Notices
RX-8 Discussion General discussion about the RX-8 that doesn't fit in one of the specialty forums.

Fuel Mileage

Thread Tools
 
Search this Thread
 
Rate Thread
 
Old 04-04-2011, 08:49 AM
  #101  
Registered
 
BigMikeATL's Avatar
 
Join Date: May 2009
Location: USA
Posts: 477
Likes: 0
Received 0 Likes on 0 Posts
I watch my mileage like a hawk and get 17mpg. That's probably 70-80% city driving and I am a little aggressive.

On a couple trips to Florida, I was getting 21-22mpg.

All fill ups are with 93 octane from Chevron or QT. I always premix 6oz of Idemitsu and 1-2oz of FP Plus.
Old 04-04-2011, 08:55 AM
  #102  
Registered
 
BigMikeATL's Avatar
 
Join Date: May 2009
Location: USA
Posts: 477
Likes: 0
Received 0 Likes on 0 Posts
Originally Posted by DocBeech
I have been doing research on the effect of ethanol for years now. Mostly to the disbelief of the majority. I believe it causes poor fuel mileage, and I started looking into it on my drives to and from the ranch in Llano Texas. We have a 2500HD farm truck that we drive back and forth. On the trip down to Llano its filled with Dallas fuel. On the trip back its filled with ethanol free 89octane fuel from the ranch. Now the trip from Llano to Dallas is down hill. The airport there is 1040 ft and Dallas is about 440ft. I only know this because sometimes we choose to fly the Cessna. So its a down hill trip back of only 700 feet. But my fuel mileage increases by 3.5 mpg. This has been tested over the course of 250,000 miles put on the truck. 700 feet over the course of 220 miles.

220 miles is 1,161,600 in terms of feet. So that means I am traveling 1 foot down for every 1700 feet forward. Or about 3 feet a mile. Thats not enough to make a significant difference.

Secondly I think its the cause of the poor performance of our water pumps.

Ethanol is a well known and common cause of airplane engine failure. We had to learn all about it when I was getting my pilots license. Its extremely harmful to engines despite what the EPA says it destroys engines.
It is a proven fact that you get fewer MPG from ethanol. Ethanol is especially bad for rotaries since it strips lubrication provided by the oil that's metered into the engine. That's why premixing is so crucial.

Ethanol only destroys engines that weren't designed for it. Older cars and lots of yard equipment (mowers, string trimmers, chainsaws, etc) have been damaged by ethanol.

Newer engines can handle ethanol just fine.
Old 04-04-2011, 09:05 AM
  #103  
The RX-8 is missed
iTrader: (3)
 
2tone's Avatar
 
Join Date: Aug 2005
Location: Houston, TX
Posts: 2,084
Likes: 0
Received 0 Likes on 0 Posts
I drove using the vacuum gauge as my only guide. Ethanol Free Fuel. No traffic 96% highway. The rough estimate but I only drove about 24 miles city (highway to my home is 3 miles). Using only the vacuum gauge I ignore my speed. 70mph was my zero. When I went up hill I completely ignored the speed decline and when I went down hill (limiting to 10mph) I let the car do its thing. Two of the keys to note, Ethanol Free Fuel/Vacuum Gauge Driving. Redlined only once per 1/4 tank. Now I never made it below the last 1/4 was just about right at. My fuel light comes on at a little over 13 gallons even though we have a 16 gallon tank. So Gauge wise I drove three full redlines (Redline through 3 gears) 3 times. Redlined only at safe temps. All other shifting was done between 2-3K. No launches, no hard acceleration. All acceleration was limited as much as possible to slightly over cruise vacuum levels.
that's awesome. where did you find ethanol free gas though?!


edit: i average about 19-20 if i drive 80-0-% highway with occasional red line. that's w/ ethanol. i can get low 20's if i'm really careful (ie cruise control 55-65mph and no higher!)

