Hey Southbay,

My 305 TPI system has the stock 19lbs injectors (not sure which brand, but that's not important) and I want to replace them, along with a higher output fuel pump. My 305 has been heavily modified top to bottom (ported tpi plenum, as&m runners, accel manifold, ported heads, cam, forged internals, bored block, etc.). I have all of the PROM programming stuff from MOATES to reprogram the chip if need be, but my question to you is that, my crank HP rating right now is 271, but I have 19lbs injectors. My engine makes more power than a stock 350, which have 22lbs injectors. So my question is: Will my engine benefit from having bigger injectors such as 22lbs? (I already have a billet adjustable fuel pressure regulator).

Thanks!

 

If you are running 271 hp you need 22lb injectors, but If you do not want to spend the additional money for another set of injectors
you are going to have to bump up your pressure to at least 55psi, you might be better off getting a set of 22's this way if you want to increase your hp you will have room to move.

 

The 271 HP is without a tune, I wanted to fully fix any problems I might have in my system before tuning, and prepare it for the coming tune. My goal is around 300HP at the flywheel, which is not too far away. I think with a better flowing pump, bigger injectors, and alot of tuning it can be had. I'm also replacing the throttle body with a 52mm one to match the 52mm plenum i have (which will also fix the worn out shaft causing minor idling issues) so that will flow more air. Once I change it to 22lbs, I will change the injector constant in the PROM. Does anyone know if there are other tables to adjust in the PROM when adding larger injectors? Or just the injector constant? Thanks!!

 

Cranking PW scalar and the injector compensation tables could use some tweaking. Most get away without it, but it isn't always the best tune.

Eight 22#/hr injectors will support 332 HP at 85% DC and .45 BSFC.

RBob.

 

Copy and paste this into the DIY PROM board. There are many members who may and will do thier best to help you out. I got so many suggestions when I started a thread about tuning a blank EPROM.

 

So 22lbs injectors it is... Is it a possibility that I lose power by putting these in? I heard the 19lbs injectors have a 'better' spray pattern?

 

Anything is possible but it all really comes down to the injector. If the injector is not clean and free of debree at the tiny fuel exit holes, then the spray pattern will most certainly be affected. You want a mist or fog of fuel, not squirts. Now as for 19 vs 22 lb'ers, the difference is the amount of fuel or total that can be injected (not sure what the time frame is). The 22 lbers are better depending on what you got. You WILL NOT benefit from 22 lb'ers if you got a 305 SB engine or 350 being ran with a 305 MemCal. It all boils down to what you combo is. You will achieve good benefits if you have a 350 MemCal, 350 SB, 22 lb injectors, and a properly running ignition system.

 

Southbay is pretty good at helping you out with what you need but of course you have the right to ask others for questions. So dont be shy. Ask around.

 

The injectors with the 4 hole spray pattern provide efficient fuel atomization, and Chevy IROCZ is correct....dirt, debris, carbon build up....anything that occludes the openings or holes will affect the spray pattern which can affect the performance of your engine. So, as long as you have a clean injector you will have the atomization/mist, and "power" that you need whether it is a 19lb, 22, 24lb,,etc injector.

 

Thanks Southbay and others...

I'll take my tuning question to the DIY PROM board and post there for that.

Chevy86: As for the memcal, I can reprogram the PROM chip so I thought that the memcal, whether from a 305 or 350, won't make a difference as long as I can change the data in the PROM chip?

 

Your right. I forgot that the injector size can be changed with TunerPro. But do keep in mind, maby you would have to change other settings to, not just the injector size. For example, if you r MemCal is a 305 TPI and you just stabbede in a 350, then you would have to change the 305 knock sensor for a 350 sensor. Both engines have a different frequency and must be a match to prevent any engine failure. Also the ESC Module must be changed out for a 350 type. There is a page that explains everything that must be switched when doing a convert from 305 to 350. It's more complicated not experienced in all of this stuff. But the focus here is the injectors. I did see that in a 87 350 TPI, the setting for the injector was 24 lbs.

