what size injectors for my 408/nitrous car?
 

ok I m about to build a ls2 408, cnc 243 heads, 92mm fast, spraying 200-250 through a plate (might go direct port later).
im thinking I need 38 lb injectors. don't want to go too big and over do it

Id go at least 42lbs. 60lbs wont hurt tho. Always good to have more room.

I agree at least 42's here. As far as going to big, the car can be easily tuned for the bigger injectors

I wanted FAST brand, but they don't have a 42#. so what about bosch?
also do I get high or low iimpedance?

If you are running off a plate the injectors arent going to matter as much. i was running my 402 with an LS6 intake and stock injectors. I have recently upgraded to 42# injectors because I got a great deal on them.

The wet plate system adds fuel for the nitrous, so your injectors wont add any fuel unless you are tuning for a dry shot and having the injectors add the fuel for the nitrous.

ok so even fast 36 lb would be plenty?

grab some FIC 42# or larger and you will be set (Fuel Injector Connection). Hell, just give them a call and chat, they will get you hooked up. I suggest 42# or 60# and a 255 pump in tank.

you will get the tuning data and all will run fine. guarantee

there really is no such thing as too big until you get to the point where they dont respond fast enough at idle to have a good idle...

are you doing a Dry shot or a wet shot?

bigger injectors mean they dont have to be on all the time, which means you can inject fuel when necessary while will usually make more power than an injector that is open at 80% duty cycle

if you are doing a wet shot with its own fuel cell and pump...
38's might be ok...but I would do a 42 and play it safe
38's are barely big enough for a Naturally aspirated 408 unless your motor is a total sissy..

also, if you are dead set on something in the range of 38's... get the FAST 36# White injectors... they are the ones used in the ASA corvette, and you can pull the injector data directly from the ASA corvette tune and put them into your tune.




for a Dry shot(using the injectors for ALL fueling)

I was on a set of 83lb injectors on a 500 shot...and it was around 75% IDC

you should go with at least a 60# injector for a 250 Dry shot


figure that you will make 700 at the crank pretty easily on a 200 shot with a 408
and that means calculating for BSFC just as a starting point(and you will use more than this)...gets you 497cc/min at 80% IDC...or roughly a 47# injector