okay... I'm planning my next round of upgrades for the Z, likely to occur sometime toward the end of summer and I have some questions for the FI gurus... particulary those with Vortech experience (booger... you listening??? )

I've had several people offer their standard Greddy TT Kit 440 injectors (as they are going with larger injectors for upgrades to the TT kit). My thought is to get a set of these to replace the stock injectors (which I'm sure I'm maxing out) and do the 3.33" to 3.12" pulley swap. I don't think I need the 2.87"... I've run 425rwhp at 9lbs of boost with the 3.33" pulley, so the 3.12" should get me up to aroun 11.5lbs of boost. The 2.87" will likely be overkill.

One issue I'm having is I know just enough about fuel delivery to be dangerous. So I have a couple of questions...

1 - Is there any reason I would not be able to use the Greddy 440 injectors?
2 - Must I have a different auxillary fuel pump (ie. Walbro 255)? Pros and cons of Vortech vs other auxillary fuel pump?
3 - Do I need a return fuel rail? Pros and Cons of adding or not adding one?

My research seems to indicate the R4 software can handle tuning. My preference would be not to spend money on stuff that would be overkill at this time. Meaning if the fuel pump and/or return fuel rails are not necessary required, but nice to haves, I'd probably put them off until I do a bottom end build.

Two objectives with this. First, my goal is not really to exceed my 425hp figure. I just want to fatten the area under the curve by making that power come at an earlier RPM. Second, I want to increase my injector reliability/life by not constantly running them at max duty cycle

Thoughts?

 

Mcduck,

I upgraded to the AAM return fuel system, 255lph pump and PE380cc injectors about a month ago. In hindsight I should have gotten 440cc's but I didn't want to splice in new injector wires on my first attempt.
Anyway, if you have the current Vortech fuel system the FMU is raising the fuel pressure around 8psi for every 1lb of boost. If this is accurate then at 9lbs of boost your fuel psi would be around 125.
I'm thinking just changing to larger injectors wouldn't reduce the amount of psi the FMU is increasing the fuel pressure. It is simply a mechanical device driven by springs and so forth.
I'm not 100% certain if using the R4 software to scale the injectors and tune your A/F would actually reduce the amount of fuel pressure you would be running. And ultimately that large amount of fuel pressure is what would be detrimental to the injectors.
I've seem some guys do only a walbro 255 pump and larger injectors on their Vortechs and others like DFW do larger injectors on top of the stock Vortech fuel system. I'm not an expert but felt doing the AAM return fuel system allowed me to significantly lower the fuel psi to the rails by using the 1:1 FPR on the return side. So far it has worked very well except I go lean (low 12's) near redline because my injectors are probably too small.
Just my 2 cents. Maybe some other folks here have better knowledge or experience.

Steve

 

1) The 440's would be perfect for your needs. You will also need a set of RC injector wiring harness plugs, and your stock connectors would need to be snipped off. You also need 4 fuel rail spacers, since the RC injectors are taller than stock. You can get these from RC or probably from any hardware store.....long bolts...obviously...too.

Answer to question 2 and 3:

In my opinion, ditching the FMU completely, and running a Walbro 255, return fuel system, and rising rate FPR is the way to go. Any other method is a semi-dangerous/unstable workaround that is anything but ideal. Yes, it is doable, but in an ideal situation, you want 52psi of fuel pressure at idle, and then 1:1 increase in pressure as boost rises. Running 100psi+ on those Vortech kits just scares me, since the fuel system parts were never designed to do that.

If you are trying to maintain a budget, then you can use the Vortech FMU and AUX pump, and tune like normal with the R4 software.

AAM and CJ Motorsports make excellent quality return fuel systems for $999 and $1299 respectively. Andy, PM me if you need help with this.

Also, I have my set of used 440's for sale...and I will make you another "friends and family" deal.

 

I may have gone to big with my injectors [ 550's ] As I just found out from Vortech that they dont have a 34 tooth jackshaft cog pulley nor a smaller blower pulley . Only thing left to do is a larger crank pulley and I dont know if there are any bad effects of doing that . With the 3.12 and at 9lb's before the rebuild ,cams , 550's , and return fuel , I was making 350whp on a Mustang dyno [ AT5 ]. I need to get this thing on a Dynojet just to compare with what every one else is getting .
I went with a return fuel system to get rid of the high preasure in the fuel rails . As Sharif said...over a 100psi in the fuel rail cant be good . The 550's because Im going to try to boost this thing as much as the blower can , and as early as possible .
Taking the ECU out tonight and have TS flash for 440's . Only thought they did 380's , so that makes things even better .From what Sharif and TS said , It should make the jump easier and help with idle .
I dont remember who it was , but he said he gain 15whp with just going with a return fuel system and the walbro . Thats with stock injectors , ditching the FMU and Aux. fuel pump . So any thing we do to ease the fuel preasure and even out the fuel flow to each cylindar is going to help .

 

Hey now... thats $1199!!!



-Charles

 

That $1199 is for just the fuel return system, right? It does not include injectors???

 

Oh dear...so sorry Charles. I know we had this conversation, and I couldnt remember which price you eventually settled at.

$1199 it is!!!

McDuck, neither the AAM kit or the CJ-Motorsports kit include a fuel pump or injectors, since most people either already have these items, or wish to chose their own.

Those two pieces would need to be purchased seperately.

 

mcduck : please contact me if you would like some details... since it is a new system no one (other than myself) really knows why exactly it costs so much more... I would love the chance to explain it to you... its definatly justified and has been test fit in 2 cars now to fit flawless

-Charles

 

McDuck
Did you happen to see the pics that Dr bonz posted of the tops of each cylinder ? Starting at the back passenger side and moving around the block , to last cylinder closest to the driver . They got lighter in color as you went around . When they took my heads off , mine looked like that , but not quite as much of a color change .
I dont know the real cause of it . Is it less air flow or less fuel ? , I dont know . But , along with the preasure being so high in the fuel rail , made me decided to go with a return fuel system .

 

I've decided to go with the fuel rail... just means I'll have to put off this upgrade a few months. Phunk, I'd love to talk to you about this. You'll be in our area in a week or so, right? Maybe I'll drop in when the tuning session is going on and we can discuss the details. I definitely cannot do it before ZDayZ... after that anything's possible!

BTW, injector and FPR deal is sealed. I'll now be looking for a the fuel rail setup and a Walbro fuel pump.

 

Hey McDuck, what about the PE 510's. They have a better spray pattern and they're slightly larger, although not as bic as booger's 550's. Plus, they drop in and don't require any "snipping"

I know they're more expensive, but with the necessity of purchasing wiring harness plugs and fuel rail spacers, they can't be all that much more expensive.

 

I just got off the phone with TS and he said they now can flash for injectors up to 750's . yeeeeehaaa . He also said he could flash the fuel and timing maps for the Vortech [ up to 10 or 11lb's of boost ] so we could get rid of the piggyback all together . I decided to keep my piggyback as I'm a little leary of doing that . We could get a better response from the car down low with it , but I want control of the A/F so I opted not to do that part of the flash .