This was my 3rd tank of 87 octane and up to now I had not seen a difference except for the price, but today I was in Palm Springs California and the temperature was 107, and the car was pinging really badly at over 6K when I got on the freeway to go home, closer to home the temperature was 91 and the pinging was gone.

I presume that regular gas is more likely to pre-ignite because it burns better and with high ambiant temprearture this is more likely to occur.

Anyone experience the same.

 

I don't understand. I have always been under the impression if you knock a rotary your apex seals would crack and your engine is SOL. On this form, I have read where people have heard knock and there is no engine failure. Is this new rotary design less prone to apex failure? Someone please reeducate me.

 

While it is bad for any engine, the turbocharged 13Bs were more sensitive to it.

 

hmm. I have been listening for sounds running 87 and have been hearing nothing different from running 91 BUT our temperature has not changed much yet either. The car is rated to use 87-91 and we may find that geographic area has an impact. It has been so hot and humid this summer here. CANT wait for it to get down to the 70-even 80 degree point. That usually happens in mid to end of Oct here.

 

i tried 87 for one tank,no pinging but power was down.never again,92 or nothing.

 

amen to that

 

Therein lies your answer gentlemen. Ron is running in South Florida where the temps are in the upper 90s, but humiditiy is also always above 60 percent.

alarabie is running in Palm Springs, which has elevation, 107F, and humidity that is probably in the 10-20 percent range.

Humidity definitely aids Ron in South Florida and helps keep his engine from detonating. Alarabie should only run lower octane in Palm Springs during the winter months when the temps (along with the humidity) are lower. If I owned an RX-8 in Palm Springs I'd ONLY run 91, but hey, that's just me.

I know that Ron has been trying to save everyone a few bucks with his suggestion to run 87 octane, but you need to take your geographic location and ambient running conditions into consideration. Above 100F with low humidity is asking for trouble.

 

If you want to compare the levels of humidity, you cannot just compare the percentages. Those percentages state the relative humidity, not the water content of the air. 20% Rh at 107ºF has the exact same amount of water as 35% Rh at 90ºF.


It's just easier to compare apples to apples........

 

Here in Spain we only have 95 and 98 octane and if the car is rated in this range, what I'm suposed to use? I think that would be a problem if the Renesis needs low octane gas, is this true?

 

Yaksplat... you are correct and I apologize for my fairly simplistic example. My point was simply that higher temps (100F+) with lower humidity like settings in the Desert Southwest greatly increase intake charge temperatures. Lower octane gas in a high performance vehicle should be avoided, especially during the most extreme time of the year (temperaturewise) in these areas.

 

Where do you actually find 91 octane? The gas stations I use have 87, 89, and 92. Obviously I'm using 92. All my cars need it (even the Miata...pings unmercifully unless I feed it the good stuff). The diff in price is minimal compared to the cost of replacing an engine!

 

Your 95 octane is pretty much equivalent to the US 91 octane fuel (different standards). So using your 95 you're in spec. Of course if you want to use lower octane, then you are out of luck.
Back home in my country (Hungary) we do have 91 octane which is close to what is an 87 octane in the US. Is 91 octane really not available in Spain?

 

Yeah, I wonder about the same thing. Here in O-town, I don't see any 91 octane at all. It's 87, 89, and 93.

 

91 is California's highest octane you can get, 87, 89 and 91.

 

Hello Tamas,

it's not available 91 octane in Spain, we only have 95 and 98 octane gas, but I don't know the equivalences for US octane. If spanish 95 octane is the same as 91 US octane that will be good, if not we have a problem because I think (readed in other threads) renesis needs low octane... and we only have high octane...

 

Zaskar,

95 and 98 are the RON ratings for the gas. Mazda recommends 95 or higher RON for the RX-8.

-Mr. Wigggles

 

The recommended octane for the Renesis is 91 R+M which is very close to your 95 RON, so you're fine.
As far as the Renesis needing lower octane, yes, I did read those other threads, but there still isn't any comprehensive proof whether using lower octane is the way to go or there might be any harm done long term by using it.
Let me just say that once I'll get my RX-8, I'll try both and see which one works out better. Of course I'll continue watching the forum and other sources of info too. I'd love to use lower octane than the US 91 due to the lower cost and the fact that the RX-8 is a real gas guzzler

 

High octane IS recommended in the RX-8. Add a turbo to your 8 and you will be glad you have 95 octane. Some people are saying there 8 run smother w/low octane .Other people say they are experiencing Knock and poor performance w/low octane. Untill I hear from an experienced tuner that it is Ok, I will not race my 8 down the 1/4 on low octane.

 

Actually you can get 103 and 105 octane, it's just not available as easily. There are a few stations around San Diego that carry the high octane gas.

*edit* I haven't tried the high octane in my RX-8 yet and doubt that I will any time soon, but I also have no desire to use less than 91.... If nothing else, I don't understand why you would want to suffer the power losses...