nagz

iTrader: (5)

I recently bought a car with a turbo 2 swap. Current mods are:

- Haltech Sprint RE
- Twin Walburo 255's
- Aftermarket FPR
- Aftermarket Fuel Rails(prim & sec)
- Aftermarket injectors(was told 850 prim's & 1650 sec's)
- stock s4 turbo

The previous owner was having trouble getting the car tuned, I noticed right off the bat it was not pulling very good vacuum at idle(4-5in/mg) so first thing I did was take the UIM off and redid the vacuum lines, fixed a bung that was jb welded up and a couple things to tidy up the wiring a bit. I now get 12-13in/mg which i figure is pretty decent. Doing this work screwed the tune up royal because I was now hitting cell's at idle I was not before and basically only the cell's above where it previously idle'd were tuned.

So now I am retuning the car, I loaded in the haltech base map to restart with and have disable'd most of the extra compensation maps except for water and air temp correction maps (disabled transient throttle, zero throttle, ect.) just made it as simple as possible.

In the vacuum area's I am getting a decent tune on the car, not perfect but I can drive it around. The trouble is though that I feel like the fuel system is way way to big for the turbo I am currently running and I am only running wastegate pressure for now at 5.5psi. As soon as the seconadries come on the car goes straight rich and hits a brick wall. Staging bar is set at the factory 1.5psi.

I know I am going to need to either change the turbo or change the injectors. I am leaning towards changing the injectors as my goals are really only to get 200hp. here is my options:

- run s4 N/A primary injectors 460's and swap my 850's to the secondary rail
- buy a second set of 850's and run 4x 850 injectors
- leave everything how it is and try to max out the pair of 850's and not ever have the secondary injectors come online.

WWYD?

Havoc

was it tuned in VE mode originally?

nagz

iTrader: (5)

The tune on the car was done by a shop. It was tuned with injector pulse time, they never setup the staging bar and set the rev limit to 4500rpm. only running the primary injectors.

i was looking around on the net and found an injector sizing calculator. 2x 850s should be good for 215hp @85% duty cycle. can anyone confirm this?

j9fd3s

iTrader: (3)

for 200hp the stock 550's are actually plenty, however since you have 850's, maybe its more cost effective to do 460/850 or 550/850.

the added plus is that 850 secondaries give you lots of room to grow

nagz

iTrader: (5)

I have a spare N/A motor kicking around so thats what made me think to go to 460's, I'd just swap the fuel rail w/injectors from the N/A motor onto my turbo motor and then move my 850's to the secondary rail. Not 100% yet if I can do this so some further investigation with the UIM off will need to be done. Not sure if my 850's will fit the secondary rail, from what I remember they looked to be the same style of injector, both being an aftermarket bosch style injector.

What I am hoping to do for now is not even utilize my secondary rail and just try to run off the 850's in the primary rail. I have a feeling thats just not enough fuel to run 5.5psi and at least 7500rpm.

j9fd3s

iTrader: (3)

it would be really close.