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Thread: Interesting info on B3702 Injection timing

  1. #11
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    Definitely interesting, I wish I was smart enough to tie this into valve timing events with the aftermarket cams, I'm just curious as to when it injects in relation to when the intake opens.

    BTW, we ran it 5 times Wednesday, the last two were no changes except the 15% added on run 4. The MPH gain compared to the prior 3 runs was .89. The DA was 7397 on run 4 and 7340 on the last. The average of the first 3 runs is 7331 so you can see that the air was real close.

    Also, the first 3 60' times averaged 1.358 and the average of the last 2 was 1.337, according to my crew chief pro software it picks up across the board each time. It's running the same times now at 7300' DA as it did in 6400' DA at the beginning of the year and I've done nothing to the dragster but play with the injector timing tables and the AFR since it showed richer.

    Lee
    Last edited by LS1_Dragster; July 17th, 2009 at 06:12 AM.

    230" Dragster - 2000 LS1, 02020003 Speed Density, PRC 2.5 Heads,
    MS3 Cam 237/242 .603/.609, Vic Jr. intake, Holley 1000CFM TB,
    PowerGlide, 5000 stall converter. 8.70@154 MPH

    My Projects Homepage: http://www.horsepowerracing.com

  2. #12
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    i found a spreadsheet for ford computers that demo'ed/explained a lot of this stuff. i modified it to work with some typical gm values. of course it was a hypothetical exercise as we dont have the same sort of injection tables as ford, but it definitely broadened my understanding of this. i'll try to find my version of the spreadsheet tonight, it should be helpful. kinda fun to watch injection angles change as you 'swap cams'

  3. #13
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    Hi Lee,

    Very interesting stuff here. I was at the same test & tune with my '98 Camaro. Wish I would have known you were from Utah, I would have tried to track you down. What color is your dragster? Is it easy to spot? I don't know anybody else in the state with EFILive, so this is definitely an interesting find. I'd love to test some of your findings with my car as I definitely have some work to do. Untuned the car still went 12.29 at 110.28. I think it's got more in it, but I have a lot to learn still. Great job on your results. Hopefully I'll run into one of these days.

    Brad

  4. #14
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    Hi Brad, I did see a few camaro's but I didnt pay too much attention, I was too concerned about dying from the heat!

    I've tuned 3 vehicles with EFI Live and it's been a challenge, the Holley commander 950 is MUCH easier! But using a factory computer and harness is way cheaper so I need to get the tuning down pat.

    Here's a picture of the dragster:




    We're mainly just going to the big events this year so we'll only be out a few more times. I only hit this TnT to see what the injector timing was going to do....

    Lee

    230" Dragster - 2000 LS1, 02020003 Speed Density, PRC 2.5 Heads,
    MS3 Cam 237/242 .603/.609, Vic Jr. intake, Holley 1000CFM TB,
    PowerGlide, 5000 stall converter. 8.70@154 MPH

    My Projects Homepage: http://www.horsepowerracing.com

  5. #15
    EFILive Distributor dfe1's Avatar
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    Quote Originally Posted by redhardsupra View Post
    wouldn't injection timing be very dependent on valve events? i know that most OEM calibrations do injection against a closed valve, but if the timing wasnt important, they wouldnt have the table for it, would they?
    I really wonder about that. Seems logical that it would be, and Lee's testing seems to prove that. Someone should do a bit of testing with an engine that has a stock cam and see if results are similar. It may well be that GM decided to trade off some power for improved emissions numbers.

