How many miles have people gotten out of Iannetti 2 piece ceramics on the street? I've heard ceramics wear faster than OEM, but I know Iannetti's are supposed to be particularly hard.

Naturally aspirated, of course.

 

Ceramics are supposed to last forever in an NA engine.

 

ceramic has the longest life of any seal, tradeoff is they are the most fragile aside from carbon seals.

other problem with ceramics are that they do not expand like metal seals, so they generally have more sealing losses and lower resulting compression at low engine speeds. once up and running, they are about the best seal you can run in an n/a.

 

i would like to build one these forever seals, but they dont idle well or start easy cold right>?

 

The one piece seals are supposed to idle poorly and start poorly. Two piece, that's how OEM works. Anyone have experience with how the two piece Iannetti cermaics start and idle?

 

no experience with the 2 piece, single piece seals can be difficult to start when cold but idle quality shouldn't be that poor in my experiences with ceramics.

2 piece seals might aid in that respect to a small degree, but not that much.

 

Why do you think two piece seals won't help much with starting and idling?

 

because there will always be gaps in a seal. while the ceramic seal wont expand, the engine will and compress around the seal so cold starting compression with a ceramic is always a compromise. with metallic seals they will size themselves, with ceramic they always must have a slightly loose fit even at operating temperature. a boot seal does not mean it adjusts and seals itself, it merely aids in that respect to a lesser degree, the boot will also help keep a longer seal from binding, while providing a byproduct which is blowby.

 

Neat. Thank you for the reply. I'd love to hear some personal experiences on how much real world difference there is between one and two piece Iannettis.

 

I have been using ceramics for a few years now. In my 13b-rew and 4 rotor. Got 1 poece NRS in the 13 and 2 piece nrs in the 4 rotor. Both engines have about the same compression.

The 13 is a bp engine and have about 95 psi of compression. The 4 rotor had 90 psi after 60 hours of running. That is pretty god on a bp and pp engine

And there is no cold or hot start issues. Idles very well. So i do not see any issues. On a 13b with normal street port and brand new housings. Expect to see 120+ psi of compression with 2 piece afger initial first run and 130+psi after 1000 miles.

 

IME the side seals/corner seals wear faster in a N/A application than the apex seals. With a 2 piece seal, if you keep the cooling system happy so the rotor housing surfaces stay flat (no center spine or warping around the plug holes), the main compression loss seems to be side seal gap more than anything.

As the apex seals wear down, they still maintain good compression, but the side seals wear against the corner seals and get shorter/wear grooves into the corner seal, and you get compression loss at the gap.

And if the rotor housings aren't flat, NO apex seal is going to seal well.

 

Beautiful. Looks like a good two piece ceramic is just right for a 10k street engine, then.

 

as long as you don't have a lot of nasty preignition or cross firing or dirt ingestion, more like a million miles.

mazda would have a lot less issues if they used ceramics in their non turbo cars.

 

10k RPM. Not 10k miles.

 

I use Atkins seals in my street engine, I shift a little past ten at the dragstrip. I put it in the car four years ago this September and maybe 50k miles ago. Still runs great, although compression is getting soft thanks to the chrome flaking progressing past where it was when I built the engine... maybe 1/4" wide and most of the way around the perimeter now.

The kicker is, I was broke when I built the engine, I didn't buy new cryo seals like the first time I used Atkins, I bought a set of low-time used seals I found on eBay!

Absolutely no more than .002" rotor slot clearance. If the clearance is wider than that, get another pair of rotors. Slot clearance is critical if you're going to spin an engine hard. I will periodically take my headers off and check this through the exhaust ports to make sure the rotors aren't wearing out.

 

To use ceramics, use brand new rotor hosuings. And the rest of the sorounding parts must be top quality. Do not use cheap coils, fuel pumps etc. Use a real engine managment and no pfc. And make sure you run it safe i. Terms of water oil and exhaust temps. Exhaust temps in the 800-850 range max. To prevent lifting of the spark plug hole. This will kill the seals/compression.

 

That's not what the Mazda 2nd gen IMSA GTO 4rotor racecar driver says. I asked him directly at Sevenstock last year why Mazda never put ceramics in the factory Na cars and he said they wear down faster than the steal seals.

 

that's BS, every ceramic seal i have pulled from an engine had nearly new tolerances where metallic seals would have channel wear lines from the rotor tips, crowns, wear on one side of the tip, or any of several other wear characteristics.

quite literally 1/20th the wear i saw in similar metallic seals, and these weren't engines putting around at 3k rpms.

maybe he was confused and thinking of carbon seals, which would be quite true.

 

Agreed, he was probably thinking of the carbon seals, which IIRC were what were used in the 13J engine, which is what the IMSA car would have. Not ceramics.

 

only the 13J-MM and R26B were ceramic, that being said no info on what is in the Rx7, it should be a 13J-M, which is carbon, non variable intake.

 

Hmmm maybe but I can always get him to clarify again.

 

metallic seals also tend to chatter if the rotor channels are even slightly vee'd at higher RPMs, ceramics might not like a worn seal channel and may be more prone to shatter under lighter detonation but chatter is eliminated for high to extreme revs.

chatter can destroy a housing and compression in a matter of a single race.

 

Come on now, I agree with just about all that you're saying...... but just because you don't like the Power FC doesn't mean it's not a 'real' ecu.

One of my best friends ran 3mm ceramics in his '94 MB FD at 400+ rwhp low boost and 480 rwhp high boost with a BW turbo setup for literally over 10 years with zero issues---- with (gasp) a PFC!!

 

If it's got a good safe tune, you could get away with Bosch D-jet and a distributor...

Good tools make a good tune easy to get and let you get the last 10% instead of compromising here for safety there, but it is hard to blame the tools for failures.

 

i'm sure most who pop for ceramics are going to go for fuel injection though, less pit stops/better fuel economy, better throttle response/tip in and overall power.