badinfluence

Degreaser can eat wires and DEFINITELY eats connector solder joints and breaks down insulation elements of wiring harnesses and connectors. There is a lot to go wrong on the RX8 so I would get a steam cleaner because it would use Distilled water and vapor to clean.

I have tried Simple Green and it works well, but the truth is you only want to do something like this on a Hot and Dry day otherwise you will end up with humidity in the bay and that can lead to shorts.

Basically the process is Simple to do it right:

Remove Negative Terminal
Remove Positive Terminal
Remove Battery Box
Remove Air Box
Remove MAF & Bag Connector
Remove ECU and Bag Connector
Cover Alternator, SJB (Fusebox), All Sensors & All Connectors
Cover TB & Any Exposed Engine Fluid such as the Oil Cap.
Cover Air Pump
Remove harness and cover sensors if you can.

Allow 8 hours of Sunlight in Hot & Dry conditions with the Hood UP to dry properly. Wait a full 24 on the car before powerup to be certain.

I would Rinse, Simple Green, Wait 15 minutes, then hit it with High Pressure.


The best result is gotten from renting a High Pressure Steam Cleaner.

badinfluence

Question What AKI is required for the RX8. Not recommended, but required for a stock engine in hot weather to not have dangerous detonation?

I mix 5 gallons E85 with 12 gallons of 93 and get 100 octane with the same gas mileage as plain 93, but everything stays colder, and I am getting the same amount of power. I am wondering if I used 87 if I could get away with it and still get the benefits of nitrogen enriched gasoline.

Basically E85 here is Min E70 for 2.89 and 87 is 3.09 right now, and 93 is 3.39. So the potential savings for the fuel quantity when it is above 90 outside is huge.

Rx8 Dave

Didn't notice the engine cover missing after an oil change until today. Garage lost it.
Anyway, how important / necessary is having the plastic engine cover? Do I need to buy another one?

Rx8 Dave

I don't think an ethanol fuel blend of 85% denatured ethanol fuel and 15% gasoline or similar high percentages of ethanol is good for the Rx8. I think the manual says not to use more than 10% ethanol. Manual says you can use 87 regular if there is no knocking. Some suggest to try using 87 octane for a few tankfuls and some Club members say 87 corrects rough idle. However, others say: "The engine should really drink at least 91 octane. 89 is technically viable, but not recommended. 87 is only "safe" on an engine that already has failing compression. The healthier your engine is, the higher the octane requirement will be to avoid detonation and a blown engine. 89 octane is safer if the highest compression face in the engine is in the mid 7s than it is if the highest compression face is in the mid 8s."

Chad_I

I have been looking at a used 2004 RX-8 6speedMT with 72000 miles on it engine feels strong(I have driven it)compression is at 7.3-7.6 kg/cm2 at 250 rmp in both rotors, is this good, bad, or are their other important factors in measuring the engines strength and longevity; I'm a newbie.

Chrishoky

iTrader: (9)

You dont need it at all.

gwilliams6

I would make that garage replace it. why should you be without it if it was their fault. It is a large piece to just "lose". Make them find it or replace it. I have the 40th Anniversary Edition and the engine cover is painted silver. It is part of the car's look. Not critical but the cover does protect some electrical parts and your coils from anything dropping down on them when anyone is in your engine bay, so better to have it.

Harrigan

iTrader: (1)

Stupid question. How can you tell an authentic mazdaspeed kit from a replica? I know there are simple things such as the black middle insert piece and obvious fitment issues. But if I am just judging from pictures what is the best way to go about it.

gwilliams6

You should have gotten numbers in a format something like this:
Rotor 1: 7.5, 7.6, 7.5
Rotor 2: 7.2, 7.3, 7.3
250 RPM

- The 6 numbers, 3 for each rotor, are your compression scores, one for each face of each rotor in the engine.
- If you don't have all 6 rotor face scores and at least 1 RPM number, your compression scores are going to be vague and hard to interpret.
- You may also have your compression scores in a different scale, such as PSI.
- The RPM is the speed at which the test was done.
- The RPM is critical to interpreting the numbers, as rotary compression changes with engine speed, especially at low RPM.
- Since the engine is spun by your starter, this is ALSO a good indication of the health of your starter!

The general guideline for how good, or bad, the scores are, WHEN NORMALIZED TO 250 RPM AT SEA LEVEL!
- 8.5 and up: Congratulations, you have a stellar engine! Compression scores this high are rare. If you think that this may be too high, there may have been excessive oil in the housing.
- 8.0-8.4: This is a very good engine! You should have very good power and as long as you stay on top of the rest of the failure points possible, it should last a long time
- 7.5-7.9: This is an acceptable engine. Most engines from Mazda seem to be in this range after the break-in period. Stay on top of the other failure points possible, and you should get at least 40-60k more out of this engine, if not more.
- 7.0-7.4: The engine has some life left in it, but start looking for replacement options. Compression loss is going to start speeding up from blow-by combustion gasses eating away at the seals.
- 6.5-6.9: Officially failing. The engine doesn't have all that long to 'live'. Compression loss is accelerating due to blow-by.
- 6.0-6.4: Failing significantly. Very prone to flooding even with new starter, battery, and ignition. It will have trouble starting when hot, power loss especially down low, and noticeable difficulty idling.
- 5.5-5.9: Failing badly. Extremely prone to flooding. Will be nearly impossible to keep it idling when hot. Significant power loss.
- 5.0-5.4: This engine is probably only able to start with a pull start, daily use is nearly impossible.
- Under 5.0: How is this engine even running!?!

