Injector Timing? Reference Periods? refereencing what?

[domestic rice]

Had both before I put the cats in. Now with them in there it's not bad at all. I thought throwing cats in was masking the problem, but was told by who I believe is a knowledgable tuner on here the gas smell is expected with a cam and normal.

[pontisteve]

It's normal, in that it happens when you put a large cam in. It's also normal that changing the injection delay will reduce that problem. Cats are big filters that help burn unburned gas, so sure they will help mask the problem.

[LSxpwrdZ]

EOIT will do little to nothing for WOT fueling. This is all for partial throttle driving and idle. Still havent had a chance to do much with this testing wise but may have an LS2 setup tomorrow to do a little testing on.... even though the method is slightly different on the E40 vs LS1.

[oakley6575]

EOIT will do little to nothing for WOT fueling. This is all for partial throttle driving and idle. Still havent had a chance to do much with this testing wise but may have an LS2 setup tomorrow to do a little testing on.... even though the method is slightly different on the E40 vs LS1.

Did you get to play with that LS2?

[LSxpwrdZ]

I didn't get to play with it however it did respond great to retarding the EOIT ~30*. The drivability increased tremendously. It was a FAST102/NW102, VRX5 Cam, LT's LS2 GTO. The smoothest VRX5 I've had yet, done about 3-4 of them all in GTO's. We are so slammed at the shop with car's needing tuned I've not had the time to experiment further than what I've already figured out.

[oakley6575]

How do you calculate 30* in terms of the EOIT make up and normal tables?

[pontisteve]

I believe each "reference period" refers to a 90 degree section of time. 8 reference periods = 720 crank degrees = 2 crank revolutions = 1 engine cycle.

So 30 degrees should = roughly .33 reference periods.

The catch is, if I remember right, a member in this thread scoped out a motor on an engine stand and came up with the fact that the whole cycle starts at -784 on the LS1, not -720 like you would think. I suppose this is putting the sensor ahead enough to read it and have the computer still be able to make changes in time.

Going a little from memory here. Feel free to read the whole 20 pages of this thread to verify.

[LSxpwrdZ]

LS2's are different than LS1's. You can simply input the physical amount of degrees on a Gen4. I have a spreadsheet to calculate the numbers on the Gen3 LS1 stuff.

[LSxpwrdZ]

Okay I had the chance today to put together a little experiement on a Cam only LS1. Here are a few details on the setup:

2000 LS1 Camaro M6
LS6 Intake
Stock '00 Injectors
Torquer V2 232/234 112lsa Cam
Hooker LT's
ORY
Dumped exhaust at Axle

I got the car completely tuned and then made a spreadsheet with various TPS points at 1500rpm and 1800rpm. I then flashed various different EOIT values into the tune and monitored AFR for any descrepencies. I only tested 3 different EOIT values because this particular setup found it's sweet spot right in the middle of the 3 I did test. I attatched a log file of the last test I did which was 6.5boundary 6.25normal.

[LSxpwrdZ]

Gonna bump this back up cause I stumbled onto this on my personal car....

Basically I picked up powerband and tq/hp all across the rpm range especially up top just changing EOIT. Here is a dyno graph of my LS1 Formula. Here's a mods list

105k mile LS1
235/243 112 Cam
60lb Siemens Injectors
FAST102 / 92mm TB
ARH 1-7/8 Headers and Ypipe with Cutout
SD with 4" pipe and 106mm Lid

On the graph the ONLY change to the tune was the EOIT. I'm not going to give specifics mainly due to every setup being different. I just thought I'd share that EOIT is a tad more important than most let on!

[oakley6575]

25 more hp up top with that little change?

[WS6FirebirdTA00]

How many runs did you do to verify?

It would be nice if you could give us some idea on the magnitude of the change so others can try and report back their findings.

Those results may be abnormal too due to the fact that you are using such a big injector with that low of a power level. I would expect at higher IDC you should not see any kind of gains, but you are probably 50% or less I would assume. Although I could be wrong

[LSxpwrdZ]

^^^ You are 100% correct

The only reason this picked up like it did was due to running HUGE injectors on a small NA setup. IDC is only 39-40% on this setup. I made multiple dyno pulls with either setting and both gave same results within 1-2hp.

The highest HP pull was with Boundary set at 7.0 and the Normal Table set to 6.0 in the warmer ECT regions. The lower dyno pull was with the Boundary set to 6.5 and the Normal table left the same. There is a tradeoff though. I've noticed the car misfires at light throttle and idles quite rougher with the later injection time. For shits and giggles I extended the EOIT another 0.25 and it lost a bit of power. When I get a free chance I will try to find the happy medium between 6.5-7.0 on the Boundary while not sacrificing power up top.

[WS6FirebirdTA00]

Cool deal man, thanks for the info.

[oakley6575]

Yea thanks for sharing. I wish I had a dyno I could play on

[jimbos'ss]

ok based on everything i've read in this thread and this one:
http://www.hptuners.com/forum/showth...highlight=EOIT
cam comparison is:
stock new
evo 105.5 107
evc 383.5 385
ivo 333 328.5
ivc 617 603.5

so based on (-784+(normal(5.55)+Boundary(6.50)*90=300.5
that's roughly 33* before the ivo on my stock cam and 28.5 degrees before the new cam's ivo.
now given the overlap on my cam i'd want to shift my SOIT to after my exhaust valve closes so I would need to know the relation between inj pw and crank degrees. without that it's just a best guess. at idle my car has a 3ms inj pw.

If I can figure that out I would be able to easily figure out what I wanted for my EOIT. anyone got a formula for ms to crank degrees so i'm not guessing on the numbers I enter into the normal table?

[jimbos'ss]

ok so after so basic math each injector fires for aproximately 1/5000th of a crank shaft revolution based on 3ms pw and 950 rpm so that means if i did the math correctly the SOIT to EOIT is on a fraction of a crank degree. sooooooo if i wanted to delay the SOIT till after the EVC i would input (-784+(boundary(6.50)+X)*90=386 and find for X. X would equal 6.50. Am I on the right path????

[yellz06]

Subscribing

[aldrichg9]

My head hurts after reading all this.

I attached the worksheet figuring my new normal and such.
I am trying to figure the best place to put my EOIT for 48* overlap.
But does the worksheet actually show my EVC 24 degrees before IVO?
Exhaust valve closes at 379* Do want injection to start after this?
Or do I need to take advantage of some of that overlap time?

How is this affecting everyone's base running airflow?
Need to re-cal all that too?

[aldrichg9]

sorry for the second post -had to change subscription settings so I can get emails for replies....