i have greddy t78 turbo set up. and pri550 and sec850 injector. i bought this from new york. should i get bigger injectors? or keep them and re-tune my car.
car runs slightly rich. personal reasons i wanna have good mpg on my ride.
i can give up little bit of power. i wanna get good gas mileage.
i have fd 93 please let me know guys. thank you

 

I did a quick search on FDs running T78s, and every one of them is running at least 1600cc secondaries. Unless you're running relatively low boost (10 psi or less), it's more likely that you're running lean, not rich.

1) Do you have a wideband air/fuel gauge in the car? If yes, what AFR under full boost? 10s-11s are ideal.

2) You're not going to get good gas mileage period. Half-decent, maybe, but you'll have to baby the gas pedal and avoid boost.

 

That injector combination is standard for a FD. It should be good for low to mid 300rwhp at least(depending on fuel delivery setup and pressure).

This means that you can tune for economy, but your tuner will limit your boost based on injector capacity.
If you have a Power FC, you can stick stupidly large injectors in it and with a good tune your economy will still be excellent.(not sure if you have a Power FC or not, just letting you know that its entirely possible to have both big injectors AND good fuel economy)

 

i use 660/1680cc on my t78 setup. When you dont boost its quite economic.. (as economic an fd can be)

 

thanks guys. yeah i have the Power FC.
i have boost controller but i don't use them. i use stock boost right now. haha.
because i know i need bigger injectors if i want to boost more. so right now i drive my car without boost controller, even though i have one.
after changing bigger injectors can i still get the good mpg?