rxseven

Ito, the interesting thing on the length is that the 86-88 factory manual has a spec length of 79.9 to 80.1 mm. So I am assuming you can get a factory one over 80 mm also. I was told by a few "experts" that the 0.0015" clearance you stated was for one piece seal only. The 2 piece seals have zero clearance because the small linear expansion is taken up at the split not the sides. It is very strange that mazda manuals of any year don't have any info on the clearance of side plate to apex seal. By the way, when I told hurley about the length, his advice was to not clearance the edges in any way since the sides would wear themselves in and fit perfect after break-in. Personally, I don't see a downside to giving a little clearance up front except it is very hard to keep the ends square when you sand it.

By the way, he also said NOT to super glue the corner piece of the seal.

Do you use super glue??? And yes, using any kind of glue makes the length even longer!

Judge Ito

That is the whole problem with the aftermarket seals like Hurleys and Atkins. I have seen .0016 of metal expansion when the engine warms up under a load. If you don't make the seals a bit shorter,(even though is a 2 piece apex seal) the shorter piece of the apex seal will slip over the larger peace when the engine is under some serious temperature,(because of the metal expansion promblem) and create some blow by or leakage from one chamber into another.I have talk to many people that did what Hurley recommended. Not to clearance the seals and all I could say is many ,many people are not using Hurleys seals anymore. I took a 2piece 2mm Atkins apex seal and measured the seal, then I heated the seal with my acetylene torch, I had the apex seal turn cherry red and let the seal cool off and re-measured and I had an apex seal that was .0016 of an inch larger from side to side. If you have a rotor housing with a width of 80mm and start with an apex seal with 80mm your going to have problems. becuase this apex seals grow like Chia Pets under some temperature. Stock seals have a totally different hardening and do not grow like the after market ones do.

Judge Ito

Getting back to Hurley for a minute. One time I had Eamon Hurley machine some 93Fd rotors that had broken the factory 2mm apex seals. he machined the rotors to fit the 3mm apex seals. When I recieved the rotors back, they were fully assembled with all the seals on.(like side seals corner seals oil seals and apex seals) I talked to Eamon and he told me the rotors were clearanced and ready for assembly.I decided to check the side seal clearance apex seal clearance oil seal ring location. and to my surprise every single measurement was way off. I'm writting here and giving some proven tips from my personal experience. Not some word of mouth from people like hurley. Basically I'm writting and giving tips on proven and reliability performance. I have build many engines that consistenly get tortured at and over 11,000rpm and they live to fight another day and another day and another season. By the same token I have seen some engine builders build engines for a one day event. after that day the engine is burned out, no compression, warpped apex seals like a banana shape. And some very disappointed racers. Now you do the math..

rxseven

What did atkins have to say about this? They do sell an awful lot of engines with their own seals in them. I take it, this problem arises in high performance t2 applications and not N/A ones?. You are correct in the fact that a softer metal will have a higher coefficient of expansion than hardened metal. But if you and I know this and they do also I don't understand why they continue to sell oversized seals.

93 R1

Thanks Ito. We all really appreciate your contributions to the forum :bigok:

Fd3BOOST

Damn am I glad I followed good advice and stayed with the stock seals.



How can they manage to stay in business with such a shitty product?

Damn those Brits!



I have another question about Hurley seals, let me jump on the correct thread.

Judge Ito

Atkins Rotary has gotten MANY negative criticizm about his apex seals. Many tunners did not get a chance to tune an engine when the seals collapsed. I started to use the Atkins seals since I build alot of N/A bridgeport and P-Port engines with Nitrous Oxide. When I had my first engine failure with the Hurleys. I liked the seal before I had the failure so I decided I wanted to find out what was going on with the Hurley seals. Then I noticed the metal expansion, and noticed the Hurley and Atkins seals were made of a softer metal then the stock cast Iron seals. I had a choice of using Racing Beat carbon seals(which I dont like for nitrous engines) and the Atkins metal expanding seal. I decided to correct the Atkins seals and use them. What I do, is tell the people that buy my seals,(mostly speed shops) to make sure and measure and clearance this seal. I just try to spread the word. I have talked to kathy Atkins about the metal expansion and she said they were going to address the problem. I always talk to Kathy, because in my opinion David Atkins is not the smartest cookie. Over all I like the stock cast iron seals for turbo application. But I cannot use the stock seals for bridgeport engines.

j9fd3s

actully now that you mention it, how are the carbon rb/mazdacomp seals for an na non nitrous, either bp or big streetport motor? i gather if you set them up right (clearances) that they will run fine for about 40-60k maybe lacking a little low end power over a steel seal. i like the fact that they dont do any damage when they go, and i'm thinking that a big plus.



mike

Dragon

Ito san.. What kind of side seal to corner seal clearance do you run on higher hp turbo engines? I'm assuming that a long side seal will expand more than the apex seal does.. I usually run a .015mm cleance and I've had no problems with blow by, but I've also heard that a tighter clearance will pick up 10 hp or so..

j9fd3s

you can tell a tight side seal motor from a not tight side seal motor spinning it by hand



mike