Bigger injectors question

[Zero to 300]

So i just got my ecu back from z1 motorsports and i'm looking to get bigger injectors most likely 555cc injectors. It was an ecu upgrade and i told them 370cc injectors(stock size for the TT) and if i get the bigger ones will i most likely have to send my ecu back?

Also will the 555cc injectors fit in the stock fuel rail or is it not worth to even try and i should go ahead and get the 300 degree fuel rail with new style injectors?

I've been told i shouldn't need bigger injectors with stock turbos but if i'm supposedly pushing more horsepower than what my injectors can provide shouldn't i get bigger ones now instead of when i get new turbos?

Thanks

[NolimitZ32]

In a perfect world the stock 370s top out about where the stock turbos should, some people push the stock turbos beyond the recommended limit and at that point bigger injectors are needed. I believe and don't quote me on this the 555s are old style and will fit your fuel rail. As far as I know Z1 will charge you for a new EPROM somethinglike 50 or 75 dollars, then you just open up your ECU and change it out. Ask Z1 this exact question, verbatim, and they will tell you everything you need to know.

[Z31toZ32]

The 555cc are still the old style injectors are still mechanical in operation and will fail, just like the originals. If you want to upgrade, you want to get the NISMO 615s/740s. These are the new style injectors anfd are essentially electronic, with no moving parts in them. the technical term is "pintle less" I believe, and they are as good as they are going to get, according to greg at specialty z. The new style injectors will fit in your 90-94 fuel rail as long as you get the detschwerks adapters with them. if you want the 300 degree fuel rail, you will be out an additional $400 over the adapters. It is better flowing and easily customizable, but as long as you aren't building a supercar you should be fine.

you dont need to send your entire ecu, you just need an your EPROM reflashed for the new injectors. options are to pull it out and send it away and re-plug it in, or make it easy and just buy a new one.

i just upgraded to the 740s myself, and my car is running incredibly smooth. partly because the new style injectors actual inject fuel from an electronically managed 4 holes in the injector as opposed to one mechanically managed 1 hole on the old style, and also im thinking because 3 of 6 of my old injectors were technically out of spec. now i run a smooth 15.5 psi on the stockers and am ready to upgrade turbos.

[canadian booster]

i just upgraded to the 740s myself, and my car is running incredibly smooth.

with the injector upgrade, do you burn through a tank of gas faster or does the ECU do a good job of only pushing out more fuel on demand?

i've had to do quite a bit of tinkering with my boost controller to find a happy medium, i get power loss at higher end, and i can never go WOT, the most i do is about 3/4 throttle ..

[Z31toZ32]

^ gas mileage is the same so far. i have a feeling it actually might be better on the highway, but i havent had a highway tank to prove that one yet.

[marty1mc]

I have the 740's, upgraded turbos, and a few other things. The Z recently went on a 1000 mile loop and was able to get 27.5mpg (with good right foot management). But, get a little impatient with traffic and it quickly dropped to under 23 mpg. Heavier foot would undoubtedly drop it into the teens...