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GM OBDI + FAST throttle body for carb to EFI conversion?

This is a discussion on GM OBDI + FAST throttle body for carb to EFI conversion? within the TBI Tuning (87-95 / OBD I) ECM/PCM forums, part of the Performance category; Originally Posted by xch3no2 (4) 85# injectors. ya buddy it could deliver some fuel... that comes out to be a ...

  1. #21
    Registered User whitelightnin92's Avatar
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    Re: GM OBDI + FAST throttle body for carb to EFI conversion?


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    Quote Originally Posted by xch3no2 View Post
    (4) 85# injectors. ya buddy it could deliver some fuel...
    that comes out to be a safe 544hp limit, and you COULD push just north of 600hp.........................................math matically that is
    Last edited by whitelightnin92; 06-26-2010 at 02:02 AM.

    69 C10
    http://www.fullsizechevy.com/showthr...y+project+pics

    72 C10 stepside RAT
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  2. #22
    Registered User whitelightnin92's Avatar
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    Re: GM OBDI + FAST throttle body for carb to EFI conversion?

    i think the motor on my 69 c10 is going to get dual smallblock tbi units with stock 350 injectors. i will be pushing around 400-450 hp with it. i will probably use the ebl. aftermarket ecms are too expensive.

    69 C10
    http://www.fullsizechevy.com/showthr...y+project+pics

    72 C10 stepside RAT
    355/350/14bolt 3.73 posi

    92 k1500
    1/4 16.024 @ 84 MPH

    2006 ECSB 5.3
    1/4 15.588 @89.96 STOCK

  3. #23
    No More Mr Niceguy xch3no2's Avatar
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    Re: GM OBDI + FAST throttle body for carb to EFI conversion?

    I was curious if the existing system was viable as a moderate performance option.
    I'm over 400hp, 550ft/lb (est. crank) so far (G-tec said 465,..wrong..nowhere close). Top end still has a "safe" tune on it.
    TBI on the EBL is very capable.

    last time I checked (@15hrs) crank cyl. pressure had climbed to 220+. I'll have to consider cam timing adjustment of a degree or two if it climbs much more.

    This is a 458, L2465F w/# 360 heads (or 236 by those whO don't know o'S), Lingenfelter patterned porting & valve enlargement. Mid level Crower street cam & 1.8 rockers.
    Power Beast is what they call the cam, I really wouldn't consider it w/o 1.8 ratio. I needed the LCA to to keep the MAP happy.
    The low lift is amazingly productive, it just seems weird running a open chamber rat under .600 lift.
    All hail velocity..for what it's worth.
    Last edited by xch3no2; 06-28-2010 at 11:25 AM.
    89 K3500 RCLB- Fat Snarling RAT..Scat/Eagle/Crower/Crane/Edelbrock/MSD..TBI/EBL/TH400/Dana 60

  4. #24
    GearheadDezign.com woody80z28's Avatar
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    Re: GM OBDI + FAST throttle body for carb to EFI conversion?

    Quote Originally Posted by whitelightnin92 View Post
    you can use the stock 94 ecm by just modding the memcal with a jumper. to control 4 injectors
    The guys on NastyZ28 were worried about trying to control 4 high-pressure injectors with ECM drivers for 2 low-pressure ones. I already have a spare 94 TBI ECM, but think a Beretta one that already controls 4 high-pressure injectors would be better.


    Quote Originally Posted by DrkZide View Post
    Just out of curiosity. Why is everyone figuring out TBI methods instead of just going direct port and using an AEM ECM? Is it a cost issue? You can buy a sensor kit from Jegs, get a used LS3 manifold and AEM for about the same cost as what was posted for that kit.
    Well an LS3 intake does my old SBC no good, and I already have a carb RPM AirGap. I'm all set up with TunerPro to log OBDI with my ALDL cable and laptop, so rather than throw something brand new in the mix, I'd rather have the fuel injection system on all my vehicles match.
    80 Camaro Z28 - 550hp AFR 383 EFI / T56 6spd
    91 Beretta "SS" - 220hp 3400 MPFI / HM282 5spd
    94 Silverado Z71 - 300hp Vortec 357 TBI / NV4500 5spd build thread

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    GearheadDezign.com woody80z28's Avatar
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    Re: GM OBDI + FAST throttle body for carb to EFI conversion?

    I gave Howell a call and they were very helpful.

