Hi,

I have been fighting two issues with my 93 R1 on the track.

Firstly, crankcase pressure. After experiencing rediculous amounts of oil consumption on the track, and on track only, I installed a vented catch can similar to Krispy's setup blocking the pcv and intake path and venting out of the top of the oil neck into a vented catch can.

Even with this setup, I still see over .5l of oil out after as little as 10 laps. It seems there is so much pressure that combined with hard right hand corners, the oil is coming right up the filler neck and out.

Excess crankcase pressure by ring blow by in a piston engine makes sense to me, will the rotary produce crankcase pressure as the apex seals wear? Will a compression check reveal this? The motor is making good power for the mods as the dyno shows it is about where it should be. The car is still running the stock sequentials. Any ideas??

Second problem,

No matter how hard I try, I can't keep the thing cool, after 5 laps or so temps are up at 230 according to the autometer temp gauge with the sending unit located in the filler neck (drilled and tapped in the flat section that appears to have been intended for a sending unit)

Currently I am running a Koyo rad, removed condenser, fans at maximum speed, I have tried 90% water solution, have tried water wetter, I have ducted the koyo rad and blocked all passages except for where the cold air is being drawn for the intake. I am also running a pettit ECU and keeping boost down to 10psi with a profec B. I know if I ask for more boost I'm just going to get more heat. What else can I do? these cars are so nice to drive on the track, it's just hard to get a rhythm going taking a cool down lap every 5 laps. I should also mention that ambient temperatures were around 28 degrees C, I think that is around 90F off the top of my head.

Please help, I have read and searched for several years now in my quest to make this car reliable, I feel like I am running out of options short of going single turbo.

Thanks so much for any help,

Andrew Wojteczko

 

solo1seven,

What intercooler are you using?

 

Andrew,
You have my sympathies. Two issues track junkies are all faced with, and two that I have also faught with for many years. For the oil issue alas I have no solution. I've tried everything also but always end up adding between a 0.5 and 1 qrt per session. Some have this problem some don't. I'm one that does...as do you. The only tihng I can suggest is just run the oil level low....very low...and watch the low oil light during your session. Don't worry too much about running very low oil as the oil pickup is in the center of the pan and the low oil sesnor is in the driver side of the pan a tad above where the pickup is so if the light flickers a bitt during hard left corners I wouldn't sweat it too much..unless it STAYS on. I run oil level at or below the half way mark...ALL THE TIME on the track and manage to get by. Best I can suggest. Oh and if it's any consolation Mazda even rocognized the problem...take a look at the location of the filler neck on the RX-8. It's now located right over the *center* of the engine and not off to the left as on the FD.
Now the temperature issue strikes me as something of concern. Temps ARE controllable...and not by backing off on the go-pedal. Look at your thermostat. Install a NEW OEM Mazda thermostat. Or buy a parts store brand and drill holes around the periphery to increase the flow...or do both - drill a mazda T-stat. What kind of oil coolers are you running? More oil cooling will help reduce coolant temps considerably. But from personal experience I've found that coolant temp sensors in the location you noted tend to read on the high side from between 5-10degF. I have a friend who has a PFC with another gauge, sensoor located like yours, where the gauge will read 230F and the PFC is still down around 105C (220F). Now I'm not saying ignore your gauge but I woudl suggest that ebfore you start spedning money on parts you may not need...verify with perhaps someone running a PFC and a gauge like yours by how much your gauge might be off. It's tough to do I know but something about your gauge sounds suspect to me.
HTH
Crispy

 

Ahh, the joys of tracking an FD.

28 C is 82 F. 230 F is ~110 C. 230 F @ 10 psi boost in 80-ish ambient temps is about par for the course if you're driving the car @ 9/10ths every lap.

I've seen water temps as high as 120 C (248 F) with 10 to 11 psi (0.70 to 0.75 kg/cm^2) boost in ambient temps in the 30 C to 32 C (86 to 90 F) range.

I have a GReddy 2-row FMIC/Koyo rad and an intact A/C condenser. Distilled water content is 80% with 20% anti-freeze, plus 1 bottle of Redline Water Wetter.

I too have CrispyRx7's Brad Barber Oil Catch Bottle with special Crispy Cap.

