Hi there,

I have been trying to work out how much petrol a generation 1 Rx-7 is going to burn, as I am keen on buying one. I have heard a lot of bad things about petrol consumption...

There doesn't seem to be much information anywhere, and the numbers I have managed to find on the message board so far are extremely varied - from 4 to 28 mpg!!

I would appreciate any input people have - if you could give engine type (12A, 13B, turbo etc), what sort of porting you have, and your mpg petrol consumption that would be greatly appreciated.

Cheers

Jacob

 

13B NA non ported, dellorto Carb, headers= 13mpg

S5 T2 non ported, stock turbo 7 lbs, 680 secondaries, 3" exhaust = 11mpg

Shooting for 20mpg with Microtech ECU

 

The official figures for the first gen1 were 28mpg on the highway and 17mpg in the city. Later models were heavier but the use of lean burn technology decreased consumption to 30 mpg highway 21 city. These were all 12A engined producing about 100hp. In 1985 the method of calculating official fuel consumptio was changed from the ideal to a more practical level, a reduction of 90% in the city formula and 78% in the highway formula. Thus, the official figure for the 13B engined GSL-SE with 135hp was not so different at 16mpg city 23mpg highway. In practice all Gen1s should give about 16mpg/24mpg, with careful driving on the freeway you can achieve 28-30 mpg.

The later gen 2 and gen 3 in both na and turbo form gave about 17mpg city-23 mpg highway.They were more powerful but more fuel efficient.

Once you modify any rotary to give more power then the fuel consumption goes way down to around 12mpg for a streetable ported and larger turboed engine. Race engines just gobble up fuel and money.

If you have a very heavy foot or a badly tuned engine then obviously consumption drops to what you deserve.

For any gen1 the secret is to keep them tuned by regular service. Any problems with spark plug, ignition or timing will show up quicker on fuel consumption on a rotary as against a piston engine. Fortunately the 12A carb equipped engine is reliable and easy to keep in good order


To sum up, any gen 1 with either a stock 12A or 13B should give you around the 16/24 mpg level. Adding a stock 13B turbo engine should not change the consumption, these engines were more powerful but this was balanced by being more efficient and with the lighter weight of the gen1 can be fuel misers. Transplanting in a modified 13BT is a different story and bigger ports means far bigger fuel consumption.


I have a 1985 12A with some bolt-on modifications giving about 150hp, and get 28mpg on long trips. The rotary does not deserve the gasguzler reputation it was given in the 1980s fuel shortage scare.

Thus, go ahead and buy a gen1 as fuel consumption is good. Don't be put off by stories from these people with highly modified cars with Ferrari tasts in fuel!

 

City= 10 mpg
Highway= 13mpg

Wallet= Empty

 

What fitzwarryne said was all good information, but it assumes a car that is properly (read: almost perfectly) in tune and a strong motor with good compression etc...

The real numbers you're probably going to get are closer to the 16-18 range from what I've seen here, but I think this should be made into a poll so that we can figure out where things lay.

Jon

 

Your overall consumption will depend on where you drive. If its primarily city, then 16-18mpg is what you would expect in heavy traffic. Continual stop-start is heavy on gas and really wears the motor.

If like me you drive mainly in rural areas at 60-70mph the engine is just ticking over at 3000rpm so I can get 400-450 miles on the 16gal tank. Its still the original engine with no rebuilds.

On reflection, I think good consumption in the long term is influenced by frequent oil and filter change, and warming it up before driving makes certain the seals do not wear and give bad compression.

 

I have just spent three days in a major city and fuel consumption fell to 20.5mpg over 160 miles, really shows how where you drive is a real major factor in fuel consumption. Fortunately fuel prices were so much lower in the city {12%}, the cost per mile was nearly the same.