Last edited by 2tone; 04-04-2011 at 09:09 AM.
Old 04-04-2011, 09:10 AM
  #104  
Flame On!
iTrader: (4)
 
1.3_LittersOfFurry's Avatar
 
Join Date: Jan 2011
Location: New Orleans, La
Posts: 1,897
Likes: 0
Received 4 Likes on 4 Posts
I average in the upper 14's, but I drive 90% stop and go city traffic. Once I got 17mpg and got worried something was wrong haha. It takes me anywhere from 20-50mins to get to work (12miles) so most of the time I'm just idling in traffic. Coming back home it's the same..... God I HATE traffic....
I use nothing but chevron +93 at the same pump, every once in awhile I'll get Shell V-Power. I would love to find some ethanol free fuel...

Question for you guys with low mpg, ever considered changing out the front O2 sensor? Did wonders for my last car, but the price for the Rx-8's is kinda steep.

-Shawn
Old 04-04-2011, 10:16 AM
  #105  
Registered
iTrader: (1)
 
longpath's Avatar
 
Join Date: Apr 2005
Location: Stamford, CT
Posts: 629
Received 0 Likes on 0 Posts
I have over half a box left of 1,1,1 trichloroethane (very volatile solvent and cleaner) that I am thinking of using to clean my MAF sensor. I've used this to degrease and clean firearms and brake rotors (when I got some grease from the caliper on the rotor by mistake) and it doesn't leave any residue.

Would 1,1,1 trichloroethane be Ok to clean the MAF sensor, or is there something better for this? As far as I know, my MAF sensor has never been cleaned and my 2004 has over 53K miles on it.
Old 04-05-2011, 04:04 AM
  #106  
I drive at Red Line.
Thread Starter
iTrader: (1)
 
DocBeech's Avatar
 
Join Date: Jul 2010
Location: Dallas, TX
Posts: 2,137
Likes: 0
Received 5 Likes on 5 Posts
Cruise control is horrible for fuel mileage. Drive with a vacuum gauge instead.

FYI cruise control the best I ever did was 20.5 and 21.5 ethanol free fuel. I get it in Anna. I have to drive there fill up plus a gas can, then drive back and when I park at home top it off. Whatever i have left goes in the 1958.
Old 06-09-2011, 04:26 PM
  #107  
Needs Boost!
iTrader: (5)
 
dmedz8's Avatar
 
Join Date: Jul 2010
Location: Lincoln, CA
Posts: 828
Likes: 0
Received 0 Likes on 0 Posts
Originally Posted by DocBeech
Reviving an old thread here after a successful experiment. I broke my own habits of redline driving to do this so I sacrificed for you:P I was able to get 25.9mpg. No thats not a mistake (I record MPG by odometer). I drove 271 Miles this last fill up and filled up on 10.4970 gallons of fuel. It really comes out to 25.88 but fuelly rounded up. How I did it.

I drove using the vacuum gauge as my only guide. Ethanol Free Fuel. No traffic 96% highway. The rough estimate but I only drove about 24 miles city (highway to my home is 3 miles). Using only the vacuum gauge I ignore my speed. 70mph was my zero. When I went up hill I completely ignored the speed decline and when I went down hill (limiting to 10mph) I let the car do its thing. Two of the keys to note, Ethanol Free Fuel/Vacuum Gauge Driving. Redlined only once per 1/4 tank. Now I never made it below the last 1/4 was just about right at. My fuel light comes on at a little over 13 gallons even though we have a 16 gallon tank. So Gauge wise I drove three full redlines (Redline through 3 gears) 3 times. Redlined only at safe temps. All other shifting was done between 2-3K. No launches, no hard acceleration. All acceleration was limited as much as possible to slightly over cruise vacuum levels.

I will do this experiment again with city blend (E10) fuel in the future. But I think the fuel had a ton to do with it. I was expecting to hit 22 or so, and was just shocked when it read almost 26.

could you explain how/where you connected this gauge to?
Old 06-09-2011, 08:23 PM
  #108  
I drive at Red Line.
Thread Starter
iTrader: (1)
 
DocBeech's Avatar
 
Join Date: Jul 2010
Location: Dallas, TX
Posts: 2,137
Likes: 0
Received 5 Likes on 5 Posts
Use the port on the throttle body.
Old 06-10-2011, 07:20 AM
  #109  
Registered
 
Surtur's Avatar
 
Join Date: Aug 2003
Location: Maryland
Posts: 43
Likes: 0
Received 0 Likes on 0 Posts
DocBeech, can you tell us how you have your vacuum gauge hooked up?