Caveats:
- If the test was done incorrectly, this can skew the numbers up or down.
- If the engine has excessive oil inside the housings, the compression numbers will be reported as higher than they actually are when the engine is running
- If the test was not done at 250rpm and at sea level (neither of which is likely), the numbers you have will need to be normalized to 250rpm at sea level. Use Mazda's calculator here: Foxed.ca - Rotary Compression Calculator
- This is largely my opinion, based on seeing hundreds of compression scores on the site over the years. I am not using anything scientific to back it up. As always, your mileage may vary.

The black line is the failing line. Any 1 rotor face at a 6.9 or lower is failing.

Chad_I

Alright I found it:
Front Rotor: 7.3, 7.2, 7.3
Rear Rotor: 7.6, 7.3, 7.4
at 250 RPM

I just am not sure how fast an engine with these numbers will lose compression and eventually need a rebuild. I'm sure there are a bunch of variables to consider and this may be an unanswerable question. All I can say is the person who owns the car is a rotary knowledgeable owner and follows all standard operating procedures. If there is a typical rate at which rotary engine compression declines maybe i can get a ballpark figure.
Thanks

Glenn09

Just reading this made me think about when I got a compression test a few years ago, almost 2 exactly and 18000 miles ago...
My numbers were:
Rotor 1: 8.2, 8.3, 7.8
Rotor 2: 7.8, 8.0, 7.8

But the dealer didn't have the rpm number... Is there a standard speed that dealers might use to do compression tests? If not...do the numbers vary that much with rpm speed change? Main question is...is my engine awesome or could it be just alright?
Thanks!

paimon.soror

iTrader: (15)

Depends on RPM and the altitude.

gwilliams6

the rpm speed is the rpm of your starter while it cranks the motor. The optimum crank speed is 250 rpm but your starter's cranking rpm can vary depending on the condition of your starter. So they have to measure the cranking rpm during the test. If your cranking speed is something other than 250rpm you then have to normalize your result numbers (the formula is posted in the stickies). Your compression numbers will definitely vary greatly with cranking rpm. Higher cranking rpm will result in higher compression numbers, the motor makes more compression with higher rpms, whatever its condition.

Also the test results are keyed to sealevel. If your car was tested at any altitude other than sea level, again you would have to normalize the numbers. Altitude affects air density, which affects compression numbers also. Less dense air at higher than sealevel would affect your compression numbers.

So the charts here are keyed to 250 cranking rpm and sealevel. Until you know these two key factors of your test you can't say for sure that your motor is awesome.

Aston177

Wow. rx8club.com looks good on an iPhone 6 Plus! :P

200.mph

iTrader: (9)

so did you bend your new ipotato in half yet?

Aston177

Hahahahaha. Damn I hope I won't!

Chrishoky

iTrader: (9)

Agree, although it is not needed it is a component of your car that the shop was responsible for and lost. I would make them replace it, if even on principal alone.

Rx8 Dave

Originally Posted by Rx8 Dave
Didn't notice the engine cover missing after an oil change until today. Garage lost it.
Anyway, how important / necessary is having the plastic engine cover? Do I need to buy another one?

Chrishoky: You dont need it at all.

Originally Posted by gwilliams6
I would make that garage replace it. why should you be without it if it was their fault. It is a large piece to just "lose". Make them find it or replace it. I have the 40th Anniversary Edition and the engine cover is painted silver. It is part of the car's look. Not critical but the cover does protect some electrical parts and your coils from anything dropping down on them when anyone is in your engine bay, so better to have it.

Thanks for taking the time to respond and for the helpful information Chrishoky and gwilliams. I did review this with the garage and - lo and behold - they have found it. Considering the cover costs $237-$250 on line, glad to have it back and they didn't sell it on eBay! From now on will check after an oil change to make sure the cover is put back on - something others should keep in mind.

badinfluence

That is about E33 at 100 Octane, not E85-E70. E85 need viton seals and extra spacing because of the "black death" or "Clear Death"
Basically 5 gallons of E85 to 8-10 gallons of Gasoline with X octane.
X =87AKI,89AKI,93AKI in my case. With 93 which is what I usually use it is 100 octane or 97AKI.

The confusing part is 91 octane is 87 AKI. AKI is what is written on the pump. 93 AKI is 97 Octane. So Octane boosters that say 5-12 points are really like 1 or 2 AKI.

I would never exceed 50% ethanol in a non-tuned car or even a FFV. It makes sludge inside the fuel pump.

Glenn09

Thanks for the help Williams 👍

Rx8 Dave

Understand badinfluence. Good points.

blckninja

iTrader: (1)

I've searched but can't find the answer.

I know that if your car is using FL22 that you need to keep using it otherwise you may compromise the gaskets. But if you are using standard coolant, would it be a good idea to do a complete flush and start using FL22, or would it not matter since you didnt use FL22 since day one?

badinfluence

You would need to do a flush depending on how long it has been in there. Obviously the more heat it has been exposed to, and the more 50/50 is in there,the more silicon **** has liquified and could be causing issues later. It is never a waste to do a full flush, just use non-boiling distilled water. It is cheap and can be gotten easily in large quantities.

Tap water is sketchy and would matter where your water comes from.

I planned on doing this myself soon. Basically I plan on draining the car cold, flushing with distilled till it dies down to clear in color. Filling with distilled all the way. Doing a hour or so of idle in front of a fan in my garage, then doing the flush over again, this time filling with FL22 instead of distilled water.

Water needs to stay below the boiling point, but does need to be hot to pick up contaminants in the lines or gaskets. Boiling water in your engine is a problem so keep it below 200, 150 if you can help it. I would monitor it with OBD and if you hit 175, I would stop the car and do the flush then.

BigCajun

iTrader: (1)

My local O'Reilly's has Beck-Arnley FL-22 compliant coolant.

Rx8 Dave

I agree. I also put in Red Line Water Wetter to help prevent hot spots in the engine.