Fuel Injector Size

[ws6ick]

My injector duty cycle is 90-92 at WOT. I need to install bigger ones but I don't know what size to buy. I think my stock injectors are 24# for a 2000 Trans Am, WS6. Can anyone tell me what size injectors I need? If I decide to install a 125 wet shot of nitrous, will the injector size you recommend work too?

[87MONTELSXTURBO]

Are you planning to add anything extra to your setup later on in life? If so you can stick with at least between 30#, 36#, or 42# injectors unless you are adding a turbo or something later down the road. 36# or 42# would be the best bet for nitrous. Also stock 2000 Trans Am injectors are 26#ers... Hope that helps...

[WS6FirebirdTA00]

A wet shot is a wet shot, it controls the fuel itself. Stock injectors are 26.4 lb/hr. You could probably pick up a cheap set of '01+ injectors which are 28.8 lb/hr and should get the IPW down enough for you. Next step I would go is 36 lb/hr GTP injector, which is 39 lb/hr at our fuel pressure.

[ws6ick]

I do want to add nitrous later. So if I get 42#, they should work just fine with my mods I have now? Will I have any issues tuning them? I heard that to big of injectors are bad.

[WS6FirebirdTA00]

Why? 42#s are big for what you have. Again, as I said, I would get GTP injectors. If you get FMS injectors, I wouldn't go bigger than 30# red tops

[ws6ick]

Why? 42#s are big for what you have. Again, as I said, I would get GTP injectors. If you get FMS injectors, I wouldn't go bigger than 30# red tops

If I get the 30# red tops, will they be big enough when I add a 125 shot of Wet Nitrous? Where do I get 36 lb/hr GTP injectors? Will they fit an LS1? What I don't want to happen is I install 30# injectors and then once I put the nitrous on, I have to buy bigger injectors.

[WS6FirebirdTA00]

Again, and I quote...

A wet shot is a wet shot, it controls the fuel itself.

A wet shot doesn't care if you have 100 lb/hr injectors or 10 lb/hr injectors, it has a fuel jet for it's fuel.

[ws6ick]

OK. I get it now. I will go with the 30# Ford SVO. Thanks who all replied.

[richard head]

so what needs to change in the computer if i were to add some 36 lb GTP injectors on my 2000 WS6? I found the table but it's written in a different language, i don't know what to do about it.

[WS6FirebirdTA00]

You need to change all the injector tables correctly (IFR, offset, short pulse, min pulse, etc.). I think the min pulse stays the same and the offset/IFR change with the GTP injectors.

[richard head]

i actually went with 42 lb/hr ford SVO units. can i just look for a file that's been done already and copy it to my car?

[richard head]

i found a file and copied it into my tune, only thing different was the IFR. car runs great now except for the STFT's are WAY off, around -17 on each side. is there something i can do with the injector tables to correct this or should i modify my VE table?

[WS6FirebirdTA00]

If the VE was right before, prob the offset that needs to be adjusted assuming your IFR is correct.

[richard head]

yeah ve was within about 5 before everywhere except like decel conditions so i feel fine about it. which way do i need to modify offset? like above, the offset table in my example car was unmodified. obviously the negative fuel trim means too much is going in which makes sense, but do i need to add to or subtract from offset table to make it right?

[RWTD]

I would have done just a set of the stock '01-'02 injectors (same on the '01-'04 C5s), which is a 28/29#, or either the GTP injector. Regardless, you weren't at 100% duty cycle before, so honestly the 01-02 injectors would have worked perfectly. Now you have an injector that you don't have the actual values for use in a GM for, so you're going to be just winging them and/or trying to absorb it in the VE or MAF table to compensate.

[richard head]

i had actually hit 113% duty cycle before ^_^

[richard head]

what's your opinion on what i should do to get closer, RWTD?