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Thread: 383 tuning help

  1. #31
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    Sorry for the confusion guys I sent that post on timing with my phone..Any way I set 0* with the spout disconnected..shut it off and reconnected the spout then started and timing is in the 20* mark at idle..

  2. #32
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    Ed just sent me back my chip with an adjustment and told me that the bored TB I have may be junk. Any way here’s his chip anyone recognize it??88F05DCB-AC87-4152-9A11-7217D769995B.jpg

  3. #33
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    The calculation for HP to pounds of fuel is universal not a short cut it's just the physics.
    1 HP = 2545 BTUís per hour

    Gasoline is 5.92 lbs per gallon
    Gasohol is 6.1 Lbs per gallon

    Flat head ford is rated at 49% Therodynamic Efficiency and BTU per pound is based on that .
    Modern engines run from the factory at @76%.
    Theoretical 18000 BTU per pound of gasoline is based on 49% conversion ratio.
    Stock 1979 and up engine is @76% or 28000 BTU per pound of gasoline.
    Rings valve seats and throttle plate sealing provides 80% on typical modified engine or 29000BTU per pound.
    1 LBS of fuel on a modern modified engine should produce 11.4 HP
    Parasytic Loses valve springs, piston skirts, oil pump timing chain ETC lower the net power.

    pumping 130 Gallons of air and 9.16 Gallons of fuel on that motor will yield 335 HP


    C2500s engine build is the Super Chevy magazines Test mule for carboration and the same build is typically 450 HP.
    These motors with carb are routinely dynode with 650 and 700 CFM at 450 HP

    As far as your results I understand you are commanding the injector to open and close.
    Have you put a scope on the injectors them selves while running and confirmed that you are getting the actual commanded on period.
    I alter the ignition with CDI after the module and give a solid 5v pp signal to the reference line.
    I get @7400 rpm no load at 4ms on 65/68 TBI injectors
    I have seen refurb ECM with cheap slow Mosfet installed could be a slew issue rather than injector flow.

    In example I had a 1995 Impala/caprice with 1996 LT-4 Corvette, Radically ported iron heads 280cc intake runners, 194/160 with orange ZZX Beehive springs, 1.6 roller rocker crane rev kit lifter springs, .575 intake .560 exhaust 117lsa cam, SPO timing chain on steel gears, Low RPM water pump drive, HyperUtetic Pistons with tungsten Disulfide coated skirts, Rods drilled with piston squirters, copper shim head gaskets final compression ration 10.8 : 1, HMV55HV millings with 5W-50 oil, oil cooler trans cooler, 4L60E with 4.3L convertor, truck low gear spray, Steel drive shaft GM 10bolt 3.73 with Eaton Posi.
    TH ignition system was/ is triggered using opti spark pick up CDI box and twin coil MSD coils. Ford 4cylinder ecoboost injectors in sequential mode rather than batch.
    Routinely ran at 7500RPM and even peeked it a few times at 8500rpm.
    According to iPhone pocket Dyno and Cats Tuner dyno hit 600HP on regular basis.
    Never drag raced the car just street racing.
    Have driven the car at Taledega at over 180MPH and at Daytona over 160
    Avatar is my motor 800 RPM 184ft Lbs Torque 18 inches x 18 inches x 9 inches thick external combustion engine.

    98 WS-6 full tube chassis rally car Aluminum Block LS2 (soon to be LSX 376)(in Storage)
    95 Suburban 6 inch drop, Zoomies, Tri-Y Headers, Pioneer DVD in Dash (Soon to Be LT-4).
    95 Caprice 9C1 Fleetwood Brougham Interior, LT-4 (retired)(Engine Donor for new truck)
    2002 Seville STS

  4. #34
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    The i on that memory chip appears to be an Intel mark.

  5. #35
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    I spoke to Ed and he said to set timing at 0* with spout disconnected.. Can’t help but all this is confusing what some are telling me and what others are saying. I’m sure there are way to do this and all get to where it should be..I need someone to help me figure this out..
    Also tuner pro web help never seems to help..lots of unanswered questions there...

  6. #36
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    There is lots of differing opinions and reasons for them. The initial timing is used only on the start and limp. The initial is added to the computer timing to get the final advance. If you just use the gm 0 degrees the spark table should be useable as it is. It you use some other initial you will have to modify the table to suit that. My two bits would be use 0 degrees and at a later date when you feel you understand it all, experiment as much as you like.
    6395, BHDF, 7.4 BBC lightly modded now 6395 BMHM back to BHDF

  7. #37
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    There is a setting in the calibration called spark bias where you set the static advance of the distributor. So, if Ed says to use 0* that is because he knows the tune is set to work with 0* at the distributor. Basically, you just match the advance you set to the setting in the tune.

    When you want to adjust the operating timing you don't the distributor or the static timing setting. You adjust the 3-D timing table.

  8. #38
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    [QUOTE=Fast355;68671]A pair of 61 lb/hr TBI injectors are good for 205-210 hp @ 85% duty cycle at the stock 13 psi and if they were static, meaning on all the time, good for about 250 hp at most. Most engines run around 1/2 lb/per hr/per hp. 61 lb/hr x 2 injectors /.5 bsfc = 244 hp. Even if you were running a Vortec head and had a very good BSFC around .45 that is still only fuel for 270 hp.


