JeffTII

Apparently the guy I got my Turbo II from claims to have had the rotors cut for 3mm seals and I was just curious if there was any real way to tell if there really was 3mm seals in there. What kind of power can the seals support? Boost? I kinda trust so the guy so I'm not calling bullshit yet.

RX7Aggie

i had 3 mm seals put in my engine when it was rebuilt last year. my mechanic claimed they are more durable and will last longer. they cost $600 for both rotors, and they are dual spring.



i cost a lot, but he claims that so longs as i lay off the boost and dont go crazy with mods, i can get another 100K off this engine.

JeffTII

Well, I'm really hoping that there is 3mm seals in there because I plan on running a little bit higher boost. It does have an FCD, 720cc Injectors, and 3in D-pipe and exhaust.

phinsup

$600 where did you buy them from? I have the atkins 3mm in the store for $234.99 for the set, that's both rotors.

andynogo

To see which seasl you have, pull the loer spark plug out, get a torch and mirror and have a look.



Turn the motor by hand until you can see a seal in the plug hole.



You should be able to tell straight away by the size of the seal which one it is- find a similar sized sample to compare with if you're not sure, or a stock 13B motor.



The 3mm seals are noticeably larger than the 2mm's.

chase78

I ball it my man. take out any of the spark plugs get a mirror and a flash light and 19mm socket and turn that puppy over untill you can see the seal the best to view them are that lead since thier opening is much larger then the trails. AND eye ball it . As far as benfit 3mm for the normal rx-7 buff is more show and talk then real application. Yes they will maybe take an extra knock but they are by no mean insurance. Also some have complained of hard starts due to the increase in friction. (your adding 50% more surface contact.) As far as lasting longer thats up for debate. People who go 3mm route tend to be some what nutting about thier cars talking about premixing all the time (which i still don't believe in) so the care level goes up leading to better parts for rebuilts later on. But on the other hand Speed and boost crazy people put in 3mm to push thier engines any were from 15 to 18 psi

But i beleve it is more advantages to go with 2mm 2 piece seals from atkins spend the extra money on a larger interccoler and boost it to 18 psi if you want. Prevent detonation with cooler denser air don't try to catch it after the fact with fancy sensors (J&s knock sensors) that don't really work that well anyways. Jacobs did a pretty good study on the subject or timing changing by hand and computor and found the the human hear is close to 80% better the the best knock sensor. oh yea by the way you stock knock sensor is worthless after 6500rpms (funny thats about the time you need it most)

j9fd3s

i agree with that. the 3mm work, but you add 50%more sliding area, and a questionable amount of greater strength.



chase: when i see the mazda factory switch to premix then i will believe it works, the 787b has a metering pump



mike

JeffTII

Thanks for the info. It was my understanding that 3mm were better for higher boost. Thanks for clearing it up. As far as pre-mixing, I think I like the factory's idea for getting things done. The day I become an engineer is the day that I might debate that.

chase78

I do not rebate factory use of it in racing applications but what i would like to say in my defense is that I use to be a rotary engine rebuilder. I learned and talk to other rebuilders with 25 years of experiance rebuildersunder thier belts . And if they say that they see no real difference between pre mixed engine and no pre mixed then I'm willing to go with experiance then thoery. Any way you have to remember 787b in strict racing and I even change thing as far as lubication wise in rebuilding engines for racing. All I'm sying is that for the normal person'r engine I haven't seen a big difference,but putting in a little mavel's mystery fluid in with the gas does help make it cleaning burning and doesn't clug up seals.



the oil metering system in all rotary engine kick in about 3500 to 4000 and they only take a small fraction of oil to lubicate the apex seals. i have aslo read the frication numbers between the two ,mixing and non, but many people forget to realize is that there is also combution involved with a moving rotor. This adds another level of complication to lubicating the engine that the study that most people point to for permixing. If you really want to go in deep about it go the Lighting and the World of Thunder web page under premix and read the numbers and not the opions. but hey its not big a deal anyways either way so whatever floats your boat man