Downsizing injectors, S5 TII
#26
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Originally Posted by Spoolerr
Maybe you could give me some guidance then how to get some better mileage then, rather then just posting nonsense?
The Mazda rotary engine is an engineering marvel, *but* fuel economy is not one of it's strong point, period.
Due to the inherent design of the motor, fuel efficiency is not one of it's strong suits.
This is due to mainly...
1) The long, rectangular combustion chamber which cannot burn as completely like a multi-valve piston engine (which is round), and...
2) The aggressive exhaust port timing which ends up shooting a lot of the combustion forces out the exhaust.
If you baby your driving, you might gain 1 - 2mpg.
Running more air in your tires might gain another 1 - 2mpg; the downside is that you might end up prematurely wearing your tires (in the centers).
As Cybaster mentioned, a CDI box might get you another 1 - 2mpg; other will argue the CDI does nothing, and one real downside is that it eats spark plugs faster.
Driving all freeway miles will easily bump up mileage over 20mpg.
But this means you will usually end up filling up gas twice as fast!
So it's end up being a matter of $ / day and not miles / gallon...
If you're stuck doing "city" driving, you'd be hard pressed to get 20mpg on any 13B.
Bottom line, you're not going to significantly raise your mileage.
If you try some of the tricks mentioned above, you risk wearing other parts of the car faster.
I would seriously recommend you get another daily driving and get rid of the FC if mileage is a primary concern.
That's the long version of my answer.
You would've found all of this info posted if you did a proper search.
-Ted
#27
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Originally Posted by Spoolerr
Smaller primary injectors is a dumb idea. What would be a better solution? safc? how can i lean it out during idle and cruise? how can i make 20ish mpg considering that my car has no emmisions devices? it consistantly runs rich and has a very inconsistant idle however i have never been able to find any vaccume leaks even after removing and reinstalling the intake manifolds and removing the rats nest.
Do some research on "closed loop", and you will find why messing with fuel injector sizes does not significantly affect closed-loop driving unless we're talking extreme changes in fuel injector sizing.
S-AFC won't do jack for fuel economy - see above on "closed loop".
How do you know it runs rich?
Do you have a wide-band on the car?
An FC *normally* gets around 15mpg with city type driving.
See other post about trying to attain 20mpg.
-Ted
#28
I think I'm addicted
Originally Posted by RETed
That's the problem...you can't.
As Cybaster mentioned, a CDI box might get you another 1 - 2mpg; other will argue the CDI does nothing, and one real downside is that it eats spark plugs faster.
-Ted
As Cybaster mentioned, a CDI box might get you another 1 - 2mpg; other will argue the CDI does nothing, and one real downside is that it eats spark plugs faster.
-Ted
so doesn't that mean it makes spark plugs last "longer"?
#29
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Originally Posted by Cybaster
i am aware of it eating spark plugs faster while using the CDI, but i thought that the spark is strong enough so that even though the spark plug gap is bigger, it still gives a strong spark so u can keep the plugs in longer =D
so doesn't that mean it makes spark plugs last "longer"?
so doesn't that mean it makes spark plugs last "longer"?
Longer than the spark plug would last without CDI? no.
The problem is that it's goign to reach that criticle wear spot a lot sooner, even though it's allowing more room than without the CDI..
You'll definately change plugs a lot more often with any form of ignition booster.
#30
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Originally Posted by Spoolerr
I ordered an S5 Jspec and cracked an apex seal because i lacked understanding of the operation of fuel injection components and used low impedence resistors with high impedence injectors. She leaned out and caboom, no compression on the rear rotor.
The car is getting 10ish mpg would probably be more accurate...
...i figured that it wasnt neccesary to have 550s as long as i kept it under 3800rpm, in very light throttle and cruise maybe i could get away with 330s since they drop right in, and use some 720s for the secondary injectors too keep a moderate balance.
I just know that my car runs too rich and i cant figure out how to lean it out a bit, maybe a safc is my best bet, i guess with the stock injectors i could trick the ecu to theink they are bigger to run the engine leaner? That would be good i think...
how can i make 20ish mpg...?
I dont mean to disrespect anyone...
I have owned many turbo cars including a 13 sec dodge caravan and an 89 probe GT that went 12.8 on a custom SDS standalone, with custom manifold and .60/63T3 pushing 28 psi on stock internals.
Originally Posted by Karack
a faulty O2 sensor can kill mileage...
Last edited by NZConvertible; 09-16-05 at 01:08 AM.
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