hey im not looking for stupid comments please so keep it simple and clean in here, but is it really necessary to add bigger injectors to the car what is this going to do for the na crossfire. I mean i know more fuel more air more power but anyway i guess im just wondering why people are adding these bigger injectors and what not if they are staying na and not adding a charger or turbo. Basically wondering if its worth it. And even with the bigger injectors the car will need to be tuned so does anyone have any dyno numbers or anything where this paid off, i would like to see.

 

tvt says that with there experience an ecu tune plus intake and exhaust upgrades left the car running lean which required larger injectors, our injectors run somewhere near 90% duty cycle. hddp did a thread on this and it was very informative.

 

really, lean?, like too lean?, doesn't seem like that would do it, but if so what size injectors should i go to if i have intake exhaust ecu tune and eventually underdrive pulleys which wouldn't make a difference i believe. and going with the bigger injectors wouldn't that require a different tune that i would get if i had the chip tune by inmotion. so basicall if i understand right ,i should wait on my ecu tune and get the bigger injectors and then have a custom tune done?, only problem for me is there is no where near me to go get a inhouse dyno tune for my car. thats why i am opting for sending my ecu out and having it tuned. sorry if i confused you but any input will help in deciding what to do, i just didn't ever hear anything about getting lean with those mods.

 

do you know if they had any af ratio numbers to know actually how lean, and what are our cars supposed to run at for af numbers

 

To clarify, this was the N/A crossfires, not the SRT6 that runs lean.

Please search for fuel injectors thread, I know it's long, but it will get you the full story... (I'm actually working today, so I don't have time to find it myself, sorry).

Cheers!

 

yes i own a na crossfire, and i will look into the thread although i would rather someone break it down cause im sure it is another crazy thread to look through for valuable info., thanks though ill check it out.

 

how about using a Vortech 12:1 FMU and a larger fuel pump for higher pressure. the FMU sells for about $85 on ebay, the only upgrade I would do is the rubber fuel line hose, convert it to a SS braided hose. The OEM rubber hose just scares me, cause it sits right on top of the exhaust manifold.

If you want a simpler way of adding fuel you can try using Snow performance Meth injection kit, just use regular gas instead of methanol. it activates the pump from a vacumm switch. the pump is adjustable from 80-150 psi and you just use a mister nozzle after the TB. I think it's $300

 

ive thought about using an fmu in place of injectors as well. but doesnt the fmu adjust according to boost pressure??? so it wouldnt work for a n/a application. would it?

 

There are figures out there showing the A/F ratio - you have to hunt for them.
From memory I think it's running about 11:1, and we should be about 13:1.
However, get a dyno done - it doesn't need to be all the way to the red line, but you'll get a good idea of the A/F trend earlier on in the rev range and that way you'll know for sure.

 

this is a little off topic but what is the stock plug for na crossfire in a ngk plug and what is one step colder, is a BRK6 one step colder?

 

FMU's work off of boost pressure. You install them on the return fuel line to the tank. The boost pressure restricts flow in the return line raising fuel pressure and in turn raises the amount of fuel the injectors release without the need to change the pulsewidth. In lamemans terms it clamps down on the return line and makes them fuel thingies spray real hard when that compressor kicks on. And it aint wort a tootie frootie to a NA.

 

AFR is about 14.7:1 which is lean in terms of making maximum HP. 12-12.5:1 is good for making power.

 

oops
? basically I could just instal an adjustable fuel pressure regulator then. no need for new injectors? Chuck, know anyone who makes one for our engines?

 

I've read some of your other posts and you are a smart cookie. With 2700+ post you should be a walking xfire encyclopedia . I'm sure you know the fuel pump and regualtor are the easiest parts to replace(you don't even have to remove the tank!). I also have seen that you are a fan of Split second..... They have all the parts you'd ever need to mod this car and any other car on the planet.

 

Well I have all the mods you're talking about and my technition never said I needed any injectors or that I was running lean. I'm not an expert at all, so if I got the injectors what wil this do to my NOS tune?
Tvt is claiming 26hp for his ECU tune is this not the most we can get?

 

I would like to play with an adjustable fuel pressure regulator before going to the upgraded injectors, much cheaper this way, would be cool if someone makes a regulator that's digitally programmable off the MAP sensor. anyone know of something like this available?

 

i no that ZEX has somthing called FUEL BOOSTER or somthing like that. Check out their website. would this work??? id really just like to purchase the tune from tvt. the injectors are alittle steep!

 

I think the ZEX fuel booster only increases the voltage or Amps going to your fuel pump, this is not worth the hassle.

the guys on MBworld have already lised all the part numbers for higher flowing OEM fuel pumps. no need to add extra electronic gyzmos to the car when a upgraded pump will do the trick when used in conjunction with an adjustble fuel regulator. they where more interested in the higher flowing pumps for custom SC projects. you won't be making enough power in stock form to require a bigger pump. unless you are adding nitrous and have to feed 8 injectors ?