My FB is now on E85!

P71 · 05-26-2008, 08:14 PM

I ran the first 3 gallons of E85 through the FB. It's 85% ethanol (corn around here) and 15% gas for "104" Octane (the RON is 114 though). After tons of reading about E85 and it's effects (alcohol eats rubber, need 20% more E85 for the same amount of gas, etc) I decided to run a few gallons through to "see what happened".

Observations:

* Cold start up was easier. It is a 230K mile 12A but it "caught" quicker and generally seemed happier. Hot start up was much improved.
* Performance (by the seat-of-my-pants) seemed better. Not loads better, but there was definite improvement. Maybe even just smoother?
* Mileage does drop. Granted 3 gallons around town wailing on it is pretty lousy anyways, but expect to see a 15-20% drop in mileage.
* Tip-in was worse. (The reaction of the engine/carb as you first touch the throttle). It's always had a "slight" hesitation from idle, the E85 made it more pronounced. Re-jetting of the carb all the way around (and honestly probably a rebuild too) needs to happen.
* Cooling was improved. My RX-7 has never run "hot" anyways, but there was a marked improvement in keeping the temp down cruising around. Cooler fuel = cooler engine.

So is it worth it? I don't know yet. With the decreased fuel mileage the cost savings isn't there. The hot-start and cooling benefits are worth it if I can cure the tip-in, I will admit. E85 is well proven on boosted applications, but the N/A 12A doesn't "need" the 104 Octane (though carbon buildup, etc might play into mine). For now I'm going back to regular 87, but if I ever rebuild the carb or swap another one (or go boosted) I think I'll be back.

Kentetsu · 05-27-2008, 12:26 PM

Interesting. How did you address the possibility of the alcohol eating the rubber gas lines?

Jeff20B · 05-27-2008, 11:27 PM

Do Sterling's accel pump mod and swap in larger primary fuel jets (stock are 92) so count on 95, 100 or 105 since those sizes are easily purchased. I have those sizes and can do the AP mod... should I try E85 on my next 12A?

P71 · 05-28-2008, 12:02 AM

Go with the 105's and yes, try it.

I used additives for the rubber as I wasn't planning on "long term exposure". New alcohol-resistant rubber/silicone fuel hose is required for permanent usage.

PercentSevenC · 05-28-2008, 06:06 PM

I'm more concerned about the effects on the carb body and intake manifold, etc.

E85 would be fun to play with on my blow-through setup once I finish it. If we ever get a station around here, that is.

05-26-2008, 08:14 PM	#1
P71 RCC Contributor Join Date: Feb 2008 Location: WA State iTrader: (1) Posts: 651 Rep Power: 17	My FB is now on E85! I ran the first 3 gallons of E85 through the FB. It's 85% ethanol (corn around here) and 15% gas for "104" Octane (the RON is 114 though). After tons of reading about E85 and it's effects (alcohol eats rubber, need 20% more E85 for the same amount of gas, etc) I decided to run a few gallons through to "see what happened". Observations: * Cold start up was easier. It is a 230K mile 12A but it "caught" quicker and generally seemed happier. Hot start up was much improved. * Performance (by the seat-of-my-pants) seemed better. Not loads better, but there was definite improvement. Maybe even just smoother? * Mileage does drop. Granted 3 gallons around town wailing on it is pretty lousy anyways, but expect to see a 15-20% drop in mileage. * Tip-in was worse. (The reaction of the engine/carb as you first touch the throttle). It's always had a "slight" hesitation from idle, the E85 made it more pronounced. Re-jetting of the carb all the way around (and honestly probably a rebuild too) needs to happen. * Cooling was improved. My RX-7 has never run "hot" anyways, but there was a marked improvement in keeping the temp down cruising around. Cooler fuel = cooler engine. So is it worth it? I don't know yet. With the decreased fuel mileage the cost savings isn't there. The hot-start and cooling benefits are worth it if I can cure the tip-in, I will admit. E85 is well proven on boosted applications, but the N/A 12A doesn't "need" the 104 Octane (though carbon buildup, etc might play into mine). For now I'm going back to regular 87, but if I ever rebuild the carb or swap another one (or go boosted) I think I'll be back. __________________ Michael Pinto 2008 PDXCGP Drag Racing Season Champion 83 RX-7 GSL; 12A/5-Speed, Red/Red; 100% Stock - 16.072@83.39 01 CV Police Interceptor; 4.6 SOHC V8/4R70W, Dk Blue/Grey; K&N FIPK/RP Oil/Optima/Superchips/Flowmaster 40's/2.5" cat-back - 14.854@92.37 Read my Rx-7 Build Thread! http://rotarycarclub.com/rotary_foru...ed=1#post70955 Get on the new RCC 1/4 Mile ET List! http://www.rotarycarclub.com/rotary_...read.php?t=368 Vote for the ROTM! http://rotarycarclub.com/rotary_foru...play.php?f=125

05-28-2008, 12:02 AM	#4
P71 RCC Contributor Join Date: Feb 2008 Location: WA State iTrader: (1) Posts: 651 Rep Power: 17	Go with the 105's and yes, try it. I used additives for the rubber as I wasn't planning on "long term exposure". New alcohol-resistant rubber/silicone fuel hose is required for permanent usage. __________________ Michael Pinto 2008 PDXCGP Drag Racing Season Champion 83 RX-7 GSL; 12A/5-Speed, Red/Red; 100% Stock - 16.072@83.39 01 CV Police Interceptor; 4.6 SOHC V8/4R70W, Dk Blue/Grey; K&N FIPK/RP Oil/Optima/Superchips/Flowmaster 40's/2.5" cat-back - 14.854@92.37 Read my Rx-7 Build Thread! http://rotarycarclub.com/rotary_foru...ed=1#post70955 Get on the new RCC 1/4 Mile ET List! http://www.rotarycarclub.com/rotary_...read.php?t=368 Vote for the ROTM! http://rotarycarclub.com/rotary_foru...play.php?f=125

05-27-2008, 12:26 PM	#2
Kentetsu RCC Contributor Join Date: Feb 2008 Location: Grand Rapids, Michigan iTrader: (1) Posts: 530 Rep Power: 17	Interesting. How did you address the possibility of the alcohol eating the rubber gas lines?

05-27-2008, 11:27 PM	#3
Jeff20B Rotary Fanatic Join Date: Mar 2008 iTrader: (1) Posts: 215 Rep Power: 17	Do Sterling's accel pump mod and swap in larger primary fuel jets (stock are 92) so count on 95, 100 or 105 since those sizes are easily purchased. I have those sizes and can do the AP mod... should I try E85 on my next 12A?