RXBeetle said:I've wondered if E85 wasn't a good idea (with tuning and proper syntetic premix oil). The Renesis runs premium anyway and lower EGTs should help keep the side seals alive. Water/meth injection?
E85 is known for diluting the crankcase oil more. There is also the fact it's going to get you ~30% worse MPG and it's already known for being thirsty.
In reply to ¯\_(ツ)_/¯ :
It ocasionally does a start sequence functional check. It's not as easy as jamming a resistor in there but an arduino could easily fool the desired feedback. True an aftermarket tuner is probably the easy answer.
A lot of this has been mentioned already, but I'm going to add my $0.02 based on several years of HPDE in an RX-8 and research on how to keep it alive:
Cooling: The stock cooling system on the RX-8 is decent for street, but can use some upgrades for track use. There is a lot of stuff directly behind the radiator (battery, air intake box). If you can clean this up and add hood vents it will help. The coolant overflow tanks can get brittle with age, and a lot of the cheap cars will likely need replacement. I seem to remember reading that rotaries reject ~50% of heat through coolant and ~50% though oil (might have been 60/40). Either way, don't forget the oil coolers. Manual RX-8's in the US have two oil coolers that reject heat into the front wheel wells. Opening up or removing the inner wheel well liner can help airflow. The stock cooling gauge is a dummy gauge. It hits center at ~160 and doesn't move again till 230. By then you are already too hot. Get aftermarket water temperature and oil temperature gauges.
Ignition: The stock ignition system is decent, but the coils do go bad. With mixed street/track use I replaced coils plugs and wires every 15-20K. If you find a car with "low compression and blown apex seals" there is a decent chance that it is just bad coils. For some reason, the coils going bad can cause it to read low compression. Bad coils will also cause the cat to clog, so watch out for that as a possible cheap fix to a "blown engine". Black-Halo-Racing has an upgrade kit to replace the coils. They used to use LS coils, but I think they recently swapped to something else. Most of the research I have done recommends BHR or stock.
Fuel: As mentioned above, you can get fuel starvation at 1/4 tank on long lefthand sweepers. I would add a fuel cell or surge tank if doing endurance racing. I want to say I got 8-9 MPG in a HPDE setting.
OMP/Premix: The Series 1 RX-8's (2004-2008) only had two oil injectors per housing. The Series 2s added the third injector back. I think the stock ECU will go into limp mode if the OMP is unplugged. I kept the stock OMP and add premix on top of it. You can also get the Sohn OMP adapter that allows you to inject clean 2-stroke instead of crankcase oil. Even if you keep the OMP, I would premix an S1 since it is missing the center injector. The OMP doesn't actually pull that much and I think I was using less than 1 qt in 2hrs of track driving.
Clutch pedal: The clutch pedal bracket is a weak spot. They are spot welded and don't have enough lateral support. There are kits out there to add support to the bracket, or you can weld it yourself. If the clutch pedal is squeaking, I would check for cracks.
Brakes: The stock brakes and ABS are really good. The only thing you need to watch out for are "grabby" or "on/off" pads. You want something with some modulation or you need to be smooth upon activation. I was running HP+ and if I got onto the brakes too fast on a cold day it would activate ICE mode on the ABS and you loose braking.
All that being said, they are good cars for track. A lot of the rotary's bad reputation is from people driving it like a Camry, not maintaining it, or trying to up the power without supporting mods. Rotary's are built for track and that is where they excel. The only reasons I stopped tracking my RX-8 and switched to a Miata were cost of consumables and not wanting to tear up the interior for a cage. I am planning on swapping a rotary into my Miata when the stock engine finally dies.
z31maniac said:RXBeetle said:I've wondered if E85 wasn't a good idea (with tuning and proper syntetic premix oil). The Renesis runs premium anyway and lower EGTs should help keep the side seals alive. Water/meth injection?
E85 is known for diluting the crankcase oil more. There is also the fact it's going to get you ~30% worse MPG and it's already known for being thirsty.
True on both points. Frequent oil changes are a given for a race car I suppose but the MPG is a bad recipe for endurance racing. This brings me back to water/meth injection. It might not get you any performance but dropping EGTs is never a bad thing for side seal and rotary exhaust system life.
RXBeetle said:z31maniac said:RXBeetle said:I've wondered if E85 wasn't a good idea (with tuning and proper syntetic premix oil). The Renesis runs premium anyway and lower EGTs should help keep the side seals alive. Water/meth injection?
