Changing Injectors

[Dale]

Ive changed fuel injectors in my motor. I have changed my B4001 per joecars xls spreadsheet. My fuel gauge has broke so I was going from memory tell I can replace that.

Anyway, Are there any other changes I need to make since I went from GM injectors to denso/Fords?

Should I expect to have to tweak the ve table again?

[98 tigershark]

Hi dale,
What peak torque are you shooting for? what Fuel rail psi, IFR and what G/S does your motor put out at 90% ve and what is the size? Lucas has a formula that seems complicated but once you play with it it is really pretty simple. Are these the 53lb ford injectors? I have heard good things about those. Can your fuel system sustain the injectors at peak torque. I have a post "understanding maf and ve", next week I was going to post the formula for IFR and ibpw as they include a little VE. Unless your running open loop most Mafs leave the VE table at 4000rpms. I think you asked a very good question. If you have the info, I will try to send some info to help but VE's are usually individual to each car when you add performance toys. Joe and bruce have tought me alot and they know way more than I do, but if I can help let me know. Do you have a WBO2? That would answer things wright away.
Regards,
98 tigershark

[Dale]

Hi Tiger, thanks for the response. Ive noticed that it did seem to change my ve table a hair.

But to answer some of your questions
1. torque, dont care. Just want it to be effiecent.
2. gauge is broke, and new one is more expensive then I thought. But last I checked it was 45-46'ish psi.
3. IFR?
4. G/S?
5. F55E-A2D Ive read they are to be 24'lb. But I think they are less then that. I set them for what I think 24 would be, and it was WAY to lean. Ive got them set now around high 22's to low 23's.
6. No MAF
7. No WB02

[joecar]

Usually [in theory], if you can get the IFR recalculated to match your new injectors, then your VE doesn't need to be adjusted...

But [in practice], the new injectors may have other differing characteristics (like turn on/off delays may be different, minimum pulsewidth may be different, etc...), this would require tweaking some of the other tables... but the problem is not having that other information readily available.

Is there a way you can find out what pressure are your new injectors are rated at...?
Is it 45, 43.5, 43, 42, 40, 39 psi (various Ford injectors are rated at various psi's)...?

You will need to at least borrow a fuel pressure gauge and check your rail pressure... it should be closer to 58 psi... also check for variation thruout the rpm/load range.

Also, I can't take credit for the spreadsheet... the 1st few lines of the spreadsheet name it's authors.

[odd boy]

give me the PN of the new injectors

[Dale]

Yea, I understand the "in theory" part. But figured I would ask. What I am trying to do is as you state, keep tweaking the injector size in the computer tell I get my trims back to where they were before.

Another problem is as you state on the what were the injectors rated at? I looked in a haynes manual and it depends on what motor they were pulled from. Some where 30-40, another was 40-50. ARGH!!!

Plan on buying a new gauge(or find the part that disappeared off mine). I didnt remember them being that expensive.

Joe, remember I am a TPI motor.. we run at 38-47PSI. 50+ would be for a CPI, LTX, LSX.

[Dale]

give me the PN of the new injectors

F55E-A2D

[joecar]

Ah, I forgot you have TPI... (you would have the manifold referenced regulator, so your IFR is flat).

[Dale]

I figured you forgot that as I am one of few here that has this setup *looks around*.

Yes, I have an on-rail regulator. And yes my IFR is flat at 3.0547 at the moment.

[98 tigershark]

Hey Dale,
I would call ford performance and they can tell you the psi and the flow rate
But her is the formula to figure out injector flow rate
Flow Rate = (horsepower x .45 BSFC) Divided by ( the number of injectors 8 x the maximum duty cycle or percent which is 80%)
flow=(240hp x.45)divided by (8 cylendersx .8)= 24.37 lb/hr injectors
Increasing PSI if possible is a cheap way to increase the injector flow.
So if ford says they are 24lb/hr injectors at the specified factory psi and you have more horse power than the calculation than you will be too lean as the IBPW wont make the motor happy. What I use for a fuel pressure gage is one that most car part stores sell. I bought mine for $34.95 and it does the job if you have someone to rev the motor so you can hold it on the fuel rail. GM performance could probably tell you the fuel psi of your system and ford could tell you the flow rate and the required PSI and then use the formula if you know the approximate HP you have or think you can have. By the way G/S is Grams per second of air. So when the ve table says 75% it means that your motor is at 75% efficency at that point. Example would be if VE is 75%, convert the VE table from percent to G/S. So at 3500 rpm and 70 map Kpa It would tell you the G/S at that point. If 75% is 150 G/S than your motor is really sucking 200 G/S of air and At 14.63 G/S air (stoich) To 1 G/S of fuel you are pretty safe. Under power enrichment you can set the motor to run richer when you get on it. I like mine to peak at 11.70 to 1.
I hope I didnt make this confusing but it is pretty simple.
Let me know how it works out and good luck.
98 tigershark
Thor