 

Wait....so the setting is 24 lbs(ECU setting?), but the actual injector size is 22 lbs?????

 

Ah, yes, ofcourse there are many other things you would need to change when converting to 350. In my case, I want to put larger injectors on my 305 SB (currently have 19's) to gain more power out of the engine, which I believe is possible, and what i mean was that i don't need a 350 memcal to run 22lbs injectors on a 305 SB.

 

OOOps. Not 24 lbs, I mean 23.04 lbs. Here is a bin file that I extracted from 2 MemCal/PROM's with Tuner Pro. The file is from a OEM 87 350 IROC-Z TPI,,,,

------------------------
TunerPro Bin Data Export
------------------------
Source File: ABWN.BIN
Source Definition: $32B.xdf
------------------------------
Constants
------------------------------
Fuel Cut Off, (Speed) 255.00 MPH
Fuel Resume (Speed) 254.00 MPH
Fuel Cut Off, (Engine Speed) 10031.02 RPM
Fuel Resume (Engine Speed) 9544.08 RPM
Fan Off Coolant Temp Threshold (A/C On) 104.75 Deg C
Fan On Coolant Temp Threshold (A/C On) 107.75 Deg C
Fan Off Coolant Temp Threshold (A/C Off) 104.75 Deg C
Fan On Coolant Temp Threshold (A/C Off) 107.75 Deg C
Injector Flow Rate, (Single Fire) 23.04 #/HR
Injector Flow Rate, (Double Fire) 23.04 #/HR
EGR Off (TPS) 7.42 % TPS
EGR On (TPS) 7.81 % TPS
TCC Unlock Speed (Low Gears) 26.00 MPH
TCC Lock Speed (Low Gears) 27.00 MPH
TCC Unlock,Speed (Higher Gears) 26.00 MPH
TCC Lock Speed (Higher Gears) 28.00 MPH
Maximum Spark Retard (Not In WOT) 20.04 Deg
Hot Engine O2 Timer 30.00 Sec's
Warm Engine O2 Timer 160.00 Sec's
Cold Engine O2 TIimer 300.00 Sec's
PROM ID 8161.00
Idle Speed Adder in Park/Neutral 50.00 RPM
Idle Speed Adder for A/C On 50.00 RPM
Max Accel. Enrich. Async Pulse Width 5.55 msec
Minimum Delta TPS For Accel. Enrich. 3.91 % TPS
Minimum Delta LV8 For Accel. Enrich. 20.00 Counts
Maximum BLM Value 160.00
Minimum BLM Value 108.00
MAF High Diagnostic (Error 33) Threshold 45.00 gm/sec
TCC Unlock Prevent/Auto O/D Engage Speed 75.00 MPH
Shifter Kickdown Prevent RPM Threshold 6375.00 RPM
TPS Kickdown/TCC Unlock Prevent -1st Gr. 3200.00 RPM
TPS Kickdown/TCC Unlock Prevent-Not 1st 3200.00 RPM
Max Spark Advance 41.84 Deg.
Initial Spark Advance 5.98 Deg.
Number of Cylinders 0.00
Min. Coolant Temp for BLM Update 50.00 Deg. C
Max. Coolant Temp for BLM Update 140.00 Deg. C
Min. MAT to Enable EGR -17.50 Deg. C
TCC Enable Coolant Temp. Threshold 50.00 Deg. C
Highway Mode Spark Enable Coolant Temp. 59.75 Deg. C
Highway Mode Spark Max Load Threshold 100.00 LV8
Highway Mode Spark Enable RPM Treshold 6350.00 RPM
Highway Mode Spark Enable Delay Time 10.00 sec
IAC Startup Park Position 144.00 Steps
IAC Control Deadband RPM Error (in P/N) 75.00 RPM
IAC Control Deadband RPM Error (Drive) 25.00 RPM
Min. Load Limit for TCC Lock, Low Speed 3.13 %TPS
Min. Load Limit for TCC Lock, High Speed 3.13 %TPS
TCC Min Load Limit Hysteresis 1.17 %TPS
TCC Min Load Limit High/Low Speed Thresh 32.00 MPH
IAC Startup Delay Time 1000.00 msec

