Don't double-stack side seal springs.

http://bdc.cyberosity.com/v/ProjectC...ideSealDamage/

B

 

Damn B. You're having an awful time. At least now you know. I always say it's not a bad situation unless you didn't learn something from it. And you're nice enough to share what you find so we can all learn. Props!

 

Damn. I've never considered doing that---what was the thought process?

 

I think it says something about stacking side seals in RB tech manual for high boost engines to help stabilize the rotor.

If you don't mind me asking a few questions.

Do you think the side seal was bending into the intake port?

Was the end of the side seal supported when over the port?

What did the iron look like?

 

Well, atleast my car is so gutted and re-done that it's easy to do an engine in it. I can have it out, rebuilt and running in a day and a half so it's not so bad. I'm enjoying it, actually.

B

 

Thanks for sharing. I thought about doubling side seal springs once. Glad I didn't.

 

Brian!
Stick to your combination.
Forget all the **** you read in the 1980's catalog man.
People still have a belief that spring pressure can over come combustion pressure. Cannot happen. All the springs are for is low speed operation. You can tell that those peole are still stuck in the NA world.
Mazda does have a stiffer side seal spring and it's the one that comes listed for the turbo motors. I don't think mazda still got it though. You'll have to check.
Now go put that Brap Brap back together.

 

I was going to lead into this in your other thread on NP, but since I've never done it before I just kept my mouth shut. Piston engines have lessened ring pressure over the years, as crispeed said its just there for low speeds and starting. Tearing down fresh engines however is the only way you really start to learn things.

 

Everything i have read has pointed the same way

infact, the whole idea behind the sealing matrix that is used on the size and faces of the rotors is designed to use combustion pressures to hold the seals in place

 

Other than fixing what I screwed up, I'm not changing a thing. I junked the side seals and the seal springs and replaced them all. The 1.32 A/R housing is also staying on as I found out why it was taking forever to build any manifold pressure -- the intercooler outlet hose clamp wasn't tight. Woops.

Back to brap brap land. /salute

B

 

like i said. 3rd times a charm B

 

i was tempted to try that with my last motor, too, but opted against it. guess that was a wise decision on my part. sorry to see it happen, but it reminds me that we are ALL still pupils - no matter how good we are ... and that's encouraging to me.

is that due to uneven distribution of the spring force when you double them?

 

I think the force created by having the two springs in there is what did them in. Underneath the 3 side seals that were stuck in the side seal groove of the front rotor, the springs underneath were in pieces.

B

 

SO, to the guys saying that springs are only present for startup...I am not sure I understand your line of thinking.

This may be the case for apex seals...as centripetal force drives them outward once the engine is running. This is still only true to a degree, as we all know that engines with warped/flattened apex springs run poorly and produce low compression even while running.

But side and corner seals need their springs all the time, in my mind at least. These seals do not feel any OUTWARD force exerted by the rotor's rotation. They do experience pressure from compression/combustion which naturally tries to force them into the rotor. The only thing holding them out against the iron faces is the springs underneath. Whether at rest, at idle, or at 9krpm, the springs are seeing the same load (e-shaft flexing set aside for the moment).

Someone correct me if I am overlooking something.

 

damn. that's odd, isn't it? i mean you'd think that the springs would flatten, not actually break. i've disassembled engines (usually an overheated motor) where the side seals themselves have broken, but i've never seen broken springs. hmmm ... i'm intrigued.

 

I have double stacked side seal springs in my 13B-PP drag motor. Seems to be fine right now, however i have no boost and my side seals are 2mm wide. I'll let you guys know what happens when the nitrous is added to the mix.

 

yeah interesting, I red about it and never wanted to try it personaly. I always do my rotor side clearancing and do every engine for another local builder here, when you see rotors rubbing on plates there is realy only one solution for that and its called proper side clearancing.

mazda have modified their rotors to include a sub land *across all models* (I like to call it) a raised section outwards of the normal lands to stop the rotor from tiliting as much and hence stoping the tips from rubbing and costing HP but nothing beats proper side clearancing as even these touch if you develop enough power (combustion pressure) and use 9krpm the one thing mazda is doing right now is making the rotor faces undersized from factory (race clearanced) to stop the faces from hitting the rotor housing surface Its across even the low comp turbo rotors (85-87 modle) now (new set landed a few days ago). if you compare them to any originals you can physicaly see how much more clearance they have.

anyway thanks for posting this result/experience on the twin side seal spring btw.

 

Suburbia.

 

Crispeed, you said that I "shouldn't change my setup". What exactly did you mean? Reason I am asking is because I am beginning to do some load tuning and am having difficulty with getting the 1.32 A/R to be a decently responsive turbine housing.

B

 

the springs are there for startup and just a light static load.

the sealing matrix is designed to use combustion pressures to force the seals against the sealing surfaces.

if my scanner worked id scan the chapter where the read is, however it doesnt

alot of good information on the actual developmental stages of the rotary engine, wayy back to the 40's when the sealing matrix was orignaly used on torpedo's (and no, not on our side ) to the develpment of many mazda rotary vehicle's is in

The Wankel Engine. Design, Development, Applications by Jan P. Norbye

very very good book, i read a chapter of it atleast twice a week, alot of very good information

http://www.amazon.com/gp/offer-listi...&condition=all

-Jacob

 

Pressure from combustion and compression would try to push the seals INTO their slots and not outward. Thus, lack of springs would result in even poorer compression. The springs, and the thermal expansion of the parts for tighter clearances, are the only things holding the side/corner seals firmly against the housings.

 

I guess you have never seen a motor run with flattened springs or no springs for that matter.
You really believe the spring pressure is greater than the combustion pressure?

 

^ hmm? i think we might learn somthing new kids lol

 

No, I dont normally see motors with totally flat springs or without springs. I suppose in your line of work/play, you see things that I do not, since I work mostly on lightly modded streetcars, so most likely you know quite a bit that I do not.

Tell me this. You have compression pressure trying to find it's way out between the gaps in the seals and irons/rotorhousings. So the pressure would tend to push the seals inward, without springs or spring pressure. The only way that I can see compression pressure helping to push the seals OUT, would be if the pressure could get underneath the seals. But, I can't see any method for this to happen in a great enough volume. What is your theory with regard to this?

 

Not my theory just the actual fact of how it works.
You actually gain power with looser clearances to a point. All motor people would know what I'm talking about. It's a balance you have to strike for the application. More power vs longevity, street vs race etc.
As for the theory you speak about just look at any rotary operated product for example air tools, fuel and oil pumps etc. Non of those use springs to keep the seals in contact with the sealing body.