    You can use all the GM OBDI logging & burning equipment to make changes. They use a 90 TPI ECM with the 8D mask and a 40-50psi pump, and the drivers only control half as many injectors as factory. All the sensors and the ECM, etc are all brand new with a warranty...so it might not even be worth trying to piece it together yourself. They will start you off with a tune that should be really close, and they will make adjustments if needed based on your data logging files.
    80 Camaro Z28 - 550hp AFR 383 EFI / T56 6spd
    91 Beretta "SS" - 220hp 3400 MPFI / HM282 5spd
    94 Silverado Z71 - 300hp Vortec 357 TBI / NV4500 5spd build thread

  6. #26
    Registered User whitelightnin92's Avatar
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    Re: GM OBDI + FAST throttle body for carb to EFI conversion?

    you know you can buy new stock ecms from summit for less than 100 bucks. you can buy stock wiring harnesses from them too. i would put it together myself if it was me

    69 C10
    http://www.fullsizechevy.com/showthr...y+project+pics

    72 C10 stepside RAT
    355/350/14bolt 3.73 posi

    92 k1500
    1/4 16.024 @ 84 MPH

    2006 ECSB 5.3
    1/4 15.588 @89.96 STOCK

  7. #27
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    Re: GM OBDI + FAST throttle body for carb to EFI conversion?

    Quote Originally Posted by whitelightnin92 View Post
    you know you can buy new stock ecms from summit for less than 100 bucks. you can buy stock wiring harnesses from them too. i would put it together myself if it was me
    I still tend to use used parts, and probably will continue to do so for my own swaps.

    When I start doing more swaps for other people I will likely look at using all new parts.
    Last edited by Six_Shooter; 07-03-2010 at 10:42 AM.

  8. #28
    GearheadDezign.com woody80z28's Avatar
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    Re: GM OBDI + FAST throttle body for carb to EFI conversion?

    Quote Originally Posted by whitelightnin92 View Post
    you know you can buy new stock ecms from summit for less than 100 bucks. you can buy stock wiring harnesses from them too. i would put it together myself if it was me
    That I did not know...thanks for the heads up.

    It might not be worth it anyway though...one of the NastyZ28 guys with a lot of EFI retrofit experience is worried about the fuel distribution due to batch fire and TBI, so there would be rich cylinders and lean cylinders. The way he explained it is when the injectors fire, the first intake valve to open will suck in most of the fuel leaving little for a cylinder next to it. It does make sense...
    80 Camaro Z28 - 550hp AFR 383 EFI / T56 6spd
    91 Beretta "SS" - 220hp 3400 MPFI / HM282 5spd
    94 Silverado Z71 - 300hp Vortec 357 TBI / NV4500 5spd build thread

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    Re: GM OBDI + FAST throttle body for carb to EFI conversion?

    Quote Originally Posted by woody80z28 View Post
    That I did not know...thanks for the heads up.

    It might not be worth it anyway though...one of the NastyZ28 guys with a lot of EFI retrofit experience is worried about the fuel distribution due to batch fire and TBI, so there would be rich cylinders and lean cylinders. The way he explained it is when the injectors fire, the first intake valve to open will suck in most of the fuel leaving little for a cylinder next to it. It does make sense...
    :facepalm:

    That's why TBI is such a bad thing. [sarcasim]

    Haw many carb or TBI equipped engines do you hear of having lean and rich cylinders?

    The injectors spray at every or every other DRP, depending on how you have it set up (every DRP might be best in this set-up), which means that the cylinder that is pulling in air is also pulling in fuel that is being injected at the same time......

  10. #30
    Registered User Jameslleary's Avatar
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    Re: GM OBDI + FAST throttle body for carb to EFI conversion?

    Quote Originally Posted by Six_Shooter View Post
    :facepalm:

    That's why TBI is such a bad thing. [sarcasim]

    Haw many carb or TBI equipped engines do you hear of having lean and rich cylinders?

    The injectors spray at every or every other DRP, depending on how you have it set up (every DRP might be best in this set-up), which means that the cylinder that is pulling in air is also pulling in fuel that is being injected at the same time......
    I think they fire 2 times, like TPI.
    1986 K10 Suburban
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    Re: GM OBDI + FAST throttle body for carb to EFI conversion?

    Depends how they are setup; can fire either in synch or asynch.


    90 454SS 496 TBI 12.43 @ 106 mph

    92 454SS Stock with WynJammer

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    GearheadDezign.com woody80z28's Avatar
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    Re: GM OBDI + FAST throttle body for carb to EFI conversion?

    He said the GM TBI atomizes the fuel more evenly because the injectors are above the throttle plates, and the FAST tb has the injectors below making batch fire an issue. What does DRP mean? I have not heard that terminology yet.

