OK, before I install the Walbro 255, I felt compelled to once and for all, explore the capabilities of the stock fuel pump with the Greddy kit.

WARNING: Dont try this at home unless you have a wideband A/F installed in your car.

I recently installed the ignition timing harness and have retarded timing progressively from 2 deg. to 8deg at readline. The retarding begins at 3000rpm and continues to redline. Better safe than sorry.

With 91 octane gas, and no octant boosters of any kind, I began making WOT runs in 2nd gear at 5psi, 6psi, 7psi, and 7.5psi.

At 6300rpm, A/F was at 11.1, 11.5, 11.8, 12.3 at 5, 6, 7, and 7.5psi.

Also note, I added fuel via eManage on each of these runs, but its obvious the injectors are maxed out with the stock fuel pump...there just isnt any more pressure availble. i was adding 50% more fuel at 6000rpm! yikes. If i didnt add any fuel, I imagine these numbers would be even leaner.

So based on this test, I feel comfortable saying that if 12:0:1 is your max safe A/F ratio, I would keep you boost around 7psi. If you wanna live on the edge and run mid to high 12's on A/F, i bet you could get close to 8psi on the stock fuel pump.

Since I did 360whp at 6psi, I think 7psi would be good for about 380whp or so.

Oh, and with the aggressive ignition retard I programmed in, there was no hint of detonation.

Any questions?

 

Thats awesome. I think ur are the first with the greddy TT to get to 7.5psi safely. Keep us posted on the rest of your testing.

 

at least with the stock fuel pump on 91 octane gas.


Oh, and dont attempt this unless you have the timing harness as well. I didnt go above 6psi until I got the timing retard....too dangerous in my opinion.

 

Is your test that is about boost levels "exploring the stock fuel pump" for Greddy TT only ?

 

Yes, this only applies to the Greddy TT. The TT puts different fuel demands on the system vs. an SC, or even the PE kit. So you'd likely have to run this same test on each specific kit before making similar conclusions.

So far, nobody has been able to keep an 8-8.5psi Greddy TT kit in the sub 11.5:1 range without an upgraded fuel pump. On the dyno, they all go lean.....and my road tests would seem to confirm that.

 

GQ, you rock. I kinda regret going Greddy instead of PE because of the lack of timing and tuning solutions for this god-damn kit. However, you give me a reason to remain optimistic. Please keep it up man, I wanna see you at 8.5...

 

slay...dont dispare. The PE kit is even more limiting right out of the box. It only boosts just over 4psi and the ECU remains totally stock. The fuel system consists of 380cc injectors, and upgraded fuel pump, and reg. To boost more than 4.4psi, you need to get the TS reflash to 8.5psi.

So you are fine.. Just get yourself the timing harness, diodes, the Walbro 255, some tuning, and you'll be boosting 10psi!

 

Hey GQ, I see you post a lot and when you post, you put valuable info. I appreciate it.

One quick question is that walbro intank or inline pump?

thank you again,

 

Thank you for the kind words...just trying to help.

Walbro intank. It is a direct replacement for the stock pump. With the Walbro 255, you do have to dremel some of the plastic buttom piece of pump. Other than that..it's a direct swap.

 

Yikes~! Now THAT is dedication.

BTW, you can send your stock FP to RC Engineering now and they'll tell you what it flows at different pressures or voltages and at what pressure the internal safety bypass opens up.

 

Where did you get the fuel pump from?

Do you recomend for stock emanage boost, until I get some time to tune?

Thank You,

 

I bought the fuel pump from Dynamic Autosports in Lake Forest. They were one of the few places that had them in stock. They'll usually match other online prices. Ask for Chip (949-457-1234)

The kit should be OK out of the box at 5psi or so without the fuel pump. My only concern was the timing issue and occasional pinging with my 2004 Z. Seems like most of the cars arent pinging, but mine was. So it really depends.

In my testing, the fuel pump was good for 6.5-7psi...depending on how courageous you are. At 7psi, you'll be near 12.5:1 at readline...maybe a tad higher.

If you wanna run 5-6psi, instead of the fuel pump, get yourself the ignition timing harness and diodes ($35 total parts) and retard your timing if you hear pinging. Like I said, most cars arent pinging at standard boost levels, but mine was on the shitty 91 octane gas we have here in LA. If you live in a place with 93 octane fuel, you should fine without the timing harness up to 6psi.

 

Haha I have 93 octane over here in Georgia. Thank you, for the reply.

 

You are golden....you car will definately not be pinging at 6psi or less. Above that...still get the ignition timing harness...and above 7psi, get the fuel pump upgrade.

 

the walbro is available everyplace online - you should ahve checked with vendors here first

As for volume, it's been tested countless times before...biggest issue is, this pump is also not a solution for the car either without sbstantial fuel system mods (ie introduction fo a return and a true 1;1 external regulator)

 

Z1, I checked online...but I got my pump at near cost. Same place I got my turbo installed and stuff, so they gave me a good deal. By all means, everyone.....check on the forum vendors as well, and support them!

The Walbro is just the first step.........my experimentation continues. I will document what the Walbro does to my car first, then move on to FPR and return line...then...who knows.....sub-injectors???

Z1...are you stalking me?

 

hehe...just try to help Lyaloty in this biz is rare - if you ahve guys you trust, thats awesome!

Sub injectors can work too, but I think you know how I am going to feel about those too - again, it's too early 90's tech for me.

let us know if you need anything

 

Is this "ignition timing harness" you speak of an upgrade for the e-manage? If so, how much can you pull and what RPM intervals can you change how much you're pulling?

BTW - nice "gutsy" test

 

Yeah, the ignition timing harness is optional, and it runs about $30. You'll also need to wire in some diodes to prevent overheating/burning out the coils. The diodes are $6 total at radio shack. ETX posted a great write-up on how to install and wire it....do a seach.

To retard timing, you'll also need either the Greddy Support Tool and a laptop, or you can use the Profec e_01 which is what everyone is doing here on the boards.

You can retard timing in different ways. The most basic way is on a 16X16 map of MAF voltage (airflow) and RPM. This is how I currently have it setup. You can also get the boost sensor cable for $20 and run timing with boost/rpm. Your choice.

Currently, I have 2 degrees of retard at 3K and gradually layer in 8 degress of retard at redline. Every car is different, so you'll likely have to experiment a bit to get it right. I think the maximum you can pull with the eManage is 20degrees, which is way more than you'll ever need.

Also, the eManage can only retard all cyclinders by the same amount. Some units, such as the J&S Safeguard, can retard timing in the individual cylinder that is knocking. That is the only feature that the eManage lacks, since it has no provisions to "listen" for the knock via the ECU knock sensor wire.

 

Hey gq, did you need a greddy RPM Box? Have any idea what it does? I was talking with my tuner and i wanna try to go for 9 lbs on the ATI kit by adding the 440cc and the emanage. Im not sure if i can run the injectors alone or do i need to keep the the inline fuel pump with the ATI kit.