RX7 Fuel Question (Gas/Ethanol mix)

[waynehussey]

Has anyone used a Gasoline/Ethanol mix (90% gas 10% ethanol) in their RX7s. The gas station next to my house recently changed to a 90% gas and 10% ethanol mix. Are there any side effects to using this type of gas in a 2nd gen ITS RX7?

Thanks

[mbuskuhl]

Hope it's not an issue, that's the pump gas here in TX I use for my 2nd Gen. I do opt for the 93 octane, haven't had any issues come up yet.

[ddewhurst]

***Gasoline/Ethanol mix (90% gas 10% ethanol)***

Don't know about the above ^ potential issue. A rotor mortor don't care about octane...........The erratic flame burn/travel of a rotor motor likes lower octane. < Per Paul Yaw.

[Andy Bettencourt]

We run the 90-10 stuff. 87 octane is all you need in these.

[lateapex911]

I've done dyno testing comparing octane, and my findings support the octane needs of a rotary at 87. I have not, however tried any ethanol but, rotaries are known to run on kerosene, so.....

[tom_sprecher]

I thought I saw somewhere that 85 is even better. The last time I rode out to Sturgis many of the "regular unleaded" pumps dispensed 85 octane.

Not good when your overbuilt Harley drinks 93+

There was one brand of gas station that had 95.

The engine ran so well I was sad when that tank ran out.

[tdw6974]

Has anyone used a Gasoline/Ethanol mix (90% gas 10% ethanol) in their RX7s. The gas station next to my house recently changed to a 90% gas and 10% ethanol mix. Are there any side effects to using this type of gas in a 2nd gen ITS RX7?

Thanks

Maybe its time to update this discussion besides its almost end of season here in frozen north. Had a rental 2013 Silverado while having cars repaired from hail damage. Looking at the estimated "Full Tank Range" Using Gasoline 465 miles on 85% ethanol 325 miles ??? Now 4 years later we are finding out many of ill effects of the mix. Contamination, rust and water accumulation especially if left in tanks. ALso the regular of today is not the regular of yesteryear. Old regular when splined on asphalt would eat holes in the pavement. I did locate a station in Montour Falls (down the hill from Watkins Glen) that sells non ethanol it is 87 and $4.57 per gallon vrs 4.10 for the "blend" also had Sunoco race fuel at $9.25 for 110 or 112. Anyhow We bought 10 Gals. to use in car. I'm not sure how much good it will be, but sure hope its better.Hmmm wonder if it would pass "Fuel Sample" test. In view the milage difference I wouls think it has to effect output.

[C. Ludwig]

Mileage observations do not equate to power potential. There is more power potential in the ethanol blends than there are in 100% gasoline. E85 is widely considered cheap, high octane race fuel. In simple terms, gasoline has more BTU per pound, but you need to burn about 1/3 more E85 to maintain a common Lambda ratio. In the end, the mass of E85 you burn for a given Lambda ratio, will have more BTU content than the mass of gasoline. There are also charge cooling and octane considerations that make E85 appealing. The one big downside is the potential for widely varying ethanol content from pump to pump. Because of this, many serious racers are sourcing E98, which, for the most part, seems to be blended to higher standard of consistency.

All of that said, don't expect to pump the cell full of E85 and set the world on fire. As stated above, you'll need roughly 1/3 more fuel by mass in the chamber than with gasoline. E85 will also want more spark advance. Get the calibration right and you can enjoy the benfits.

That said, will E85 pass SCCA fuel regs?

Also, for those wanting to experiment with high octane gasoline race fuel, the same applies. Don't expect to drop it in the tank and make more power. Octane rating has nothing to do with the fuel's energy potential. Some race fuels are heavily oxygenated and will make more power if the ECU calibration is setup for the fuel. However, these fuels will not pass fuel tech.

[Dave Gomberg]

...
That said, will E85 pass SCCA fuel regs? ...

Simple answer: No. Maximum ethanol content permitted is 10%. (See GCR 9.3.26)

Dave