ok guys i've been working on this for the past hour or so and I think I may have FINALLY solved the injector constant formula.
this ONLY works for lbs/hr so be sure to look that number up for your injectors... cc/min will not work
I used a stock injector constant and the stock injectors (24#) as the basis for this formula.
here's the formula:
liters/gram = 0.17800
seconds
firstly, you need to convert your injectors to fit into the formula and eliminate the seconds variable.
so
24lbs. = 10886.2169 grams
keep in mind, this is PER HOUR
so now, divide that number by 60 to get PER MINUTE
10886.2169 / 60 = 181.4369483grams per minute
then divide again by 60 to get PER SECOND
181.4369483 / 60 = 3.023949138 grams per second
so now we know our injector size, this is your 'gram' variable
since our seconds is "1" we can eliminate the seconds variable
liters/3.023949138 = 0.17800
multiply both sides by the injector size
3.023949138(liters/3.023949138) = 3.023949138(0.17800)
liters = .53826294672
NOW that we have this number, we can go back and solve for any injector size we want. to confirm my findings, I tried the formula for 440cc injectors (42#)
42lbs = 19050.8795 grams
19050.8795 / 60 = 317.51465839 grams per min
317.51465839 / 60 = 5.291910972 grams per second
.53826294672 / 5.291910972 = 0.101714
using shifted's scaling method, my old constant was 0.10194 AWFULLY close, and I'm willing to bet the constant I've just come up with would run much better.
simplified formula:
0.53826294672 / (injectors in grams per second) = Injector Constant
DISCLAIMER:
I haven't done any actual testing seeing as the skwirl is disabled at the moment, so I can't back this up with physical evidence, but it may help someone else who's willing to try it out?
i may try to put my 440cc injectors into my 2004 base model and flash my ecu with this new constant to see if it works flawlessly.. if thats the case, then the injector constant formula (for jbodies) is solved.
after re-checking shifted's scaling method, my number DOES come out different, but only when you get into it pretty far...
shifted's scaling method
(24/42) = .11574
multiplied by my stock constant (.17800) =
0.1017142857142857142857142857...
my calculation:
0.10171428611856851170020023534137
so there's little difference if any... bummer I was excited for a moment
PWNED.
PJ, I have to hand it to you, you just did some leg work... You really want to impress me, figure out how the hell they came up with the LD9 SC reflash constant...
P&P Tuning
420.5whp / 359.8wtq
I've tried shifted's injector constant with my 550cc injectors and it didn't work out very well. I ended up having to change the tables to get close to where i wanted to be.
Anyone else have any problems when going to 550 or bigger injectors?
12.770 @ 111.99 Intercooled Eaton M62
BTW...
1lb/hr = 10.5cc/min
I can't take credit for the original formula, that was given to me by Chris @ HPTuners, its a simple scaling formula, basically you are breaking it down to a constant for your stock injectors per lb/hr or cc/min and then multiplying it up by your new injectors to get a value that's scaled exactly the same as your stock injectors were. The reason it doesn't work as expected is because different sized injectors have different flow characteristics so the number takes some playing around with.
Also, what is even more interesting (and disappointing) is that multiple cars of the same year, same injector size, same engine, have different injector constant numbers, and seems only to depend on the calibration of what the number actually is. Even HPT couldn't explain how this number is determined (and it was during me asking that question that I was provided said formula).
I'm sure the s/c constant was an attempt by GM to not have to do much in the way of tuning the VE tables, because they are making the injectors seem smaller (instead of them actually being larger), the ECU injects more fuel than what is in the tables.
Edited 1 time(s). Last edited Friday, September 05, 2008 6:55 AM
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Cool to see your stock value actually means something but really thats all you got out of it since at the end of the day those conversions all boil down to a single conversion factor that gets canceled out on both sides of the equation(when you ratio your stock value to the new value) and your left with what shifted uses....lol. The only real value at all is maybe proof that the number is actually based on actual units rather than a "make it work fudge factor" type of a deal.
EDIT: Also, the differences between your and Rons value out ~5 places past the decimal is because of the rounding errors you have, there no way to say either Ron or you are correct really since all the conversions only go out what....3 places past the decimal....so thats as far as you can claim to be accurate. The rest is BS........SigFigs!!!!!
Edited 1 time(s). Last edited Friday, September 05, 2008 3:07 PM
I gave up on doing the injector constant for my car all i know is my stuff runs PIG rich ( under 9 ) for around 4 mins untill it warms up. Then when its warm its perfect. I have 650cc. It would be nice if i could actully drive it when i just start it.. Good work man when i got time imma have to figure new constant out. It seems almost all your post are godly. lol
Joshua Dearman wrote:Cool to see your stock value actually means something but really thats all you got out of it since at the end of the day those conversions all boil down to a single conversion factor that gets canceled out on both sides of the equation(when you ratio your stock value to the new value) and your left with what shifted uses....lol. The only real value at all is maybe proof that the number is actually based on actual units rather than a "make it work fudge factor" type of a deal.
