What do you believe causes the apex seals to become brittle? Is it engine heat?

thats interesting i've never heard that before. i know the old 2 piece seals either have some kind of harmonic, or going over the exahaust port hurts them because they all break the same way. actually most of the 3 piece ones break the corner off, next to the triangular end piece.



mike[/quote]

Pony-up and pay for the ceramic seals. I wont run anything else now, They are way more forgiving than steel, when they go.

arent the ceramic apex seals like $300 per seal?

By the way the reason I said i dont plan on it making to 50K anyway isnt because of the motor its because I dont have good tuning facilities within a days drive. I believe the motor would make it to 50K pushing over 400rwhp but when it get to that point its days will be numbered.



I talked to a engine builder down in south FL that builds alot of race engines for some of the teams and such.....no, he doesnt have a store he does it in a shop behind his house I believe.



Anyway, he told me to go back to my shop and grab a old seal from a old motor and try to break it. Anyway, you can pretty much drop it on the floor and it will break. Then get a new seal and try to break it.....its VERY hard you'd have to slam it with a hammer or something. He told me he rebuilds all his engines about everyother year reguardless if they are broke or not. I also recall Steve Kann mentioning in a post years ago that he also rebuilds his engines every other year. And to be quite honest I dont know for sure why they get brittle over time but I think its due to the heat and type of material.



STEPHEN

thats interesting i've never heard that before. i know the old 2 piece seals either have some kind of harmonic, or going over the exahaust port hurts them because they all break the same way. actually most of the 3 piece ones break the corner off, next to the triangular end piece.



mike[/quote]

Pony-up and pay for the ceramic seals. I wont run anything else now, They are way more forgiving than steel, when they go.[/quote]

hmm, I've heard the opposite. I've heard that ceramic seals will destroy everything they touch when the blow. The most forgiving seal when it blows is the Hurley....at least thats what 90% of the rx7 community thinks, I tend to believe them as I blew a Hurley seal with no damage to the housing. As a matter of fact I didnt just blow a seal, I blew EVERY seal in the rear housing!!! They broke so bad that one was completely gone, one was half gone and the other was missing chunks....lol



I'd never seen seals blow so bad, anyway out of all that my housing was still perfect, my rotor wasnt quite so luck though. I still cant figure out how the seal can get smashed between the rotor and housing bad enough to destroy a rotor and leave the housing spotless!!!!!



Wierd



STEPHEN

Stephen,



That has to be the WEIRDEST thing I've ever heard! You blew ALL 3 apex seals and the rotor housing survived? WTF?



I've heard good things about the atkins 2 piece ones as well. Cost the same as the Hurley's. They're both supposed to be made of soft material that flexes under detonation vs. cracking under detonation.



The Ceramic's are CRAP! Don't believe the hype!

well you see.... vosko wants to make that kind of power, not tear down the motor annually, and not have it pop due to mildly poor tuning. (a piston engine can withstand a few pings...) i just don't think an rx-7 is what he should be driving. don't get me wrong i think they're very nice cars (especially since he got his fd back) - i just don't think jon understands the exact amount of [I]maintenance[I] ($$$$$) they need. someone here should school jon.

also, i would imagine that just due to the size of these seals no matter what you manufacture them out of or what you treat them with they're still going to break.... good luck guys https://www.nopistons.com/forums/pub...#>/biggrin.png

Well, it is true that tuning playes a large part in the life of a 7.....especially a high hp one. That being said, its not so much that the tuneing needs to be "spot on" rather just that it needs to be safe. The biggest problem I see with alot of cars is the timing. Most people dont mess too much with the timing and if your running the Power FC base timing map or any piggy back system or upgraded ecu that feeds off the stock timing map its VERY advanced and dangerous over 13psi of boost.



If you run low 11 afr and a leading timing of 12-14 with a 8-15 degree split while under boost it'll be good and safe. You shouldnt have any problems.



I know of 2 people that ran over 30psi of boost for over 2 years before tearing down thier motors to freshen them up. Thats on stock OEM apex seals. Also if you tear your motor down everyother year or so to freshen it up its only going to cost about $500-$700(if you do it yourself), dont wait till it blows, thats when it gets expensive, having to buy housings and all that.



STEPHEN

I've seen a stock tranny FC go to 550+ rwhp...but his entire drive line was replaced since he was breaking axle/half shafts/diffs...



I've seen a BP FD with roughly 500+ untuned rwhp do the same on a stock tranny/axle/half shafts and a Cusco Diff.



They'll hold WAY more than ANY SR20DET...no doubt.[/quote]

i would look into that if i were you. i don't think you know nissan very well.

I've seen a stock tranny FC go to 550+ rwhp...but his entire drive line was replaced since he was breaking axle/half shafts/diffs...



I've seen a BP FD with roughly 500+ untuned rwhp do the same on a stock tranny/axle/half shafts and a Cusco Diff.



They'll hold WAY more than ANY SR20DET...no doubt.[/quote]

i would look into that if i were you. i don't think you know nissan very well.[/quote]

Show me one that has more than 500 rwhp that has all the stock drive train(minus differential and clutch).



All my buddies here are SR20DET owners, so let's just say that I know what the sr20det is capable of.



We have a local shop here(H.A.S....Japanese owned, but VERY bad ass 180sx) and he has a cross-mission with ALL AFTERMARKET drivetrain...with only 400-450~ rwhp...reason why?...because he said he was tired of always breaking EVERYTHING. https://www.nopistons.com/forums/pub...IR#>/smile.png