fuel injector size

[Needsoles]

i am wondering what size injectors to get for my car? i am running a 16g turbo with stock 450cc injectors. so any advice?

 

[lordnikon_04]

Depends on what kind of boost you want to run and what types of goals you have for your car.

 

[Killa_dsm]

Depends on what kind of boost you want to run and what types of goals you have for your car.

+1 on that. Do you plan on upgrading to a larger turbo after the 16g?

 

[oldman]

i am wondering what size injectors to get for my car? i am running a 16g turbo with stock 450cc injectors. so any advice?

Let's try it again with caps. Yes, I'm on to you.

 

[Needsoles]

I plan on keeping the 16g for a while and I'm planning to run 16psi.

 

[oldman]

I plan on keeping the 16g for a while and I'm planning to run 16psi.

Then rewiring the stock pump and stock 450s will be sufficient for now.

 

[Killa_dsm]

I would run some 650cc's to give you some room to grow. I use to run my b16g on 20psi with 560cc injectors with no problem.

 

[peypey's ride]

Get a set of 650's that way you really wont have to worry about maxing out the duty cycle and if you wanted you can still turn up your boost with a lil more tuning.

+1 I second that! , beat me to it!

 

[Needsoles]

Thanks A lot guys

 

[oldman]

Keep in mind that larger injectors won't do you any good with the stock pump/fpr.

 

[Killa_dsm]

Yeah, a fuel pump will be needed. And some kind of fuel control will be needed.

 

[Needsoles]

Thanks A lot I'll keep that in mind

 

[JohnnyT]

So, if I get bigger injectors would I need a fpr? How exactly do they work, how do you set them up? I understand that the regulate fuel pressure, but how do you know what to set it at? Or do they do it on their own?

 

[oldman]

So, if I get bigger injectors would I need a fpr? How exactly do they work, how do you set them up? I understand that the regulate fuel pressure, but how do you know what to set it at? Or do they do it on their own?

No, AFPR goes with fuel pump, not injectors. In fact in the case of stock FPR overrun caused by a larger pump, the larger the injectors, the shorter the duration of the overrun because you're able to use up the excess fuel quicker. In the case of using an AFPR as a tuning tool is a whole other discussion.

 

[snowborder714]

So, if I get bigger injectors would I need a fpr? How exactly do they work, how do you set them up? I understand that the regulate fuel pressure, but how do you know what to set it at? Or do they do it on their own?

No. If you get bigger injectors, you will need some sort of fuel management system (S-AFC, DSMlink, etc.).

If you get a bigger fuel pump, you might need an AFPR. Typically, if you get a Walbro 255, you need an AFPR because your stock one will be overrun. There are a few how-to's on installing an AFPR on this site that you could reference on how to set one up. You know what your fuel pressure is set at by a fuel pressure gauge (either in the cabin or on the AFPR itself). Since you have a 1G, your base fuel pressure will be 37 psi and will rise with a 1:1 ratio as compared to boost. So, if you boost to 10 psi, your new fuel pressure at 10 psi will be 47 psi. The AFPR has an adjuster on the top of it so that you can set your base fuel pressure.

And once again oldman, you beat me to it

 

[DGajre777]

So, if I get bigger injectors would I need a fpr? How exactly do they work, how do you set them up? I understand that the regulate fuel pressure, but how do you know what to set it at? Or do they do it on their own?

An adjustable FPR is needed when you get a big fuel pump like the 255 to turn down your base fuel pressure because the big pump overruns the stock FPR. If you stick with a 190 pump and 650cc injectors, you won't need an AFPR because the overrun is not as bad as compared to the 255. You'll find some people come on here and say that their car with a 255 runs fine without an AFPR, but Bruce (Oldman) can tell you about those people.

As for where to set your fuel pressure if you get an adjustable one (with FPR nipple/port unhooked):
1G Turbo = 37 psi base fuel pressure
2G Turbo = 43 psi base fuel pressure

 

[oldman]

Bruce (Oldman) can tell you about those people.

Those people are special.

 

[jemsoccer]

I know it may not be a concern to most guys on here... but how would the 650s compare to the 550s and 450s when talking gas mileage? Given that everything else is the same. (Will bigger injectors decrease gas mileage if the fuel pump remains the same?) Reason I ask is because I have a GSX in the works now and it will be my DD. It will have a big 16 w/ a 190 fuel pump. I plan to go bigger in the near future, so if the only diff in the 650s and 550s is the grow-ability, and gas mileage isn't really affected, then I think I would rather get the 650s from the start.

 

[oldman]

I know it may not be a concern to most guys on here... but how would the 650s compare to the 550s and 450s when talking gas mileage? Given that everything else is the same. (Will bigger injectors decrease gas mileage if the fuel pump remains the same?) Reason I ask is because I have a GSX in the works now and it will be my DD. It will have a big 16 w/ a 190 fuel pump. I plan to go bigger in the near future, so if the only diff in the 650s and 550s is the grow-ability, and gas mileage isn't really affected, then I think I would rather get the 650s from the start.

As long as the system is properly tuned, the answer is no.

 

[cotsi95]

Do you plan on running e85 at all?

 

[fastfour]

how you going to control the fuel?

AFC isnt the greatest thing to control injectors over 550.

Theres always people buying 550's I wouldnt worry about being able to get rid of them. 550'sshould give you enough fuel for 20 psi no problem. Maybe even enough with a set of cams but that may be stretching it, may have to just turn the regulator up a few psi.

 

[JohnnyT]

What type of fpr would you all recommend? Aeromotive FPR Fuel Kit looks pretty good.

 

[Splitpi]

Ryan at Import Evolution has a nice kit for a decent price.

For the FPR Kit + 255 Pump $275 + S/H

For just the FPR Kit $189 + S/H

Don't forget to get a fuel pressure gauge so you set the pressure correctly.

 

[snowborder714]

I second that kit at IE. Very good products and has everything you need (minus the gauge which they sell). Aeromotive seems to be one of the top AFPR brands used on the forums (and I'm one of them).

 

[95gsxgrimsquad]

I need help! I just got a 95 gsx it runs but blows smoke when the turbo kicks.its my 5th dsm but first 4g63. it has 20g turbo,apexi safc 2 (that I know nothing about )and hks 272 cams. it had rc injectors but I have no clue how big they are? any advice in how to tell,also tuning?