Here is a bin from an aftermarket for the 87 350 IROC-Z TPI,,,

------------------------
TunerPro Bin Data Export
------------------------
Source File: ********
Source Definition: $32B.xdf
------------------------------
Constants
------------------------------
Fuel Cut Off, (Speed) 192.00 MPH
Fuel Resume (Speed) 1.00 MPH
Fuel Cut Off, (Engine Speed) 84.24 RPM
Fuel Resume (Engine Speed) 3825.06 RPM
Fan Off Coolant Temp Threshold (A/C On) -28.00 Deg C
Fan On Coolant Temp Threshold (A/C On) 151.25 Deg C
Fan Off Coolant Temp Threshold (A/C Off) 74.75 Deg C
Fan On Coolant Temp Threshold (A/C Off) 118.25 Deg C
Injector Flow Rate, (Single Fire) 0.22 #/HR
Injector Flow Rate, (Double Fire) 23.04 #/HR
EGR Off (TPS) 2.34 % TPS
EGR On (TPS) 8.20 % TPS
TCC Unlock Speed (Low Gears) 3.00 MPH
TCC Lock Speed (Low Gears) 255.00 MPH
TCC Unlock,Speed (Higher Gears) 39.00 MPH
TCC Lock Speed (Higher Gears) 51.00 MPH
Maximum Spark Retard (Not In WOT) 20.04 Deg
Hot Engine O2 Timer 2.00 Sec's
Warm Engine O2 Timer 430.00 Sec's
Cold Engine O2 TIimer 266.00 Sec's
PROM ID 8201.00
Idle Speed Adder in Park/Neutral 50.00 RPM
Idle Speed Adder for A/C On 50.00 RPM
Max Accel. Enrich. Async Pulse Width 5.55 msec
Minimum Delta TPS For Accel. Enrich. 23.05 % TPS
Minimum Delta LV8 For Accel. Enrich. 20.00 Counts
Maximum BLM Value 12.00
Minimum BLM Value 108.00
MAF High Diagnostic (Error 33) Threshold 45.00 gm/sec
TCC Unlock Prevent/Auto O/D Engage Speed 75.00 MPH
Shifter Kickdown Prevent RPM Threshold 6375.00 RPM
TPS Kickdown/TCC Unlock Prevent -1st Gr. 3200.00 RPM
TPS Kickdown/TCC Unlock Prevent-Not 1st 3200.00 RPM
Max Spark Advance 5737.51 Deg.
Initial Spark Advance 72.42 Deg.
Number of Cylinders 0.00
Min. Coolant Temp for BLM Update 50.00 Deg. C
Max. Coolant Temp for BLM Update 140.00 Deg. C
Min. MAT to Enable EGR -17.50 Deg. C
TCC Enable Coolant Temp. Threshold 144.50 Deg. C
Highway Mode Spark Enable Coolant Temp. 72.50 Deg. C
Highway Mode Spark Max Load Threshold 37.00 LV8
Highway Mode Spark Enable RPM Treshold 175.00 RPM
Highway Mode Spark Enable Delay Time 132.00 sec
IAC Startup Park Position 5.00 Steps
IAC Control Deadband RPM Error (in P/N) 12.50 RPM
IAC Control Deadband RPM Error (Drive) 2412.50 RPM
Min. Load Limit for TCC Lock, Low Speed 9.77 %TPS
Min. Load Limit for TCC Lock, High Speed 79.30 %TPS
TCC Min Load Limit Hysteresis 27.34 %TPS
TCC Min Load Limit High/Low Speed Thresh 4.00 MPH
IAC Startup Delay Time 1000.00 msec

 

Well if you install 22 lb injectors into a 305, wouldnt you be running a little too rich. Im guessing that if your running too rich, would the ECM re-adjust causing a decrease in performance?

