Frazer

Hi,

Need some advice on injectors.


I've bought a hybrid twin scroll to fit on my Spec C and will be needing new injectors. I want to future proof them so I can go for 500+ HP eventually and not have to buy new injectors again. Also is there anything else i need to upgrade along with the injectors? (ive got a new fuel pump)


Also where can I buy them from?

Cheers in advance

N

Shaun

Frazer,
Let's deal with the injectors first.

You can crack that nut several ways and it entirely depends on which nut you want to to pick up and crack first.

It is not just your injectors you need to consider. It is also the type of fuel system you will be using. You can either go an injector matched to your power output and required fuel pump set-up without upgrading the fuel pressure regulator, or you can get away with smaller injectors, but also up the fuel pressure to get them to flow more.

Different tuners prefer different methods.

Assuming you were going for 500bhp, you could use your existing Spec C pump as a lift pump and add a Bosch external pump as the main supply. You would be border line using 800cc injectors here, but you could up the flow capacity by upping the fuel pressure with an adjustable FPR. Alternatively, you could stick with the same fuel system, not use a FPR and go for 1000+cc injectors.

This is two ways you could do it, and a few more options exist on top of that.

If you are not building / mapping the car, it may be worth discussing this with said person.

I run a 500+ Spec C and have the standard pump, bosch pump, 1150cc injectors and standard FPR at standard fuel pressure.

Just to give you an idea of what the standard Spec C fuel system is capable of, I was running 470bhp with 800cc injectors and the standard fuel pump with no issues. I upgraded my fuel system to give me more headroom and reliability on track.

As regards to what else you need to upgrade.... is this question regarding the 500bhp upgrade, as that is another topic altogether.

Frazer

Hi Shaun,

Thanks for that reply, loads of good info.

What would you recommend for me going to around 400 hp on this hybrid turbo i've bought. I thought I would be able to just whack on some 800 cc's and that would be ok, would I be better getting say 650 CC injectors? If I did get 800 cc would I need the fuel pressure regulator? And if I went for 650 CC I wouldnt need one?

Loads of questions I know!

Cheers
N

Shaun

You could run 800's for 400bhp, but it would be overkill. 650's would be fine and 740's would give you more headroom. With those injectors at the 400bhp level you would not need an adjustable regulator.

The adjustable FPR is to enable you to flow more fuel than the injector was designed for at standard fuel pressure (which is what they are normally rated at). Anyone that sells and knows about the injectors, will be able to tell you what they flow at for standard and "adjusted" fuel pressure.