Tuning for bigger injectors 63lb

[Isaiah48]

I currently have the stock injectors in my 05 corvette with H/C. I ordered 63lb units and was wandering how to go about adjusting my tune to compensate for the increase in volume. Please talk at a newbie to intermediate tuner level.

[EC_Tune]

Since the Injector flow limit is 63.49 #/hr you will definitely go over that limit with Mototron 60's. However I have had good luck with maxing out the IFR table with the Mototrons and adjusting VE & MAF like normal.

BTW: A 42# injector might have fit the bill a bit closer with an NA combo.

[Isaiah48]

EC_Tune, I went with the 63#/hr injectors to allow for a possible 150hp Dry shot of Nitrous in the future.

I'll give the advise you gave a try, thanks for the help!

The injectors I purchased were the "Racetronix Siemens / Motoron Injector 63lb/hr - P/N LU107FM" Are these the ones you had good luck with?

[5_Liter_Eater]

Search for the injectors.xls spreadsheet. Plug in your numbers and look at row 26. Those are the numbers you "should" use, but they are well above the 63.5#/hr limit. Keep lowering the "injector rated flow rate (cell B6) until the last column in row 26 is at or just below 63.5. This should be ~50#/hr. Use those numbers for your IFR table. Then you will have to lower your MAF flow table because you're running 63# injectors but telling the computer they are 50#'ers so you will be way too rich. 50/63=.794; so ,multiply both MAF tables and your VE table by .794.

Then search for SJSchafer's post about getting 60#'ers to run to get better offset and min pulsewidth numbers.

[Isaiah48]

Search for the injectors.xls spreadsheet. Plug in your numbers and look at row 26. Those are the numbers you "should" use, but they are well above the 63.5#/hr limit. Keep lowering the "injector rated flow rate (cell B6) until the last column in row 26 is at or just below 63.5. This should be ~50#/hr. Use those numbers for your IFR table. Then you will have to lower your MAF flow table because you're running 63# injectors but telling the computer they are 50#'ers so you will be way too rich. 50/63=.794; so ,multiply both MAF tables and your VE table by .794.

Then search for SJSchafer's post about getting 60#'ers to run to get better offset and min pulsewidth numbers.

Just when it was looking easy you went and complicated everything 10 fold. Oh well,what has to be done, has to be done... I'll start researching what you clued me into to now.
Thanks for your help and stayed tuned, I'm sure I'll have a lot more questions.

[z0sik]

what injectors are they? I know some of the FAST injectors for the LS motors are rated at 58psi. The 65lb FAST injectors for the LS7 are rated at 58 psi.

[EC_Tune]

Not to sound obtuse here but I just use the MAX value for the injector and slope down where it slopes down. Then tune appropriately. I would rather have the injectors as close as possible to the "correct" values and not have to worry as much about VE/MAF trans torque issues (on autos).

[Isaiah48]

Not to sound obtuse here but I just use the MAX value for the injector and slope down where it slopes down. Then tune appropriately. I would rather have the injectors as close as possible to the "correct" values and not have to worry as much about VE/MAF trans torque issues (on autos).

What do you mean "slope down where it slopes down"? Where do you see slope at? Also I have a manual not an auto, so how does that play in?
Thanks,

[Isaiah48]

what injectors are they? I know some of the FAST injectors for the LS motors are rated at 58psi. The 65lb FAST injectors for the LS7 are rated at 58 psi.

The injectors I purchased were the "Racetronix Siemens / Motoron Injector 63lb/hr - P/N LU107FM" They are 63lb at 43psi and 72 at 58psi... When I ordered them I thought they were 63lb at at 58psi which would of worked great when I setup my 175hp dry shot, but 72lb's may be too big to tame,we'll see...

[EC_Tune]

On some of the LS2's & on the LS3 the injector slope isn't just 0-80Kpa Vacuum. Some are set up for differential pressure across the injector and the table is much bigger. In your case the IFR is the same as an LS1 series 0-80 Kpa Vacuum. So you don't have to worry about "roll off" under boost because yours doesn't because it just uses the 0 Kpa line in boost.

[Isaiah48]

On some of the LS2's & on the LS3 the injector slope isn't just 0-80Kpa Vacuum. Some are set up for differential pressure across the injector and the table is much bigger. In your case the IFR is the same as an LS1 series 0-80 Kpa Vacuum. So you don't have to worry about "roll off" under boost because yours doesn't because it just uses the 0 Kpa line in boost.

Thanks, no boost, no worries... Here is a question though; should I even try to tune these huge 72lb'rs or should I just backup and regroup with some 42's and use a wet shot instead of dry like I was planning? After reading threads for hours yesterday, I'm really second guessing my decision to go with the 72's... I'm not sure if anyone has really gotten these things down pat yet, they're just so much bigger than what the ecm allows for, it seems like it really complicates alot of different things that I'm not sure I'm ready for just yet. I like a learning curve as much as the next car geek guy, but come on... Any thoughts? If I do go into doing this, it looks like there is a lot of support here.

[EC_Tune]

I'm probably the wrong one to ask about nitrous... LOL I don't have a high opinion of it yet. Not enough safeties built in IMHO.

What if the fuel solenoid doesn't come on (wet shot)? Is there a safety built in for that? What about fuel pressure as well? Nitrous pressure? Lots of variables that need to be taken into account.

[BobDoLe]

fuel solenoid failure? - dry shot with harris speed works interface = no fuel solenoid and computer controlled fueling while spraying.
fuel pressure? - fuel pressure safety switch (shuts off nitrous if pressure drops too low)
nitrous pressure? - nitrogen push system keeps pressure at 950psi while spraying

any other variables?

[Blown]

Sounds like a lot of $$$$$$$$ .....not to mention the bottle fills.
I'm with EC-Tune on this one.

[ALB]

Guys sorry to be dumb but how do I get that spreadsheet to work. I can't seem to input any numbers just get a plus sign or something. Or could somone just give me the IFR for 60 pound mototrons. I need to get my car running asap.