As many of you know the stock fuel system even with a 5 bar fpr can only safely support ~600 crank horsepower while retaining any actual fueling control by the stock ecu.

I've been exploring different injector options for these cars and have come to 2 solutions....

1. Spend $600-700 on a set of 60lb (or bigger) drop in injectors that require no fuel rail modifications. This isnt a bad option if you dont want to be bothered with a little additional work of fitting injectors.

2. Spend $325 on a set of 60lb injectors that require a simple fuel rail modification and a set of injector spacers to make them function and fit correctly.

This modification coupled with proper tuning is HIGHLY recommend on all cars making 600+ crank horse power.

Below is a picture of stock injectors vs a 60lb Siemens...




This is the first problem. Note the difference in hight. This is an easy fix with a set of these..... Fuel rail spacers.




A secondary benefit of using a nylon injector spacer is it helps to eliminated heat transfer from the cylinder head to the fuel rail itself.

The second problem is the offset of the fuel rail to the mounting tab on the cylinder head. You will need to drill a second hole in the mounting tab to allow the rail to sit at the correct location for the injector sit at the correct angle in the injector bung....

The picture below show how the hole is off set with the taller injector. Be careful not to drill the new hole too close the the end of the tab on the tab.

 

Oh God.. I spent 2 months chasing what I thought at the time an imaginary boost leak... turned out that my O ring on the injectors were leaking after I took it apart... Hence, I pressurized each cylinder and out that the fuel rail was simply not lined up correctly after I screwed it down... WOW that was a freaking project...
hence, nice write up ...
markski

 

Stop trying to get me to spend more money/make more power!!

Seriously though, after seeing where my injector duty cycle was at 600 crank and 1.1 bar, there's no way I'd add more power without dropping in some injectors.

When I've got the tranny out for the clutch I may just pop a set in... just in case that devil on my shoulder yelling "more power, more power!" gets any bigger.

 

Sounds like a problem I might be having. One of my banks is running a little leaner than the other and my idle is hunting. What is the best way to go about checking for leaks?

 

First do a pressure test at the TB... so take out the Y pipe.... spray some soap water on the rails... it will bubble up.... actually spray the injectors... an dit they leak then its either the O ring or the rail is not lined up and u may need to use a tiny washer... I realized my problem after changing my O rings 3 times. LOL I didnt screw on the rail all the way and pressure tested at the TB... NO leak...

If you find the leak at the injectors and u just want to do it right... u will have to take everything out and pressure test each cylinder head after taking out the black plastic runner going to each inlet of the head. YOu keep the injectors and the plenum they are in intack...

 

Come on, you wont need injectors until we install your epl 800 kit .

 

Have you done anything else to the fuel system to support the larger injectors ?

 

Nope. Just the injectors.

 

Tony, how hard is it to get the clearance to install the injectors?

I just got my car back from powertech last week with the new clutch, and I'm still debating wether to install my k24/18g's or sell them and get my k16's done up with the 16g comp wheels before I bring it up to you.

Tommy.

 

Hey Tommy,

Its tough with the motor in the car... If you were doing direct drop in injectors, its tight but do'able. If your using the 60lb Siemens is MUCH easier if the motor is out.

I can arrange rides in both turbo set ups if your interested.

Give me a call sometime soon. We have some other stuff coming up you may be interested in.

 

Cool, I'll try to give you a call Monday.

I must say that I like the fact that the 16g's spool quicker and cost over 2 g's less.

 

Cool Nice work Tony! Can't wait to hear more about these...

 

Who makes and were do you get the drop in ones? I was not aware you can get 60lb units in the stock size? I know 997TT units are 60lbs but also require a little work to get them in.

 

Also interested, I appreciate the information.

 

Let me help your debate. If you want more than 700 crank hp, keep your K24/18gs and get fueling, 16gs will not get you there. If you know you don't want more than 600 crank, get the 16gs... they spool so early the car feels naturally aspirated.