What are the official limits of most steel apex seals? The number I hear most often is to plan for under 8500rpms..... but no I can't really find any information beyond that. Are there any set numbers for rpms or power figures?

 

New apex seals should be kept under 8,500rpms. The older the apex seal is...the thinner it gets (No kidding huh?) and the less rpms they will handle. CJ

 

it also depends on what size apex seals you're speaking of.

 

I beleive the motor has 3mm apex seals in it. I'm pretty sure, Randy (The owner before Casper) at one point was thinking about running nitrous in it...so he whent with 3mm ones.

I have ran motors as high as 9k with steel apex seals, but would'nt do it on purpose.

The two different 1990 n/a Rx-7s I've owned, had a factory rev limiter of 8,560rpms for a reason. (89+ Rx-7s) According to the S-AFC. The blue 90 made peak power under one "tune" at the rev limiter. Later on, we played with the timing and managed to get it peak a little lower in the revs, at a much better 7,500rpms (167rwhp on a mustang dyno).

Bottom line is Casper, if you want the motor to last, keep it under 8,500. Drop Blake on this forum a PM. He works with Rob, and will confirm that you'll want to keep it under 8,500rpms. BTW, the motor I had Rob build me for my REPU, had carbon apex seals, so I could buzz it higher. CJ

 

I had a 4 port 13b that I streetported and ran in a first gen. It had 3 mm stock OEM seals and I ran it to 10,000 rpm EVERYDAY, multiple times a day. The engine needed to be freshed up at 121,000. Ran like a champ.

 

If you are going to rev higher at least give it lots of premix; you are fighting frictional forces.

I think this is partly why the more lax emmisioned 1st gen motors are lasting so well- more generous apex seal lubrication.

I run 1 qt per fill up (~50:1) plus stock OMP for my 3mm RA seals, took 5k miles (w/4k of those including racing) to fully break in, but I expect it to last a bit longer than it would otherwise.

 

bottomline is you'd probably be better served to build your motor to make it's maximum power safely under 8500 RPM if you're going to be running steel apexes.

 

Its stupid to run the engine over 8,500 rpms because of apex seals bounce that causes "chatter" marks on the rotor housings. (Or even worse...broken apex seals.) I've seen it tons of times on race motors that see constant high rpms. (Even sub 8,500rpms)

Also something else to think about is the oiling system. If that motor does'nt have a loop line, I realy would'nt be spinning it over 8,500. CJ

 

Loop line ??

 

Loop line ??

Oil line added off of rear oil galley to front bearing to lower pressure drop to front stat gear and rotor bearings.

Mazdacomp sells this loop line adapter (fits under oil filter pedastal), but it requires mods to front sidehousing and even the eccentric shaft to fully take advantage of it.

Search "oil mods" and you should find this and many other mods.

 

I understand what you are talking about. Thanks for the tip. I may incorporate it into my PP race engine build.

 

I have to strongly disagree with 8500 rpm,ive taken my personal stock cars on metal seals way above that mark.And i know many 8 and 9 sec cars out there that are running stock metal seals (new of course) and are boosting over 30lbs and running them over 8500 rpms.

 

You can run the engine over 8,500rpms, but all you're doing is taking chances with this older style engine. (Not talking Renissis) And we are not talking boosted applications. Its well known that stock apex seals will handle alot of boost. Besides apex seals, the motor needs to be built for 8,500rpms+.

Rotor clearancing
Deep grooved bearings/multi window bearings are nice
Hardended Stationary gears if going above 8,500 alot. (I have been guilty of skimping on this before)
The T2 (or newer) oiling pump or something larger.
Premixing (Like Blue TII said)

I've worked for Rob@Pineapple Racing for multiple years. Owned multiple Peripheral port engines, large street port engines, as well as stock ported engines. On non boosted applications, (You can use nitrous on carbon seals) Rob allways had me use carbons. They are lighter and don't float/bounce as easily.

I'm done with this. Casper, go see the guy who built the engine. CJ

 

what's "way above" 8500?

anyway, boosted applications aside, i don't think anyone is saying that the stock seals CAN'T go above 8500 RPM, i think we're just saying that it's not suggested to do so. well, at least that's what i'm saying. i'm shamelessly guilty of running at least one engine in my past at 8500+ with stock seals. it chattered and eventually gave up on life after a few months. it would just seem that building a motor with the expressed expectation of making power (or just revving under load) past 8500 RPM on stock seals is, as pp13bnos stated, is taking a chance and i just can't see why when the is available guidance to do it right.

 

This is a lot of good information. This is the kind of stuff I had been searching for. This car has a pretty aggressive port, and from what some of the people in on the build are telling me, it wants to built power around 8500 and onward. I was trying to get some info from Rob at Pineapple, but I guess I need to prove that I own the car now so that I can get a more indepth break down of the porting and build on it.

I need to get the carb up to the task of making more power near redline, but once that's out of the way I'll be looking into dyno time to figure out how high it's really peaking.