EDIT: Also, the differences between your and Rons value out ~5 places past the decimal is because of the rounding errors you have, there no way to say either Ron or you are correct really since all the conversions only go out what....3 places past the decimal....so thats as far as you can claim to be accurate. The rest is BS........SigFigs!!!!!
yea I think we can all agree the only thing I accomplished here is finding a more difficult equation to figure out what Ron's already posted up LOL
BOOSTED BABY wrote:
Good work man when i got time imma have to figure new constant out. It seems almost all your post are godly. lol
eh, i wouldn't go that far.. I pretty much accomplished nothing here. False alarm basically.
use ron's equation its easier lol
is that little of a difference really going to be noticeable?
1989 Turbo Trans Am #82, 2007 Cobalt SS G85
If any of you have the chance to play with an LS1 file take a close look at it. I am convinced that there are a LOT of tables we are not seeing for the eco so this question might not be able to be answered at all. Without all the information about what is going on in the background (hidden tables) the equation can't be answered. The two OS's are different I know (eco being an SD style and the LS1 being a MAF based one) but I'm sure that the eco has a lot more tables than we are seeing. Here are two screen shot's comparing the general fuel tab's in HPT between the eco and the LS1...
Eco
LS1
As you can see there is a lot more going on in the LS1 file than the eco file (not just the general tab either, pretty much all tabs in the LS1 file are filled up). I have just started to play with the LS1's and I can tell you the math and tables involved will make your head spin compared to the eco. Now yes the two systems are different but the LS1 does revert back to a SD system in certain situations so the underlying tables for that type of control should be similar.
Just some food for thought
Quoth the Raven 'Nevermore
raven@accesswave.ca
Raven Autosports
55 McQuade Lake Cres,
Halifax, Nova Scotia, Canada
(902) 850-3330
10.82@132
Why would you think that GM would spend anywhere near the time or effort on the tune for an L61 as it would for an LS1? The LS1 was GM's sports car motor, used in a car that costs between $35-$75k retail new (Camaro to top of the line Corvette). The cars that get the L61 are budget minded money makers for people who were never meant to get performance cars.
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I never said I thought that GM spent the same amount of time on the L61 (but since you brought it up it probably would of taken longer to do the main VE tables for the eco just because it's SD based and every cell has to be done manually). Of course there was more work put into the LS1. The point I was trying to make was that there are probably some basic modifier tables for the injectors and other area's that the L61 has that we are not seeing. GM combined a lot of what they were doing in the past with a lot of newer things to come up with the LS1 tune. Why would you think that some of the more basic things could not also be in the L61? GM has a history of building off what they already know. Even the 3800, who's computer code is older than the L61 has way more modifier tables, and tables in general than what is available in HPT when I tune it with the PowerTuner. It's the main reason I didn't switch completely to HPT for my car. I will scan and use histogram data from HTP, but all of my changes are made through the Power Tuner. Maybe I'm wrong but I have seen a lot of different things happen when adjusting the injector constant with HTP...sometimes the math works out and sometimes it doesn't. I don't have the answer, I have been able to play with different cars and sort things out to the point where they run pretty good but I can't really explain why. With the 3800 and with the LS1 there is a little more depth and if you search and read enough you can usally get your head around exactly what is happening with fueling and airflow. I can't believe that an engine like the eco would not also share some of the basic settings that these other files share. Just because we can't see it in HPT doesn't mean that they don't exist. Even with the PowerTuner on the 3800 there is lots of evidence to support tables that can't be seen but are in fact there. After talking about this exact subject with Ray Bates I was convinced that HPT does not show you enough of the puzzle for high horse power applications. I have been successful tuning up to about 400whp and 7000RPM but I wouldn't want to push it much higher. This winter we are going to be converting Andy's car over to a full AEM EMS unit which will give us much more control at higher boost and RPM levels, might even do my car as well.
Now don't get me wrong guys, HPT is a great product and something we are even lucky to have. All I'm saying is that there is more to the puzzle than what you are seeing and without knowing all the variables it's going to be hard to say for sure. Posts like this are great though...it brings out good discussion on the subject and maybe one day we will be able to say for sure.
Quoth the Raven 'Nevermore
raven@accesswave.ca
Raven Autosports
55 McQuade Lake Cres,
Halifax, Nova Scotia, Canada
(902) 850-3330
10.82@132
raven wrote: Now don't get me wrong guys, HPT is a great product and something we are even lucky to have. All I'm saying is that there is more to the puzzle than what you are seeing and without knowing all the variables it's going to be hard to say for sure. Posts like this are great though...it brings out good discussion on the subject and maybe one day we will be able to say for sure.
