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Old 07-13-2008, 05:08 PM   #1
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Default Head work on 99 or 95 head?

So I came to the point where I have to decide whether I should port, polish and put 1mm over intake and exhaust valves, ferrea springs and retainers on a 95 and just sell my 99 head? or should I try to sell the 95 and just do everything to the 99?
Is there a huge difference between the two head? or if I port and put all the work in them they would actually be the same?

Btw. where can I buy camshaft blanks cheap for a 1.8 miata?
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Old 07-13-2008, 06:19 PM   #2
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I would say that the evidence suggests that a 99 head is a better platform for HP gains. I thought that was common knowlege, no??
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Old 07-13-2008, 06:24 PM   #3
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I know that a 99 head is a better head, but was wondering if after the port and polish, diff valves and springs it wouldn't be the same...
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Old 07-13-2008, 06:34 PM   #4
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Quote:
Originally Posted by Dhaark View Post
I know that a 99 head is a better head, but was wondering if after the port and polish, diff valves and springs it wouldn't be the same...
It's not the same. I have a 96 and had the head ported and polished. It's a definite improvement over stock but it's still not the same as the 99.
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Old 07-13-2008, 06:52 PM   #5
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ok. I guess I'll just do the 99 one then.

Another question then... what is a good price for port, polish and assembling the whole thing?
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Old 07-13-2008, 07:07 PM   #6
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From Solomiata.
It sounds like you've already decided but for future askers... look closely at the two port profiles. one shows air coming in and making a hard turn into the combustion chamber. the other is the 99.

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Old 07-13-2008, 09:36 PM   #7
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y8s, do you know what type of cams would be good for a turbocharged car with a gt3076r?
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Old 07-13-2008, 09:42 PM   #8
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Old 07-13-2008, 10:19 PM   #9
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hey heres a quick noob question: the obviously better flowing head, is that JUST on the 99 or on all 99+ cars? meaning is that THE ONLY year it is that nice?
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Old 07-13-2008, 11:19 PM   #10
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99-00 are the same
anyone know if the 01-05 is the same as the 99-00 on the inside?
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Old 07-13-2008, 11:41 PM   #11
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Dhark, def. build the 99 head, that is the route I am looking to take myself on my car.
Cam blanks can be had from Mazcomp, not cheap, but cheaper than anyone else to my knowledge.
It may be best for you to buy an off the shelf cam though, since you don't really know what cam specs would be good for your build, I'd suggest leaving that alone and going with something known to work.
Port&polish-if ya gotta ask...ya cant afford it pal.
The prices are all over everywhere, no real standard pricing, I'd say pay as much as you are comfortable that you can afford, and as much as you trust the shop thats doing it.

What are your power goals, you looking to go over 350-400 with your set-up?
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Old 07-13-2008, 11:47 PM   #12
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Zabac, I just want to find out what range it is everyhwere because MI is kind of expensive. But I got a quote and want to find out if it is a good one or it would actually be better to trailer the car south and get it done there.
I found blanks for $200 a set.

So what are good off the shelf camshafts that don't cost $700 and are full race cams. because I can most likely regrind the stock ones and if that wouldn't work I would buy blanks.

And Yes, I'm planning on going over the 400whp mark, well over that mark.
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Old 07-14-2008, 12:17 AM   #13
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i wonder what the kia sephia head is like, those are fairly common in junkyards and have the exact same BP engine.
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Old 07-14-2008, 12:48 AM   #14
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Mach929-- No 99-00 are not the same as 01+ they have VVT. I think some people have used it but it required custom cams.

I recently was quoted $250 for valve job, $60 to resurface, and $250-750 for port/polish depending on how crazy I was getting. You could get out with minor work for $600.

Anyone have an opinion on how much head work is appropriate? I'm thinking you won't see much gain from extensive head work so it's probably not worth it.

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Old 07-14-2008, 12:49 AM   #15
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There is a Cam thread floating around, there are two links in one of my posts, check it out, I don't know off the top of my head.

