Just got done with meeting my tuner at the dyno shop here in Layton, Utah. Car only got 325 whp with Deatschwerks 440cc injectors, Walbro 255 fuel pump and he says the injectors are maxed out. WTF!? I thought I would be overkill with 440's. My goal was around 350-400whp. Berk hfc's, DC catback, 3.12 pulley, 1 step colder plugs, Motordyne 5/16 spacer are the only other mods. He's tuning with UpRev Osiris. The only thing we can think of is a clogged fuel filter?? Please help, going back on the dyno Monday with a new fuel filter.

 

did you upgrade fuel pump? if not, i see it very possible to max out 440's on the oem fuel pump. especially if youre running a higher amount of boost.

 

How much boost are you running? and I can only assume that your AFR is around 13:1? It doesnt seem like the injectors are max'd out unless there is an issue with them. Your supporting mods should get you to 400 all day…no formal fuel filter on these cars(unless you dropped one in with your pump). If I had to guess, taking a stab in the dark from what information you've provided I think your air fuel ratio is off from a issue with your tune.

 

Without an RFS you need bigger injectors then those 440. I recommend 725cc Injector Dynamics with the 255 fuel pump using a 3.12 pulley. Supercharge are fuel gobblers.

 

What type of dyno are you on?

 

I'm not sure what dyno it was on (I didn't ask and it was my first time around one) I'll throw up a picure if that would help. It was dyno meter, dyno pack something. The A/F at WOT is below 12. We saw between 8-9lbs boost. No fuel filter to save me?? It was a thought shot in the dark I guess. Woke up with an uneasy feeling in my stomach and a bad headache and I didn't even drink last night haha.

 

I'll ask my tuner today what dyno it is. Here's a pic of it last night.

 

prolly dynodynamics as they use red platforms.

Id bet you are truely out of injector. I was out of 600cc injector around 450whp on that kind of dyno with 11.8-12.0 AFR.

Like someone else said, go to ID725s or any high Z injector over 600cc.

Whoever sold you that fuel setup was misinformed as to your actual needs.

 

Dynodynamics sounds right. Would a RFS suffice with 440's?

 

I'm honestly still not convinced that my injectors are "maxed" out or 80-90% at only 325whp. It just doesn't make sense.

 

blower cars always take more fuel for the same power level as a turbo car.

 

Well dont guess.

There are 2 things you need to check to determine if your injectors are too small

1. Fuel pressure. If you fuel pressure holds rock steady and
2. AFR. leans out regardless of how much more duty cycle is added

= injectors too small.

With a properly functioning Walbro 255, thats enough fuel pump for around 550whp on pump gas. SO as long as you properly installed it with the swirl nozzle drilled out properly, that is fine.

If your tuner cannot keep a steady AFR throughout the powerband, you are out of injector.

325 on a DD is prolly close to 375whp on a dynojet

 

Yeah it's leaning out top end and the fuel pressure is good throughout. I did "phunks" swirl jet mod so all is good there. Thanks for the info str8dum1, I feel a little better about it. My tuner said he'd hook me up on the tune after I get some 600's or bigger. Anyone need some 440's? They're for sale haha.

 

Good post str8dum.

 

My Stillen V3 SC kit came with that same Walbro pump and I'm quite sure the injectors are 570cc; didn't give size on invoice or parts list, but when I called Stillen the guy said they should be 570cc.

 

that was a pretty informative post -

whatever happened to 1cc per whp? with my procharger setup at 9psi and my OEM injectors (~300cc) I was pushing 375whp, also at elevation...

 

^just mentioned it because he has the same sc as me; my kit came with larger injectors than he has with same fuel pump.

 

If you keep Adding Fuel Up Top, and it is still leaning out, then you do not have enough Fuel Supply…….

Not to confuse you, but with the Vortech supplied Aux Fuel Pump and FMU, 440cc injectors will work with the 3.12 pulley, because of the High fuel Pressure.

 

bigblue, I was genuinely referring to Str8dum earlier post - should have quoted him -

 

supercharged car will not make 1hp per cc out of 6 injectors.

you will want bigger injectors. the reason that basic vortech kits and procharger kits can make more from the small injectors is high offset fuel pressure risers. they skyrocket fuel pressure into boost to force more through the injector. this is considered a bandaid these days since the means are there to properly do it.