RotaryResurrection

iTrader: (8)

Actually this is a testimonial for the rotaryaviation seals themselves, as well as the 3mm seal upgrade. I see a lot of talk on here about how "bad" 3mm seals are, etc etc. with no real reasoning to back that up. Here's proof for my side of the debate.

This engine I built last year, for a customer's street/race FC turbo II. This dude is known to be hard on his equipment, and races at the strip weekly. Only mods were full exhaust, intake, fuel cut defenser, large streetport, and walbro 255 fuelpump. He's running stock ecu, stock turbo, stock intercooler, and stock fuel injectors, and is aware of the consequences of pushing this setup so hard. In this form, the car is a high 12 second with good launches on street tires, while the same car in stock form runs a 15 flat.

He was recently playing with the nitrous, for whatever reason, running about a 100 wet shot. Apparently it worked well for several passes, and they changed the jetting or something, because the fuel was too rich. He claims the nitrous switched on and the boost spiked up well above 20psi, on a car with fuel for 12-14 at most. HE said the car idled a bit rough, but still ran okay, except for a major external oil leak. So he pulled it and brought it to me.

The engine was built by me with rotaryaviation 3mm seals. Upon teardown I found that the rear iron had been broken in 3 places at the upper dowelpin slot, a common weakness on the early FC blocks above 250rwhp caused by twisting of the plates under load (namely detonation). I also found that the rear rotor had actually slapped the rotorhousing quite severely, forcing one edge of the apex seal slot inward onto the seals. The seals themselves however appear excellent, unbroken, and mic out with almost no wear at all on them after several thousand hard track/street miles.

Anyone here who believes that a 2mm seal, mazda or otherwise, could have withstood such abuse, is full of ****. There are definite advantages to a 3mm seal setup in a modded turbo engine, with no real disadvantages. I can measure no low rpm compression loss with the use of 3mm seals, compared to 2mm seals, in rebuilt engines. I cannot measure that they wear more than 2mm seals, upon teardown. I certainly can say that they break less than 2mm seals.

importrx7

Nice Post!!! You just talked me into getting 3mm seals when my motor needs rebuilt.

XSTransAm

i dont think the real argument is whether 2mm or 3mm are better. i think its an issue of tuning when your talking about horsepower. i run 2mm seals and push in the neighborhood of 400whp daily driven (and beaten) with no problems. so 2mm are proven to hold the power.

the question then comes, WHY would you "upgrade" to 3mm seals. I can think of a couple of reasons.

1. want to reuse worn housings.
2. plan on doin dumb stuff to your car (like run a 100 shot on top of stock ecu ect )

so other then reason #1 i dont see why people would use the 3mm's unless they are just out to blow up engines.

lastly the argument about idle compression loss is about as worthless as they come. that should not be the reason to not go with a 3mm seal since the difference will be negligable at most.

i dono, just chippin in my .50

Mike

dubulup

I friend of mine detonated on RA 2mm, I think a primary injector failed at 17psi...after the fix, the car ran fine. Later, upon break down of this engine (HBP) some of the rotor faces had dents in them. Seals were fine.

Compilez

iTrader: (3)

This is EXACTLY what I needed to read today. I had decided not to rebuild it myself and have a local shop guy do it and he only recommends 3mm apex seals. He doesn't like 2mm seals . He said there really is no downside to 3mm. He had a 700hp (T88) 13B on 3mm seals. I just made the deposit last night for my new engine. Thanks for the reasurance.

RotaryResurrection

iTrader: (8)

True, there are documented instances of people running 2mm seals, of different varieties, making lots of power and not breaking them. This assumes everything is perfectly setup and maintained. For many, this is not the case, so I see nothing wrong with a little insurance policy. Furthermore, for each instance of 2mm seals holding up to abuse, I can show you 20 where they do not.

IN fact, this same guy broke a set of 2mm seals about 2 years ago with this same car, less modified than he is now.

