98 Camaro, stock FPR, 42.5lb inj, Flat IFR?

[Blizzard242]

I've been trying to figure this out forever. I've read so many formulas for correctly sizing the injectors for the IFR table and now I don't know what's right. I've upgraded to lucas 42.5lb injectors btw. Anyways, the formula I'll be trying now will be 42.5/22=1.931818etc.. Then multiplying my stock table by that.

The other formula "([Rated Flow]*Sqrt[(vacuum+fuel_pressure)/rated pressure] = flow rate" Got me all lost because I don't know any of the information that's needed to plug into it.

I've read the injector spread sheet and tried that in the v6 tab but it doesn't make sense to me.. The numbers it told me to plug in started at like 5.3 so I knew that wouldn't work out.

But I had read somewhere recently in this forum that since I'm using a vacuum referenced FPR I should have a flat IFR at 42.5 straight across the board. How much truth does that hold?

I want to get these injectors out of the way so I can get to MAF and VE tuning but I feel as if I've hit a brick wall. How can I even tell if I've gotten my injectors tuned in correctly?

I'm running a turbo with 7-9lbs of boost so from what I've read I want to keep my FPR's vacuum reference line still connected and not have a flat IFR. Help?

[xcdarrel17]

I just installed the same injectors on my 98 camaro 2 weeks ago. I had the same question about scaling the table or using a flat number and never found a good answer. For now i just threw 42.5 in there all the way across and it runs fine for regular street driving. I don't know if this will cause a problem once I really get into tuning and dialing in it in right. I'd certainly be interested in finding out too.

[Blizzard242]

Ok.. as for the formula ([Rated Flow]*Sqrt[(vacuum+fuel_pressure)/rated pressure] = flow rate

I'm gonna be entering 42.5 in for a lot of those values. I was told my rated flow was very close to 42.5 by Scott A. Cook from intense. That's about exactly what he said. Anyways, my fuel pressure is at 42 or possibly 42.5 at idle, and the rated pressure of 42.5lbs So I have all of those values except vacuum. I'm at a bit of a loss on that one. Wait a minute.. I have a boost and FP gauge. After doing a few tests while standing on the brake in my driveway I've got a few numbers to plug in now.. lol. I'll post back in a little bit.

[Blizzard242]

No go. I'm getting values that would be way too rich at idle. I'm lost.

[dbyoho]

ok guys i used this site to tune them but you have to have a fuel presure gauge so you can read your wot and idle pressures..
turbov6camaro.com under the tuning section then fuel section
i dont know of any way without knowing the pressures

[Blizzard242]

Yeah I read that site a while back before I even got HP tuners. I didn't really like that method. Still seemed eh.. Anyways

This is gonna work good for xcdarrel hopefully too.. I looked at the repository tunes for 98 camaros/firebirds and they all have a flat IFR table. (I lost my stock tune in a computer crash) Well after learning this since I was previously comparing and calculating with a stock 2002 camaro IFR table which is curved, I plugged in my numbers again in the smaller formula.. 42.5/22=1.93181818181... multiplied the stock IFR number 22.18 by that and got 42.84. I put that straight across my IFR table, reset the fuel trims and took it for a test drive. The car is running better than it ever has now with these new injectors, while in gear and in idle/park.

Now I just have to take care of this PLX wideband offset nonsense..