As far as the headwork goes, I am not sure, have not done any legwork myself yet, but I would not be surprised to drop a grand into a fully built head. not including any of the parts themself.
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Old 07-14-2008, 01:54 AM   #16
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so I guess my price is really good on the port/polish, new valve seats, everything without parts is $600. they are putting it on a flow bench before and after, and doing everything to it.
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Old 07-14-2008, 11:47 AM   #17
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I would probably jump on that, do not skimp on the head.
I would not stop at the port polish though, there are lots of other things that will net you just as big of gains. What Manifold do you have, I feel to get the best gains out of any headwork you should address the manifold at the same time as well. No point in optimizing the head if your manifold will pose as a restriction.
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Old 07-14-2008, 12:43 PM   #18
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I don't have a manifold currently. but it's going to be something that I will make, just have to figure out how long the runners have to be - any calculators for that??
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Old 07-14-2008, 12:59 PM   #19
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[QUOTE

I recently was quoted $250 for valve job, $60 to resurface, and $250-750 for port/polish depending on how crazy I was getting. You could get out with minor work for $600.

Anyone have an opinion on how much head work is appropriate? I'm thinking you won't see much gain from extensive head work so it's probably not worth it.

Smythe[/QUOTE]

I guess it depends on what your ultimate goals are. Typically the best bang for the buck on a street car is a high quality 3 angle or 5 angle valve job (improves low lift flow), gasket matching the ports and pocket porting the valve bowls (often referred to as a Stage I). Shops may or not not provide you with before and after intake/exhaust flow numbers with a Stage I job; if they do it is usually for only one cylinder.

Getting beyond that gets more expensive, Stage II jobs usually add on new after market high performance valve guides, upgraded valve seals, springs, keepers and retainers, after market SS valves (standard or oversize), un shrouding of valves in the combustion chamber, combustion chamber smoothing, reworking short side radius of intake and exhaust ports and more extensive porting of the entire intake and exhaust ports. On work like this, you really want to know what the stock port volume is going to be enlarged to; hogging 80cc intake ports out to 100cc can increase high lift flow but do so at the cost of reduced port velocity and throttle response.

Stage III typically represents the maximum flow (focused on higher lifts) that a porter can get out of a particular casting before "hitting water". Not at all something you want to consider on a street car.

Make sure the shop working on your head is familiar with the lift characteristics of DOHC Mazda cams...factory 1.8 solid lifter non- VVT cams are about .326I/.350E and .400 lift is pretty big on a Miata cam. Unless you are going with an all out race engine, you don't need to concerned about port flow past .450 lift. Improving flow from .100 -.300 lift is much more important than trying to get good numbers at .400 or .450 because the valves spend much more time at the lower lifts than at peak lift. More sophisticated porting shops develop porting programs (manual prototypes which are then digitized to be run on multi-axis CNC machines for production) based upon maximizing the area under the curve (e.g., calculation on the average flow from .100 -.500 lift).

For what is worth, flow bench numbers are best viewed in relative vs. absolute terms. The same head will not always have the same flow numbers on 2 different flow benches due to calibration differences and operator techniques. Most reputable shops use a 28" water standard, test the head using a test pipe or bore fixture that is the exact same size as cylinder bore of the engine the head will be run on, use a molded clay radius around the inlet of the intake port and short section of test pipe (same ID as the header or turbo manifold which will run) on the exhaust port.


Ooops, this is probably a lot more info than ya wanted to know...sorry I'm on the third cup of Starbucks already this morning!

YMMV,

Mitch
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Old 07-14-2008, 01:08 PM   #20
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Dhaark, I intend to use similar numbers that are known to be good on similar/same motors. The biggest thing I am focusing on (besides plenum and runner sizes) is the angle of the runners. I want it to be as close as possible to the head I end up using for the best possible velocity due to straightest possible route (most likely a 99-00 head).
Mitch summed it up quiet nicely for you to get an idea here, but I think you need to share a bit more on your set-up and ultimate goals you hope to reach after headwork.
Are you planning to have a high revving motor? What does your parts list look like?
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