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Thread: Vortec Heads, Tbi tuning questions

  1. #1
    Carb and Points!
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    Vortec Heads, Tbi tuning questions

    Have a 95 C1500 that has a tired old 305 in it, going to be putting a Vortec 350 out of a 97 into it mated to the NV3500. For now everything will stay basically stock, stock exhaust manifolds (for now), stock cam, unbored throttle body. The only modifications will be the Jegs Intake Manifold, Holley TBI Adapter, and Vortec fuel pump. I also have an 18psi Spring in the throttle body as well as the typical pod spacer and Hypertech Bowl. I originally was going to go with TBIChips, but after reading numerous complaints, and reading more in depth articles on this site, I decided not to. My question is; what is the most cost effective way to tune this setup, should I attempt to do it myself, or should I find a dyno in my state (AZ) that has experience tuning this trucks? It will be a daily driver so I want to make sure it runs as close to 100% as possible.

    I appreciate any help and feedback.

  2. #2
    Super Moderator dave w's Avatar
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    One option is the Moates.net Ostrich 2.0 combined with a G1 adapter board. The Ostrich 2.0 is an Emulator, so you can "Flash" even when the engine is running. The emulator is flashed with a USB connected to a Laptop. The emulator can be flashed with TunerPro RT software.

    dave w
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  3. #3
    Carb and Points!
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    Is there already a set of basemaps for this setup, due to it being so common?

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    Super Moderator dave w's Avatar
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    Quote Originally Posted by TheMrFlippers View Post
    Is there already a set of basemaps for this setup, due to it being so common?
    I think the base maps available, like the ones offered from the various aftermarket chip companies, will not perform as well a custom tuned chip. Myself and other gearhead-efi members have been able to achieve optimal performance using TunerPro RT to "Tune" a chip. Myself and other gearhead-efi members have reached the conclusion, there is not a one size fits all base map for "common" engine modifications.

    dave w

  5. #5
    Fuel Injected!
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    I thought there may be a way to shortcut things too so I downloaded a few vortec bins I found one here. Most of them had mistakes, none where even close to what I have now. I do not know it all either, that's one thing I tried to do with mine is actually test things to see if the results were what I thought they should be. Some settings I ended up setting back to stock with no ill effects. Its surprising how little was changed with the 1996 tbi vans that had vortec heads. I borrowed a few things from that bin but not a lot. My fuel table shape ended up being very different than factory. The table after about 4400 is just pulled out and not developed as I never run it past that anyway. Check your pressure, the "18 psi" spring I got from ebay ended up being a lot higher without adjustment. I screwed the adjuster out and ended up with 19.5 lbs. I am pretty sure that spring can be had from Mcmaster carr for a lot less money than I paid. One thing others do not talk about is the plenum volume a carburetor manifold has over the tbi intake. I keep finding the GM TBI vortec manifolds used and cheap, as no one in this area wants to mess with TBI anymore. I think the smaller plenum volume is one reason I did not need near the AE increase that others talk about here. Replace your o2 with a new one before you start tuning, they are cheap. I got a new old stock AC delco for a few dollars on ebay. An old sensor with thousands of miles will not respond as well as a fresh sensor.

    Last edited by donf; 04-15-2019 at 07:59 PM.

  6. #6
    Fuel Injected!
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    Quote Originally Posted by donf View Post
    I thought there may be a way to shortcut things too so I downloaded a few vortec bins I found one here. Most of them had mistakes, none where even close to what I have now. I do not know it all either, that's one thing I tried to do with mine is actually test things to see if the results were what I thought they should be. Some settings I ended up setting back to stock with no ill effects. Its surprising how little was changed with the 1996 tbi vans that had vortec heads. I borrowed a few things from that bin but not a lot. My fuel table shape ended up being very different than factory. The table after about 4400 is just pulled out and not developed as I never run it past that anyway. Check your pressure, the "18 psi" spring I got from ebay ended up being a lot higher without adjustment. I screwed the adjuster out and ended up with 19.5 lbs. I am pretty sure that spring can be had from Mcmaster carr for a lot less money than I paid. One thing others do not talk about is the plenum volume a carburetor manifold has over the tbi intake. I keep finding the GM TBI vortec manifolds used and cheap, as no one in this area wants to mess with TBI anymore. I think the smaller plenum volume is one reason I did not need near the AE increase that others talk about here. Replace your o2 with a new one before you start tuning, they are cheap. I got a new old stock AC delco for a few dollars on ebay. An old sensor with thousands of miles will not respond as well as a fresh sensor.

    You are also not moving nearly as much air through your engines as some of us that needed the huge AE increase. My Vortec 350 had ported heads with 2.05/1.6 valves, a healthy roller cam, headers and a single plane intake. It was in making 356 RWHP and ran a 14.1 @ 101 in the 1/4 with a stock 1,600 rpm converter and 3.08s in my 1983 G20 Van.

  7. #7
    Fuel Injected! woody80z28's Avatar
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    Not sure if that manifold has a spreadbore pattern, but I went from the thin adapter plate to the BBC adapter with coolant running through it for better cold weather driveability.

    For the actual tuning, I went the Autoprom route with a wideband.
    80 Camaro Z28 - 550hp AFR 383 / T56 6spd (Holley HP EFI)
    91 Beretta "SS" - 260hp 3400 MPFI / HM282 5spd (7730/$A1)
    94 Silverado Z71 - 300hp Vortec 357 TBI / NV4500 5spd (7427/$0D)

  8. #8
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    Quote Originally Posted by woody80z28 View Post
    Not sure if that manifold has a spreadbore pattern, but I went from the thin adapter plate to the BBC adapter with coolant running through it for better cold weather driveability.

    For the actual tuning, I went the Autoprom route with a wideband.
    I had a water heated Holley Peojection 2" bore carb to TBI adapter on my 2bbl Victor Jr Vortec intake.

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