23-2011, 09:47 AM   #16
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I to would agree, porting may not be needed at this point, how ever it would help make the inefficiency of the miata head flow better, thus resulting in not only throttle response out side of "boost" but also increase "spool time" it self. I will say that if the head is off, look into minor up grades. Don't look at it as being needed for power but try looking at it to become a for reliable runner. This though process of only needing to upgrade only if more power is decided is a common mistake. I say protect your investment and and build a reliable fun car. most of us know from experience that if one thing brakes you replace 10 other things that broke as well.

If you are interested we can offer you some smoking deals on what you need to finish your build. Keep that engine running long and strong.
Thank you for the advice, I looked at your website and there are definitely some things on I will be contacting you about in the future
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Old 12-23-2011, 10:09 AM   #17
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This might be a dumb question but i haven't ever had anything machined, If i get my head rebuilt will i have to buy all new valves, retainers, and valve springs? And the stock cams should be fine to reuse right?
I ddi some work to my head. Other than the port work, I had some BP springs put in (in a B6 head), supertech valves, supertech valve guide seals and new OEM valve guides. It didn't cost that much... I think around $600 or so. The most expensive part and time consuming was doing valve guides.
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Old 12-23-2011, 10:34 AM   #18
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A little more summing up.
You don't need to do any headwork to run 250whp. Bone stock tired-*** 1.6 motors w/ 200k miles can make 250whp with no problem. You don't need any headwork for your power goal.

On the other hand, you'll already have the motor apart, and there is definitely room for improvement with some headwork. For your '97 motor, the most cost efficient upgrade would be to buy a used stock '99 head and drop it straight in.

If you want a "new" head for piece of mind in your new motor, your next most cost efficient route would be to buy a remanufactured '99-00 head. Most of the remanufactured heads come with some very basic flow work done to them, and most places can upgrade you to whatever "stage" you want.

There are at least 4 forum sponsors in this forum who specialize in head-stuff.

Renown Performance is having a holiday special on headwork:
https://www.miataturbo.net/showthread.php?t=62258

There was a thead awhile back about this company who somebody had good luck with: http://www.shop.headsonly.com/main.sc
They only list a single type of 1.8 head... so if you decide to go with them, be DAMNED SURE that you can provide your 94-97 head and core exchange it for a 99-00 head (ie, BP4W).

There's also another nifty little trick you can do called an exhintake swap. On all 94-00 motors, you can install an exhaust cam as an intake cam. The exhaust cam has a slightly better grind and can be directly installed on the intake side. You have to remove (hacksaw will work) the cam-sensor gear from the cam, but it's a straightforward process.

Emilio at 949Racing sells the Mazdaspeed Miata (BP5W) intake cam which is actually a pinch better than the exhintake swap and would be easier to convince your machinist to put in your head than a used cam you chopped the end off of.
http://949racing.com/mazdaspeed-miata-intake-cam.aspx

In any case, there are lots of options... use your current stock head, do nothing and put it on your new engine is cheapest. Or for about $400, you can have a remanufactured '94-97 head. Or for about $1500, you can have a decently worked over head with MS intake cam.

OH, and people are ALWAYS selling used heads in the classifieds here... sometimes fully built heads for far less money than you'll spend new.
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Old 12-23-2011, 10:35 AM   #19
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Don't forget that there are other mods you must do to install a 99 and later head. That will take time and money to source the parts. If you decide that you want to go with the later head; valves, springs, and lifters will work on the newer head.

In saying that, I too agree that it would not make much economic sense to invest heavily in port work in the older head. the newer heads are that much better.

You will not need the older head to be ported anyway. You can easily meet your goals without it.

Edit: Samnavy you beat me to the post. I like how you mentioned the inexpensive cam option.
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Old 12-23-2011, 11:15 AM   #20
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Thanks for all the info, it helps a lot. Since the stock head is fine for the power I want, I will most likely get the head rebuilt with OEM parts, just because I am on a budget. Does anyone know if Supertech valves will work with a stock drivetrain? Or would I have to get Supertech retainers, springs, exc.. for the valves to work?
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