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Thread: 4.3 tbi w/ CPI heads??

  1. #1
    [IMG]http://i577.photobuc S-10 Hawaii's Avatar
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    4.3 tbi w/ CPI heads??

    I been tryin to find the answer but there's jus to much people saying it will and won't work.. But can I throw sum CPI heads On and use my tbi manifold.. I bored out my tbi and response is beautiful..the CPI heads are free from a parts blazer down the road from my house.. I read they might flow better than the stock tbi heads?

  2. #2
    Omaha Stylie!! 87SBLAZER's Avatar
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    if your gonna go through the trouble jus take the tbi heads and port them? i have no clue if they would swap tho..lol

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    [IMG]http://i577.photobuc S-10 Hawaii's Avatar
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    Thanks for the advise but it's also my dayley driver..

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    Omaha Stylie!! 87SBLAZER's Avatar
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    or you should jus go ahead a build a smallblock..deff worth the time and money

  5. #5
    Blazin no mo Forklift's Avatar
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    If I had a 4.3 TBI, Id much rather just swap in a 350 with the 4.3 electronics and bigger injectors. All it would take is the engine, a tbi intake or adapter plate, extending 2 wires, the headers, and motor mounts, thats it. You looking at a weekend at most
    04 EC Silverado 4.8L,Pioneer, Rockford Fosgate, K&N, Viper, ACT, USSpeedo, Matrix, Whelen, Blackbear, 22" Eagles, Nittos,Russel,Magnaflow
    85 S-15 2.5L/4spd, RF P1 subs, highs & T4004, JL 250/1, SD 4-link, AIM LCAs, 1/2 valves, Blazer interior, 17" Eagles w/BFGs, phantom grill, 140 amp alt

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    [IMG]http://i577.photobuc S-10 Hawaii's Avatar
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    I like the advise guys, don't get me wrong I love my v8s but my question never got answered yet.. I wana build my 4.3.. I love beating on hondas and cookin rice..

  7. #7
    Zombie Killer 6SpeedBlazer's Avatar
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    cpi heads are a great upgrade to a tbi motor.

    cpi heads flow a LOT better than the stock tbi LB4 heads. it will still allow you to use the stock intake and retain all emission equipment.

    i say go for it. I had cpi heads and a cam in my old 4.3 and it was quick.

  8. #8
    Blazin no mo Forklift's Avatar
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    oh yeah, I loved beating up on Mustangs and rice with my 4.3 CPI Blazer. Nothing like popping the hood on a full bodied S-10 Blazer and having the Mustang GT guy's jaw drop to see a V-6
    04 EC Silverado 4.8L,Pioneer, Rockford Fosgate, K&N, Viper, ACT, USSpeedo, Matrix, Whelen, Blackbear, 22" Eagles, Nittos,Russel,Magnaflow
    85 S-15 2.5L/4spd, RF P1 subs, highs & T4004, JL 250/1, SD 4-link, AIM LCAs, 1/2 valves, Blazer interior, 17" Eagles w/BFGs, phantom grill, 140 amp alt

  9. #9
    [IMG]http://i577.photobuc S-10 Hawaii's Avatar
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    Thanks for the info.. The heads are free.. Ima get them after work today.. And try port them out a little.. Then throw um on when I got a day off.. I love my v6.. Little power house.. I love goin down to the steer races and smokin all them F-in fart cars.. We got alot of um in Hawaii., the other day I soaked a v8 Titan.. Old boy was all sour.. Lol

  10. #10
    Zombie Killer 6SpeedBlazer's Avatar
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    Quote Originally Posted by S-10 Hawaii View Post
    Thanks for the info.. The heads are free.. Ima get them after work today.. And try port them out a little.. Then throw um on when I got a day off.. I love my v6.. Little power house.. I love goin down to the steer races and smokin all them F-in fart cars.. We got alot of um in Hawaii., the other day I soaked a v8 Titan.. Old boy was all sour.. Lol
    my 4.3 had a small cam, cpi heads and long tubes with full exhaust.

    on a stock tune with junk tires i ran a 15.6

    on slicks and a good tune it would have been a 14 second truck

  11. #11
    Blazin no mo Forklift's Avatar
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    my 94 2-door with the 4.3 and a few goodies ran a 14.77, stock cam, stock heads all that, stuff like headers, shift kit, tube intake, chip, etc
    04 EC Silverado 4.8L,Pioneer, Rockford Fosgate, K&N, Viper, ACT, USSpeedo, Matrix, Whelen, Blackbear, 22" Eagles, Nittos,Russel,Magnaflow
    85 S-15 2.5L/4spd, RF P1 subs, highs & T4004, JL 250/1, SD 4-link, AIM LCAs, 1/2 valves, Blazer interior, 17" Eagles w/BFGs, phantom grill, 140 amp alt

  12. #12
    [IMG]http://i577.photobuc S-10 Hawaii's Avatar
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    I pulled the heads off that CPI motor.. Was wandering how much more flow is it compared to the LB4 heads??.. Also was wondering If I could port these out myself?..

  13. #13
    Blazin no mo Forklift's Avatar
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    maybe do the gasket matching yourself and maybe smooth out the inside of the combustion chambers, but Id leave the rest to the pros
    04 EC Silverado 4.8L,Pioneer, Rockford Fosgate, K&N, Viper, ACT, USSpeedo, Matrix, Whelen, Blackbear, 22" Eagles, Nittos,Russel,Magnaflow
    85 S-15 2.5L/4spd, RF P1 subs, highs & T4004, JL 250/1, SD 4-link, AIM LCAs, 1/2 valves, Blazer interior, 17" Eagles w/BFGs, phantom grill, 140 amp alt

  14. #14
    Zombie Killer 6SpeedBlazer's Avatar
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    Well I finally got around to testing out my old pair of pocket ported CPI heads verses the pocket ported 96 Vortec heads that I just got done with.

    Here are the results


    Stock 1996 vortec head flow
    28” of water

    Lift Intake Exhaust
    .050 31.7 25.4
    .100 63.6 52.1
    .200 127.9 96.8
    .300 179.4 130.9
    .400 223.2 147.5
    .500 227.7 156.3


    Pocket Ported 1996 Vortec heads
    Stock valve size, performance valves and 3 angle valve job
    28” of water

    Lift Intake Exhaust
    .050 33.2 27.1
    .100 65.7 54.9
    .200 133.4 102.9
    .300 181.7 137.7
    .400 224.6 155.0
    .500 246.3 180.9


    Pocket Ported 1992 L35 (CPI) heads
    Stock valve size, performance valves and multi angle valve job
    28” of water

    Lift Intake Exhaust
    .050 31.9 24.4
    .100 63.9 50.6
    .200 126.1 95.1
    .300 175.7 120.5
    .400 204.8 137.2
    .500 221.3 148.6

    Here is a last minute update!!

    I have done alittle more port work on the 1996 vortec heads. I also deshrouded the valves alittle bit which helped the airflow in the upper lift range.

    Now the final airflow is 268.7 CFM intake and 203.1 CFM exhaust. The deshrouding also oped up the combustion chambers to 69CC.... and in my application that helped out alot.

    cut the cpi numers by about 25% and you have tbi numbers.

  15. #15
    [IMG]http://i577.photobuc S-10 Hawaii's Avatar
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    I talk to my mechanic friend that works next door to me and he said not to go overboard on soupin my motor because of the computer.. If I put the potted CPI heads on my truck, will the stock tune be okay.. Or will I have to get a chip or a programer?.. Don't wana skrew some shit upp

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