Originally Posted by Khurram

I have an 06 ported motor with AEM, BhR Ignition , BHR Midpipe and Full cat back exhaust.
It netted at 225ish WHP.

I have a few friends who dynoed their 8's all stock at 185-200 whp.
One friend dynoed his 8 with cat delete 210 WHP
I guess it also depends on engine's health.
The most I recall seeing N/A build pushed 230 WHP thats with porting, polishing and etc

Rx8 came pretty refined from factory and Mazda milked every last drop of juice out of this renny motor.

Best and Cheapest mod by far has been CAT Delete and it also helps your engine last longer

Originally Posted by hufflepuff

I have heard a healthy / factory fresh RX-8 will dyno in the 175-180ish WHP range. I feel the RX-8 was quite over-rated, and it is sensitive/prone to loosing power through loss of compression, loss of spark strength, and other losses (gumming of intake components, fuel pump woes, etc). So it's not uncommon for RX-8s to lay down low numbers, say 150-165WHP.



Headers and a tune would maybe be worth 10ish WHP? The consensus is that CAI is a few HP tops, catback is a few HP tops, some folks say the mid pipe is worth a bit but other say it's not worth much at all. Dynos talk, but too few people dyno a single component back-to-back, they lump a bunch of mods together and it's tough to say WHICH component produced the best gains.


Lightweight cars have their own advantages. I'm okay with getting beat by trucks or Camrys in a straight line, because that's not what I consider "competition". The RX-8s prowess is displayed on a winding road, autocross, or road course.

Originally Posted by Brettus

Yeah ... you might not make much more power but still worth doing IMO.
Hard to find a tuner competent with the Cobb and rx8 combo though . PM me if you geet stuck.

Originally Posted by CelestialGryphon

I'm glad I finally sat down and did some reading, this answered a lot of underlying questions I had about mods and such. The only thing I didn't think I saw was cooling, but the answer there is really always "Bigger radiator and fans." Glad to see that the BHR coils was listed, I've looked at others but don't really have any information on them.

Originally Posted by Shinka1195

Maybe I missed it in here, but what about the oil cooler thermostats? I understand the factory ones don't open until 220* and close at 190*, yet the oil temps should stay closer to 180*. I have seen the 180* thermostat oil cooler kit, but does anyone know if this actually keeps the oil that much cooler?

Also, oil pans... I am looking a the mazdatrix or RX8Performance oil pan for extra capacity and the baffling. Since I do track days, the baffling and capacity could help, but is one a better design than the other?

Originally Posted by hufflepuff

I have oil and temp gauges. Cruising around, my oil temps rarely go over 180F. I think the OEM oil cooler t-stat is set to 180F, and it has a bypass, which often leads to overcooling. I taped over both oil cooler ducts during the winter and my oil temps settle around 200-210F; this also helps prevent oil foam on the dipstick. I wouldn't recommend this unless you have gauges to keep an eye. on track with both ducts open I see 200-210F oil temperatures.


I also use the OEM oil pan on track. I keep the car topped off between sessions. No oil pressure issues out on track. I am running NASA TT at a good pace, but I'm not on Hoosiers.

Originally Posted by Dutchsrx8

I was driving my rx8 the other day and I started hearing a loud thump from my back right tire. I’m thinking it might be my struts. Any ideas? It doesn’t sway or anything weird but anytime I hit a slight bump or crack in the road the thumping starts going nuts. It also thumps when I speed up.

Originally Posted by RIWWP

Oiling Modifications

SOHN Adapter (2004-2008 RX-8s only)
(can create warranty hassle)
The SOHN Adapter is an adapter that changes the source of injection oil for your RX-8 (or other rotary). From the factory, the source of oil used for injection is the 4-stroke oil that you change at regular intervals and you have to check to see consumption of periodically. This is a compromise made for consumer benefit reasons, but is certainly not the most ideal oil, as 4-stroke oil wasn't meant to be burned. The SOHN Adapter is just a plate that mounts to the OMP (oil metering pump) and allows you to supply an alternate source of oil for injection instead, also allowing you to inject your choice of oil as well. This means that instead of injecting dirty heat cycled 4-stroke that wasn't meant to be burned and leaves behind all sorts of residue, you can inject clean 2-stroke that hasn't been heat cycled and is designed to burn cleanly!
Costing around $150 for the pump with shipping, and plus a bit more for whatever tubing and alternate reservoir you use, it's a really cheap mod that can significantly help your engine's health.

Single Oil Cooler
(can create warranty hassle)
This isn't a common modification at all, but can produce benefits with higher oil pressure from the reduced oil system complication. The main drawback is that it can be difficult to find a good point to mount the cooler, though there have been successes with a horizontal splash pan mounted one and a low one in front of the radiator.

Oil Pressure increase (series 1 only)
(can void warranty if found, though it is unlikely)
This is growing in popularity, especially as our engines are dropping out of warranty. It is basically a set of shims that changes the spring strength in the oil pump's bypass, and increases the oil pressure to approximately the same oil pressure as the RX-7s and the Series 2 RX-8s have. This may also be accomplished with a complete replacement moving to the FD RX-7 unit. While there are no real direct know or documented benefits, and there have been significant debates over pressure vs flow, it is oil pressures that Mazda used to have, and returned to for 2009+ RX-8s.

If you do decide to increase your oil pressure to the Series2 oil pressure values, make sure you use higher pressure bypass oil filters. The easiest way to determine this is to simply use Series2 oil filters once you make the switch. On a Series1, it's a tight fit, but doable as long as you don't have any sandwich plates under the filter.

