zapp168

iTrader: (7)

I will be honest, I searched and found formulas that made my head spin Could I get some opinions please?
I am seeing 100% duty cycle at 5000 RPM with 60# Mototrons, the car is also leaning out near that area. What size are other people running for injectors? Thanks

Jimmy P

iTrader: (177)

You should be ok with your current setup and the 60lbs. What is your base fuel pressure at? If you dont already have one, get an adjustable FPR with boost referance. We had to set my base fuel pressure at about 72lbs with my 402 and D1SC.

zapp168

iTrader: (7)

I was going to do that with the second fuel pump install, but was told that it was not needed, so I am still running the stock return style plumbing. As you changed the fuel preasure, did you re-tune the IFR to compensate? If I add the FPR to the front, I should be able to just leave the regulator in the tank as the tank regulator is after the front regulator?

Jimmy P

iTrader: (177)

I already had the adjustable FPR on the car, so we changed the base fuel pressure as the car was getting tuned the first time.

FICINJECTORS

iTrader: (30)

What crank HP are you making? I can run the math for you if you like

zapp168

iTrader: (7)

Care to calculate for 650 RWHP? I am still trying to get the car running well enough to take it to the dyno. I don't want to go there to hear, "you need this, you need that, come back" The place is not so close. I have posted to ask people with similiar setups and the "guestimate" is 600-650. We just added the second pump and I made my first full 1/4 mile run without it falling on its face. Thank you for the offer.

FICINJECTORS

iTrader: (30)

Alright, doing a 15% parasitic loss being a manual, I came up with just about 750CHP.

On a 58psi rail that the LSx has, you need a 60lb injector at an 80% duty cycle.

Mototrons are very good injectors, so the problem lying there is fairly small, that is unless someone sold you something other than 60's without telling you.

I would check fuel pressure first and foremost. If its not at 58 throughout the band, they wont give you what you need.

zapp168

iTrader: (7)

THANK YOU! I ASSumed that the second pump and rails would be more than enough to solve my pressure woes, next purchase = better gauge, and a regulator. As for getting duped on the injectors, I used a calculation table I found here and tuned the IFR table with it and the car fired and ran with almost perfect AFR, is that enough of an indication that they are correct?

FICINJECTORS

iTrader: (30)

Thats a pretty good indication. And no problem at all, car sounds like a beast

zapp168

iTrader: (7)

Thanks again, it is gettin there!

Jimmy P

iTrader: (177)

I am curious, what type of math did you do to come up with this? Just wondering if there are different variables to put into this calculation because its a FI build.
I just know from personal experienc that with a 3.4 pulley on a D1SC blower setup, a base fuel pressure of 58 will not be enough for 60lbs injectors.

FICINJECTORS

iTrader: (30)

Hp X B.s.f.c
--------------
No Of Injectors X .80ds = Lbs/hr Per Injector

Bsfc = .50 For Na
.60 For Supercharger
.65 For Turbo Charger

ZL1Killa

iTrader: (17)

anyone ever been to www.rceng.com ?? and go to the TECHNICAL SIZING PAGE .... I do have a sticky....


grab you some racetronix 79#ers or something larger

zapp168

iTrader: (7)

Ok I went there, 60# injectors should be enough for me then? If that is the case I either still have low fuel pressure after adding the second pump, or I am making more HP than I think I am (but I don't think so). I had the plan to get larger injectors when I saw the duty cycle go that high. Sorry I missed your sticky. I did not see it when I searched.

ZL1Killa

iTrader: (17)

they for some reason don't show up when searching. its at the TOP of the fuel and injector page here

Racetronix

iTrader: (2)

If you are not using a rising rate regulator your injector constant decreases as your manifold pressure increases. If for example you are running 12PSI of boost the pressure differential across the injector drops 12PSI. If you have stable fuel pressure at the factory set 58PSI then the injector would behave as a 73PPH injector at zero manifold pressure. At 12PSI boost the injector would behave as a 65PPH injector. These numbers are approximate.

You should consider a rising-rate regulator setup. It will make tuning the A/F under light load easier and extend your HP support under boost.

Assuming everything is working properly with your current fuel system setup you should be able to support apx. 700 crank HP with a duty cycle of apx. 80%. This does not factor in the parasitic load of the blower or other power accessories.

zapp168

iTrader: (7)

Sold...I was honestly looking into that and asked an "expert" and was told it would not be needed. Now as for the in tank regulator, as long as I disconnect the return line from the T- block and plumb the return from the front regulator I don't have to drop my PITA tank again correct? I would rather run a new line than use the EVAP line. BTW thanks everyone for all the help!!!

Racetronix

iTrader: (2)

You can silver solder / braze some -8 fittings on the back end of your factory fuel rail and run both sides to either side of a universal regulator. A -6 TEFLON SS line should be run from the regulator return to the factory return at the back of the car. The factory return can be adapted to mate with the -6 Teflon SS line with a push-lock adapters or some compression fittings. The return port on the factory y-block (where the metal return was removed from) can be plugged with a Saginaw fitting. You can cut the Saginaw nut assembly off of the factory return line and braze a SS nut into the end of it. This makes a cheap and effective plug. Make sure to remove the o-ring before heating the fitting. If it is nicked replace it with a Viton o-ring. Unplug the regulator from the F98 factory sender and cut off the reduced/tapered part of the return tube. This can all be done for under $200.00 and will support upwards of 800+RWHP with a properly built DP system such as the one Lonnie's Performance supplies.

Racetronix

iTrader: (2)

These images should help. All this can be done easily with a cutoff tool, file, sandpaper, MAP gas torch, silver solder and some flux. This setup can support 1000HP+ with a proper pump system.
The D/S rail fitting has a -8 Teflon line running to the P/S 'T' fitting. The other side of the 'T' fitting runs to a regulator. Make sure you remove the pulse dampening strips inside the rails once the end caps are cut off. This particular rail setup is from a 950RWHP TT C5 Z06 using a Racetronix / Lonnies DP fuel system.

zapp168

iTrader: (7)

Thank you, that was a lot of information, I am running aftermarket rails, but I get the ides, I am just not looking forward to dropping Mr. fuel tank down, and no....I don't want to cut my car . We got a little busy here so as usual my car moves to the back burner. Thank you very much for all your information.