hondahater

iTrader: (2)

I know most of the consensus is that 3mm is over kill and really doesn't even protect that much and doesn't seal as well either however i was talking to someone not to long ago ( a well known tuner) and he stongly suggested using 3mm apex seals because of the added protection. He said an experianced tuner can tell before a car detonates however if it does happen he has seen on a few occations that a 3mm apex seal can take it where as a 2mm would have broken hands down! So I was thinking to myself about this re rebuild I have to do and what I should do to make it have more hp and one thing I'm going to do is go with s5 n/a rotors while pushing around 15-17psi of boost on a bnr stage IV so I will probably need all the protection I can get. Would you guys agree that 3mm apex seals are the way to go? Also I brought up to this tuner that everyone on this board always says it doesn't seal as well as the 2mm and he said the compression number differances between 2 and 3mm is very very small. Only thing that I'm worried about is that the regular 3mm apex seal from mazda only has one spring and I'm guessing that coupled with the wieght of the 3mm apex seal is what causes the sealing issue but what else would it cause only having one very inexpensive spring holding that 3mm apex seal up?

Icemark

See I built a couple motors with 3mm seals and decieded against them for the increased friction issues, not sealing issues.

I never had compression issues, just lower output than I expected. On the one of the two that we switched out rotors back to 2mm seals after dyno testing and then broke the motor in again and tested, there was about a 5% across the board difference in HP (at 200 hp on the 3mm seals there the same motor with same compression 2mm rotors and seals there was 210 hp).

Although many people wouldn't notice a 10 Hp difference at 5000 RPM, it was enough to set me down the "why bother with 3mm seals" mentatlity.

The only way I would use 3mm seals is if I used the angled tip seals that Rob (from Pineapple) and I talked about at 7 stock, where the seal is a 3mm seal that it bevelled down to a 2mm edge.

But even then, the extra mass may have a disadvantage on a higher reving motor. See the tuning is the biggest issue. I personally believe (based only on my personal experience) that 2mm seals will hold up just as well as 3mm seals with the current formulations used by Mazda and RA. That if you shatter a seal, the extra 1mm is not gonna make a difference, and that you may be less likely to tune correctly if you think you have an extra buffer that 3mm seals may provide.

But also I don't run motors above 15 psi boost either, so take my comments into consideration of that.

hondahater

iTrader: (2)

well thats interesting because I had no idea about the hp loss with 3mm seals. That is definatley something to take in to consideration. I am going to have to choose between hp or "added protection". That 5% loss starts to get fairly large in the 400 and above range. If the lower commpression doesn't cause the hp loss then what exactly is it that causes losses? See here is my dilema. I put the RA seals in my rebuild but really thought about it aftwards and said you know what I should have put oem seals in so now that I get to rebuild my motor I would like to put oem seals in and since I know a guy selling 3mm apex seals for 200 bux then I figured how could i go wrong? Even with the added expense of getting my rotors milled for 3mm apex seals it's still a damn good deal. However if it doesn't protect me as much as I think it would and makes for less hp then I may just gow ith some 2mm oem seals. Damn these descisions are horrible cause after you close it you can't just go in and open it back up, or at least I can't.

edit: thanks for the reply, it was very informative!

KompressorLOgic

iTrader: (6)

all i can say is you better be real careful tuning if your using the s5 na high compression rotors, 9.7:1 and running high boost!

hondahater

iTrader: (2)

steve kan will be doing it!

pluto

I am??!?!?

I strongly against 9.7:1 rotors, If you want that, I got the entire assembly milled already and balanced with the proper counter weight at the shop. The problem with the high compression rotor is that it'll detonate alot easier because of the added compression. If I remembered correctly, the engine with the 9.7:1 I tuned can only get up to 12-13psi before expericing detonation.

I would stick with 8.5:1 or 9:1 rotors for pump gas applications.

hondahater

iTrader: (2)

hum...............well I only do what the tuner says i guess, lol. Well i'm the guy that went by there not to long ago with the black tII with silver stipes. I've been experiancing a crap load of blow by (2 quarts within 2 days of an oil change) so i'm guessing somewhere like a side seal or something is stuck. This may explain the 90psi in the front rotor and 100psi in the rear. Well I desided since I was going to have to open up the engine anyways I may as well do somethings to make it a bit quicker and was going to go with those rotors and 3mm OEM seals. I figured since I've got a microtech, wideband and now an egt probe you tune for whatever psi being that we can change timing, fuel and know exactly where the egt's are the hole time. However if you say I will only get 12-13psi on those rotors without detonating I guess I'm stuck. What do you think?


Ps. you get that win2k cd ok?

edit: I know this doesn't mean anything to you but a guy on this site guitarjunkie has 9.7.1 rotors in his car with a gt35r and hasn't had a problem............that I know of, lol. Also what would you charge for the set like your talking about just in case we do this.

Skabidat

With a microtech, wide band, and egt probe and good tunning you should be more than fine. And you wont be limited to any particular boost level with the correct set up. You will need a big intercooler, radiator, and possibly a vented hood. Anything you can do to keep intake temps down would be good, but really with the right tunning it shouldnt be a problem.

hondahater

iTrader: (2)

thats what i was thinking but I'm no tuner or expert for that matter so I kinda do what people that know more than me tell me I've got a koyo radiator and an old school greddy front mounted intercooler. I'm going to be getting a new oil cooler and fitting some 7" automotive fans to it to keep the oil temps down cause they where a bit high last time I was tuning with steve so i think everything should be cool enough now to go to n/a rotors.

Turblown

iTrader: (12)

I'd agree with that.

$200 is a steal!

hondahater

iTrader: (2)

thats what I'm thinking, haha thats why I was going to pick em' up and do this little project.

jacobcartmill

iTrader: (6)

hey man,

15-17psi on pumpgas with 9.7:1 rotors? you're dreamin! you'll need atleast a 50/.50mix of 93/110 octane to run that safely. use the 9.0 rotors for sure.

edit: kan just said that

RotaryEvolution

iTrader: (30)

yea that compression is a bit too high.

2mm seals have a tendency to chatter at high RPMs, 3mm seals if the springs are tough enough would either scrape away the chrome surface more rapidly or if the spring tension is too loose it will chatter worse than a 2mm seal would due to weight and surface area. i still advise against 3mm seals in any application unless absolutely necessary due to no stock rotor availability and worn rotors on hand.

like i mentioned in another thread, chatter is caused by the back pressure in the exhaust port pressing the seal fully against the rotor, once it is past the exhaust port at high RPMs it tends to bounce and cause rotor housing chatter, the higher the RPMs the further the chatter is drawn around the rotor housing ultimately resulting in lower compression and power due to the mixing of exhaust gases and intake charge.

hondahater

iTrader: (2)

interesting info karak and others, maybe I'll just stick with the 9.1 compression rotors but damnit this would have been fun What if I went with some sort of water alcohol injection?