OEM oil cooler vents
(no impact to warranty)
Similar to helping the radiator breath, the OEM oil coolers can be helped by opening up the wheel well liner behind the oil coolers, allowing better air flow. The only drawback is in how you modify the liners. Open them up too much, and you could end up having your front wheels throwing road debris into the back of the oil cooler, which isn't helping you at all. Care should be taken in the modifications to make sure you are still shielding the cooler from the debris being thrown by the wheels.

Premix
(no impact to warranty)
Premix thread: https://www.rx8club.com/tech-garage-...-thread-99636/
Premix is mixing 2-stroke oil with the gas in the gas tank to assist with lubrication of the apex seals. Why 2-stroke? Because 2-stroke (in general) is designed to be burned. Unlike 4-stroke that you use in during oil changes. Why premix? This gets a bit more vague when answering. The short answer is as noted, to assist with apex seal lubrication. But do we need it? That's a tougher question to answer with facts. Some people swear by it, others do just fine without it. Series 1 has 2 injectors pointing at the side seals, Series 2 adds a center injector to help with lubricating the center of the apex seal. Mazda added this, so they must have found excessive wear in the center of the apex seal, so it's circumstantial evidence for the need to premix. It's hard to say if this will save your engine from apex seal wear failure though. About the only confirmed difference premixing really makes is that the carbon buildup inside the engine appears to be "softer". In theory, makes it easier to clean, and if it comes off it won't come off in dangerous flakes that could cause carbon lock.

Which premix to use? Lots of debate here too. There are lots of options, and not all of them are even oil. The list below is ordered from most ideal at the top, least ideal/not recommended at the bottom.

Idemitsu Premix is generally considered to be the best out there. The only draw back to it is accessibility in that you have to order it, and there are minimum order quantities. Often a member here will order a larger case and split it with locals, making this a bit easier, but it's also usually a 1-time thing.

Amsoil Saber Pro is highly regarded, and a bit easier to get than Idemitsu.

JASO FC and ISO oils basically other oil brands of the same type and grade as the two items above. May be easier to obtain than those.

TWC-3 Oils are usually easy to find, however it's not likely that you are doing much good with them. Not much harm, but small engines that require this type of oil can fail due to lack of lubrication from it, so it might not be sufficient for us. Post from Emery on this:


Marvel Mystery Oil (MMO) is common, and easy to obtain. Some people swear by it, others denouce it totally. The people that love it can't prove that it does anything good, and the people that say that it is worthless can only point at it's cleaning agents as being a problem, which doesn't even sound like it's that big of a problem. All in all though, it probably doesn't have much lubrication compared to some of the other options above, so it could be considered to probably be on the same level as TWC-3. I.e., not doing much.

Lucas Upper Cylinder Lubricant (Lucas UCL) is a non-oil you can find out there, but we can't recommend it. We can't prove that it causes any fuel filter problems, but for some unknown reason it shows up in a significant percentage of fuel filter problem threads (>2 in 3 threads at a guess). Doesn't even make sense why it would cause problems since it's still just a liquid that can go through the filter, but often fuel filter problem threads include the owner using it for a while before hand, and then stops using it and the problem clears up.

How much premix? The standard amount is about 1oz for every 2 gallons of gas. Some people go 1oz for every 3 or 4 gallons, and some go for 1oz to 1 gallon. 1oz for 1 gallon is getting on the high end though, so don't just use that to use it. Dig into why you want that much. One of the common reasons for going to 1oz to 1 gallon is for a track day. Lots of heat means a bit better lubrication could be a good thing in the end. Note that these values are for how much fuel you are putting into the gas tank. So if you are filling up at halfway and adding 7 gallons, then about 3.5oz is ideal. If you never fill till the light comes on, then around 6.5oz is more accurate. Some premix containers come with a measuring method built right into the top, otherwise it might be useful to find some small plastic containers of the ideal size to keep several on hand. I lost them in a prior move and haven't replaced them, but for a while I was using four 6oz bottles that were originally intended for hair products. Clean them out thoroughly, let them dry, fill ahead of time, and keep tucked in the car to easily add when I fill up. If you opt for this and don't use glass bottles, I'd recommend replacing the bottles periodically, maybe every 6 months. Most plastics aren't of a grade that is designed to hold petroleum products, and it will start to break down from the inside after a while.

Originally Posted by FatherSonRX8

Just bought my youngest son his dream car, 04 RX8 (fell in love with it at first sight). Made it clear we'll be spending quality time & money but that it's an amazing car.
First problem: EPS light comes on, PS doesn't work at all.
Have replaced the 60A fuse twice, did the left right reset... worked.
Watched YouTube Driven by Madness, pulled the airbox and cleaned the (2) EPS connectors. Battery terminals look clean. Changed air filter same time.
Installed new fuse, worked fine for a week.
Today, worked on the way to playing golf. Got in... light on & EPS not working.
Already ordered new fuse, but this is just treating a symptom & not the cause. Installed new fuse, did left right reset, din't work. I drove it home. Pulled into garage. Did nothing with the fuse. Turned off, switched ign to ON, did reset, started, EPS light WENT OFF. Ok great. Shut it off went in the house, thought I don't like short starts and stops but go drive it to make sure we're ok until I can research this more. Started up, EPS light back ON & NOT working again.
I'm prepared to take it into a local EURO shop... but is there something obvious this ultra-newbie is missing?

Originally Posted by Jack O'Mahoney

I am aware that there are two coolers mounted behind the front bumper, Are they both engine oil coolers and are BOTH of them completely necessary. Would you be able to run say an engine oil cooler on one side and a Power Steering cooler for example on the other without overheating issues?

Thanks