tak tak tak tak.... only 3rd gear....

 

What wideband are you using? When I had an LC1 it would sometimes go out of calibration and read leaner than the mixture really was. It would cause the ecu to dump more fuel in and result in shitty mileage.

 

I use Spartan WB from 14point7.

 

oh wow....I have a theory about your issues now

 

I get 20-22mpg with a 5 speed/4.3 diff and when it gets driven, it gets driven hard.

 

I use 5 speed with NB dif - I think it's 4.1, how can I make sure ?

My speedometer shows around 10kph less the gps speed, with the original dif it was 10kph more then gps speed.

 

I'm trying the best I can to get a better MPG, I don't see much improvement, even with low boost (>10psi) and 16:1 AFR cruise.

17.5MPG would be an achievement.

I noticed that my normal cruise is 60-70kpa that is a bit high, if I under stand correctly.

Anything I can try more or that is it with the current turbo combo ?

My current AFR:

 

That's a very high kpa for cruise. There is something wrong.

 

I know you'd think leaning it out like that would better your fuel consumption, but perhaps you should post your spark/ all of you enrichments. I get 29mpg and no less than 24 when I am mad at life and take it out on my car for a week.

 

Log:
https://www.miataturbo.net/attachmen...4_18.25.32.rar

You can see that my cruise 2700-3200rpm is above 60kpa

 

You can typically run 30 degrees up to 100kpa. Your high boost high rpm cells have too much timing. You don't need more than 14 on the top row.

 

After reading around about Volovs S70 (my turbo donor) mileage I think 18mpg is a normal number...

What is it's what it is...


Bigger turbo ?...

 

That's not really how that all works.

 

Will it not give any idea of mileage ?

 

You're wondering if the gas mileage a Volvo S70 gets has anything to do with your Miata?

 

I use its turbo

 

I use a radiator hose from an Escalade. Does that mean my cooling system could cool a 6.2L?

 

Uh, but you don't use it's manifold, down pipe, engine, injectors, intake, exhaust, engine design, head design, ecu, weight, or ANYTHING else related to the Volvo.

You have a LOT to learn if you think you can compare the car you've taken your turbo from to your Miata for mileage comparisons.

 

Just using the turbo won't give you similar mileage as the Volvo. Your fuel table and spark table need to be tuned properly and you will get decent gas mileage. On my 94 on the interstate I could hit 32mpg if I stayed out of boost.

 

When you go out shopping for a turbo one of the turbo specs are "supported" HP.

If I understand right: HP=air+fuel+spark.

The turbo HP spec is given without any consideration to your car/build.
The turbo HP spec is based upon the turbo capability of moving air, and for any given air volume you must apply a specific amount of fuel.

The air volume and fuel volume will be quite the same for any given HP on any car/build with the same turbo, this is way you can calculate your injector size without any consideration of the car/build.

There for I think it will be safe to say that for a specific HP output you can calculate the fuel amount that will be needed hence mileage.

Of course I'm talking rough numbers and just a rough estimation of mileage with a specific turbo - combined mileage - boost and no boost.


(Don't kill me)