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TPI Injectors, what ones to go with?

Discussion in 'The Garage' started by sled_dog, May 1, 2005.

  1. sled_dog

    sled_dog 1 ton status

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    On a 383. ANyone have a chart of the different injectors and their flow ratings? Namely, stock TPI, Stock LT1, some of these aftermarket ones. I see some on Ebay really cheap I think they are 27lbs injectors. There are 60lbs ones for quite a bit, but I'm pretty certain I'd be drowning my motor on that.
     
  2. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    Depending on what mods you have done such as hotter cam and aftermarket heads and headers depends on what injectors you get but for a 383 i would go with 24 lb. hr.

    I used 24 lb/hr. in my 383 with a hotter cam and AFR heads with headers and they were perfect. Also use an adjustable fuel pressure regulator and adjust it to about 47 PSI for a 383.
     
  3. r_pogo

    r_pogo Registered Member

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    Fuel Injectors

    I remember way back when L98s were the thing (I have a 87 vette).

    Dyno tests at TPI Specialities showed that using 302 injectors at higher pressures would consistantly produce more power on modestly cammed street engines including 406s up to about 360 HP.The stock 350 TPI induction system seems to be air flow limited (air filter, mass flow sensor, throttle body, intake maniforld etc), not lmited by fuel delivery.

    In short, with most of the stick setup you will run out of air before the injectors run out of fuel. TPIS also suggested that the 302 injectors at higher pressure had better atomization and thus the better combustion properties. I wonder if they also might produce a bit better gas mileage. Anyway it appears that bigger injectors might not do as well at metering and atomization, particularly at shorter pulse widths such as those at cruise speeds where gas at $2.50/gal gets important.

    If you have a high flow air filter, screens out of the mass flow sensor, bigger throttle body, and maybe bigger manifold and tubes and are pushing 6,000 RPM with a hotter cam you will need bigger injectors to get the last bit of performance. If not, consider tinkering with the pressure on the stock injectors and see how it pulls. If it goes "flat" at higher RPMS could be either air or fuel -- a dyno check monitoring the injector pulse-width tells the tale.
     
  4. sled_dog

    sled_dog 1 ton status

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    Plan is an LT1 intake with bigger throttle body, little intake restriction. So some slightly larger injectors may be a good idea.
     
  5. dave_90_blazer

    dave_90_blazer 1/2 ton status

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    stock 305 TPI is 19#, stock 350 TPI is 22#, stock 92-93 LT1 is 22#, stock 94+LT1 is 24#
     
  6. dyeager535

    dyeager535 1 ton status Premium Member

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    SVO injectors can be had for a bit over $200 for a set of 8. Pretty hard to beat these with anything else.

    SVO injectors are rated at a different fuel pressure, so have to modify the injector constant in the PROM. You know you'll be into the PROM anyway, so that shouldn't be a big issue.

    Something like this though, I'd wait until you were absolutely in need of before purchase, so you don't end up changing your mind or finding out you need something different and have brand new injectors that you can't/won't use.
     

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