Stg IV SBEC with larger than +40 injectors?

[iTurbo]

One of my friends picked me up tonight to give me a ride in his Spirit R/T. Holy crap that car is waaay faster than when I used to own it! Believe it or not, it was my first real ride in a Spirit R/T with a big turbo and most all the bugs worked out. He's running about 20-21 psi right now using a grainger valve boost controller.

He has an AEM wide band gauge on the car. In 1st and 2nd gear, the A/F seems just fine, although it's pretty hairy with all the wheel spin and the gears go by pretty fast. It spins in third too, and the A/F gauge starts going past 12.0, to 12.5. In 4th gear it finally hooks, but I'm worried it's running dangerously lean at this point. I seem to recall it was getting near 13.0 at the top of 4th gear.

I built the engine for this car and it seems to be running beautifully, and I'd like to make sure it stays that way so he can keep having fun with it. Here's a short list of the mods:

Garrett T3/T4 turbo, 50 trim/stgIII, with a .72 A/R Cosworth turbine housing (no problems with spool at all)
'budget' FMIC from FWDPerformance
3" exhaust from FWDP (no cat)
ported exhaust manifold from FWDP
StgIV SBEC from FWDP
fuel rail from FWDP
Aeromotive adjustable FPR (60 psi base pressure)
ATP Turbo fuel filter
Mopar Performance +40 injectors
3-bar MAP sensor
Walbro 255 ltr/hr fuel pump
TurbosUnleashed clutch (yellow plate/4-puck)
battery relocated to trunk
air intake is 2.75 mandrel bent aluminum with an open element filter where the battery was

The fuel system is completely redone by myself on the car. All the stock lines have been replaced with 3/8" PolyArmour. All the hose sections are braided stainless -6AN hose from Summit. Everything is connected with 6AN fittings. I even had the fuel pump sender modified with 3/8" steel tube brazed on all the way into the tank.

I'm a little surprised the car is running lean already. The car runs really strong. I was afraid that it might be laggy with the choice of turbo, but that is not the case at all. What should be done about the lean condition at WOT though? Does this car already need another injector upgrade? Any way he can do that without having to have another recalibration to the SBEC as well?

[glhs727]

You could try running 65lb injectors, and lowing FP a little. Most people, including us at the shop, have used te+40's then added a progressive methanol kit. We had a 50 trim r/t at 28 psi of boost running 11.7's with single #5 nozzle.

[iTurbo]

Thanks. I will tell him about that and also tell him he might want to turn the boost down a bit while we test some other things. Kinda wondering if that Walbro pump is getting tired since it's about 10 years old.

[glhs727]

yes, have him check fuel pressure pressure and make sure that isn't an issue first before you start modifying anything

[iTurbo]

Thanks for all the help Cindy, greatly appreciated. I think the next thing we'll check is the fuel pressure and see what the dead head pressure is by pinching off the return line. As it is right now, his base pressure is set at 60 psi. When you add on 20+ lbs of boost (80+psi fuel pressure) I'm afraid the pressure/flow is falling off at WOT, so we'll check that first. If it is the pump, I'm thinking of looking into one of the newer Deatchwerks pumps, although I'm not clear if those will work in-tank like we'd like.

If it were still my car, I would probably get a fuel pressure gauge mounted in the A-pillar pod, using a sender mounted into the Aeromotive FPR. That way we'd be able to see it while driving. We'll probably look into recalibrating the WBO2 sensor too, and check the fuel filter screen.

[iTurbo]

Also, I would like to add that I haven't yet heard any detonation with the car at WOT, for whatever that is worth. I have an OTC scanner so we'll probably hook that up too to check for knock retard just to be sure. It is running 91 octane pump gas. I told him to check the spark plugs the next morning and tell me how they are..

[glhs727]

Thanks for all the help Cindy, greatly appreciated. I think the next thing we'll check is the fuel pressure and see what the dead head pressure is by pinching off the return line. As it is right now, his base pressure is set at 60 psi. When you add on 20+ lbs of boost (80+psi fuel pressure) I'm afraid the pressure/flow is falling off at WOT, so we'll check that first. If it is the pump, I'm thinking of looking into one of the newer Deatchwerks pumps, although I'm not clear if those will work in-tank like we'd like.

If it were still my car, I would probably get a fuel pressure gauge mounted in the A-pillar pod, using a sender mounted into the Aeromotive FPR. That way we'd be able to see it while driving. We'll probably look into recalibrating the WBO2 sensor too, and check the fuel filter screen.

sounds like he would be better of running 65lb injectors and turning down the pressure to 45 psi, give you more room at the top and plenty of fuel

[iTurbo]

I tend to agree, especially considering the fuel pressures involved and decreasing headroom...Does FWDPerformance sell the 65 lb/hr injectors?

[glhs727]

yes, we do!! LOL

[tman1999]

What's the part number on those injectors

[contraption22]

I had good luck with with running larger injectors that the cal was tuned. My cal was tuned for 72lbers at 55psi. I dropped put in 83Lb injecors and dropped it to about 46psi. This give me a bit more fuel pump capacity.

As your fuel pressure rises, your max volume decreases. So lowering the pressure requirement raises the system's volume capacity.

[iTurbo]

Thanks for the info Mike. I was kinda thinking that was the case and it's nice to know we are on the right track with the car.

I can't wait for the day that this car walks the Caliber SRT. All will be right with the world then