FPrep2ndGenRX7

I posted this in the tech section but not much action there so its here now.

I'm rebuilding a stock 88 6-port engine that will be mildly ported. I'm hesitant to use factory apes seals due to the wear characteristics of the factory seals on the rotor housings. At 105,000 miles the rotor housings are junk. The engine locked up when one of the apex seals came out of the groove. The rotor tip was wore some and the factory three piece seals didn't like that.

What are the pros and cons of the different types of apex seals and corner seals available for a rebuild in my 88 13B N/A engine? How will these seals wear the new rotor housings? I'm interested in the one piece apex seals and the corner seals without the rubber insert if they are available in 2mm. This engine will be a race only engine for my F-Prepared car but I would like for it to last many years without rebuilding.

FPrep2ndGenRX7

bump

anyone? anyone? voodoo economics

mazdaspeed7

I dont know for sure how accurate this info is, but I got it from reliable sources.

The corner seals with the rubber piece seal better than the solid ones, and aren't any less durable.

There has been lots of argument over apex seals. If you would like to get lots of info, post in the single turbo section about it. Hurley racing apex seals are softer than the mazda ones, and therefore are much nicer to rotor housings. The Madza 3 piece 2 mm seals are said to seal the best, even at high rpm, of all the iron seals. If youre running n/a, carbon seals would be an excellent choice for a race car. The carbon seals done seal as well as the 3 piece iron seals at lower rpm, but they seal better at high rpm. Also, when the carbon seals fail, the disintegrate, so there is zero rotor housing damage from killing a seal. Carbon seals can last as long as 50K before a rebuild, but I think 30K is the recommended replacement interval for carbon seals. Also, carbon seals are one piece, and are cheaper than the stock iron seals.

Like I said, if you really want to see the **** hit the fan, post this in the single turbo section. All the people who really know rotaries like RICE racing, crispeed, etc, are always there.

niner

an engine builder told me there is no reason to use solid corner seals. i would stick with the ones that have the rubber piece

i dont think that there is any need for a one piece seal unless your running a full bridge port. for your use i would go with some sort of aftermarket 2 piece, which one you decide would depend really on how reliable you want it to be. i cant really explain pros and cons of different ones as well as others though

mazdaspeed7

Carbon seals only come in 1 piece. If you use iron seals, stay with multi-piece. Carbon sounds better suited to his needs though, especially for racing, since most of the engines life is spend at high rpm's. He also wanted seals that were kinder to rotor housings, whuch carbon seals are.

RETed

Apex seals in general...
Stock OEM Mazda 3-piece apex seals is a very good design considering they had to balance longevity, combustion chamber sealing, and rotor housing wear.&nbsp I doubt you're going to beat the stock apex seals for a street car.&nbsp Hurley Engineering in the UK offers other options for apex seals; some are even cheaper than the stock Mazda seals.

For (NA) racing...
The carbon apex seals were designed for HIGH (over 7kRPM sustained) RPM use.&nbsp Also, if these seals get damaged, they tend to leave very little damage to the engine internals.&nbsp Note, these seals do not seal very well at lower RPMs.&nbsp Hell, I think the stock cast steel apex seals seal better than the carbon apex seals.&nbsp Less sealing means less power due to combustion blow-by.

For FPrep2ndGenRX7, SCCA Solo I/II would be a little elevated over street use.&nbsp Your only other option is to go with the Hurley stuff.&nbsp 100k miles on original rotor housings is about the norm; most of the time, the apex seal corner assist piece (triangle end piece) likes to gouge the rotor housing in the end(s).&nbsp Hurley designed their apex seals to not do this.&nbsp I think the carbon apex seals are not the most appropriate application for your use.

As for corner seal, you either got the stock ones with the rubber "plugs" or run the "solid" ones.&nbsp I dunno if anyone makes a 2mm solid corner seal, but those who use 3mm ones just use the older 1984-1985 GSL-SE corner seals?&nbsp The stock FC corner seals have much better sealing, but the solid ones do last longer - it's always a compromise.&nbsp I do recommend using FD3S corner seal springs, as these units are superior to the stock FC3S units.



-Ted

affinitee

Who offers the best price on the stock corner seals and apex seals???

What is Hurly's webpage?

mazdaspeed7

Just FYI, 12A and 13B corner seals are the same diameter. The only difference is for 2 mm and 3 mm apex seals. I have a torn apart 12A and a torn apart S5 n/a 13B, and the corner seals are interchangable. I agree with Ted on the corner seal springs. FD springs are the way to go.

FPrep2ndGenRX7

Thanks for the info guys. Its given me something to think about. Right now I'm leaning toward Hurleys one piece seals. This engine will probably not do 300 miles a year and after 3 to 4 years I'll be ready for another engine. I just want to get the most out of what I can afford to buy. Its no fun wasting money on useless items when your on a limited budet.