I think I posted this in one of the other threads maybe not. US Seal is a large supplier to OEMs (they don't sell to the public). Here's the 2 seals they supply for the BP engine ( 2 materials) to other companies and you can look at dimensional information (not toleranced btw) and also car model cross-reference.

1998-02 DOHC L4 16V "BP"

And theoretically, all the positive seal 6mm X .43X metal body seals that could apply and fit onto the guide. The guide profile that the seals fit onto is different from OEM to OEM so use caution when using this list.

SEALS BY SIZE - 6mm X .430-.439, Metal body with rubber inside skirt

I ordered one of each to send to Mudflap. They did sell to the public over the phone. :)

If these are truly OEM, they're significantly cheaper than buying from Mazda. They were .50 and .81 each, plus reasonable shipping fees (I didn't get an actual price, but she said around $2.50 to ship)

Someone else is gonna have to get the FelPros to you, haha.

I guess there's no shame where an order is concerned...

I'm doing a rebuild on a VVT head and ordered the MR bronze guides+seals set. I'll have at least a few weeks before the head is assembled with new seals so I'm interested to see what this thread comes up with.

For what it's worth, I had my 99 head rebuilt in 2013 with bronze guides and viton seals and have not had any burning oil or leaking. I believe they were Supertech seals, but cannot say with certainty.

I borked a felpro installing new seals, and had to buy a whole new kit. I can donate a felpro to the cause. PM me & I can mail it to you

OK! I've finished a fairly exhaustive test to evaluate these valve seals. Somehow I've ended up with 7 different seals to test.

I decided to make up some kind of test in order to evaluate actual performance. Measuring the various dimensions is all well and good. But due to the spring, material type and shape/form of the lip, I can't positively establish which is really any better/worse.

So I made up a way to mount each valve seal as mounted on a valve stem. Then I'd simply add weight until the grip on the stem is lost.
Now all of these basically have a 'slip point' at which they whip right out. So I tried to very carefully measure that point. Using engine oil for lube, I put these on and gave them a chance to fall (over and over) in order to establish a repeatable measurement. In most cases I tested 3-5 samples. Unfortunately, some of these only had one or two samples to test (US Seal EOK, Felpro)

http://i66.tinypic.com/25throj.jpg

The results make perfect sense. Something we already know: DON'T INSTALL SUPERTECH VALVE SEALS.

http://i68.tinypic.com/2z6tcg2.jpg

Overall winner? A seal that I don't even have a new one to test. OEM. I'm going to guess that the seals on this motor are fairly well used. But I have no idea.

The Supermiata are great. Really tight fit and strongest grip overall.

Great work, man. I feel better about the MR seals in mine now.

I showed my son the hot wheels track - we're gonna be including tunnels now. :)

Way to science the crap out of it. Props awarded.

A couple more points.

1. The stem was .2354" from a 2004 MSM. I did the measurements and test near the tip, where no use/wear is present.
2. All results are only indicative of holding power and do not necessarily reflect performance during use (heat, moving, vibration, lubrication).
3. I believe Shibby shipped me both the MR and the US Seals - Thanks!
4. Thank you to Wackbards for the Felpros.
5. The Lamborghini won. Photo finish.

This was all tested with the same valve, dry?

So...
My head is at a shop that builds a lot of non miata heads (toyota, subaru, Nissan, Mitsubishi, Porsche etc).

I've let them know about the Supertech stuff, and as previously mentioned they have also had issues with Supertech themselves which is why the go with Ferrea stuff. But what I found interesting in the message below, although perhaps hearsay, is that Supertech mislabeled their product.
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https://cimg0.ibsrv.net/gimg/www.mia...d1345d0612.jpg



Now I did some digging and found this document:
https://www.supertechperformance.com..._Inner-WEB.pdf


In that document I was able to find the following values for valve stem diameters of their products

Miata BP 1.8 - vlave seal p/n VS-T6I/E
5.97mm( intake)
5.94mm (Exhaust)


EJ20/25 WRX Sti- valve seal p/n VS-TS6I/E
5.96mm (intake)
5.96mm (exhaust)

Could subaru seals work despite their more compact form? I know we just settled that OEM and Supermiata are definite replacement options, I just want to see if there's any downside other than shelling out funds for another set for one torn seal when the shop uses Subaru valves on the regular.


Subie valve seal on my VVT head

https://cimg9.ibsrv.net/gimg/www.mia...bb2bf242ee.jpg



Supermiata (brown) vs replacement Subie (blue) valve seal
https://cimg2.ibsrv.net/gimg/www.mia...8d14b19955.jpg



Any subie people on the forum have some seals to send in for science? I should just probably fork up the $30 for the supermiata ones, but just fodder for thought.

Make sure you understand that I never really stated "smaller is better". You want the correct size. Which I can nearly guarantee is the OEM dimensions. Under heat, pressure (due to our overstressed PCV systems), and RPM, these little seals do a remarkable job.

Too tight (small) and they will tear themselves apart with the additional friction. They'll work at first and then not so much...

Props to Mudflap for testing and measuring the seals. Psyber Optix, how come you don't want to use genuine Mazda ones? Are they crazy expensive? I've also had a bunch of Subarus and I always use genuine factory parts unless there's a big benefit to using an aftermarket item.

Is there a detriment to worrying about 0.01mm (0.0004") in diameter difference given how much variation all these valve seals have for a spec'd application?

If it it snaps onto the valve guide, and fits the valve stem, is it still possible for it to work?

I don't believe that the actual diameter tells much of a story. Only if it is WAY off. If I look closely under a 30x microscope - I can see slight shape differences between the various seals. Also, the viton itself could be of various unknown grades. So really the bottom line would be people installing (PROPERLY!!) and saying, "Hey these [insert seal here]'s suck donkey balls" if they don't function well (or for long).

Do you have any Kia seals you can send to mudflap for science? That might be the best option if it's a factory part for a reasonable price.

Mazda Seals