I'm thinking about adjusting the tune in my Hawk. I currently use a Boost Referenced FPR and have the base(0 atm) psi set to 60. But I'm running out of pump to get the FP past 65. So once I go above 5psi of boost I start to go lean. So I've upgraded my lines and filter and am thinking about lowering my base pressure.

I'm curious if you all think this is a good idea. If I set my base pressure at say 50 psi, I'd see ~30psi at idle and up to 63 psi at WOT. Now by lowering my FP I'm using my injectors more. But has anyone tried this method? How successful was it for you?

So if I lower my base pressure, I'd have to raise my IFR table, correct? Would I need to adjust anything else?

I'd have to monitor my injector's more closely to see if they've reached their limit. I've never broken the Injector cycles down. Can anyone tell me what features I need to monitor in Edit and the formula used to calculate the duty cycle of the individual injector?

Thanks guys, I'm curious to hear your thoughts on this.

Mike

 

Do you out-flow the maf and if so at what rpm? Do you have a wideband?
IMO i think it would be easier to just add some fuel in via the PE table.... and being a blower it should be easier to get the afr right.

 

What are you runing for fuel pump? Also how much hp are you making?

 

I haven't monitored the maf in a while, but the last time I did, I don't recall maxing it out. I have wideband now, but haven't before. So the car has never been run with incar wideband, but in a few short days all that will change.

I was originally planning to upgrade the fuel lines to -8AN, upgrade in the fuel filter to an allstar performance stainless element, and add a second pump that would kick in under boost. Well the boost switch and pump never made it in time so I just have upgraded the line and filter and am still running a single pump. This might be better for testing cause now I can see if the line and/or filter were the restriction all along. But ultimately I want to add that second pump.

At Dave's suggestion I picked up the AEM wideband setup you have. So I'm hoping that helps me keep the engine safe.

Adjusting the PE table seems sort of like a bandaid to a bigger issue. Because my FP will bounce around the 65 mark, sometimes staying stuck at 65, and sometimes dipping, sometimes it gets stuck at 64 or 63 psi. You know what I mean? How can I accurately tune with inconsistant FP like that?

I have an intank Walbro GSS340. In the year and a half I have had this blower I have never dynoed it, so I don't know the numbers. Up until a couple of months ago I was pullied for 8#s, but with the 6-rib ATI belt problems I almost never saw more than 5#s. Now with the SDCE spring tensioned 8-rib setup I have accidentally hit 10#s without really even trying. So I have to be much more cautious with this setup and is what prompted me breaking the car down to finally try and address the nagging issues, like fuel and compression. So I hope that gives you an idea of what I'm running.

Thanks for the help so far guys. I'm really interested to hear more of your thoughts on this.

Mike

 

You know I have been thinking about this, and I want to do the same thing.

Right now with my one intank 340 pump set at 60psi (no vacuum) and aeromotive regulator outside the tank but in the stock configuration (Y'd like the stock regulator set-up is, before the fuel block underneath the rear driverside seat), I should see ~69psi at WOT, but I am not. Fuel pressure goes up then falls back to around 45-50psi. It is doing this now with the new dyno #'s in my sig.
I eventually plan to get a real fuel system but I need something to get me by for just two more street nights at the drag strip and it's colder now so I will be making more power.

My IFR now is 7.871 all the way across (for the mototron 60#er's), could I put it to 5.63 (just did a proportion for IFR based on the fuel pressure at 60psi versus 43), set my fp to 43psi and expect it to go to 52psi at WOT? My reasoning is since these injectors have supported 790rwhp, I have some room to spare and since a fuel pump's flow goes down with pressure, I'll let my injectors just stay open longer versus trying to keep the pressure up. Will this work or am I just out of pump at this hp level?
FYI, I just changed my fuel filter and it helped a little but not much, maybe ~2psi and my pump is hot wired. I do have an underdrive crank pulley but that shouldn't really hurt voltage levels at WOT should it? I would think the alternator is still spinning fast enough.
And my reasoning for not getting either a second pump or a boost-a-pump is I will end up replacing it next season with probably a sumped tank, external pump/s, lines etc.

Thanks for any help

 

Do it.

Do it, just make sure you have the injectors for it.