I agree 100% with Raven's statement. Also, for anybody else that has tuned LSx platforms, have you noticed that some tables are now missing that there there in older versions? I don't remember the exact tables, but there were timing related...... Anyway, to get back on topic, we don't need all the tables that the LSx guys have, but more idle modifier tables and adaptive tables would be nice. I have written HPT many times about it and I understand that we don't the demand of support that the LSx guys have, but I want to give my customers 110% . When I tune a Jbody, I don't feel I can give that(granted I make it the best I possibly can), but with an LSx or a Cobalt, no problems... I guess I am happy to have what support we have, but sometimes it feels like we are just left behind and told that "when time allows" speach we all hear over and over, Problem with that is our platform is essentially a dead one and I feel that the longer we "wait" for the further support, we won't get it...
P&P Tuning
420.5whp / 359.8wtq
I agree 100%
DRIVE HARD OR DONT DRIVE AT ALL!!!
Compare the EFI Live parameters to that available on HPT, that might help clue us in if there is anything missing. Supposedly they now have support for the eco (non S/C), but I don't know anyone with it.
___________________________________________________________________
Mitsu TD06-20g |3" Turbo-back Exhaust | 61mm Bored TB |
HP Tuners | Innovate WB02 | Spec Stage 3 | Team Green LSD | TurboTech Upper | Full Addco Sways | Sportlines & Yellows |
You cant really compare a MAF based car to one thats MAP based, a MAF car is simply far more complex and much easier to tune. Even a LSJ which is MAF does not have near the amount of things that a LS1 does. HP tuners was made for the LSx thats their bread and butter its what they cater to. They will always have the most features. I wouldnt expect ANYTHING new for the jbody platform
1989 Turbo Trans Am #82, 2007 Cobalt SS G85
Rodimus Prime wrote:You cant really compare a MAF based car to one thats MAP based, a MAF car is simply far more complex and much easier to tune. Even a LSJ which is MAF does not have near the amount of things that a LS1 does. HP tuners was made for the LSx thats their bread and butter its what they cater to. They will always have the most features. I wouldnt expect ANYTHING new for the jbody platform
Actually you can compare them, some what. When a MAF sensor fails on a MAF based car the computer will revert to an SD style system to calculate airflow and fueling needs. It also uses the SD calculations to judge, "check" what the MAF sensor is telling it for metered airflow. When there is too much of an error between the two the computer will assume that the MAF sensor has failed and revert back to the SD system to calculate airflow. So yes you are correct to say that the two systems are different (MAF sensor is an actual meter that meters the air into the engine and an SD setup calculates the airflow (guesses) based off of a preset VE table using the MAP sensor and RPM as it's main variables) but when and if the MAF fails it will go back to SD calculations. Also a big draw back to MAF based car is the switch from steady state air flow to a transient air flow condition. Without the SD VE table in the background the MAF would not be able to meter the air into the engine at all times and during transient conditions fuel would be all over the place, but that is a whole other topic in itself.
And yeah I think we are not going to get any more support from HPT's about this. Like it was posted the LSx is there bread and butter and nothing we can do to change that.
Edited 2 time(s). Last edited Thursday, September 11, 2008 1:05 PM
Quoth the Raven 'Nevermore
raven@accesswave.ca
Raven Autosports
55 McQuade Lake Cres,
Halifax, Nova Scotia, Canada
(902) 850-3330
10.82@132
It doesn't make sense, as a company, if you have guaranteed business then hire more people.
From what I have gathered, working on the being able to edit the GM S/C Eco reflash would not be impossible, just a matter of devoting some resources to it.
___________________________________________________________________
Mitsu TD06-20g |3" Turbo-back Exhaust | 61mm Bored TB |
HP Tuners | Innovate WB02 | Spec Stage 3 | Team Green LSD | TurboTech Upper | Full Addco Sways | Sportlines & Yellows |
raven wrote:Rodimus Prime wrote:You cant really compare a MAF based car to one thats MAP based, a MAF car is simply far more complex and much easier to tune. Even a LSJ which is MAF does not have near the amount of things that a LS1 does. HP tuners was made for the LSx thats their bread and butter its what they cater to. They will always have the most features. I wouldnt expect ANYTHING new for the jbody platform
Actually you can compare them, some what. When a MAF sensor fails on a MAF based car the computer will revert to an SD style system to calculate airflow and fueling needs. It also uses the SD calculations to judge, "check" what the MAF sensor is telling it for metered airflow. When there is too much of an error between the two the computer will assume that the MAF sensor has failed and revert back to the SD system to calculate airflow. So yes you are correct to say that the two systems are different (MAF sensor is an actual meter that meters the air into the engine and an SD setup calculates the airflow (guesses) based off of a preset VE table using the MAP sensor and RPM as it's main variables) but when and if the MAF fails it will go back to SD calculations. Also a big draw back to MAF based car is the switch from steady state air flow to a transient air flow condition. Without the SD VE table in the background the MAF would not be able to meter the air into the engine at all times and during transient conditions fuel would be all over the place, but that is a whole other topic in itself.
And yeah I think we are not going to get any more support from HPT's about this. Like it was posted the LSx is there bread and butter and nothing we can do to change that.
Ummmmm....ya.......... and thats why u do my tuning and i run the peddles!!!!!!!!
491whp, 393wtq
11.93@ 127mph
Raven Autosports (902)850-3330
