Advice:427 supercharged LS9 injector/LS7 MAF

[exploder]

The reason we chose these injectors over the 80lbers is they are not offered in the short style. With these injectors we will not have to fab spacers for the fuel rails and have to find the correct o rings to adapt them as well.

The supercharger did arrive today as planned and I am going to start installing it tommorow. I will most likely be done either this weekend or early next week. Any more help on the ifr tables would be appreciated.

[joecar]

If the LS9 injectors have been modified, then you will need to know the new measured flowrate...

you will need to recompute B4001 to rescale for the new flowrate and the intended/measured rail pressure...

modifying the injector may alter its other "characteristics", but probably not very much... the other injector tables (B3701, B4002, B4003, B4005) should be sufficiently close enough to use with the modified injectors... (...and you have no other tables/values).

[Chuck L.]

Good analysis.

Would BSFC .6 be typical for boosted application...?

that's what I usually use. If the engine has really good VE, then that number could be lower.
Some use even higher, like .62 for FI, .5 for NA. We all wish we could get down to NASCAR area.. Maybe <.4 !
Maybe, someone that's doing some dyno testing could post some BSFC's they are seeing w/ really hi flow systems??

[Redline Motorsports]

I just laid down 855 RWHP and 840 RWFT with 63.5#'s with a boost regulated fuel system at 1:1 ratio.

That was on 12 psig of boost. Lambda was a solid .78-.80 and I still have more room for more.

Howard

[exploder]

I guess what your saying is you have a similarly setup car and those are the numbers you laid out. Great numbers for sure. I hope we are that lucky.

[exploder]

OK.....

I got the supercharger on and everything running pretty good with the stock injectors. I installed the new 80lb LS9 injectors this morning and my day has gotten a whole lot worse. I can't get these things to idle anywhere near 14.7ish. The best I have gotten it to idle is 12.2ish. I have tried upping the ifr table 20% and lowering it 20%. I then tried to decrease the ve tables by as much as 40% and I still have not gotten anywhere close. I used the marcintechnology IFR calculator and input the info from the injector flow paper that came with them. I then used the conversion chart that joecar was nice enough to do the legwork on and filled in the small pulse and other transient tables based on what the STOCK ls9 injectors show. What is my next step? Here is a tune file of what we are working with.

I also got a tune from andy at A&A corvette that is running these identical injectors and has them running smoothly however he is using hptuners and is also tuning on a c6 vette not a c5. Here is his tune file for comparison as well. I don't know how to extrapolate between the two files.

[joecar]

Exploder,

Is FPR un-referenced or manifold-referenced...?

What is your measured running rail pressure (remove reference hose if FPR is referenced)...?

What is the flowrate of the injectors...?

[exploder]

The car is boost referenced. The FPR is set to 58psi with the vacuum line plugged in. The injectors are rated at 80.5 at 43.5. Anything else you may want to know? I can adjust rail pressure wherever you guys say it should be.

[joecar]

Measure and set the rail pressure with the reference hose unplugged... set it to 58 psi.

Then when done setting it, remember to reconnect the hose.

[joecar]

With rail pressure set to 58 psi (measured with reference hose unplugged), this is the IFR:

ifr = 80.5[lb/hr] * sqrt(58[psi]/43.5[psi]) = 92.9534[lb/hr] = 11.7119[g/s]

Set B4001 to this value all across (flat static since FPR is manifold-referenced).