    Here is a link my buddy shared with me on NastyZ28: http://www.thirdgen.org/techboard/df...drive-4-a.html

    va454ss: I see you are running some numbers with your TBI! That's the same trap speed as my Camaro. Care to share your setup?
    80 Camaro Z28 - 550hp AFR 383 EFI / T56 6spd
    91 Beretta "SS" - 220hp 3400 MPFI / HM282 5spd
    94 Silverado Z71 - 300hp Vortec 357 TBI / NV4500 5spd build thread

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    Re: GM OBDI + FAST throttle body for carb to EFI conversion?

    Synch and asynch are something completely different than injector pulses per DRP, that I am talking about. TBI generally fires every DRP, MPFI is generally every other DRP.

    Synch is when the injectors fire at the same time as a DRP, asynch is when the injectors are fired every 11.5 (IIRC) ms apart.

    DRP = Distributer Reference Pulse.

    If the fuel pressures were tha same between the TBI and the above pictured throttle body, I would agree that TBI would have better atomization, but since the MPFI type injectors would use a pressure that is 3 to 4 times that of the TBI injector and have nozzles designed to atomize the fuel very nicely I just don't even consider it an issue.

    Actually the more I think about it, just being below the throttle plates and in a vacuum would help with atomozation...

    Your buddy is thinking about it too hard, and coming up with things just don't seem to ever have been a problem.

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    Re: GM OBDI + FAST throttle body for carb to EFI conversion?

    Quote Originally Posted by woody80z28 View Post
    va454ss: I see you are running some numbers with your TBI! That's the same trap speed as my Camaro. Care to share your setup?
    496, 10.75 CR, ported Vortec heads, Hedman headers, single plane intake, ported TB, custom ground hydraulic roller, EBL, 4.10's, TH400 w/9.5" vigilante converter...................

    Tune is still off a bit. Went 7.81 in the 1/8 mile, so that's 12.20's in the 1/4...........


    90 454SS 496 TBI 12.43 @ 106 mph

    92 454SS Stock with WynJammer

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    GearheadDezign.com woody80z28's Avatar
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    Re: GM OBDI + FAST throttle body for carb to EFI conversion?

    Quote Originally Posted by va454ss View Post
    496, 10.75 CR, ported Vortec heads, Hedman headers, single plane intake, ported TB, custom ground hydraulic roller, EBL, 4.10's, TH400 w/9.5" vigilante converter...................

    Tune is still off a bit. Went 7.81 in the 1/8 mile, so that's 12.20's in the 1/4...........
    Well I've got a dual plane and less cubes...but I'm interested in your throttle body. It's got to flow pretty well for low 12s in a heavy-ass truck!
    80 Camaro Z28 - 550hp AFR 383 EFI / T56 6spd
    91 Beretta "SS" - 220hp 3400 MPFI / HM282 5spd
    94 Silverado Z71 - 300hp Vortec 357 TBI / NV4500 5spd build thread

  16. #36
    GearheadDezign.com woody80z28's Avatar
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    Re: GM OBDI + FAST throttle body for carb to EFI conversion?

    Quote Originally Posted by va454ss View Post
    496, 10.75 CR, ported Vortec heads, Hedman headers, single plane intake, ported TB, custom ground hydraulic roller, EBL, 4.10's, TH400 w/9.5" vigilante converter...................

    Tune is still off a bit. Went 7.81 in the 1/8 mile, so that's 12.20's in the 1/4...........
    Well I've got a dual plane and less cubes...but I'm interested in your throttle body. It's got to flow pretty well for low 12s in a heavy-ass truck!
    80 Camaro Z28 - 550hp AFR 383 EFI / T56 6spd
    91 Beretta "SS" - 220hp 3400 MPFI / HM282 5spd
    94 Silverado Z71 - 300hp Vortec 357 TBI / NV4500 5spd build thread

  17. #37
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    Re: GM OBDI + FAST throttle body for carb to EFI conversion?

    Quote Originally Posted by woody80z28 View Post
    Well I've got a dual plane and less cubes...but I'm interested in your throttle body. It's got to flow pretty well for low 12s in a heavy-ass truck!
    Its been bored and sleeved to 2.2", stock is 2.0". The guy that did the mod for me no longer does em. Got tired of people complaining about the price


    90 454SS 496 TBI 12.43 @ 106 mph

    92 454SS Stock with WynJammer

  18. #38
    GearheadDezign.com woody80z28's Avatar
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    Re: GM OBDI + FAST throttle body for carb to EFI conversion?

    Bet ya it was cheaper than the FAST unit though... haha
    80 Camaro Z28 - 550hp AFR 383 EFI / T56 6spd
    91 Beretta "SS" - 220hp 3400 MPFI / HM282 5spd
    94 Silverado Z71 - 300hp Vortec 357 TBI / NV4500 5spd build thread

 

 
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