E85 is known for diluting the crankcase oil more. There is also the fact it's going to get you ~30% worse MPG and it's already known for being thirsty.
True on both points. Frequent oil changes are a given for a race car I suppose but the MPG is a bad recipe for endurance racing. This brings me back to water/meth injection. It might not get you any performance but dropping EGTs is never a bad thing for side seal and rotary exhaust system life.
The funny thing is that the fuel economy isn't actually bad in a racing situation. Rotary's real weak point in fuel economy is in the stop and go, low-RPM normal stuff that people use it for as a real car. In racing conditions, I'd imagine you're going to be competitive with the other cars you're on track with (BMW 330s, Firebirds, etc.).
Please tell me this is not your plan for the next rally car lol...
I feel like you could just use one of Sara's riding crops to whip yourself on the back repeatedly if you just want more punishment than the merkur ;)
In reply to ¯\_(ツ)_/¯ :
I've rebuilt a handful of rotary's and the Renesis I did was the worst. While I only replaced seals the compression was never great and only lasted about 4 years before it became hard starting due to low compression. Then I purchased a rebuilt engine from Rotary Resurrection shipped for about $3000. This engine has been great. His engine removal and break-in instructions were invaluable. Others have rebuilt these themselves with new housings but have suffered low compression in 3 years. Don't know exactly what the problem is with the Renesis but they are just not robust like the older rotary's.
I will never spend money on another Renesis rebuild, if the Rx8 needs another engine it will be an REW from the mid nineties Rx7.
irish44j said:Please tell me this is not your plan for the next rally car lol...
DO IIIIIIIIT!
In reply to Brett_Murphy :
Rally is always the answer!
I was just at Olympus Rally this past weekend (top picture shows the car was running there) and there were a definite lack of rotaries. There was a 964... but no rotaries. Someone should fix that.
There was a RX-7 at Tour de Forest last year, but it had an interesting history... all I know is that there was no rotary under the hood.
If I am not mistaken, the Renesis apex seals are narrower. It may be why they wear out faster. The side exhaust also makes them run hotter.
But note this engine makes 200+ hp. The rx7 NA motor almost identical made what 160hp?
In reply to nimblemotorsports :
The Renesis actually has the same apex seal thickness (2mm) as the 86-02 RX-7. Earlier RX's had 3mm seals and some of the very early rotaries had 5mm. The apex seal usually isn't what fails on a Renesis. It is usually the side seals due to the side exhaust port or wear to the housings since they don't have the center OMP injector.
The '09+ (S2) Renisis got a center oil injector, 3 total per rotor. I don't think they would have added the cost if it didn't really help lower the warranty claims.
The Renisis apex seals are 4.5mm tall and the 13B are 8mm. They don't see bending in the peripheral exhaust port so the shorter, lighter seal is a big improvement for high rpm.
People were milling the rotors to take the taller apex seals. I think some high compression RX-8 rotors got used in 13bs, but some were just used in RX-8s.
I didn’t know until now that the temperature gauge was a poser…explains why when I blew my first engine the temperature went from “ALL’S GOOD” to “YOU’RE SO HOSED” in ¼ of a nanosecond.
BTW, I cleared a five-lane highway with a massive cloud of smoke when the first engine blew it’s brains out.
As others have said, keep it cool. On my R3 I opened up the grille, opened up behind the oil coolers and did plenty of sealing around all 3 coolers and it was ok for my use, but for running in 100 degree weather, especially for longer than 20-30 minutes, you'd need upgraded coolers. This is important not just for reliability, but the ECU will start to pull power once the temperature starts to climb, IIRC 220F was the number.
For an S1, especially if you're rebuilding it anyway, go with a higher pressure regulator, at least 90 psi and use at least 10W-30.
I'm not so sure about oil passages on the Renesis vs the older 13B's, but on the old ones the oil pump fed the coolers through the front cover and it could flex and bypass. One could drill out the plugged galley in the front iron and run the feed through there instead to stop that from happening. Another upgrade is to run an external oil feed to the front bearing, through the plugged galley in the front iron.
For fuel starvation, I've read about people putting a stock pump assembly on the right as a transfer pump to get away from the siphon system if you don't want a fuel cell.
I've also read to keep the revs under 8500, as going higher mostly just means more wear and tear and more heat.
The S1 transmissions were also said to be more fragile than the S2's, but that's probably highly influenced by the user.
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