Specifically, which hose did you tap to get vacuum, which hole in the firewall did you use to route to the gauge and how do you have the gauge mounted?

Edited to add more specific questions.

Last edited by Surtur; 06-10-2011 at 08:10 AM.
Old 06-10-2011, 10:55 AM
  #110  
Needs Boost!
iTrader: (5)
 
dmedz8's Avatar
 
Join Date: Jul 2010
Location: Lincoln, CA
Posts: 828
Likes: 0
Received 0 Likes on 0 Posts
I can't comment on how DOC did it but I am going to hook one up soon. I'm still a little unsure as to what hose to spice into but I will run the wiring through the grommet near the clustch and mount the gauge on the steering column next to my A/F guage
Old 06-10-2011, 06:55 PM
  #111  
I drive at Red Line.
Thread Starter
iTrader: (1)
 
DocBeech's Avatar
 
Join Date: Jul 2010
Location: Dallas, TX
Posts: 2,137
Likes: 0
Received 5 Likes on 5 Posts
Let me start off by saying you have to be really careful when tampering with the firewall. Some associations wont let you run events if they know you have altered the firewall.

When I get back to my car I will snap a couple of photos for you. Right now they are talking about totalling it, so I am in a bit of a battle over wanting to keep my car.
Old 06-10-2011, 09:59 PM
  #112  
Needs Boost!
iTrader: (5)
 
dmedz8's Avatar
 
Join Date: Jul 2010
Location: Lincoln, CA
Posts: 828
Likes: 0
Received 0 Likes on 0 Posts
Originally Posted by DocBeech
Let me start off by saying you have to be really careful when tampering with the firewall. Some associations wont let you run events if they know you have altered the firewall.

When I get back to my car I will snap a couple of photos for you. Right now they are talking about totalling it, so I am in a bit of a battle over wanting to keep my car.
damn dude that sucks... uninsured drivers are the enemy

If you can salvage that sexy hood and don't want it anymore......
Old 06-11-2011, 12:08 AM
  #113  
I drive at Red Line.
Thread Starter
iTrader: (1)
 
DocBeech's Avatar
 
Join Date: Jul 2010
Location: Dallas, TX
Posts: 2,137
Likes: 0
Received 5 Likes on 5 Posts
The hood needs a new clear coat.
Old 06-11-2011, 12:16 AM
  #114  
Needs Boost!
iTrader: (5)
 
dmedz8's Avatar
 
Join Date: Jul 2010
Location: Lincoln, CA
Posts: 828
Likes: 0
Received 0 Likes on 0 Posts
Originally Posted by DocBeech
The hood needs a new clear coat.
I will trade you my very nice, ultra cool, super JDM WB hood
Old 06-12-2011, 08:32 AM
  #115  
Veho Ergo Sum
 
RX-ed's Avatar
 
Join Date: Jan 2011
Location: Ontario
Posts: 76
Likes: 0
Received 0 Likes on 0 Posts
ON

I bought my 8 in mid-January this year and have been averaging about 15-16mpg on my daily commute, which is basically 20k of bumper-to-bumper stop and go plus some downtown driving. Pure highway average is 21-22mpg, with an all-time best of 23.1mpg using cruise control at 70mph.

In the past couple of months I have cleaned the MAF, replaced coils/plugs/wires, changed tranny + differential fluids, done a seafoam treatment. Oil was changed 2,500km ago and I premix (4oz Lucas). I always fill-up with 91 octane.

I have noticed I am getting slightly better mileage in the last 2 months, but I can't tell how much of it is due to the warmer weather / summer gas.
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
Hunterkelley24
Series I Engine Tuning Forum
14
06-14-2022 08:32 AM
fourwhls
RX-8's For Sale/Wanted
7
02-20-2019 05:16 PM
urbanvoodoo
RX-8 Discussion
2
09-30-2015 12:41 AM
RotaryMachineRx
RX-8 Parts For Sale/Wanted
1
09-29-2015 10:26 PM
DeltaJ802
RX-8 Discussion
3
09-29-2015 01:20 PM



You have already rated this thread Rating: Thread Rating: 0 votes,  average.

Quick Reply: Fuel Mileage



All times are GMT -5. The time now is 12:48 AM.