BNA_ELLIS

This is what hardened steel seals can do to a housing.

GUITARJUNKIE28

wtf??? that double post wasn't there last night!

bna--been there, done that

couturemarc

By the looks of those housings you were one of the lucky ones. Most of the housings i see that have run the aftermarket steel seals are much worse. Even housings with as little as 5000mi sometimes look worse than those.

bobybeach

I built my engine about 12-18months ago only replacing 2 seals that the original owner had blown, all the rest checked out ok. anyway 2 months ago with a bigger turbo and a little to much ignition caused the rear plate to cracked from detonation, and yet my combination of standard new and used apexseal are all good! no chips or breaks.

RETed

Care to back that up with proof?
There are different grades of ceramics, and I don't have 1st hand experience with any of the ceramic apex seals that are made for the Mazda 13B, but there is such a thing as "abrasive" ceramics.

Also, I question your claim about tighter tolerances.
You're still using a steel rotor, which does have thermal expansion characteristics.
If the rotor (groove) and apex seal are identical materials (or very minimal thermal expansion) then I can see running almost "0" clearances...



-Ted

couturemarc

I was refering to end clearance on the seals. Whenever someone mentions 1 pc seals people always associate this with low compression. With a 1 pc steel seal this is true to some degree because you have to leave clearance for the seal to expand lengthwise. Once the engine is warm it runs better, but if the engine gets too hot you have issues.

I was just trying to explain that with ceramics the difference between 1 and 2 pc is very insignificant because the expansion rate of ceramics is very low and thus a 1pc ceramic seal does not have the problems that a 1pc steel or alloy seal would exhibit. All this assuming of course that the motor is built to very tight tolerances.

Ted, im not clear on what you want me to proove...

Yes, you are correct in stating that ceramics can be abrasive, silicon carbide is used in grinding wheels... very abrasive , aluminum oxide is used on sandpaper (abrasive as well) and we all know that carbide is used to machine some of the hardest materials as well. All i am saying is that these grades and types of ceramic are not used for apex seals and the finnish quality of the seals is intended to provide a long-lasting low friction seal, not to cut the chrome or cermet off like a cutting bit or sandpaper.

Bottom line is that there is generally only one type of ceramic that works very well as an apex seal and different grades of this material is what are available for various rotary engine applications today.

I don't make ceramic seals, just the cermet components. I do know about the manufacture and specifications of ceramic seals but this is not my information to give out. Best people to ask about this are Iannetti or NRS.

Cheers, hope this answers your questions

epitrochoider

i have taken old core engines apart, and have seen box full of used 2mm and 3mm seals. quess what, they are not worn out. when rebuilding the engine, used stock seals are fine usually, because if the seals were properly lubericated in operation (engine didnt run out of oil) then the seals last 4ever. I think that loosing compression after 40,000 miles is false. I would picture the seals breaking in, and seating into their small grooves along the housing even better. I would say apex seals last over 500,000 miles easy. I would use used stock seals for stock rebuild, and race rebuild. If the same seals are used w/ original housing, no break in required. If new housings don't match the seals, used and new seals still have break in period. I doubt a rotary with 40,000 miles on it that was properly maintenanced would have lost any compression from day one, and it would have more. sdminus: dont waste money on new seals, and if u would like to take a high boost pressure, use 3mm seals. 12as use them, and pre 86 13bs use them

Think of used seals this way: they have prooved that they have high integrity, and if they haven't failed so far, they wont in the future. Don't think of them as worn out inless they are. Take a new seal, and used one. The small wear on the edge will soon be on the new one, and the used seal's edge is what seals the best. Now look at the heigth on the new one compared to the old. Bet u dont need to spend that much money!

epitrochoider

just built my race motor with used 3mm stock seals, ill let u know what hp it makes naturally aspirated once its in my car