is fuel economy really that bad?
An RX-7 Guy
Joined: Feb 2007
Posts: 32
Likes: 0
From: Seattle, WA
carcrazy95: Also don't overlook that the mechanical efficiency of the rotary is good because it doesn't lose energy pushing pistons and valves up and down. This is a big part of why it gets better compared to piston engines at higher speed - the faster piston engines go, the worse their mechanical losses get, but Mazda goes mmmm.
A rotary that could run at its most efficient speed all the time (driving a generator, pump, or something) would potentially have *better* fuel economy than a comparable piston engine delivering the same power.
A rotary that could run at its most efficient speed all the time (driving a generator, pump, or something) would potentially have *better* fuel economy than a comparable piston engine delivering the same power.
Originally Posted by MichaelBrown
Hey guys! I own a 2006 Mazda Miata! (The new body style) and we at the miata forums have noticed alot of similarities between the RX-8 and our MX-5's. For one thing, we can use to same sway bars from the RX-8 (its actually a popular upgrade). Also someone in Germany has successfully pulled off a Renesis Swap into our car.
My question is basically, being that the Mazda Miata's stock weight is somewhere between 2,400 and 2,500, we are so far about 500 pounds lighter than you guys. Would the swap of your engine into our car increase its MPG noticably?
The fact that our cars come with an Inline 4 is another advantage. If we take out our heavier conventional engine and put in the rotary, not only would we make more power than the stock engine, but lighter. so that 500 pound difference could turn into 700! Thus improving acceleration, cornering, and once again, possible MPG.
My question is basically, being that the Mazda Miata's stock weight is somewhere between 2,400 and 2,500, we are so far about 500 pounds lighter than you guys. Would the swap of your engine into our car increase its MPG noticably?
The fact that our cars come with an Inline 4 is another advantage. If we take out our heavier conventional engine and put in the rotary, not only would we make more power than the stock engine, but lighter. so that 500 pound difference could turn into 700! Thus improving acceleration, cornering, and once again, possible MPG.
On the topic...my economy is dismal...15 mpg city/20 highway. By comparison, my 1989 Porsche 944S2 (3 litre 4 cylinder) consistently got 30 mpg highway.
But like others have said it is inherent in the rotary engine. Complaining about rotary mpg is like complaining that chiles are hot.
An RX-7 Guy
Joined: Feb 2007
Posts: 32
Likes: 0
From: Seattle, WA
It's not as easy as you would expect given that they are both Mazdas and so "fit together" relatively well. The eccentric shaft comes out of the middle of the engine on a rotary engine whereas the crankshaft comes out of the bottom on a piston engine. So clearance can be kind of a bummer because the engine sits so much lower and stuff gets in your way. IIRC the steering rack has to be moved.
I know people have put 13Bs in Miatas and while as swaps go it's not astonishingly bad it's not as easy as you might expect.
All this is hearsay, of course.
I know people have put 13Bs in Miatas and while as swaps go it's not astonishingly bad it's not as easy as you might expect.
All this is hearsay, of course.
Registered
Joined: Sep 2005
Posts: 1,364
Likes: 2
From: Chicago
The RX-8 mpg is like playing Russian Roulette. 5 out of 6 times you will get poor mileage 15-16 city but 1 out of 6 gets horrendus mpg 10 to 12 in the City. I am on the horrendous end and the worst thing about it is Mazda will not acknowledge you have a problem. They will blame it on your driving or road conditions and send you on your way.
I was like you and figured I wouldn't get a bad one and if I did Mazda would fix it because it is a new car...WRONG. So be prepared for the worst and hope for the best because you are pretty much on your own, Mazda will not honor their warranty here.
I was like you and figured I wouldn't get a bad one and if I did Mazda would fix it because it is a new car...WRONG. So be prepared for the worst and hope for the best because you are pretty much on your own, Mazda will not honor their warranty here.
Registered
Joined: Sep 2003
Posts: 230
Likes: 0
From: Newport Beach, CA
Olddragger got a higher gear rear end?
Originally Posted by 4 years to Supercharge
Wait Olddragger has gotten 29mpg with his shorter final gear in the rear. 
Anyway, back on topic: Track days < 12mpg. City < 17, Hiway < 20. Btw, I did get a Prius and am living in HOV lane heaven. Just take the '8 out for track/fun days.
Last edited by MPG > HP; Feb 14, 2007 at 05:33 PM.
Originally Posted by encorez
18/24 is a crime, should be listed as 14/20.
Registered
Joined: Oct 2005
Posts: 939
Likes: 28
From: Port Royal, SC
For the amount of power the 8 puts out, yes, it is pretty bad. But it is a totally different engine so what can you expect? What I love about mine is that even though the mileage is bad, it is very consistant regardless of my driving style on that tank
Forbidden Donut
Joined: Jun 2003
Posts: 237
Likes: 0
mpg
For a 232 horsepower car to get 11-15 (or 17 or 20 or even 24, which is not likely) miles per gallon is completely uncalled for.
It is also the nature of the beast.
You make sacrifices to have a rotary engine beneath the bonnet.
Runs like silk, drinks like a fish.
It is also the nature of the beast.
You make sacrifices to have a rotary engine beneath the bonnet.
Runs like silk, drinks like a fish.
⎝⏠⏝⏠⎠
Joined: Apr 2004
Posts: 8,625
Likes: 5
From: USA
Originally Posted by encorez
If 14/20 was pasted on the windshield, how many would buy the car?
Thanks for sharing.
Registered
Joined: Aug 2006
Posts: 5,027
Likes: 5
From: Northern Virginia
Originally Posted by encorez
Stating the truth here, and you want bans. What a joke.
What, exactly, is your point in trolling and picking fights? Trying to get into the Guinness book for getting banned from fora? Seems like a pretty dumb goal. Dumb enough that I'm now convinced that whatever trouble you're having with your 8 must be driver error.
A forum like this is not a complaint department. It's a community with a common interest, out to share and help each other. Most people tend to figure that out.
Ken
2005 Black RX-8 GT 6M
Joined: Jul 2006
Posts: 6,350
Likes: 0
From: San Jose Area
Another MPG thread!
If we all drove 55MPH on a flat straightaway, we'd all get good gas mileage. However, we all drive much differently than that. Ranges vary depend on each car. I've settled at 20.5MPG highway going 75MPH.
If we all drove 55MPH on a flat straightaway, we'd all get good gas mileage. However, we all drive much differently than that. Ranges vary depend on each car. I've settled at 20.5MPG highway going 75MPH.
Registered
Joined: Sep 2005
Posts: 1,364
Likes: 2
From: Chicago
Originally Posted by CTrx8
you have to consider how they drive to get EPA numbers. none of us are going to be crawling up to and then shifting at 2500rpms. any EPA sticker number is deceptive and i don't know anyone that would rely on them.
Registered
Joined: Aug 2004
Posts: 278
Likes: 1
From: Canberra, Australia
Originally Posted by Greyfixer
It gets similar gas mileage to a Mustang GT. If you're looking for economy, a sports car is probably not for you.