TomQ

I installed TR224 cam and FLP LTs and according to Team-ZR1 scanning software with un-tuned 30lbs injector i was useing them at about 70%-80% cycle duty(can recall exact numbers), so with stock injectors i would've pushed them up to 100%+ cycle duty.

Car felt much better with bigger injectors!

needmoremoney

So can i install 30LBser's to, and not worry about needing custom tunning? I would love to do this, cause im sure my stock 26LBs'ers are maxed out to the extreme if you look at my sig.

malibu350

More than likely you could....because with the 30# injectors the computer will still think that you have the stock injectors so the pulse width will be the same, and the injectors will be spraying more fuel for the same pulse width. But if you don't need all of that fuel it cause you to run too rich. And then you would need some tuning. Because with our increased fuel pressure the 30# SVO injector will be more like a 36 or so...I can't remember the correct formula...but maybe somebody else will. Good Luck.

needmoremoney

I will not be doing tunning, so do you think this might be a worth while upgrade? Any performance differance maybe? With all my mods, using the stock injectors, they must be @ 100% duty cycle at idle...

WICKED SS

iTrader: (36)

I have the same cam and FMS 30lbs and my car seems to be running really rich, so you have stock tuning with those 30lbs?

Team ZR-1

If your running real lean then you can swap the injectors to the SVO 30 and over a period of drive time the PCM will shorten the pulse width due to the O2s reporting too rich and will run OK but best case is to tune for that gives the best overall performance and daily driving conditions.

You must do an idle relean with and without A/C on so PCM can also recal for idle conditions/trim cells.

In Anton's case I did tune the PCM and before PCM had enough drive time to recal all the tune changes his testrun on the street was:

MAF flowing 43.4 lbs/min MAX
138 Max MPH
431 Max FwTq
6752 Max RPM
483 FWHP

( this gave close to 400 RWHP on dyno after PCM cal'd in, about 4 days after testrun was done)

The Injector pulse width hit 18.3 mSec ( 80% duty cycle) so it is clear being the SVO 30 gives an increase of just under a 30% fuel flow gain that the stock injector would have been working much harder and easier to fall behind the engine load, esp peak loads.
Being he is still using stock aircleaner setup ( sucking in engine bay heated air) the IATs were :

Intake Air Temp: 107 Average ( in 73 degree weather)
thus would be even leaner with stock injectors so having larger injector allowed more flow adjusted in tune to overcome the hotter air temps.

This allowed his Z06 to run at 26 degrees of timing at PE and WOT and had zero knock.

This overall allowed using Ca smog gas and the fact he lives in a very hilly city to tune out knock, maintain higher timing then stock Z06s and
end result was about 35 RWHP gain shown on a dyno, plus can just use the smog gas and not worry about knock/ping.

SDB

iTrader: (7)

Team ZR-1...

Is there a way to use a scan tool or Snap On OBD-II to see what my injector duty cycle is, or a way to "interpret" what it is? I would love to see what mine are, and then myabe buy teh 30 lb. SVO units...I would assume I am pretty maxed out as well, but would hate to buy injectors and do tuning if it isn't a problem now...is pulsewidth something I can look at to interpret duty cycle (above post)?

Thanks
SDB

Team ZR-1

SDB,
scan/record injector pulse width and then use my table to get a close idea if and when the injectors are at 80% or higher duty cycle

Injector Duty Cycle as to Pulse Width

RPMs -- 80% -- 90% -- 100%

3000 32 ms 36 ms 40 ms
3500 27 ms 31 ms 34 ms
4000 24 ms 27 ms 30 ms
4500 21 ms 24 ms 27 ms
5000 19 ms 22 ms 24 ms
5500 17 ms 20 ms 22 ms
6000 16 ms 18 ms 20 ms
6500 15 ms 17 ms 18 ms
7000 14 ms 15 ms 17 ms
7500 13 ms 14 ms 16 ms
8000 12 ms 14 ms 15 ms

If your stock injectors are outside the 80% duty cycle window often then you could do the injector swap, let PCM auto adjust for them and you could use them that way but if you see after 3 - 4 days of use that its now running a bit too rich for best performance then a tune would be a must.

If the fuel trims are only out of wack when the engine is in high load then of course fuel trims would be too rich during part throttle and a tune is really needed to control injector flow to bring the fuel trims to a level you want them.

As conditions occur requiring more or less flow then again the tune allows the same larger injector to act as if they were stock or allow the additional flow the larger injectors supports.

Mekkadon

iTrader: (3)

very useful information TeamZr-1. I will be using this table for future purposes.

SDB

iTrader: (7)

Thanks for the table TeamZr1....I will try to get a Snap on OBD II and run my car with it to look at stuff...I will post when I have done that

SDB