    I don't know if this is relevant, but when GM switched from batch to sequential (for the 1994 model year) the engineers stated that there wasn't much difference in power. The switch to sequential was primarily a result of the need to improve emissions and economy. I was somewhat doubtful at the time, and have become more so over the years. I don't know that they were "mis-speaking" as much as the computers of the day may not have had the capacity to alter injection timing. It may also be that the engineers were basing their comments on little or no comparative testing. If they were chasing emissions, they probably didn't look at power. Sounds strange, but on at least one occasion, when I asked about results outside the operating range of the program focus, I had engineers say, "I don't know, we didn't test there". Be interesting to do a back-to-back batch-to-sequential test and see what the power difference is.
    DigitalEFI- EFILive US Distributor
    sales@digitalefi.com
    678/344-1590

  6. #16
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    The holley MPFI is batch mode and I had a 975HP 632 pump gas running like a hot street car, idled at 950 RPM like a kitten. During my testing with these units I was in close contact with a Holley engineer and I was told on many occasions that batch vs. sequential resulted in no power difference and it was implemented for emissions. I have heard that the boosted guys out there are getting more reliable power with sequential....

    All in all though, I've seen a huge drop in et and gain in MPH from a setup that we've been running for 1.5 years and has 72K miles on it, so no engine break in, new tires or any change what-so-ever mechanically or otherwise to account for the reductions by just changing this parameter!

    230" Dragster - 2000 LS1, 02020003 Speed Density, PRC 2.5 Heads,
    MS3 Cam 237/242 .603/.609, Vic Jr. intake, Holley 1000CFM TB,
    PowerGlide, 5000 stall converter. 8.70@154 MPH

    My Projects Homepage: http://www.horsepowerracing.com

  7. #17
    Senior Member exploder's Avatar
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    anything new on this subject...has anybody else tried this?
    03 z06 auto
    ver7.5.5 custom OS5
    415 ci
    239/255 .624 lift LSr grind
    16psi
    Meth injection
    PLX WB02

  8. #18
    Lifetime Member 5.7ute's Avatar
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    Quote Originally Posted by exploder View Post
    anything new on this subject...has anybody else tried this?
    I had booked some dyno time to have a play with this a few weeks ago. Unfortunately the dyno operators car took precedance over mine & after two days of being stuffed around I cracked the shits & gave up.
    We have a 2 day meet next weekend, so if I can get some consistant runs in I will give it a shot.
    The Tremor at AIR

  9. #19
    EFILive Distributor dfe1's Avatar
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    I haven't had a chance to do any testing, but it seems logical that optimum injector timing is somewhat dependent on valve timing. My guess is that Lee has a pretty aggressive cam in his dragster engine, which is the reason it responded so well to the change in injector timing. Might be a good idea to include cam duration along with the data pertaining to values and results of injector timing experiments.
    DigitalEFI- EFILive US Distributor
    sales@digitalefi.com
    678/344-1590

  10. #20
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    Quote Originally Posted by dfe1 View Post
    I haven't had a chance to do any testing, but it seems logical that optimum injector timing is somewhat dependent on valve timing. My guess is that Lee has a pretty aggressive cam in his dragster engine, which is the reason it responded so well to the change in injector timing. Might be a good idea to include cam duration along with the data pertaining to values and results of injector timing experiments.
    Sorry, here's the specs:

    TSP XS Series Camshaft:
    Magic Stick V.3 237/242 .603/.609" 112 lobe sep. Camshaft.

    The Magic Stick V3 camshaft is Texas Speed's premier LS1 camshaft! This camshaft has gone as fast as 10.50s n/a with stock heads in our 98 Z28 test car.
    This camshaft features Comp Cams XER lobes! The XER lobes have been proven to make big horsepower & torque thanks to their aggressive ramp rates & healthy lift.

    2300-6800 RPM Power Band with a peak around 6400rpm; This is an excellent performance camshaft with a rough idle! Custom tuning required

    230" Dragster - 2000 LS1, 02020003 Speed Density, PRC 2.5 Heads,
    MS3 Cam 237/242 .603/.609, Vic Jr. intake, Holley 1000CFM TB,
    PowerGlide, 5000 stall converter. 8.70@154 MPH

    My Projects Homepage: http://www.horsepowerracing.com

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