    What injectors would you recommend for my set up?? Thanks for any help

  9. #39
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    [QUOTE=C2500;68791]
    Quote Originally Posted by Fast355 View Post
    A pair of 61 lb/hr TBI injectors are good for 205-210 hp @ 85% duty cycle at the stock 13 psi and if they were static, meaning on all the time, good for about 250 hp at most. Most engines run around 1/2 lb/per hr/per hp. 61 lb/hr x 2 injectors /.5 bsfc = 244 hp. Even if you were running a Vortec head and had a very good BSFC around .45 that is still only fuel for 270 hp.


    What injectors would you recommend for my set up?? Thanks for any help
    Keep the same injectors, get a fuel pump for a 1993-1995 Astro/Safari van with a 4.3 "W" vin code CPI engine and get your hands on one of the 28-32 psi marine TBI regulators. That will boost your 61 lb/hr injectors up to about 104 lb/hr each. At that point you are good to over 350 HP at 0.50 bsfc and 85% duty cycle. I am sure you can get a TBI to run to 7,200 rpm without load at 4 msec, but when you go to full load that same rpm would require a good 4-5x the fuel. Because the TBI injector fires twice per crank rotation, 4x per complete engine cycle, at 5,000 rpm you have something like 6 msec between injector firings. At 6,000 rpm you have 5 msec between firings injector. During that time you need to stay under 85% duty cycle and factor in both intake and closing times of the injectors. If it takes the injector 300 usec to open, its going to take roughly the same time to close. So that 5 msec cuts down to 4.25 msec to stay under 85% duty cycle and finally allowing opening and closing times it drops to 3.65 msec to spray the necessary fuel accurately without running the injectors static. What will happen if you get to 100%+ duty cycle is the the engine will develop a high rpm misfire and if you get into the 110% range it will quit pulling all together under load. Running an asynch fueling strategy will help this condition but you should closely watch the air/fuel mixture distribution if you run that.

  10. #40
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    Fast, Thanks for the above post. I have a new Delco EP376 pump Not sure what it is but I’ll look it up. I would think you want a AFR in the 13’s at wide open correct? I got a wide band hooked up and an LM1 on the seat next to me and went for a drive..Runs fairly well driving it normal but it has a lean heasation if you run at 25mph and lightly step on the throttle.. Also I went WO up a hill and in no time the AFR went into the 17’s. Not good
    So I’m trying to tunerPro up and running as that’s another challenge with my limited skills with a laptop..

    Delco EP 376 pump. Will this do?
    http://www.gmtuners.com/tech/fuel_pumps.htm
    Last edited by C2500; 01-13-2018 at 11:01 AM.

  11. #41
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    Quote Originally Posted by C2500 View Post
    Fast, Thanks for the above post. I have a new Delco EP376 pump Not sure what it is but I’ll look it up. I would think you want a AFR in the 13’s at wide open correct? I got a wide band hooked up and an LM1 on the seat next to me and went for a drive..Runs fairly well driving it normal but it has a lean heasation if you run at 25mph and lightly step on the throttle.. Also I went WO up a hill and in no time the AFR went into the 17’s. Not good
    So I’m trying to tunerPro up and running as that’s another challenge with my limited skills with a laptop..

    Delco EP 376 pump. Will this do?
    http://www.gmtuners.com/tech/fuel_pumps.htm
    You want a cast iron head small block around 12:1 under and near peak tq and about 12.6:1 at peak hp. Those heads usually like a pretty quick advance curve and about 30-34 total advance at WOT. Cruise timing can be upwards of 42 at 3,000 and no load. If you set the initial timing at the distributor to 10* and set the Initial timing in the .BIN to match you can experiment up to about 52* of timing to see what works best at cruising speeds without load. Generally to get the no load timing right, I will use my Autoprom, hold the engine at a steady 1,200 rpm. Look at the timing cell the engine is running in KPA wise, holding the throttle steady, I will then slowly advance the timing until the RPM stops rising. I will repeat this process at every RPM value of the timing table up to about 5,000 rpm. For a good starting point you can then interpolate the values down to your WOT timing. Works well as a starting point for me.
    Last edited by Fast355; 01-13-2018 at 11:22 AM.

  12. #42
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    Quote Originally Posted by C2500 View Post
    Fast, Thanks for the above post. I have a new Delco EP376 pump Not sure what it is but Iíll look it up. I would think you want a AFR in the 13ís at wide open correct? I got a wide band hooked up and an LM1 on the seat next to me and went for a drive..Runs fairly well driving it normal but it has a lean heasation if you run at 25mph and lightly step on the throttle.. Also I went WO up a hill and in no time the AFR went into the 17ís. Not good
    So Iím trying to tunerPro up and running as thatís another challenge with my limited skills with a laptop..

    Delco EP 376 pump. Will this do?
    http://www.gmtuners.com/tech/fuel_pumps.htm
    Looking at that chart that pump should be fine, good for 550 hp @ 32 psi. I did not realize you had already upgraded the pump.

  13. #43
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    Fast pumps not in yet I have it here new inn the box and was asking if that one will do and it will.. Thanks

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