Some road courses are worse than others with oil blowby. Putnam Park's the worst. It's short, fast, with long 1-G right hand turns. With longer courses like IRP and Mid Ohio, oil blowby isn't so bad.

Sorry I have no other solutions. Like Crispy, I can only offer sympathy.

Short of going with a Spec Miata, there's not much else you can do to get those two issues (oil blowby and water temps) under control in a tracked FD.

 

Andrew,
If you got a FMIC.....a tunneling system would help also opening the front mouth up a bit....

I finnaly got all mine together correctly and my car runs too cool at crusing speeds....

 

Like others, I agree with Crispy about the T-stat. That one has burned me before. I go through them quite often. Some last awhile, others only a couple of months. Just check it in some boiling water. It should be all the way open at 212 deg.

Also, are you running an underdrive pulley on the water pump? I think the stock water pump cavitates (stops pumping) around 6800 rpm's with a stock pulley set. I think that is right. If you are spending a considerable time at or above this rpm range on the track, you may want to consider a pulley set.

 

I'm running a stock intercooler right now, the rad is completely exposed. Is it possible the baby turbo comes out of it's efficiency range and starts producing the excess heat?

I have replaced the Tstat with a new Mazda unit, Crispy, the Power FC reading cooler at another location is interesting, possibly the car isn't too too hot. I would like to upgrade to a PFC but funds don't currently comply. I am running the stock R1 twin oil coolers.

SleepR1, where are you reading your temps from?

Thanks guys

 

Power FC is reading water temps from the stock location thermosensor.

 

Sensor reading at the filler neck is about 10-15 deg higher than the coolant coming out of the block into the Throttle Body.

Try running Evans NPG+. I don't have any issue with high boiling temps. Can't tell for sure but in 90 deg heat, my car is not losing power even though my gauge at the filler neck is reading 220F.

Even with the coolant temp at 250 during shutdown after a hard run, I don't hear the boiling sound anymore.

 

I am going to hook up one of our scan tools and see if I can get a datastream, I should be able to cross reference the factory sender with the autometer one and determine if I actually am running too hot.

As for the oil, what if I fab up a filler neck that will locate near the center of the motor? The RX8 filler comes off the side and then over, or off the back in the middle?

Crispy, did you get anywhere trying a baffle plate in the filler neck? How about plumbing a return line from the bottom of the catch can back to the pan, or would the pressure from the crankcase just prevent that line from gravity feeding and backfill the catch can?

Thanks again

Andrew Wojteczko

 

One more thing, how hot are we safe to go at the factory location, is 230 the upper bounds of that sensor, or at the filler neck. From discussions I've had 230 keeps coming up as the upper limit, but at which point?

Thanks

 

solo1seven,

I'm monitoring temps with the Autometer gauge (with the sender in the hex bolt location). I see around 220-230F on the hot days. I don't have a FMIC (Pettit Coolcharge II), but the FMIC guys usually are around 230-240F on the hot days.

I have yet to track my car on days hoter than 95F, but RTS3GEN did about 2 years ago (it was around 102) and he was seeing 230-240F with his Apexi FMIC (he also has the Scoot hood as well as custom ducting for the radiator).

As far as the oil, you can check Crispy's thread in the Race Tech section about different attempts to solve the problem and their results:

https://www.rx7club.com/showthread.p...hreadid=226214

 

Andrew,
As a datapoint I typically see between 100C and 107C on the track from the stock sensor *regardless of how hot the ambient* temps are. I've driven in ambients as high as 105degF and managed to go about 10 laps before having to lift when the temps hit 110C. 110C is my threshold at which point I back off. No point in pushing harder as the ECU pulls timing and drops your HP by about 30-40 so you will be slower anyways.
Short of a 105deg day I push as hard as I want for as long as I want at 12psi and have no concerns at all with temps or cooling.
As for the oil issue check the link Mahik posted. But to the point the RX8 filler neck won't fit with the FD plenum...no even close

Crispy

 

I have the same catch can setup. I had to run the oil level uncomfortably low (bottom of the stick) to avoid overflowing the can during a normal 20min track session on some tracks. I added the "turkey baster" fix and that has greatly raised the level that I can run the oil. Now I fill to half way on the stick. In short, try the turkey baster if you haven't done so already.

Mark