Just got an FC RX7 race car. What do I need to know?

Our race team has now acquired an FC RX7 to replace the Z32 that someone crashed on its maiden outing.  Cheap Z32 chassis are now hard to find, so we pivoted.  This FC was previously an ITS car so it already had the basic race car stuff done to it.  Has a fuel cell, big radiator, oil cooler, etc.

Car has a freshened S5 engine and electronics, 5 lug hubs/brakes, coilovers, 5.12 torsen rear.  

What do I need to know about care and feeding of an FC RX7 race car?  Any setup tips?  When is a good shift point?  What oil to run (aside from the Idemitsu premix in the gas)? Any unobtanium spares?  Any spares that are a must have at the track? Anything to watch out for? 

We are going to play with spinning triangles for a bit, then eventually swap the 4.8 in that we had in the Z32.  

Thanks!

N/A? If you still have the stock oiling system in place, make sure you feed it good (doesn't need to be synthetic) oil and keep an eye on the level. If the oil injection system has been deleted, just feed it good oil and keep an eye on the level, although it shouldn't be using much oil.

Other than that, feed it large quantities of fuel with premix in it, and drive it like it owes you money. Rotaries like to be revved, not lugged.

Yup, N/A.  Any suggestions on viscoscity? I'm partial to Rotella 5w40 in the other race cars. 

I like 15W40-20W50.  If you have the patience to not exceed about 3000-4000rpm until the oil is up to operating temp, straight 40 is best.

If there is a rev limiter, do not hit it under load.  That will rapidly kill an engine.  If your oil pressure is at least 80psi then you can safely run to 9200-9500 or so.  If the sides of the rotors are clearanced, depending on apex seals used (and how good the slots are in the rotors - no more than .0025" clearance! Spec is .004" max but not if you want to run hard) you should be okay to a zing to 10,5 or so.  Higher RPM makes wear happen exponentially faster, so you may want to keep the revs lower and only use them as necessary.  I have seen 11k under load with nothing more than good clearancing, good oil pressure, and not holding it there for too long   (aka "I broke 3rd gear again and I am not going to try to upshift to 4th before this corner")

Speaking of.  The transmissions seem to handle higher RPM okay-ish but change the fluid regularly, get a heat shield between the exhaust and transmission if at all possible.  The synchronizers hate life if you try to shift over 8000rpm or so, so patience and/or short shifting will help trans life.

If the oil injection system has been deleted, premix at about 50:1.  If it is still present, premix at about 100:1.  The oil injection system is biased to keeping converters from being poisoned by oil consumption, they really do need a lot more oil than that.

I'll let the FC experts chime in on unobtainium spares, but from my vantage point of having a half FC 1st-gen, pretty much everything is unobtainium anymore.

Oh!  CLEAN AIR.  You need a good air filter and meticulous attention to ensuring that all air going into the engine will go through the filter.  The #1 killer of rotaries is unfiltered air.  Dust and debris gets stuck between the rotor and side housings, and quickly erodes the side housings and side seals.

If you aren't sure what has been done to the engine with clearances etc. shift at 8700 and it will be fine. I like 20w-50 but I have run Rotella in many engines. I've been running Amsoil Saber at 100-1 for years.  The main unobtanium piece is that 5.12 diff you have.

Keeping rotaries cool is paramount. They'll like to stay cooler than a lot of piston engine cars can tolerate. An underdrive pulley may be required to keep the water pump from cavitating depending on your chosen redline. The stock oil cooler is large, but lots of people install a second one in parallel. They have a built in thermostat, but it can be blocked and an external one used instead if you like. They also want lots of oil pressure and stock FC oil pressure regulators aren't necessarily good enough, but they can be disassembled and shimmed for higher pressure. I ran an oil pan baffle in mine, which is basically just a plate across the top of the pan with holes in it for oil drain back. For transmissions, the one to get is the GTUs trans, as it has a shorter 5th gear, which you'll be using with that 5.12 rear end.

Where are the pics? 

In reply to RX8driver :

I make my own oil pressure regulators with a stock one and a hammer 

Good point on the underdrive pullies, too. I would hope that an ITS car already has them, but who knows?  Coolant basically stops flowing over 6000rpm or so with the stock pullies.

RX8driver said:

... The stock oil cooler is large, but lots of people install a second one in parallel. They have a built in thermostat...

If you have need for another oil cooler let me know.  I have a few spare FC coolers (with thermostats) I pulled out of pick-a-part years ago and have not found a use for them.  I am very willing to sell them for a very good price especially to rotory projects.

Good info so far, thanks everyone.  
 

apparently this has the FD oil pressure regulator to bring up the oil pressure, as that seems important from what you have said.  
aircooled, we will probably take you up on that. 
 

Here are some crappy pictures my friend sent. 

Dave Estey knows his way around rotaries pretty damn well, and his team ran a Lemons rotary FC for a few years.  IIRC, it finished one race?  Put a 4.8 in and popped off 2 or 3 top-15 finishes with zero DNF's...  

That is all I have to offer on this topic, haha. 

