After a very interesting conversation with Sven i decided to ask a few other experts what they thought **cough Ito, Lynn cough**. The engine will be a high boost 40+ on methanol. I have heard of drag cars with .004 clearance have the seals contact the irons and explode. I was thinking somewhere in the .0055-.0060 but that sounds awful high. Will i experience very low cylinder pressure or hard cranking? Any advise is welcome and appreciated https://www.nopistons.com/forums/pub...1047683329.gif





Thanks

Allen

I have sold hundreds of sets of ceramic seals and have used helped end users with the most powerful rotaries in the world make them live.



If you want to know what I suggest you are free to e-mail me or even call my time.



You need to talk with people who have actually have experience with this https://www.nopistons.com/forums/pub...DIR#>/wink.gif



Peter



p.s. If you want a short answer, YES you will notice a massive drop in compression and power with the clearances you are talking about above, again i have tons of real data on this from the largest base of end users around and will freely pass onto you comparisons to the only other ceramic apex seal maker worthy of comparison to NRS who runs a much tighter clearance.

The secret is in your tuning 99.99% of cases I have seen https://www.nopistons.com/forums/pub...#>/BURNOUT.gif RE ceramic seal failures.

NRS uses .0055" http://www.nrsrotorsports.com/specification.html



Racing Beat says .015" to .002" Those are probably Factory race seals.



I had one set for years, and they really work well. No housing wear at all, Just about like carbons.

I sold the ceramics just last year and kept all of my carbons. Carbons just make the housings look better on each review.



Most of them use two apex seal springs. They have very low drag, and it is a bolt in 5 HP if you change nothing else. Different seal materials need different amounts of clearance, depending on growth rate.



Contact the manufacturer of your seals for the correct clearance. I talked to one source who had two piece seals with the stock looking corner piece, for the lowest amount of leakage, but I forgot who that was. If it comes to me I will get back to you.



There you go............no secrete decoder ring required. No secrete phone number.



Lynn E. Hanover

Thanks Lynn, i didn't know they had a new site! So .0055"-.0060" Is just about perfect!

It is VERY HIGH and you will find MASSIVE differences in compression readings, Ianetti pull much high compression due to the lower end clearance.

The clearance Sven builds in is idiot factor compensated with the SIDE EFFECT being less power and compression (proven).



Believe me the Apex seal to use if you want the best is the 2 piece design *if you can afford them* (from various makers), if your end plates have any level of wear then the one piece NRS will show allot less compression than they normally will do, I have had customers who's engine could not start! when fitted with worn plates and super low compression rotor sets as I pioneered and used is highly turbocharged petrol engines.



I only use the one piece design on 100% brand new 13B-REW engine stock of my own. I have probably 5 different customers who complained about hot starting ability with conventional Mazda 230rpm cranking system still attached.

^YES! https://www.nopistons.com/forums/pub...IR#>/smile.gif



If the engine has significant late intake closing and high exhaust port overlap on his one piece seals on other wise inspec rebuild parts the compression will be low, on 8.5:1 rotors is will be "very low" and on racing rotors it will be lower again! This is all due to the higher than normal end clearances.



The two piece design while still having this high end clearance on the main bar, obviously is self adjusting so one side is taken out of the equation! and the one that is left has a very small leg length exposed as its end clearance is taken up by the 2nd sliding piece. The end result is about a 25 to 30psi gain! in compression at cranking on the exact same engine specification.



IF you are worried about seal length then the NRS is the one to use.

IF you want the best sealing integrity then the 2 piece is the only option if you are real fussy and want the best of both worlds.

Hi Peter,

Do you know of any other starters that we can use on an auto fd Bell housing? that would offer better cranking.

No I am not sure of what options there are out there.



But I would say that if you have a deficiency at 230rpm then that will carry through at a *albeit* diminished rate all the way through your rpm range. I do have some figures on it on file somewhere, it is in single digit percentage terms for loss of power and increase of fuel consumption. < still a loss is a loss.

i do not know if it fits, but the rx8's had an updated faster starter available. it does look similar.

thanks for the input and sorry for the high jaking every one:)