 

If I understand how injectors work, the only real thing that changes going from 19 lbs to 22 or 24 lbs injectors is how long they stay open to deliever fuel into the engine. Its fine to go from EX. 19lbs to 22lbs, but NOT 22lbs down to 19lbs. When stock, keep the jumps small unless using aftermarket prom's and chips. But you would also need to upgrade the fuel pump if using much larger injectors.

 

Logically I thought that if making more power, bigger injectors are needed (along with a tune to make it run right ofcourse). At 271HP, the 19lbs injectors are pretty much maxed out for fuel delivery. I will definitely get a higher pressure fuel pump along with bigger injectors (going to do it all together). So, those two variables need to be changed... But, the first one reads 23.04 for single and double fire.. whereas the 'aftermarket' one reads 0.22 for single and 23.04 for double fire... Why is that?

 

Just to let everyone know who helped me on this thread, I found out what injector this is. Is as follows;
1985-88
305
Lucas 5720D780
GM P/N 10108480
Lucas Service P/N 5207002

A good local friend from my area let me borrow his Chevy TPI fFuel Injection Swappers Guide and it is loaded with good stuff. If anyone is interested in the material that Im looking at, here is the cover so that you can search for one of your own.

 

Whats the ISBN number on the book, please.

 

1-884089-12-7

There you go bro.

 

what he said

 

Can you give me approx hp this way i can size them out for you.

 

Here is a list of OEM F.I. that came with our TPI Camaro's.

 

Idk hp yet the engine is going into machine shop this coming weekend. Maybe they can give me a better idea of what it will make. Its a 383 with *113 heads and lunati voodoo cam #60121 roller rockers at 10.5:1 compression ratio and its Tune Port injected .. Maybe you have an idea Thank you

 

Hoping someone can help me out with either where to get a tune (if needed) and also a good fuel psi level to be @ with my adjustable reg gonna give a link to the "replacement" injectors I bought and installed....http://www.ebay.com/itm/Camaro-Corvette-Firebird-TPI-Fuel-Injectors-5-0L-5-7L-305ci-350ci-Genuine-Bosch-/201340792680?hash=item2ee0d8af68&vxp=mtr I'm a father of 3 and went with cheaper injectors I know but I have a 91 z28 (305) tpi with only a 52mm TB edelbrock lower and upper intake with a cat back...so my question is what is a good fuel pressure to run with and where can I get a tune if need be? thank you to anyone that can give any useful advice!!! I have no idea if they are 19's 22's etc

 

Cheaper but not better than Bosch 3s.
Since the flow 19#hr at 3bar you don't need a custom engine tune.
If you have made modifications, camshaft, cylinder heads, intake/exhaust modifications.
You would need to datalog to see where your blm is at and go from there for tuning correction .btw you should pick a newer date thread or start one lol.

 

the way they advertise them I wasn't sure if they were 19's or not! cause if they are infact 19's I can go to a higher fuel pressure like 42psi etc but if they were considered 22's I was thinking I would have to lower the psi to like 37psi is what I got off a facter chart online lol

 

Thank you and sorry kinda still new on here but will try and post a new thread like I said I'm a newbie. 3bar and blm are things I don't even understand.

 

Can't find where to create a new thread??? I've only replied to existing posts so far.

 

 

 

They both have just about the same flow rate. What does like new mean? That they're stock injectors that were rebuilt? IMO don't do it.... Unless they are brand new. They're multecs….you don't want any problems down the road with those things....they're junk.
I'm going to be posting a black Friday sale....20% off just about everything on my website...so if you want a set of bosch injectors you'll get a good price. Even if you don't get them from us...don't buy used multecs