XSTransAm

does this guy just have more money then brains or something? seems to me getting the necessary mods to do the quartermile times safely would cost alot less then rebuilding the engine all the time.

RotaryResurrection

iTrader: (8)

No, he's an old school hotrod/domestic type guy, and readily admits that he likes to have fun and push the envelope constantly.

He's now putting a 60-1 turbo on this engine, with plans for an intercooler upgrade of some sort, and a set of 720cc secondary injectors.

Hey, I've told him...but I can't make him do what I say. He will be the first to tell you that he doesnt mind re-rebuilding the engine if it breaks because of his fault. That, and I don't charge him a whole shitload to go back through it and replace what he tore up. This time, we're reusing everything but the back iron, and possibly that rotor if it doesnt clean up. I'll charge him about 600 for water seals, another iron, portmatching it, and putting it back together.

scathcart

I purpose-built an engine with RA 2mm apex seals a while back and induced detonation on the rear rotor by cutting the secondary injector voltage. Engine audibly knocked and died. Rear iron cracked, apex seals were fine.

I think this is more of a brand thing than a 2mm vs. 3mm thing.

Hex7E

I didnt think 13B's could hold 700hp.

maxcooper

Here's a 13B that makes 750 WHP without nitrous:
http://reactiveracing.com/modules.ph...view_photo.php

-Max

Howard Coleman

iTrader: (6)

thanks for sharing the info, a valuable post.

howard coleman

patman

iTrader: (3)

ive been telling you guys about the RA seals for along time... i have em, i abuse the **** out of em, theyre fine. (2mm)

I dont know **** about 3mm, always thought they were for super high hp motors, so i'll keep my trap shut.

Sesshoumaru

iTrader: (1)

i've been in a car that detonated a few times with the RA seals (2mm).

now it's getting a bigger turbo on the same engine.

mcnannay

i like to see testimonials for the RA seals, makes me feel better about mine. Although im just running them in my NA, i got real worried after reading that article in rxtuner....

thanks for the info kevin

ddub

I love hearing these things about RA seals

AZ'sFastFD3S

My car has a single turbo Mazda 3mm motor. During tuning at 17psi I detonated several times. The car ran fine except it had high oil pressure. We tore it down and the 3mm seals were perfect, the side seal was stuck. We replaced them and the car runs perfect.

RotaryResurrection

iTrader: (8)

This is how much the engine twisted...





Rotor slap...

c00lduke

With rotor slap do you usually have signs on the bearings also?

ghostrx7

Well 3mm seals are pretty bad ***...My motor had 2 counts of audible detonation, still ran for 9 months after that. Just recently blew, after over a year of abuse. btw they are hurley ceramics. I may rebuild with those RA seals though after reading this thread.

RotaryResurrection

iTrader: (8)

No, it didnt run long enough in that condition to hurt the bearings, stat gears, or eshaft. In this case, it'd be hard to do so...you'd lock the engine up from oil loss from the crack in the iron, before the bearing would get damaged from the stress of the slap itself.

Compilez

iTrader: (3)

Yeah, I think I have a video clip of a 13B 3rd Gen in Japan that made 700hp. Didn't use nitrus either. 2 or 3 guys were sitting on the back end with the trunk open.

t-von

iTrader: (8)

How many miles were on the rebuild? Also there is a thread floating around here showing how the RA seals supposedly caused chatter marks on a rotor housing. What kind of condition were the housings in after tear down?

RotaryResurrection

iTrader: (8)

It had about 3k hard miles on it, from what I'm told. We're talking used rotorhousings which normally like a solid 1000-1500 mile breakin, but probably got a 250 mile breakin on the trip from TN to GA. Then we're talking lots of hard launches and drag pulls on a weekly basis, for about a year, not much street time.

Rotorhousings looked fine, just like any other engine would.

c00lduke

I've seen that thread too but over on nopistons. Those housings almost looked as if seal chatter had occured.