fuel consumption

[RobDickinson]

Originally posted by re10
Can someone find a motorway, fill up with gas... turn off the traction control COMPLETLY and don\'t exceed 3000rpm as you drive down-wind.  You will meet the factory spec\'s easy

On the return trip (after filling up and recording miles / gas consumption) drive it like a mad thing...

Then decide if you want factory figures or fun.

The figures are NOT factory figures but goverment test figures, following a standard test procedure.

This involves starting the car from COLD driving a simulated urban cycle with speeds between 0 and 30 , averaging 12-15 I think, then continues (on same run) to do extra urban etc, this is done on a rolling road. Then they modify the numbers down to compensate for air resistance etc.

I used to think it was done under best possible conditions - which it isnt, and all the info is available on the web if you look for it. Of course they dont drive the car hard but those figures should be attainable, or almost anyhow.

I do get above the minimum of 18mpg, but cant see how i could get 32mpg.

http://www.vca.gov.uk/faq/fuel.shtm#faq4

[Yvonne]

I think somewhere an important point sometimes gets missed in this discussion.

We are all getting between 18 and 23mpg depending on driving style etc.  Apart from the guy who claims his car was altered and he is getting 27 mpg.

The sense of complaint does not come from the actual mpg as most of us appreciate that a fast, fun car will use up the gas.  The issue is that the official test figures are so different from the ones we are getting in practise.  This descrepancy is too much to be explained by driving style alone.

My last car was an Astra Coupe Turbo 2L with 187 bhp and 0-60 in 7 secs the official fuel figures were 32mpg on combined cycle.  I used to thrash that car and I was getting 23urban - 28 motorway.

Of course the RX8 is a much better car in everyway I am not argueing that for a moment.  But the fuel consumption should bear more resemblance to the official figures than it does and there seems no explanation for this.

all the best
Yvonne

[pnb]

I agree with  Rob - ths minimum 18mpg
seems very hard to improve upon.

F.Y.I -

[CaptainRX8]

......i love putting loads of petrol in my RX8....its directly proportional to the amount of fun you have.....but how much oil are you guys putting in and how often....
...incidentally the super unleaded is more fun to put in as it is more expensive and might make my Rocket Car go faster...

Captain RX8

[Yvonne]

Yeah - I love those Petrol bills too :confused:

anyway as for oil. half a litre at 800 miles and then another half litre at 1800 miles.
that\'s it so far.

still wish the dip stick was longer or more easily accessable in some way.

all the best
Yvonne

[RobDickinson]

1litre of oil every 2k ish miles or so.

[J4P RX]

How often are you guys changing the oil (or rather, what is the Mazda service interval).  I have only ever topped the FD up once, normally I do an oil change before it has used a significant amount.

PS - 25MPG on Saturday in the FD.  It was a long motorway trip at about 3000 rpm the whole way.  

Lee

[johnf]

"PS - 25MPG on Saturday in the FD. It was a long motorway trip at about 3000 rpm the whole way."


Was it worth it, how much did you save?

Boredom can kill - hope you took enough breaks on the journey:D

[Yvonne]

I just used the whole tank on motorway driving and was hopeful that it was better mpg but when I worked it out, it was only 21mpg which is the same as I had before on motorway and the best I seem to be able to achieve.

Yvonne

[J4P RX]

Was it worth it, how much did you save?

Well no not really, but I was going with a friend to collect a car and it was still being run in hence the 3000rpm (or just over).

Compared to my normal MPG I saved over £50 on the whole trip, but then as it was all motorway for 500 miles I expected it would be better than my normal 15mpg so its not a real saving.  Probably saved abotu 10-15 in reality.

Lee

[Norton]

Originally posted by J4P RX
How often are you guys changing the oil, normally I do an oil change before it has used a significant amount.

Oil changes? What lube\' system does the Mazda use? The Norton uses an enviromentally unfriendly total loss oil system like a 2 stroke engine, i.e. the oil is stored in a tank and fed into the engine at a rate of about 1 litre per 1000 miles. Having lubed the bearings and eccentric shaft etc the oil is then routed through the carbs mixing with the petrol/air mix and is then (mostly) burnt off in the combustion process. The number of times ive heard.."your engines a bit smokey mate, is it knackered?\'
So, as a matter of interest, how does the Mazda system work?

[Carl]

Hi Norton,
All bearings are pressure fed through the eccentric shaft which runs on plain bearings.Unlike the Nortons roller bearings.
Oil is taken from the sump to an oil metering pump which varies it\'s rate proportionaly as to how much accelerator is being used.This oil is fed through to the inlet side of the rotor housing.
Oil usage is less than the Norton engine,but it runs at a maximum of 150 to one in proportion with the fuel.
Usage varies with driving habits,with 1 liter per 1000 miles indicating that the engine is tired and the oil contol rings on the side of the rotors are getting worn whch is letting oil into the combustion chamber.
On new engines more oil may be used at first until the engine is run in.
Kind regards
Carl

[Norton]

Thanks Carl, sounds quite similar to Nortons system, variable rate metering pump included. I take it that the \'sump\' is really in effect just an oil tank?, is any oil re-circulated back into it? (it isnt on the Norton).

[Carl]

Hi Norton,
yes the oil also is sprayed into the rotors for cooling and then drains back to the sump from the rotors and bearings too.From there its pumped through an oil cooler and back into the engine.
Kind regards
Carl