As others have mentioned, you can run these engines at the upper end of the RPM range and  they love it. I've been time trialing mine since 2006.  I just had the engine rebuilt this past winter, the previous one ran for 9 seasons, hope i can get about the same out of this one. I used to run 100:1 premix ( just Mercury 2 stroke outboard from wally world) but the guy who rebuilt the engine this time suggested 200:1. He didn't seem to think any particular brand was better than another. I haven't seen too much smoke yet so 200:1 seems OK, but I've only just started breaking it it, < 100 miles so far.  Always have spare plugs with you, they foul easily and once they are fouled best bet is to just swap in a fresh set. Keep an eye on coolant temps, they run hot and don't like to be hot, usually as long as you are moving things are fine but if you get stuck in pit lane they can sometime heat up quick. I like to see mine run around 180 on a hot day, most times on track it stays 150-170. I have the thermostat removed and some passageways bypassed as it is a track only car. The only parts that seem to be hard to find lately are front calipers, the 3rd gens will work but just barely fit if you still run 15" wheels and even the 3rd gens are getting harder to find. Start looking for a spare set of 2nd gens to rebuild your self.  Most other stuff is available from various places including Mazda. They stil have alot of OE parts readily available; gaskets, odd engine compartment pieces, etc. Mazdatrix and Atkins have great selection of go fast goodies but can sometimes be pricey. Many bolt on componants are as close as NAPA, Rock Auto and your local O'AutoQuestBoys. Parts cars are scarce, your diff is rare and is the best of the bunch. Have fun with it, I love the way mine handles and sounds.

premix for sure, dosent have to be indemitsu.  I was recomended supertech 2 stroke from walmart, bought by the gallon by a freind that keeps rotaries alive like its his religion

If you need another one. FBM ad link.

200:1 is waaaaay lean.  Mazda did 150:1 drooling oil directly against the rotor housing surface, premixing will have most of the oil blow right out without touching anything.

Racing Beat said they premixed at up to 6oz/gallon on endurance racing engines.  That is 20:1!

Sonic said:

.... aircooled, we will probably take you up on that. 

Certainly, just send me a PM when you want one.

In reply to hobiercr :

There's a green one in the area also, gotta catch them all!

https://www.facebook.com/groups/1163821863645385/permalink/5656751964352330/?ref=facebook_story_share

Re the premix - if you're running at fairly high dilutions, make sure you're using fully synthetic 2 stroke oil, which the Idemitsu is. I know there are others as well - Yamalube comes to mind, and I wouldn't be surprised if there is a SuperTech as well.. I personally only would run at that level of dilution on an engine that still has the the stock oil injection system fitted.

Pete. (l33t FS) said:

200:1 is waaaaay lean.  Mazda did 150:1 drooling oil directly against the rotor housing surface, premixing will have most of the oil blow right out without touching anything.

Racing Beat said they premixed at up to 6oz/gallon on endurance racing engines.  That is 20:1!

I had my math backwards, I was adding 1 oz of oil to 1 gallon of gas, now I add 2 ozs per gallon.

Racing Beat recommends 3.5 oz two stroke oil to 5 gal fuel for naturally aspirated race engines. I just use 1 oz oil to 1 gal fuel for simplicity's sake. If the car has been sitting for a while it's a little smokey on cold start ups but it clears up quickly. As for engine oil I've always advocated for running the thinnest oil possible that still maintains target pressure. You're balancing engine wear (viscosity) and engine temperature (flow). I've found 10W40 works well in a naturally aspirated engine. I've been running Redline 40WT (actually a 15W40) for the past couple years. I have the FD regulator. It bypasses at 110 psi but at race temperature I normally see pressures in the 90-100 psi range. Radiator and oil cooler ducting is critical. Without them it will quickly overheat. I've seen stated maximum coolant and oil temperatures all over the place. I usually see max 200F coolant and 225F oil temperatures during a 20 min sprint in the Summer. Personally, I'd like to see lower oil temperatures but if pressure is still ~90 psi I don't think it matters too much. S5 engine in race form, I'd shift at 9000 RPM, but I'd be concerned about the drivetrain. Unless it's running a race flywheel and clutch most off-the-shelf versions aren't rated for continuous use over 8500 RPM. A scatter shield would be a good investment. That 5.12 torsen rear end is unobtainium. There was also a 4.8 or so (can't remember if it was 4.77 or 4.88). You'll definitely be shifting into 5th on larger tracks and the stock 5th gear is a highway cruising gear (like 0.7:1). Due to the nature of the transmission you can swap 5th gear with ratios from other cars. A common transmission mod is to swap the Miata internals over for much better ratios.

In reply to infernosg :

The Comp ratio options were 5.12 and 4.88.  The 4.78 was a Kia gearset not a direct swap into an FC.

I like temperature discussions because it always boils down to "I would like to run at X but I can't get it any cooler than X+20" . Oil seems to be more critical than coolant for making power (over 180 is bad) and coolant seems to be more important for engine life (cooler is better, scream and shout and back off at 220, shut down at 230)