 

See this is where I get confused. When I was still running the TTi kit @ 12psi I made #s very similar to yours Rice Etr 550rwhp 575rwtq. I'm still running stock lines, stock regulator, stock rails, stock fuel pump with a T-rex inline and 42lb injectors being the only real upgrades. My fuel pressure will stay rock solid at 57psi all the way to 6500rpm and even with the 42lb injectors at that power level the D/C was at 86%. I have a brand new Walbro gss340 on the shelf in my garage but I haven't installed it cause i don't need it yet. I know a few other local guys that are getting the same results as me also with there cars.
So my question is, why do I hear alot of people with twice the fuel system as me and my freinds having pressure and flow problems at similar power levels?
Is there any chance it could be in the regulators maybe the regulators won't flow enough fuel for out engines Or maybe it has somthing to do with the tune. I don't know, but if i were you i'd start checking the parts you have before you start upgrading IMO the fuel system either of you guys have should support 650rwhp easy.

 

Yours would be the first I have ever seen that had rock solid fuel pressure with a stock regulator at any horsepower level. Are you sure the gauge was working properly?

 

Honestly, I think it's flaw of design. I'll admit I'm new to fuel systems. I approached this initially with the "bigger is better" mentality. I didn't really examine all the peices and understand how they might work together. Now I have a bulkhead going into the tank to get rid of any restriction. And boy was there a restriction in there. When you pull your center section out and look at the size of the supply line, you think it's not all that bad. A tad smaller than a -6AN line, but looks like it would flow. What I realized after cutting that supply fitting off the cetner section was that there is a massive restriction in there. A hole about half the size of what you see is what the fuel has to squeeze threw to get out of the tank. Now take that bottle neck and dump it into a larger than stock fuel line, and a tiny fuel filter and I can see some serious flow issues arising.

Now I have a full -8AN going from tank to rail with a very larger fuel filter in between. This is my guess to the problem, but I'm still not sure till I test it out.

Mike

 

Yes the gauge is working perfect. I swaped it out with a new one because I was surprised my fuel system was supporting the amount of power i was making. I thought for sure that my gauge was jacked.

 

Mine is the same way. All I have is 42 lb injectors and 255 inline fuel pump. I am only making 520 rwhp and 504 Ft. lbs of torque.

 

Well I tried it.

5.64 IFR straight across, base fp at 43 w/o vac.... turned my boost back to 7psi so I should see 50psi at WOT and hold it...... but instead the fp jumps up to 48 or so then quickly falls back down to 37ish or so, I let out when I saw that. My AFR was safe but I definitely don't want to run it like this.
Now my question is obviously I have some sort of problem with my fuel system. Where should I look? I am running the 13301 aero reg, I called the tech guy... I have the 20-60psi spring in it and whatever amount of boost I have on top of that, it's good for... just adds to the spring pressure.
So does this sound like a fpr problem or the single walbro I have in it? Or am I out of pump?

Thanks

 

regulators bad is what it sounds like.

 

I would definately trace down the problem whatever it may be, but I would also leave the fuel pressure/IFR like you just set it since you will have more flow capability from the pump at that lower FP and the injectors still have the room.

 

Jarrod, How is your fuel line run?

How did you run your AEM UEGO wideband unit? Did you replace one of your O2s with the wideband and then run ther 0-5V output to the PCM? I'm trying to figure out how to run mine. Just curious how you've got your setup. Aldo, how did you run the cable? Through the firewall or through the shifter boot?

Thanks bro,
Mike

 

Yea I agree, especially with a single pump... and i think the car has better driveability with the injectors at a lower psi.

hopefully you can see in the pic I attached below.


The line going straight up is going to the stock hard return line going into the tank and the one going to the right is going to the stock hard line going to the fuel block... all I did was replace the plastic line between these two points with this regulator and of course remove the stock intank reg. Do you think having all that boost line is a bad idea?

No still using both stock O2's, just welded another bung in the downpipe for this, though you can let the car run off of the WB if you can cut the signal down to 0-1V.... haven't tried that yet though a guy in our club did successfully.
The sensor cable I just ran out the pod, underneath the dash (above your feet) then around under the console and made a little cut in my shifter boot as you mentioned and ran it right out that way. Seemed the easiest way to do it and keep the cabling away from moving parts and heat.
Ws6rufus sent me a how to on tapping into the A/C pressure sender to log the AFR via the 0-5v output of the WB box.... I will send it to you, though I have not tried it myself.

no prob man..... he he thanks for letting me hi-jack your thread

 

Jarrod, here's what I found out about the stock fuel feed for us 99s.

Here's the Stock feed:


Here's the size of the opening you can see from the outside:

Most assume it's that diameter the whole way through.

But in fact it is far smaller. If you cut the feed line off here's what you find:

That's about half the diameter. Like I said, I'm no pro, but that seems like a hell of a restriction to me.

I'm not sure of 98s have the same restriction, but if you're using the stock bulkhead feed then you might want to check it out.

Mike